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Selected Papers from the NMJ2018
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Selected Papers from the NMJ2018

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Optics and Lasers".

Deadline for manuscript submissions: closed (1 January 2019) | Viewed by 103870

Special Issue Editors

Dr. Anming Hu

E-Mail Website
Guest Editor
Department of Mechanical Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, TN 37996, USA
Interests: nanomaterials; metals; smart materials; materials for environment and energy; light sensitive materials; biomass materials; materials for welding and joinning
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Jolanta Janczak-Rusch

E-Mail Website
Guest Editor
Überlandstrasse 129, Laboratory for Joining Technologies and Corrosion, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
Interests: micro- and nano-joining; soldering; brazing and diffusion bonding; new joining materials and technologies; nano-multilayers; composite materials
Prof. Dr. Tomokazu Sano

E-Mail Website
Guest Editor
Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, Osaka 565-0871, Japan
Interests: laser nano-micro-macro-processing; laser nano/micro-joining; laser-matter interaction
Dr. Peng Peng

E-Mail Website
Guest Editor
Department of Materials Processing and Control Engineering, School of Mechanical Engineering and Automation, International Research Institute for Multidisciplinary Science, Beihang University, Beijing 100191, China
Interests: micro/nano-joining and manufacturing; laser sintering; low temperature packaging for electronics; nanoengineering for water treatment

Special Issue Information

Dear Colleagues:

After the successful conferences in Niagara Falls, Canada in 2016 (NMJ2016), Emmetten, Switzerland in 2014 (NMJ2014) and Beijing, China in 2012 (NMJ2012), it is our pleasure to invite you to the 4th International Conference on Nanojoining and Microjoining (NMJ2018), which will be held in Nara, Japan on December 2–5, 2018. The conference provides a platform for scientific and industrial discussion and exchange in the emerging fields of nano and micro joining technologies, as follows:

  • Joining for integration of nano-/micro-scale materials and devices
  • Micro joining for assembly of implantable medical devices
  • Method development for nano/micro joint characterization
  • Mechanisms and materials science of nano-/micro joining
  • Process issues in nano/micro joining

The main goal of this special issue, “special issue of NMJ2018”, is to advance the new science and technology in the fields of e.g. micro-electronics, medical implants, sensing devices and packaging, which have an urgent need for advanced joining technologies to integrate, package and assemble nano- and micro-scale materials and components at ever-low temperatures. In the micro-devices and micro-systems, innovative microjoining are still needed to allow faster and more reliable fabrication and long life services. In the field of nanojoining, printed electronics, wearable and flexible electronics, 3D printing at nanoscale resolution and molecular electronics are the emergent applications in the coming decades. We invite investigators interested in nano- and microjoining innovation to contribute to this issue with 400CHF publication discount, the topics will cover all fields of NMJ2018.

Dr. Anming Hu
Prof. Dr. Jolanta Janczak-Rusch
Dr. Sano Tomokazu
Dr. Peng Peng
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Nanojoining Microjoining Interfacial diffusions for micro- and nanojoining
  • Micro- and nanoscopic additive manufacturing
  • nano-/micro-scale materials
  • nano-/micro-scale devices
  • implantable medical devices
  • nano/micro joint characterization

Published Papers (28 papers)

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Editorial

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9 pages, 768 KiB  
Editorial
Joining Technology Innovations at the Macro, Micro, and Nano Levels
by Anming Hu, Jolanta Janczak-Rusch and Tomokazu Sano
Appl. Sci. 2019, 9(17), 3568; https://doi.org/10.3390/app9173568 - 01 Sep 2019
Cited by 17 | Viewed by 3212
Abstract
With the growing joining requirements of emergent engineering materials and new applications, conventional welding continues to evolve at all scales spanning from the macro- down to the micro- and nanoscale. This mini review provides a comprehensive summary of the research hot spots in [...] Read more.
With the growing joining requirements of emergent engineering materials and new applications, conventional welding continues to evolve at all scales spanning from the macro- down to the micro- and nanoscale. This mini review provides a comprehensive summary of the research hot spots in this field, which includes but is not limited to selected papers from the international nanojoining and microjoining conference (NMJ) held in Nara, Japan on 1–4 December 2018. These innovations include the integration of nanotechnology, ultrafast laser, advanced manufacturing, and in situ real-time ultra-precision characterization into joining processes. This special issue may provide a relatively full picture of the state-of-the-art research progress, fundamental understanding, and promising application of modern joining technologies. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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Research

