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Surface Modification to Improve Properties of Materials
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Surface Modification to Improve Properties of Materials

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: closed (31 December 2018) | Viewed by 116324

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editor

Prof. Dr. Miran Mozetič

E-Mail Website
Guest Editor
Department of Surface Engineering, Jozef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia
Interests: surface engineering; non-equilibrium gaseous plasma; polymers; organic materials; plasma technologies
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Surface properties of modern materials are usually inadequate so they should be modified prior to application or further processing such as coating with functional materials. Both morphological properties and chemical structure/composition should be modified in order to obtain a desired surface finish. Various treatment procedures have been employed and many are based on application of non-equilibrium gaseous media, especially gaseous plasma. Although such treatments have been studied extensively in past decades, and actually commercialized, the exact mechanism of interaction between reactive gaseous species and solid materials is still poorly understood. This Special Issue will provide recent trends in nanostructuring and functionalization of solid materials with the goal of improving their functional properties such as biocompatibility.

It is my pleasure to invite you to submit a manuscript for this Special Issue. Full papers, communications, and reviews are all welcome. Critical reviews in specific modern topics such as bio-compatibility of advanced polymers and polymer composites are particularly welcome. The authors are encouraged to submit manuscripts reporting unexpected results providing they can present scientifically spotless explanations.

Prof. Dr. Miran Mozetič
Guest Editor

Manuscript Submission Information

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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. Materials 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 2600 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

  • surface properties
  • nanostructuring
  • functionalization
  • grafting

Published Papers (22 papers)

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Editorial

Jump to: Research, Review

8 pages, 203 KiB  
Editorial
Surface Modification to Improve Properties of Materials
by Miran Mozetič
Materials 2019, 12(3), 441; https://doi.org/10.3390/ma12030441 - 31 Jan 2019
Cited by 105 | Viewed by 6816
Abstract
Surface properties of modern materials are usually inadequate in terms of wettability, adhesion properties, biocompatibility etc., so they should be modified prior to application or any further processing such as coating with functional materials. Both the morphological properties and chemical structure/composition should be [...] Read more.
Surface properties of modern materials are usually inadequate in terms of wettability, adhesion properties, biocompatibility etc., so they should be modified prior to application or any further processing such as coating with functional materials. Both the morphological properties and chemical structure/composition should be modified in order to obtain a desired surface finish. Various treatment procedures have been employed, and many are based on the application of non-equilibrium gaseous media, especially gaseous plasma. Although such treatments have been studied extensively in past decades and actually commercialized, the exact mechanisms of interaction between reactive gaseous species and solid materials is still inadequately understood. This special issue provides recent trends in nanostructuring and functionalization of solid materials with the goal of improving their functional properties. Full article
(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)