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11 pages, 3254 KiB  
Article
Processing of Single-Walled Carbon Nanotubes with Femtosecond Laser Pulses
by Zeyad Almutairi, Kaleem Ahmad, Mosaad Alanazi and Abdulaziz Alhazaa
Appl. Sci. 2019, 9(19), 4022; https://doi.org/10.3390/app9194022 - 26 Sep 2019
Cited by 1 | Viewed by 2875
Abstract
There are continued efforts to process and join single wall carbon nanotubes (SWCNTs) in order to exploit their exceptional functional properties for real-world applications. In this work, we report experimental observations of femtosecond laser irradiation on SWCNTs, in order to process and join [...] Read more.
There are continued efforts to process and join single wall carbon nanotubes (SWCNTs) in order to exploit their exceptional functional properties for real-world applications. In this work, we report experimental observations of femtosecond laser irradiation on SWCNTs, in order to process and join them through an efficient and cost-effective technique. The nanotubes were deagglomerated in ethanol by an ultrasonicator and thin slurries of SWCNTs were spread evenly on glass substrates. A laser micromachining workstation for laboratory FemtoLAB (workshop of photonics) has been employed to irradiate the different SWCNTs film samples. The effect of laser parameters, such as pulse wavelength, laser power, etc., were systematically tuned to see the possibility of joining the SWCNTs ropes. Several experiments have been performed to optimize the parameters on different samples of SWCNTs. In general, the nanotubes were mostly damaged by the infrared (1st harmonics femtosecond laser) irradiation on the focal plane. However, the less damaging effect was observed for second harmonics (green wavelength) irradiation. The results suggest some joining of nanotubes along the sides of the focus plane, as well as on the center at the brink of nanotubes. The joining is considered to be established within the region of the high field intensity of the exposed femtosecond laser beam. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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8 pages, 7625 KiB  
Article
Erosion Resistance Properties of Iron–Carbon Composite Plating to Molten Lead-Free Solder
by Jun Watanabe, Kenji Hatsuzawa, Shigeyuki Ogata, Shinichi Yoshida and Ikuo Shohji
Appl. Sci. 2019, 9(13), 2724; https://doi.org/10.3390/app9132724 - 05 Jul 2019
Cited by 2 | Viewed by 2717
Abstract
The use of Sn-3mass%Ag-0.5mass%Cu lead-free solder (SAC305) has become common. Since SAC305 has a higher content of tin than conventional tin–lead eutectic solder, erosion of the Fe plating layer used in the solder iron tip and the point soldering machine nozzle frequently occurs. [...] Read more.
The use of Sn-3mass%Ag-0.5mass%Cu lead-free solder (SAC305) has become common. Since SAC305 has a higher content of tin than conventional tin–lead eutectic solder, erosion of the Fe plating layer used in the solder iron tip and the point soldering machine nozzle frequently occurs. In this study, to prolong the life of the Fe plating layer, the applicability of composite plating in which a carbon-type filler is compounded with Fe was studied. Graphite and a multi-walled carbon nanotube (MWCNT) were used as filler materials in the composite plating layer. For both Fe-graphite and Fe-MWCNT composite plating layers, solderability testing and erosion-resistance testing were carried out. In the solderability test, although the spread rates of SAC305 to both Fe-graphite and Fe-MWCNT plating layers slightly decreased compared to the Fe plating layer, SAC305 solder was not repelled against both plating layers. In the erosion-resistance test, the Fe-MWCNT composite plating layer performed the best with the least erosion depth. The erosion depth of the Fe-graphite composite plating layer and the Fe plating layer were 10 and 100 times larger than that of the Fe-MWCNT composite plating layer, respectively. It was confirmed that the diffusion of Fe into molten SAC305 could be greatly reduced due to the composing carbon filler in Fe. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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14 pages, 5231 KiB  
Article
In-Situ Observation of Adhesion Behavior During Ultrasonic Al Ribbon Bonding
by Yasuo Takahashi, Kazumasa Takashima, Kouta Misawa and Yusuke Takaoka
Appl. Sci. 2019, 9(9), 1835; https://doi.org/10.3390/app9091835 - 03 May 2019
Cited by 9 | Viewed by 3433
Abstract
In-situ observation was performed on a transparent silica substrate during ultrasonic Al ribbon bonding, using a high-speed video camera with differing frame rates, 104 fps and 103 fps, to clarify the adhesion behavior. The bonding process was observed as follows. Initially, [...] Read more.
In-situ observation was performed on a transparent silica substrate during ultrasonic Al ribbon bonding, using a high-speed video camera with differing frame rates, 104 fps and 103 fps, to clarify the adhesion behavior. The bonding process was observed as follows. Initially, friction slip occurred, producing multiple island streaks in the direction parallel to the ultrasonic vibration. The island streaks were formed as a scratch, due to surface waviness of the Al ribbon. Momentarily, a belt-shaped bond zone was formed at the center, normally due to the ultrasonic vibration. The island streaks could be clearly observed at 104 fps. However, the central belt zone was unclear and appeared translucent at 104 fps; although it was clear when observed at 103 fps. The island streaks were unclear at 103 fps. The positional relation of the island streaks and the central belt zone was confirmed from in-situ observation results of a twist and peel test of Al ribbon bonded to silica substrate. The central belt zone was between the island streaks and the silica substrate. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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10 pages, 2095 KiB  
Article
Thermal Fatigue Properties of Ultrasonically Bonded Copper Joints
by Takahito Fushimi, Yo Tanaka, Shinnosuke Soda, Tomoki Matsuda, Tomokazu Sano and Akio Hirose
Appl. Sci. 2019, 9(8), 1556; https://doi.org/10.3390/app9081556 - 15 Apr 2019
Cited by 3 | Viewed by 2288
Abstract
Thermal fatigue generally occurs in ultrasonically bonded copper joints in electronic devices as the bonding substrate is composed of plural materials, leading to differences in the coefficient of thermal expansion. In this study, we found that the thermal fatigue resistance of the ultrasonically [...] Read more.
Thermal fatigue generally occurs in ultrasonically bonded copper joints in electronic devices as the bonding substrate is composed of plural materials, leading to differences in the coefficient of thermal expansion. In this study, we found that the thermal fatigue resistance of the ultrasonically bonded copper joints was influenced by the grain size and hardness of the bonding substrate through the evaluation of the thermal fatigue properties. Copper alloys C1020 and C1940 were used as substrate materials to investigate the influence of the initial properties of the bonding material on the thermal fatigue resistance. We evaluated the crack propagation due to thermal fatigue via thermal cycle tests. Microstructural observations of the region fractured because of thermal fatigue revealed that cracks resulting from thermal fatigue did not progress in the fine grain region formed at the bonded interface. It was inferred that grain boundaries were an obstacle to crack propagation. C1940 has higher hardness and finer grains than C1020, and showed a lower decreasing rate of the peel strength and bonding area after the thermal cycling test than C1020 joints. Thus, a hard copper material with fine grains is effective in suppressing thermal fatigue fracture of ultrasonically bonded copper joints. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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9 pages, 2396 KiB  
Article
Acquisition of Multi-Modal Images of Structural Modifications in Glass with Programmable LED-Array-Based Illumination
by Ryo Sugimoto, Ryoji Maruyama and Wataru Watanabe
Appl. Sci. 2019, 9(6), 1136; https://doi.org/10.3390/app9061136 - 18 Mar 2019
Cited by 3 | Viewed by 2479
Abstract
Ultrashort laser pulses can induce structural modifications in bulk glass, leading to refractive index change and scattering damage. As bright-field, dark-field, and phase imaging each provide complementary information about laser-induced structures, it is often desired to use multiple observations simultaneously. As described herein, [...] Read more.
Ultrashort laser pulses can induce structural modifications in bulk glass, leading to refractive index change and scattering damage. As bright-field, dark-field, and phase imaging each provide complementary information about laser-induced structures, it is often desired to use multiple observations simultaneously. As described herein, we present the acquisition of bright-field, dark-field, and differential phase-contrast images of structural modifications induced in glass by femtosecond laser pulses with an LED array microscope. The contrast of refractive index change can be enhanced by differential phase-contrast images. We also report on the simultaneous acquisition of bright-field and dark-field images of structural modifications in a glass with LED-array-based Rheinberg illumination. A single-shot color image is separated to obtain bright field and dark field images simultaneously. We provide an experimental demonstration on multi-modal imaging of structural modifications in a glass with an LED array microscope using temporally-coded illumination and color-coded illumination. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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17 pages, 17217 KiB  
Article
Microstructural Investigations of Low Temperature Joining of Q&P Steels Using Ag Nanoparticles in Combination with Sn and SnAg as Activating Material
by Susann Hausner, Martin Franz-Xaver Wagner and Guntram Wagner
Appl. Sci. 2019, 9(3), 539; https://doi.org/10.3390/app9030539 - 06 Feb 2019
Cited by 2 | Viewed by 2961
Abstract
Quenching and partitioning (Q&P) steels show a good balance between strength and ductility due to a special heat treatment that allows to adjust a microstructure of martensite with a fraction of stabilized retained austenite. The final heat treatment step is performed at low [...] Read more.
Quenching and partitioning (Q&P) steels show a good balance between strength and ductility due to a special heat treatment that allows to adjust a microstructure of martensite with a fraction of stabilized retained austenite. The final heat treatment step is performed at low temperatures. Therefore, joining of Q&P steels is a big challenge. On the one hand, a low joining temperature is necessary in order not to influence the adjusted microstructure; on the other hand, high joint strengths are required. In this study, joining of Q&P steels with Ag nanoparticles is investigated. Due to the nano-effect, high-strength and temperature-resistant joints can be produced at low temperatures with nanoparticles, which meets the contradictory requirements for joining of Q&P steels. In addition to the Ag nanoparticles, activating materials (SnAg and Sn) are used at the interface to achieve an improved bonding to the steel substrate. The results show that the activating materials play an important role in the successful formation of joints. Only with the activating materials, can joints be produced. Due to the low joining temperature (max. 237 °C), the microstructure of the Q&P steel is hardly influenced. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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10 pages, 7463 KiB  
Article
Microstructure of Joint between Stranded Wire and Substrate Welded by Ultrasonic Welding
by Chihiro Iwamoto, Keisuke Yamauchi, Kazuki Motomura, Yoichi Hashimoto and Kensuke Hamada
Appl. Sci. 2019, 9(3), 534; https://doi.org/10.3390/app9030534 - 05 Feb 2019
Cited by 9 | Viewed by 3902
Abstract
In order to improvement electronic and mechanical properties, welding between stranded wires and terminals is important. However, welding methods to obtain high-quality joints using stranded wires are still limited. In this report, we applied ultrasonic welding to join a Cu stranded wire to [...] Read more.
In order to improvement electronic and mechanical properties, welding between stranded wires and terminals is important. However, welding methods to obtain high-quality joints using stranded wires are still limited. In this report, we applied ultrasonic welding to join a Cu stranded wire to a Cu substrate. Cross-sections of the weldments were taken and observed by several microscopy techniques to elucidate the weldability and soundness of the joints. After ultrasonic welding, each wire in the stranded wire was joined together at the region where the stranded wire was joined to the substrate without any defect. Each wire was welded through the Ag coating layer, and the stranded wire and the substrate was also welded through the outermost coating layers. It was found that ultrasonic welding is an efficient technique for producing high quality joints without any defect at the interface. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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10 pages, 3695 KiB  
Article
Transient Liquid Phase Bonding of Copper Using Sn Coated Cu MWCNT Composite Powders for Power Electronics
by Sri Harini Rajendran, Jung Do Hyun, Jeon Wook Sang and Jung Jae Pil
Appl. Sci. 2019, 9(3), 529; https://doi.org/10.3390/app9030529 - 04 Feb 2019
Cited by 8 | Viewed by 4032
Abstract
In this paper, a novel transient liquid phase bonding material was fabricated by consequent electroless plating of Cu and Sn on a multi-walled carbon nanotube (MWCNT). The resulting Sn-Cu-MWCNT composites were used to join the Cu interconnects at 260°C. After 8 min of [...] Read more.