Research

Jump to: Editorial, Review

21 pages, 5839 KiB  
Article
Development of Organosilicon-Based Superhydrophobic Coatings through Atmospheric Pressure Plasma Polymerization of HMDSO in Nitrogen Plasma
by Siavash Asadollahi, Jacopo Profili, Masoud Farzaneh and Luc Stafford
Materials 2019, 12(2), 219; https://doi.org/10.3390/ma12020219 - 10 Jan 2019
Cited by 44 | Viewed by 5438
Abstract
Water-repellent surfaces, often referred to as superhydrophobic surfaces, have found numerous potential applications in several industries. However, the synthesis of stable superhydrophobic surfaces through economical and practical processes remains a challenge. In the present work, we report on the development of an organosilicon-based [...] Read more.
Water-repellent surfaces, often referred to as superhydrophobic surfaces, have found numerous potential applications in several industries. However, the synthesis of stable superhydrophobic surfaces through economical and practical processes remains a challenge. In the present work, we report on the development of an organosilicon-based superhydrophobic coating using an atmospheric-pressure plasma jet with an emphasis on precursor fragmentation dynamics as a function of power and precursor flow rate. The plasma jet is initially modified with a quartz tube to limit the diffusion of oxygen from the ambient air into the discharge zone. Then, superhydrophobic coatings are developed on a pre-treated microporous aluminum-6061 substrate through plasma polymerization of HMDSO in the confined atmospheric pressure plasma jet operating in nitrogen plasma. All surfaces presented here are superhydrophobic with a static contact angle higher than 150° and contact angle hysteresis lower than 6°. It is shown that increasing the plasma power leads to a higher oxide content in the coating, which can be correlated to higher precursor fragmentation, thus reducing the hydrophobic behavior of the surface. Furthermore, increasing the precursor flow rate led to higher deposition and lower precursor fragmentation, leading to a more organic coating compared to other cases. Full article
(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)
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14 pages, 5508 KiB  
Article
Visible Light Assisted Organosilane Assembly on Mesoporous Silicon Films and Particles
by Chloé Rodriguez, Alvaro Muñoz Noval, Vicente Torres-Costa, Giacomo Ceccone and Miguel Manso Silván
Materials 2019, 12(1), 131; https://doi.org/10.3390/ma12010131 - 03 Jan 2019
Cited by 8 | Viewed by 3410
Abstract
Porous silicon (PSi) is a versatile matrix with tailorable surface reactivity, which allows the processing of a range of multifunctional films and particles. The biomedical applications of PSi often require a surface capping with organic functionalities. This work shows that visible light can [...] Read more.
Porous silicon (PSi) is a versatile matrix with tailorable surface reactivity, which allows the processing of a range of multifunctional films and particles. The biomedical applications of PSi often require a surface capping with organic functionalities. This work shows that visible light can be used to catalyze the assembly of organosilanes on the PSi, as demonstrated with two organosilanes: aminopropyl-triethoxy-silane and perfluorodecyl-triethoxy-silane. We studied the process related to PSi films (PSiFs), which were characterized by X-ray photoelectron spectroscopy (XPS), time of flight secondary ion mass spectroscopy (ToF-SIMS) and field emission scanning electron microscopy (FESEM) before and after a plasma patterning process. The analyses confirmed the surface oxidation and the anchorage of the organosilane backbone. We further highlighted the surface analytical potential of 13C, 19F and 29Si solid-state NMR (SS-NMR) as compared to Fourier transformed infrared spectroscopy (FTIR) in the characterization of functionalized PSi particles (PSiPs). The reduced invasiveness of the organosilanization regarding the PSiPs morphology was confirmed using transmission electron microscopy (TEM) and FESEM. Relevantly, the results obtained on PSiPs complemented those obtained on PSiFs. SS-NMR suggests a number of siloxane bonds between the organosilane and the PSiPs, which does not reach levels of maximum heterogeneous condensation, while ToF-SIMS suggested a certain degree of organosilane polymerization. Additionally, differences among the carbons in the organic (non-hydrolyzable) functionalizing groups are identified, especially in the case of the perfluorodecyl group. The spectroscopic characterization was used to propose a mechanism for the visible light activation of the organosilane assembly, which is based on the initial photoactivated oxidation of the PSi matrix. Full article
(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)
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12 pages, 4289 KiB  