In this paper, a novel transient liquid phase bonding material was fabricated by consequent electroless plating of Cu and Sn on a multi-walled carbon nanotube (MWCNT). The resulting Sn-Cu-MWCNT composites were used to join the Cu interconnects at 260°C. After 8 min of reflow time, a complete transformation of Cu3Sn intermetallic compound (IMC) occurred, leaving a Cu/MWCNT-Cu3Sn /Cu joint capable of withstanding the high operating temperature. Due to flake-like morphology, the Sn-Cu-MWCNT composite particles were well packed with lesser voids. The shear strength of the Cu/Cu3Sn-MWCNT/Cu joint was measured as 35.3 MPa, thus exhibiting the scope for replacing conventional transient liquid phase (TLP) powders in the future. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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10 pages, 1159 KiB  
Article
Femtosecond Laser Irradiation of Carbon Nanotubes to Metal Electrodes
by Jianlei Cui, Yang Cheng, Jianwei Zhang, Huanhuan Mei and Xuewen Wang
Appl. Sci. 2019, 9(3), 476; https://doi.org/10.3390/app9030476 - 30 Jan 2019
Cited by 43 | Viewed by 3507
Abstract
Carbon nanotubes (CNTs) have excellent performance, which means that they could be better electrical conductors. However, the problem of the connection of CNTs to electrodes limits their application. Particularly, improving connection efficiency while ensuring the quality of the connection is a big challenge, [...] Read more.
Carbon nanotubes (CNTs) have excellent performance, which means that they could be better electrical conductors. However, the problem of the connection of CNTs to electrodes limits their application. Particularly, improving connection efficiency while ensuring the quality of the connection is a big challenge, because it is difficult to form Ohmic contact between CNTs and electrodes. To address this issue, we propose the use of a femtosecond laser to irradiate the contact surface between the CNTs and the electrodes to obtain a good connection quality and electrical performance. At the same time, since the laser-induced connection acts on all the contact surfaces in the irradiation area, the connection efficiency can be improved, which provides a new idea for the large-scale preparation of the connection. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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10 pages, 2059 KiB  
Article
Laser-Scribed Lossy Microstrip Lines for Radio Frequency Applications
by Ruozhou Li, Jing Yan, Yuming Fang, Xingye Fan, Linkun Sheng, Daye Ding, Xiaoxing Yin and Ying Yu
Appl. Sci. 2019, 9(3), 415; https://doi.org/10.3390/app9030415 - 26 Jan 2019
Cited by 16 | Viewed by 2971
Abstract
Laser-direct writing has become an alternative method to fabricate flexible electronics, whereas the resistive nature of laser-scribed conductors may distort the radio-frequency characteristics of circuits for high-frequency applications. We demonstrate that the transmission characteristics of microstrip lines are insensitive to the resistance of [...] Read more.
Laser-direct writing has become an alternative method to fabricate flexible electronics, whereas the resistive nature of laser-scribed conductors may distort the radio-frequency characteristics of circuits for high-frequency applications. We demonstrate that the transmission characteristics of microstrip lines are insensitive to the resistance of laser-scripted conductors when the sheet resistance is not above 0.32 Ω/□. On the other hand, the transmission and reflection characteristics of the MS lines can be simply modified through the accommodation of the resistance of the conductors, because a laser can trigger the sintering and melting of laser produced silver nanostructures. This could provide an alternative way to fabricate radio frequency (RF) resistors and promote their applications to flexible radio-frequency devices and systems. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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8 pages, 5276 KiB  
Article
Porosity Elimination in Modified Direct Laser Joining of Ti6Al4V and Thermoplastics Composites
by Haipeng Wang, Yang Chen, Zaoyang Guo and Yingchun Guan
Appl. Sci. 2019, 9(3), 411; https://doi.org/10.3390/app9030411 - 26 Jan 2019
Cited by 27 | Viewed by 3376
Abstract
Hybrid lightweight components with strong and reliable bonding qualities are necessary for practical applications including in the automotive and aerospace industries. The direct laser joining method has been used to produce hybrid joints of Ti6Al4V and glass fiber reinforced polyamide (PA66-GF30). Prior to [...] Read more.
Hybrid lightweight components with strong and reliable bonding qualities are necessary for practical applications including in the automotive and aerospace industries. The direct laser joining method has been used to produce hybrid joints of Ti6Al4V and glass fiber reinforced polyamide (PA66-GF30). Prior to the laser joining process, a surface texturing treatment is carried out on Ti6Al4V to improve joint strength through the formation of interlock structures between Ti6Al4V and PA66-GF30. In order to reduce the generated micro-pores in Ti6Al4V-PA66-GF30 joints, a modified laser joining method has been proposed. Results show that only very few small micro-pores are generated in the joints produced by the modified laser joining method, and the fracture strength of the joints is significantly increased from 13.8 MPa to 41.5 MPa due to the elimination of micro-pores in the joints. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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9 pages, 3427 KiB  
Article
Effect of Aging Treatment on Microstructural Evolution of Rapidly Solidified Eutectic Sn-Pb Alloy Powders
by Jianfeng Yan, Dezhi Zhu, Yingjie Liu and Jun Xu
Appl. Sci. 2019, 9(3), 392; https://doi.org/10.3390/app9030392 - 24 Jan 2019
Cited by 4 | Viewed by 6290
Abstract
The microstructural stability of rapidly solidified eutectic Sn–Pb alloy solder powders was investigated through aging at room temperature (25 °C) and temperatures of 40 °C–120 °C. The coarsening behavior of the Pb-rich phase both at room and elevated temperatures was observed. The evident [...] Read more.
The microstructural stability of rapidly solidified eutectic Sn–Pb alloy solder powders was investigated through aging at room temperature (25 °C) and temperatures of 40 °C–120 °C. The coarsening behavior of the Pb-rich phase both at room and elevated temperatures was observed. The evident coarsening of the Pb-rich phase was detected upon storage after 40 days. At elevated temperatures, a similar sequence of Pb-rich phase coarsening was observed; however, it occurred substantially more quickly. Pb-rich coarsening rate kinetics at different temperatures were estimated using the Arrhenius equation. The apparent activation energy was 45.53 ± 4.23 KJ/mol, which indicates that grain boundary diffusion is a crucial mass transport mechanism controlling Pb-rich phase coarsening under annealing. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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10 pages, 2900 KiB  
Article
Femtosecond Pulse Laser Near-Field Ablation of Ag Nanorods
by Dezhi Zhu and Jianfeng Yan
Appl. Sci. 2019, 9(3), 363; https://doi.org/10.3390/app9030363 - 22 Jan 2019
Cited by 4 | Viewed by 3039
Abstract
Ag nanorods (Ag NRs) with a mean aspect ratio of 3.9 were prepared through a wet-chemical method, and the absorption spectra for various aspect ratios were obtained. The morphology transformation of Ag NRs irradiated with a femtosecond pulse laser was investigated through transmission [...] Read more.
Ag nanorods (Ag NRs) with a mean aspect ratio of 3.9 were prepared through a wet-chemical method, and the absorption spectra for various aspect ratios were obtained. The morphology transformation of Ag NRs irradiated with a femtosecond pulse laser was investigated through transmission electron microscopy (TEM). The near-field ablation was dependent on the laser polarization and wavelength. Laser-induced high electric field intensity was observed at the ends, middle, and junctions of the Ag NRs under various ablation conditions. Through simulation, the evolution mechanism was analyzed in detail. The effect of laser polarization angle on plasmonic junction welding was also investigated. By controlling the electronic field distribution, several nanostructures were obtained: bone-shaped NRs, T-shaped NRs, dimers, trimers, curved NRs, and nanodots. This study suggests a potentially useful approach for the reshaping, cutting, and welding of nanostructures. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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11 pages, 7591 KiB  
Article
Joining of Carbon Fiber Reinforced Plastic to Aluminum Alloy by Reactive Multilayer Films and Low Power Semiconductor Laser Heating
by Ying Ma, Denzel Bridges, Yongchao Yu, Jitai Han, Hong Li and Anming Hu
Appl. Sci. 2019, 9(2), 319; https://doi.org/10.3390/app9020319 - 17 Jan 2019
Cited by 9 | Viewed by 4100
Abstract
This study investigated the characteristics and strength of the dissimilar joints between carbon fiber reinforced plastic (CFRP) epoxy composites and aluminum alloys using two different heating methods, Ni/Al reactive multilayer films (RMF) and a low power continuous wave diode laser. To enhance the [...] Read more.
This study investigated the characteristics and strength of the dissimilar joints between carbon fiber reinforced plastic (CFRP) epoxy composites and aluminum alloys using two different heating methods, Ni/Al reactive multilayer films (RMF) and a low power continuous wave diode laser. To enhance the adhesion, the top resin layer of the CFRP and the surface of the aluminum alloy were patterned by femtosecond laser. Polycarbonate (PC) was used as a filler material during the joining processes. ANSYS simulation was applied to elucidate the thermal kinetics of the self-propagation reaction and the thermal profile, and evaluate the possibility of joining CFRP to aluminum using Ni/Al RMFs. The SEM image of the cross-section shows that melted PC flowed into the CFRP–aluminum alloy interface, suggesting strong mechanical bonding. A tensile strength of 9.5 MPa was reached using Ni/Al multilayers as heat sources, which provides a new way for joining CFRPs and aluminum alloys in space or under water. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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11 pages, 2704 KiB  
Article
Joining with Reactive Nano-Multilayers: Influence of Thermal Properties of Components on Joint Microstructure and Mechanical Performance
by Bastian Rheingans, Irina Spies, Axel Schumacher, Stephan Knappmann, Roman Furrer, Lars P. H. Jeurgens and Jolanta Janczak-Rusch
Appl. Sci. 2019, 9(2), 262; https://doi.org/10.3390/app9020262 - 12 Jan 2019
Cited by 13 | Viewed by 3220
Abstract
Reactive nano-multilayers (RNMLs), which are able to undergo a self-heating exothermal reaction, can, e.g., be utilised as a local heat source for soldering or brazing. Upon joining with RNMLs, the heat produced by the exothermal reaction must be carefully adjusted to the joining [...] Read more.
Reactive nano-multilayers (RNMLs), which are able to undergo a self-heating exothermal reaction, can, e.g., be utilised as a local heat source for soldering or brazing. Upon joining with RNMLs, the heat produced by the exothermal reaction must be carefully adjusted to the joining system in order to provide sufficient heat for bond formation while avoiding damaging of the joining components by excessive heat. This heat balance strongly depends on the thermal properties of the joining components: a low thermal conductivity leads to heat concentration within the joining zone adjacent to the RNML, while a high thermal conductivity leads to fast heat dissipation into the components. The quality of the joint is thus co-determined by the thermal properties of the joining components. This work provides a systematic study on the influence of the thermal properties upon reactive joining for a set of substrate materials with thermal conductivities ranging from very low to very high. In particular, the evolution of the microstructure within the joining zone as a function of the specific time-temperature-profile for the given component material is investigated, focusing on the interaction between solder, RNML foil and surface metallisations, and the associated formation of intermetallic phases. Finally, the specific microstructure of the joints is related to their mechanical performance upon shear testing, and suggestions for optimum joint design are provided. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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12 pages, 8119 KiB  
Article
Evolution of Transient Liquid-Phase Sintered Cu–Sn Skeleton Microstructure During Thermal Aging
by Hiroaki Tatsumi, Adrian Lis, Hiroshi Yamaguchi, Tomoki Matsuda, Tomokazu Sano, Yoshihiro Kashiba and Akio Hirose
Appl. Sci. 2019, 9(1), 157; https://doi.org/10.3390/app9010157 - 04 Jan 2019
Cited by 28 | Viewed by 4296
Abstract
The evolution of the transient liquid-phase sintered (TLPS) Cu–Sn skeleton microstructure during thermal aging was evaluated to clarify the thermal reliability for die-attach applications. The Cu–Sn skeleton microstructure, which consists of Cu particles connected with Cu–Sn intermetallic compounds partially filled with polyimide resin, [...] Read more.
The evolution of the transient liquid-phase sintered (TLPS) Cu–Sn skeleton microstructure during thermal aging was evaluated to clarify the thermal reliability for die-attach applications. The Cu–Sn skeleton microstructure, which consists of Cu particles connected with Cu–Sn intermetallic compounds partially filled with polyimide resin, was obtained by the pressure-less TLP sintering process at 250 °C for 1 min using a novel Cu-solder-resin composite as a bonding material in a nitrogen atmosphere. Experimental results indicate that the TLPS joints were mainly composed of Cu, Cu6Sn5, and Cu3Sn in the as-bonded state, where submicron voids were observed at the interface between Cu3Sn and Cu particles. After thermal aging at 150, 175, and 200 °C for 1000 h, the Cu6Sn5 phase fully transformed into Cu3Sn except at the chip-side interface, where the number of the submicron voids appeared to increase. The averaged shear strengths were found to be 22.1 (reference), 22.8 (+3%), 24.0 (+9%), and 19.0 MPa (−14%) for the as-bonded state and specimens aged at 150, 175, and 200 °C for 1000 h, respectively. The TLPS joints maintained a shear strength over 19 MPa after thermal aging at 200 °C for 1000 h because of both the positive and negative impacts of the thermal aging, which include the transformation of Cu6Sn5 into Cu3Sn and the formation of submicron voids at the interface, respectively. These results indicate an excellent thermal reliability of the TLPS Cu–Sn skeleton microstructure. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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8 pages, 3240 KiB  