Article
Preparation of Textured Surfaces on Aluminum-Alloy Substrates
by Markéta Kadlečková, Antonín Minařík, Petr Smolka, Aleš Mráček, Erik Wrzecionko, Libor Novák, Lenka Musilová and Radek Gajdošík
Materials 2019, 12(1), 109; https://doi.org/10.3390/ma12010109 - 31 Dec 2018
Cited by 21 | Viewed by 4760
Abstract
The ways of producing porous-like textured surfaces with chemical etching on aluminum-alloy substrates were studied. The most appropriate etchants, their combination, temperature, and etching time period were explored. The influence of a specifically textured surface on adhesive joints’ strength or superhydrophobic properties was [...] Read more.
The ways of producing porous-like textured surfaces with chemical etching on aluminum-alloy substrates were studied. The most appropriate etchants, their combination, temperature, and etching time period were explored. The influence of a specifically textured surface on adhesive joints’ strength or superhydrophobic properties was evaluated. The samples were examined with scanning electron microscopy, profilometry, atomic force microscopy, goniometry, and tensile testing. It was found that, with the multistep etching process, the substrate can be effectively modified and textured to the same morphology, regardless of the initial surface roughness. By selecting proper etchants and their sequence one can prepare new types of highly adhesive or even superhydrophobic surfaces. Full article
(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)
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12 pages, 7579 KiB  
Article
Development of Compact High-Voltage Power Supply for Stimulation to Promote Fruiting Body Formation in Mushroom Cultivation
by Katsuyuki Takahashi, Kai Miyamoto, Koichi Takaki and Kyusuke Takahashi
Materials 2018, 11(12), 2471; https://doi.org/10.3390/ma11122471 - 05 Dec 2018
Cited by 10 | Viewed by 4895
Abstract
The compact high-voltage power supply is developed for stimulation to promote fruiting body formation in cultivating L. edodes and Lyophyllum deeastes Sing. mushrooms. A Cockcroft-Walton (C-W) circuit is employed to generate DC high-voltage from AC 100 V plug power for the compact, easy [...] Read more.
The compact high-voltage power supply is developed for stimulation to promote fruiting body formation in cultivating L. edodes and Lyophyllum deeastes Sing. mushrooms. A Cockcroft-Walton (C-W) circuit is employed to generate DC high-voltage from AC 100 V plug power for the compact, easy handling and high safety use in the hilly and mountainous area. The C-W circuit is connected to high-voltage coaxial cable which works for high-voltage transmission and for charging up as energy storage capacitor. The output voltage is around 50 kV with several microseconds pulse width. The dimension and weight of the developed power supply are 0.4 × 0.47 × 1 m3 and 8.1 kg, respectively. The effect of the high-voltage stimulation on enhancement of fruiting body formation is evaluated in cultivating L. edodes and Lyophyllum deeastes Sing. mushrooms using the developed compact high-voltage power supply. The conventional Marx generator is also used for comparison in effect of high-voltage stimulation for fruiting body formation. L. edodes is cultivated with hosting to natural logs and the pulsed high voltage is applied to the cultivated natural logs. The substrate for Lyophyllum deeastes Sing. cultivation consists of sawdust. The results show that the fruiting body formation of mushrooms of L. edodes for four cultivation seasons and that of Lyophyllum deeastes Sing. for two seasons both increase approximately 1.3 times higher than control group in terms of the total weight. Although the input energy per a pulse is difference with the generators, the improvement of the fruit body yield mainly depends on the total input energy into the log. The effect for promotion on fruiting body formation by the developed compact high-voltage power supply is almost same that by the conventional Marx generator. Full article
(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)
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11 pages, 2553 KiB  
Article
Green Procedure to Manufacture Nanoparticle-Decorated Paper Substrates
by Werner Schlemmer, Wolfgang Fischer, Armin Zankel, Tomislava Vukušić, Gregor Filipič, Andrea Jurov, Damjan Blažeka, Walter Goessler, Wolfgang Bauer, Stefan Spirk and Nikša Krstulović
Materials 2018, 11(12), 2412; https://doi.org/10.3390/ma11122412 - 29 Nov 2018
Cited by 8 | Viewed by 4129
Abstract
For this study, a paper impregnated with silver nanoparticles (AgNPs) was prepared. To prepare the substrates, aqueous suspensions of pulp fines, a side product from the paper production, were mixed with AgNP suspensions. The nanoparticle (NP) synthesis was then carried out via laser [...] Read more.