Article
Interface Growth and Void Formation in Sn/Cu and Sn0.7Cu/Cu Systems
by Jieshi Chen, Yongzhi Zhang, Zhishui Yu, Peilei Zhang, Wanqin Zhao, Jin Yang and Di Wu
Appl. Sci. 2018, 8(12), 2703; https://doi.org/10.3390/app8122703 - 19 Dec 2018
Cited by 13 | Viewed by 3983
Abstract
In this work, the effects of electroplated Cu (EP Cu) and Cu addition (0.7%) in Sn solder on the intermetallic compounds (IMCs) growth and void formation were clarified by comparison with solder joints comprising of high purity Cu (HP Cu) substrate and pure [...] Read more.
In this work, the effects of electroplated Cu (EP Cu) and Cu addition (0.7%) in Sn solder on the intermetallic compounds (IMCs) growth and void formation were clarified by comparison with solder joints comprising of high purity Cu (HP Cu) substrate and pure Sn solder. After aging processes, a new IMC, Cu3Sn, was formed at the interface, in addition to Cu6Sn5 formed in the as-soldered joints. The EP Cu and Cu addition (0.7%) both had limited effects on the total IMCs thickness. However, the effects varied on the growth behaviors of different IMCs. Comparing to the void-free interface between Sn and HP Cu, a large number of voids were observed at the Cu3Sn/Cu interface in Sn/EP Cu joints. The formation of these voids may be induced by the impurities and fine grain, which were introduced during the electroplating process. The addition of Cu suppressed the inter-diffusion of Cu and Sn at the interface. Consequently, the growth of the Cu3Sn layer and formation of voids were suppressed. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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13 pages, 23482 KiB  
Article
The Effect of Interfacial Ge and RF-Bias on the Microstructure and Stress Evolution upon Annealing of Ag/AlN Multilayers
by Claudia Cancellieri, Elizaveta Klyatskina, Mirco Chiodi, Jolanta Janczak-Rusch and Lars P. H. Jeurgens
Appl. Sci. 2018, 8(12), 2403; https://doi.org/10.3390/app8122403 - 27 Nov 2018
Cited by 13 | Viewed by 3386
Abstract
The present study addresses the structural stability and mass outflow of Ag 10 nm/Ge 1 nm/AlN 10 nm nanomultilayers (NMLs) during thermal treatments in different atmospheres (Ar and air). The nanomultilayers were obtained by magnetron sputtering under different deposition conditions (with [...] Read more.
The present study addresses the structural stability and mass outflow of Ag 10 nm/Ge 1 nm/AlN 10 nm nanomultilayers (NMLs) during thermal treatments in different atmospheres (Ar and air). The nanomultilayers were obtained by magnetron sputtering under different deposition conditions (with and without the RF (Radio-Frequency)-bias application). The microstructure of the as-deposited and thermally treated NMLs were analyzed by XRD and SEM techniques, deriving morphology, microstructure and internal stress. Bias application during the deposition is found to create highly disordered interfaces and to have a very strong influence on the morphology and structural evolution with temperature of the nano-multilayers. Complete multilayer degradation is observed for the bias sample when annealed in Ar at 700 ∘C, while the periodic multilayer structure is preserved for the non-bias samples. Structural and morphological changes are observed starting from 400 ∘C, accompanied with Ag surface migration. The highest Ag amount on the surface is detected in air atmosphere for bias and non-bias samples annealed at temperatures as high as 700 ∘C. The presence of Ge is found to strongly hinder the Ag surface migration. Ag outflow is measured to take place only through the network of surface cracks in the AlN barrier formed upon heating. The crack formation and Ag migration are discussed together with the stress relaxation. The present study demonstrates the feasibility to tailor the stress state of as-deposited NML structures and observe different structural evolution depending on the initial conditions. This paves the way for advanced experimental strategies to tailor directional mass outflow in nanoconfined filler systems for advanced nano-joining applications. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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10 pages, 3494 KiB  
Article
A Modified Interposer Fabrication Process by Copper Nano-Pillars Filled in Anodic Aluminum Oxide Film for 3D Electronic Package
by Chunjin Hang, He Zhang, Yanhong Tian, Chenxi Wang, Yuan Huang, Zhen Zheng and Chunqing Wang
Appl. Sci. 2018, 8(11), 2188; https://doi.org/10.3390/app8112188 - 08 Nov 2018
Cited by 5 | Viewed by 3773
Abstract
Though copper nano-pillars (CNPs) filled in anodic aluminum oxide (AAO) film has been developed for many years, the high pore-filling percentage in AAO is still a bottleneck. We have demonstrated a new electrodeposition method to fill CNPs in AAO without the seed layer [...] Read more.
Though copper nano-pillars (CNPs) filled in anodic aluminum oxide (AAO) film has been developed for many years, the high pore-filling percentage in AAO is still a bottleneck. We have demonstrated a new electrodeposition method to fill CNPs in AAO without the seed layer which is required in the traditional electrodeposition process. CNPs with uniform heights were obtained and the pore-filling percentage reached up to 97.5%. Low current density is beneficial for the high pore-filling percentage due to the uniform growing rate in different nanoscale pores. The high temperature increased the diffusion velocity of ions and enhanced the pore filling percentage but also corroded the AAO film simultaneously. Results showed that CNPs grains with <220> orientation were fabricated. Electrodeposition with low electric current could contribute to the forming of CNPs with (220) preferred orientation due to the promotion of dehydration reduction processes. The thermal conductivities of Cu-AAO interposers reaches 92.34 W/(m·K) and 3.19 W/(m·K) in vertical and horizontal directions, respectively. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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10 pages, 3736 KiB  
Article
Electrical and Mechanical Properties of Ink Printed Composite Electrodes on Plastic Substrates
by Xinda Wang, Wei Guo, Ying Zhu, Xiaokang Liang, Fude Wang and Peng Peng
Appl. Sci. 2018, 8(11), 2101; https://doi.org/10.3390/app8112101 - 01 Nov 2018
Cited by 28 | Viewed by 4408
Abstract
Printed flexible electrodes with conductive inks have attracted much attention in wearable electronics, flexible displays, radio-frequency identification, etc. Conventional conductive inks contain large amount of polymer which would increase the electrical resistivity of as-printed electrodes and require high sintering temperature. Here, composite electrodes [...] Read more.