For this study, a paper impregnated with silver nanoparticles (AgNPs) was prepared. To prepare the substrates, aqueous suspensions of pulp fines, a side product from the paper production, were mixed with AgNP suspensions. The nanoparticle (NP) synthesis was then carried out via laser ablation of pure Ag in water. After the sheet formation process, the leaching of the AgNPs was determined to be low while the sheets exhibited antimicrobial activity toward Escherichia coli (E. coli). Full article
(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)
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13 pages, 6765 KiB  
Article
Lectins at Interfaces—An Atomic Force Microscopy and Multi-Parameter-Surface Plasmon Resonance Study
by Katrin Niegelhell, Thomas Ganner, Harald Plank, Evelyn Jantscher-Krenn and Stefan Spirk
Materials 2018, 11(12), 2348; https://doi.org/10.3390/ma11122348 - 22 Nov 2018
Cited by 7 | Viewed by 3262
Abstract
Lectins are a diverse class of carbohydrate binding proteins with pivotal roles in cell communication and signaling in many (patho)physiologic processes in the human body, making them promising targets in drug development, for instance, in cancer or infectious diseases. Other applications of lectins [...] Read more.
Lectins are a diverse class of carbohydrate binding proteins with pivotal roles in cell communication and signaling in many (patho)physiologic processes in the human body, making them promising targets in drug development, for instance, in cancer or infectious diseases. Other applications of lectins employ their ability to recognize specific glycan epitopes in biosensors and glycan microarrays. While a lot of research has focused on lectin interaction with specific carbohydrates, the interaction potential of lectins with different types of surfaces has not been addressed extensively. Here, we screen the interaction of two specific plant lectins, Concanavalin A and Ulex Europaeus Agglutinin-I with different nanoscopic thin films. As a control, the same experiments were performed with Bovine Serum Albumin, a widely used marker for non-specific protein adsorption. In order to test the preferred type of interaction during adsorption, hydrophobic, hydrophilic and charged polymer films were explored, such as polystyrene, cellulose, N,-N,-N-trimethylchitosan chloride and gold, and characterized in terms of wettability, surface free energy, zeta potential and morphology. Atomic force microscopy images of surfaces after protein adsorption correlated very well with the observed mass of adsorbed protein. Surface plasmon resonance spectroscopy studies revealed low adsorbed amounts and slow kinetics for all of the investigated proteins for hydrophilic surfaces, making those resistant to non-specific interactions. As a consequence, they may serve as favorable supports for biosensors, since the use of blocking agents is not necessary. Full article
(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)
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10 pages, 2626 KiB  
Article
Physical and Morphological Changes of Poly(tetrafluoroethylene) after Using Non-Thermal Plasma-Treatments
by Jorge López-García, Florence Cupessala, Petr Humpolíček and Marian Lehocký
Materials 2018, 11(10), 2013; https://doi.org/10.3390/ma11102013 - 17 Oct 2018
Cited by 11 | Viewed by 3650
Abstract
A commercial formulation of poly(tetrafluoroethylene) (PTFE) sheets were surface modified by using non-thermal air at 40 kHz frequency (DC) and 13.56 MHz radiofrequency (RF) at different durations and powers. In order to assess possible changes of PTFE surface properties, zeta potential (ζ), isoelectric [...] Read more.
A commercial formulation of poly(tetrafluoroethylene) (PTFE) sheets were surface modified by using non-thermal air at 40 kHz frequency (DC) and 13.56 MHz radiofrequency (RF) at different durations and powers. In order to assess possible changes of PTFE surface properties, zeta potential (ζ), isoelectric points (IEPs) determinations, contact angle measurements as well as Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) imaging were carried out throughout the experimentation. The overall outcome indicated that ζ-potential and surface energy progressively changed after each treatment, the IEP shifting to lower pH values and the implicit differences, which are produced after each distinct treatment, giving new surface topographies and chemistry. The present approach might serve as a feasible and promising method to alter the surface properties of poly(tetrafluoroethylene). Full article
(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)
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18 pages, 2742 KiB  
Article
Reinforcement of Stearic Acid Treated Egg Shell Particles in Epoxy Thermosets: Structural, Thermal, and Mechanical Characterization
by Ahmer Hussain Shah, Yuqi Zhang, Xiaodong Xu, Abdul Qadeer Dayo, Xiao Li, Shuo Wang and Wenbin Liu
Materials 2018, 11(10), 1872; https://doi.org/10.3390/ma11101872 - 01 Oct 2018
Cited by 30 | Viewed by 3848
Abstract
This work reports the modification of egg shell (ES) particles by using stearic acid (SA) and their reinforcement in the epoxy matrix. The ES treatment via SA was optimized, the optimum conditions for concentration, temperature, and time were found to be 2.5%, 85 [...] Read more.
This work reports the modification of egg shell (ES) particles by using stearic acid (SA) and their reinforcement in the epoxy matrix. The ES treatment via SA was optimized, the optimum conditions for concentration, temperature, and time were found to be 2.5%, 85 °C, and 50 min, respectively. The untreated ES (UES) and treated ES (TES) particles were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscope (SEM), particle size distribution, and contact angle. FTIR confirmed the chemical modification of SA on ES surface and DSC reflects an endothermic peak at 240 °C. XRD reveal a decrease in crystal size and crystallinity, while contact angle increases to 169° from 42°. The SEM observations clearly reflect a distinct decrease and separation of small domains of ES particles thus improving an increased surface area. Afterwards, the UES and TES particles were reinforced in epoxy at 15 and 20 weight (wt.) % loading. The tensile tests confirmed a 22% increase in elongation as compared to pure epoxy due to the hydrogen bonding between TES particles and matrix. The lowest brittleness was recorded for TES/epoxy composites on 20 wt % loading. The TGA confirmed the improved thermal stabilities at 20 wt % loading of TES particles in matrix, the improvements in T5%, T10%, and T20% values were recorded as 33, 26, and 21 °C higher than the corresponding values for neat matrix. The TES/epoxy composites on 20 wt % showed 41% increase in storage modulus as compared to the pristine epoxy, and cross-link density reaches to 2.71 × 10−3 from 1.29 × 10−3 mol/cm3 for neat matrix. The decline in tan δ height and improvement in Tg were also observed. The best adhesion effectiveness was recorded for TES/epoxy composites. This simple and economical modification technique can enhance the application of ES particles in various polymeric coating and composites applications. Full article
(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)
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17 pages, 11399 KiB  
Article
Tribological Performance of Microhole-Textured Carbide Tool Filled with CaF2
by Wenlong Song, Shoujun Wang, Yang Lu and Zixiang Xia
Materials 2018, 11(9), 1643; https://doi.org/10.3390/ma11091643 - 07 Sep 2018
Cited by 15 | Viewed by 3232
Abstract
To enhance the friction and wear performance of cemented carbide, textured microholes were machined on micro Electron Discharge Machining (EDM) on the tool rake face, and Calcium Fluoride (CaF2) powders were burnished into the microholes. The friction and wear characteristics of [...] Read more.
To enhance the friction and wear performance of cemented carbide, textured microholes were machined on micro Electron Discharge Machining (EDM) on the tool rake face, and Calcium Fluoride (CaF2) powders were burnished into the microholes. The friction and wear characteristics of the microhole-textured tool filled with CaF2 were investigated using sliding friction tests and dry cutting tests. Results exhibited that the working temperature could affect the tribological performance of the microhole-textured tool filled with CaF2 due to the temperature-sensitive nature of CaF2. There is no obvious lubrication effect for the textured tool filled with CaF2 at room temperature, while it was shown to be more effective in improving tribological property at a cutting speed of higher than 100 m/min with a corresponding to cutting temperature of 450 °C. The possible mechanisms for the microhole-textured tool filled with CaF2 were discussed and established. Full article
(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)
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14 pages, 2878 KiB  
Article
The Effect of Plasma Pretreatment and Cross-Linking Degree on the Physical and Antimicrobial Properties of Nisin-Coated PVA Films
by Zuzana Kolarova Raskova, Pavel Stahel, Jana Sedlarikova, Lenka Musilova, Monika Stupavska and Marian Lehocky
Materials 2018, 11(8), 1451; https://doi.org/10.3390/ma11081451 - 16 Aug 2018
Cited by 29 | Viewed by 4265
Abstract
Stable antimicrobial nisin layers were prepared on the carrying medium-polyvinyl alcohol (PVA) films, crosslinked by glutaric acid. Surface plasma dielectric coplanar surface barrier discharge (DCSBD) modification of polyvinyl alcohol was used to improve the hydrophilic properties and to provide better adhesion of biologically [...] Read more.