Printed flexible electrodes with conductive inks have attracted much attention in wearable electronics, flexible displays, radio-frequency identification, etc. Conventional conductive inks contain large amount of polymer which would increase the electrical resistivity of as-printed electrodes and require high sintering temperature. Here, composite electrodes without cracks were printed on polyimide substrate using binder-free silver nanoparticle based inks with zero-dimensional (activated carbon), one-dimensional (silver nanowire and carbon nanotube) or two-dimensional (graphene) fillers. The effect of fillers on resistivity and flexibility of printed composite electrodes were evaluated. The graphene filler could reduce the resistivity of electrodes, reaching 1.7 × 10−7 Ω·m after low power laser sintering, while the silver nanowire filler improved their flexibility largely during bending tests. The microstructural changes were examined to understand the nanojoining process and their properties. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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12 pages, 4900 KiB  
Article
Influence of Interfacial Intermetallic Growth on the Mechanical Properties of Sn-37Pb Solder Joints under Extreme Temperature Thermal Shock
by Chunjin Hang, Ruyu Tian, Liyou Zhao and Yanhong Tian
Appl. Sci. 2018, 8(11), 2056; https://doi.org/10.3390/app8112056 - 25 Oct 2018
Cited by 13 | Viewed by 3918
Abstract
Solder joints in thermally uncontrolled microelectronic assemblies have to be exposed to extreme temperature environments during deep space exploration. In this study, extreme temperature thermal shock test from −196 °C to 150 °C was performed on quad flat package (QFP) assembled with Sn-37Pb [...] Read more.
Solder joints in thermally uncontrolled microelectronic assemblies have to be exposed to extreme temperature environments during deep space exploration. In this study, extreme temperature thermal shock test from −196 °C to 150 °C was performed on quad flat package (QFP) assembled with Sn-37Pb solder joints to investigate the evolution and growth behavior of interfacial intermetallic compounds (IMCs) and their effect on the pull strength and fracture behavior of Sn-37Pb solder joints under extreme temperature environment. Both the scallop-type (Cu, Ni)6Sn5 IMCs at the Cu lead side and the needle-type (Ni, Cu)3Sn4 IMCs at the Ni-P layer side changed to plane-type IMCs during extreme temperature thermal shock. A thin layer of Cu3Sn IMCs was formed between the Cu lead and (Cu, Ni)6Sn5 IMC layer after 150 cycles. The growth of the interfacial IMCs at the lead side and the Ni-P layer side was dominated by bulk diffusion and grain-boundary diffusion, respectively. The pull strength was reduced about 31.54% after 300 cycles. With increasing thermal shock cycles, the fracture mechanism changed from ductile fracture to mixed ductile–brittle fracture, which can be attributed to the thickening of the interfacial IMCs, and the stress concentration near the interface caused by interfacial IMC growth. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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10 pages, 34322 KiB  
Article
Mechanical Property of Sn-58Bi Solder Paste Strengthened by Resin
by Lu Liu, Songbai Xue and Siyi Liu
Appl. Sci. 2018, 8(11), 2024; https://doi.org/10.3390/app8112024 - 23 Oct 2018
Cited by 12 | Viewed by 5459
Abstract
Sn-58Bi solder has been widely used for microelectronics packaging due to its low melting point temperature, good wetting performance, good mechanical properties, and low cost. Compared with Sn-Bi solder alloy and Sn-Pb solder alloy, the strength and plasticity of Sn-Bi solder are not [...] Read more.
Sn-58Bi solder has been widely used for microelectronics packaging due to its low melting point temperature, good wetting performance, good mechanical properties, and low cost. Compared with Sn-Bi solder alloy and Sn-Pb solder alloy, the strength and plasticity of Sn-Bi solder are not enough, due to the higher brittleness of bismuth, which thus limits the application of Sn-Bi solder. In order to improve the properties of Sn-Bi solder, a novel solder paste strengthened with resin was developed by mixing epoxy resin (ER) with Sn-58Bi solder, which enhanced the joint strength at a low cost. Aimed at the electronic industry, in this study, the spreadability of the novel solder paste was investigated, and the mechanical properties and microstructure of solder joints after reflow soldering were tested and analyzed. The results showed that when the content of epoxy resin was in the optimum range, the shear strength was significantly higher, reaching nearly twice that of Sn-58Bi solder alone. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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15 pages, 9794 KiB  
Article
Study on Microstructure and Fatigue Damage Mechanism of 6082 Aluminum Alloy T-Type Metal Inert Gas (MIG) Welded Joint
by Chenfeng Duan, Shanglei Yang, Jiaxing Gu, Qi Xiong and Yuan Wang
Appl. Sci. 2018, 8(10), 1741; https://doi.org/10.3390/app8101741 - 27 Sep 2018
Cited by 12 | Viewed by 3423
Abstract
In this experiment, the T-joint of a 6082 aluminum alloy was welded by metal inert gas (MIG) welding and a fatigue test was carried out at room temperature. The mechanisms of generating pores and of fatigue fracture in welded joints are revealed in [...] Read more.
In this experiment, the T-joint of a 6082 aluminum alloy was welded by metal inert gas (MIG) welding and a fatigue test was carried out at room temperature. The mechanisms of generating pores and of fatigue fracture in welded joints are revealed in the case of incomplete penetration. There are two main types of pores: pores that are not welded and pores that are near the upper weld line of the weld. During welding, bubbles in the molten pool are adsorbed on the surface oxide film that is not penetrated, and cannot be floated to form pores; since it is a T-shaped welded joint, the molten pool is overhanged during welding, thereby forming pores near the fusion line. The fatigue strength of the welded joint based on the S–N curve at 107 cycles is estimated to be 37.6 MPa, which can reliably be predicted in engineering applications. Fatigue tests show that fatigue cracks are all generated in the pores of the incomplete penetration, and it and the pores form a long precrack, which leads to large stress concentration, and the fracture occurs under a small applied load. Grain morphology around the pores also has a large effect on the fatigue properties of the T-weld joint. In the weld’s fatigue fracture, it was found that the crack stable-extension zone exhibited ductile-fracture characteristics, and the instantaneous fault zone is composed of a large number of tear-type dimples showing ductile fractures. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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8 pages, 6058 KiB  
Article
Study on the Reliability of Sn50Pb49Sb1/Cu Solder Joints Subjected to γ-ray Irradiation
by Jianhao Wang, Songbai Xue, Zhaoping Lv, Li Wen and Siyi Liu