Stable antimicrobial nisin layers were prepared on the carrying medium-polyvinyl alcohol (PVA) films, crosslinked by glutaric acid. Surface plasma dielectric coplanar surface barrier discharge (DCSBD) modification of polyvinyl alcohol was used to improve the hydrophilic properties and to provide better adhesion of biologically active peptide-nisin to the polymer. The surface modification of films was studied in correlation to their cross-linking degree. Nisin was attached directly from the salt solution of the commercial product. In order to achieve a stable layer, the initial nisin concentration and the following release were investigated using chromatographic methods. The uniformity and stability of the layers was evaluated by means of zeta potential measurements, and for the surface changes of hydrophilic character, the water contact angle measurements were provided. The nisin long-term stability on the PVA films was confirmed by tricine polyacrylamide gel electrophoresis (SDS-PAGE) and by antimicrobial assay. It was found that PVA can serve as a suitable carrying medium for nisin with tunable properties by plasma treatment and crosslinking degree. Full article
(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)
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13 pages, 5164 KiB  
Article
Increase in Strength and Fretting Resistance of Alloy 718 Using the Surface Modification Process
by Auezhan Amanov, Rakhmatjon Umarov and Tileubay Amanov
Materials 2018, 11(8), 1366; https://doi.org/10.3390/ma11081366 - 06 Aug 2018
Cited by 24 | Viewed by 3672
Abstract
This work comparatively investigated the strength (hardness, yield strength, dynamic elastic modulus, and surface residual stress), fretting failure, and corrosion resistance of the as-received and treated Ni-based superalloy Alloy 718. The goal of the current research is to improve the hardness, fretting wear, [...] Read more.
This work comparatively investigated the strength (hardness, yield strength, dynamic elastic modulus, and surface residual stress), fretting failure, and corrosion resistance of the as-received and treated Ni-based superalloy Alloy 718. The goal of the current research is to improve the hardness, fretting wear, and corrosion resistances of Alloy 718 through the ultrasonic nanocrystal surface modification (UNSM) process with the aim of extending the lifespan of aircraft and nuclear components made of Alloy 718. The experimental results revealed that the surface hardness increased by about 32%, the fretting wear resistance increased by about 14%, and the corrosion resistance increased by about 18% after UNSM process. In addition, the UNSM process induced a tremendous high compressive surface residual stress of about −1324 MPa that led to an increase in yield strength and dynamic Young’s modulus by about 14 and 9%, respectively. Grain size refinement up to ~50 nm after the UNSM process is found to be responsible for the increase in surface hardness as well. The depth of the effective layer generated by the UNSM process was about 20 µm. It was concluded that the UNSM process played a vital role in increasing the strength and enhancing the corrosion and fretting resistances of Alloy 718. Full article
(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)
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13 pages, 2541 KiB  
Article
Surface Functionalization of Polyethylene Granules by Treatment with Low-Pressure Air Plasma
by Hana Šourková, Gregor Primc and Petr Špatenka
Materials 2018, 11(6), 885; https://doi.org/10.3390/ma11060885 - 25 May 2018
Cited by 17 | Viewed by 3627
Abstract
Polyethylene granules of diameter 2 mm were treated with a low-pressure weakly ionized air plasma created in a metallic chamber by a pulsed microwave discharge of pulse duration 180 μs and duty cycle 70%. Optical emission spectroscopy showed rich bands of neutral nitrogen [...] Read more.
Polyethylene granules of diameter 2 mm were treated with a low-pressure weakly ionized air plasma created in a metallic chamber by a pulsed microwave discharge of pulse duration 180 μs and duty cycle 70%. Optical emission spectroscopy showed rich bands of neutral nitrogen molecules and weak O-atom transitions, but the emission from N atoms was below the detection limit. The density of O atoms in the plasma above the samples was measured with a cobalt catalytic probe and exhibited a broad peak at the pressure of 80 Pa, where it was about 2.3 × 1021 m−3. The samples were characterized by X-ray photoelectron spectroscopy. Survey spectra showed oxygen on the surface, while the nitrogen concentration remained below the detection limit for all conditions. The high-resolution C1s peaks revealed formation of various functional groups rather independently from treatment parameters. The results were explained by extensive dissociation of oxygen molecules in the gaseous plasma and negligible flux of N atoms on the polymer surface. Full article