Appl. Sci. 2018, 8(10), 1706; https://doi.org/10.3390/app8101706 - 20 Sep 2018
Cited by 9 | Viewed by 2922
Abstract
Cosmic radiation has always been the most obvious barrier to planetary travels, especially in long-duration deep space exploration missions. Therefore, the reliability of satellite materials and the requirements of satellite miniaturization have received considerable attention. In this paper, the effect of γ-ray [...] Read more.
Cosmic radiation has always been the most obvious barrier to planetary travels, especially in long-duration deep space exploration missions. Therefore, the reliability of satellite materials and the requirements of satellite miniaturization have received considerable attention. In this paper, the effect of γ-ray irradiation on the reliability of Sn50Pb49Sb1/Cu solder joints was investigated. It was found that the influence of γ-ray irradiation on the thickness and morphology of the intermetallic compound layer in Sn50Pb49Sb1/Cu was not obvious. However, the formation and growth of micro-voids and micro-cracks was observed in Pb-based solid solutions. Due to the Compton effect, the γ-ray photon could knock the electron out of its orbit, which created the energetic electron. The accumulation of dislocated atoms and lattice vacancies generated by energetic electrons could be the main factor that caused the formation of micro-voids and micro-cracks. The pull force of Sn50Pb49Sb1/Cu solder joints was reduced by 22% after being irradiated at the dose rate of 0.25 Gy(Si)/s for 960 h. Fractographic analysis showed that after irradiation, the fracture type of solder joints was still ductile but the ductility of the solder joints decreased with slightly inconspicuous dimples. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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10 pages, 3927 KiB  
Article
Influence of Preheating Temperature on Cold Metal Transfer (CMT) Welding–Brazing of Aluminium Alloy/Galvanized Steel
by Youqiong Qin, Xi He and Wenxiang Jiang
Appl. Sci. 2018, 8(9), 1659; https://doi.org/10.3390/app8091659 - 14 Sep 2018
Cited by 9 | Viewed by 4110
Abstract
Bead-on-plate cold metal transfer (CMT) brazing and overlap CMT welding–brazing of 7075 aluminium alloy and galvanized steel at different preheating temperatures were studied. The results indicated that AlSi5 filler wire had good wettability to galvanized steel. The preheating treatment can promote the spreadability [...] Read more.
Bead-on-plate cold metal transfer (CMT) brazing and overlap CMT welding–brazing of 7075 aluminium alloy and galvanized steel at different preheating temperatures were studied. The results indicated that AlSi5 filler wire had good wettability to galvanized steel. The preheating treatment can promote the spreadability of liquid AlSi5. For the overlap CMT welding–brazed joint, the microstructure of the joint was divided into four zones, namely, the interfacial layer, weld metal zone, zinc-rich zone, and heat affected zone (HAZ). The load force of the joints without preheating and 100 °C preheating temperature was 8580 N and 9730 N, respectively. Both of the joints were fractured in the fusion line with a ductile fracture. Further increasing the preheating temperature to 200 °C would decrease the load force of the joint, which fractured in the interfacial layer with a brittle fracture. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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14 pages, 6305 KiB  
Article
Self-Powered Fast Brazing of Ti-6Al-4V Using Ni/Al Reactive Multilayer Films
by Denzel Bridges, Christopher Rouleau, Zachary Gosser, Cary Smith, Zhili Zhang, Kunlun Hong, Jinquan Cheng, Yoseph Bar-Cohen and Anming Hu
Appl. Sci. 2018, 8(6), 985; https://doi.org/10.3390/app8060985 - 15 Jun 2018
Cited by 11 | Viewed by 4103
Abstract
Self-powered brazing of Ti-6Al-4V was performed using Ni/Al reactive multilayer films (RMFs) as self-propagated heat resources. BAlSi-4 was first coated on Ti-6Al-4V by plasma welding, then alternating layers of Ni and Al were successfully deposited on BAlSi-4 up to 32.9 μm thick with [...] Read more.
Self-powered brazing of Ti-6Al-4V was performed using Ni/Al reactive multilayer films (RMFs) as self-propagated heat resources. BAlSi-4 was first coated on Ti-6Al-4V by plasma welding, then alternating layers of Ni and Al were successfully deposited on BAlSi-4 up to 32.9 μm thick with e-beam deposition. The joint microstructure was investigated and the AlNi and Ni5Al3 phases were identified in the RMF. The cause for the two phases was determined to be differences in the diffusivity of Ni and Al, ultrafast brazing time, and faster cooling at the interface between brazing filler metal and the RMF. The maximum temperature of 683 °C was reached in the brazed joint, with a total RMF thickness of 135 μm, which is more than sufficient to melt the BAlSi-4 brazing material. The maximum bonding strength obtained was 10.6 MPa, with a self-power brazing procedure conducted in a minute. It is possible to further improve the bonding strength by using more ductile RMFs and/or modifying the bonding interface configuration. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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11 pages, 4582 KiB  
Article
Diode Laser Welding/Brazing of Aluminum Alloy to Steel Using a Nickel Coating
by Jin Yang, Jieshi Chen, Wanqin Zhao, Peilei Zhang, Zhishui Yu, Yulong Li, Zhi Zeng and Norman Zhou
Appl. Sci. 2018, 8(6), 922; https://doi.org/10.3390/app8060922 - 04 Jun 2018
Cited by 21 | Viewed by 4743
Abstract
Joining Al alloy to steel is of great interest for application in the automotive industry. Although a vast number of studies have been conducted to join Al to steel, the joining of Al to steel is still challenging due to the formation of [...] Read more.
Joining Al alloy to steel is of great interest for application in the automotive industry. Although a vast number of studies have been conducted to join Al to steel, the joining of Al to steel is still challenging due to the formation of brittle Fe–Al intermetallic compounds. In this work, the microstructure and mechanical properties of the dissimilar Al/steel joints with and without a nickel coating are comparatively investigated. A homogenous reaction layer composed of FeZn10 and Fe2Al5 is formed at the interface in the joints without Ni coating, and the joint facture load is only 743 N. To prevent the formation of brittle Fe2Al5, Ni electroplated coating is applied onto a steel surface. It has been shown that a nonhomogeneous reaction layer is observed at the interfacial region: Ni5Zn21 is formed at the direct irradiation zone, while Al3Ni is formed at the fusion zone root. The microhardness of the interfacial layer is reduced, which leads to the improvement of the joint mechanical properties. The average fracture load of the Al/Ni-coated steel joints reaches 930 N. In all of the cases, failure occurs at the Ni coating/fusion zone interface. Full article
(This article belongs to the Special Issue Selected Papers from the NMJ2018)
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