(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)
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18 pages, 9033 KiB  
Article
Evaluation of Surface Roughness by Image Processing of a Shot-Peened, TIG-Welded Aluminum 6061-T6 Alloy: An Experimental Case Study
by Anas M. Atieh, Nathir A. Rawashdeh and Abdulaziz N. AlHazaa
Materials 2018, 11(5), 771; https://doi.org/10.3390/ma11050771 - 10 May 2018
Cited by 7 | Viewed by 5253
Abstract
Visual inspection through image processing of welding and shot-peened surfaces is necessary to overcome equipment limitations, avoid measurement errors, and accelerate processing to gain certain surface properties such as surface roughness. Therefore, it is important to design an algorithm to quantify surface properties, [...] Read more.
Visual inspection through image processing of welding and shot-peened surfaces is necessary to overcome equipment limitations, avoid measurement errors, and accelerate processing to gain certain surface properties such as surface roughness. Therefore, it is important to design an algorithm to quantify surface properties, which enables us to overcome the aforementioned limitations. In this study, a proposed systematic algorithm is utilized to generate and compare the surface roughness of Tungsten Inert Gas (TIG) welded aluminum 6061-T6 alloy treated by two levels of shot-peening, high-intensity and low-intensity. This project is industrial in nature, and the proposed solution was originally requested by local industry to overcome equipment capabilities and limitations. In particular, surface roughness measurements are usually only possible on flat surfaces but not on other areas treated by shot-peening after welding, as in the heat-affected zone and weld beads. Therefore, those critical areas are outside of the measurement limitations. Using the proposed technique, the surface roughness measurements were possible to obtain for weld beads, high-intensity and low-intensity shot-peened surfaces. In addition, a 3D surface topography was generated and dimple size distributions were calculated for the three tested scenarios: control sample (TIG-welded only), high-intensity shot-peened, and low-intensity shot-peened TIG-welded Al6065-T6 samples. Finally, cross-sectional hardness profiles were measured for the three scenarios; in all scenarios, lower hardness measurements were obtained compared to the base metal alloy in the heat-affected zone and in the weld beads even after shot-peening treatments. Full article
(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)
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18 pages, 5847 KiB  
Article
Gradient Nanostructured Tantalum by Thermal-Mechanical Ultrasonic Impact Energy
by Jong-Min Chae, Keun-Oh Lee and Auezhan Amanov
Materials 2018, 11(3), 452; https://doi.org/10.3390/ma11030452 - 20 Mar 2018
Cited by 17 | Viewed by 5017
Abstract
Microstructural evolution and wear performance of Tantalum (Ta) treated by ultrasonic nanocrystalline surface modification (UNSM) at 25 and 1000 °C were reported. The UNSM treatment modified a surface along with subsurface layer with a thickness in the range of 20 to 150 µm, [...] Read more.
Microstructural evolution and wear performance of Tantalum (Ta) treated by ultrasonic nanocrystalline surface modification (UNSM) at 25 and 1000 °C were reported. The UNSM treatment modified a surface along with subsurface layer with a thickness in the range of 20 to 150 µm, which depends on the UNSM treatment temperature, via the surface severe plastic deformation (S2PD) method. The cross-sectional microstructure of the specimens was observed by electron backscattered diffraction (EBSD) in order to confirm the microstructural alteration in terms of effective depth and refined grain size. The surface hardness measurement results, including depth profile, revealed that the hardness of the UNSM-treated specimens at both temperatures was increased in comparison with those of the untreated ones. The increase in UNSM treatment temperature led to a further increase in hardness. Moreover, both the UNSM-treated specimens with an increased hardness resulted in a higher resistance to wear in comparison with those of the untreated ones under dry conditions. The increase in hardness and induced compressive residual stress that depend on the formation of severe plastically deformed layer with the refined nano-grains are responsible for the enhancement in wear resistance. The findings of this study may be implemented in response to various industries that are related to strength improvement and wear enhancement issues of Ta. Full article
(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)
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17 pages, 4554 KiB  
Article
Modification of Physico-Chemical Properties of Acryl-Coated Polypropylene Foils for Food Packaging by Reactive Particles from Oxygen Plasma
by Tomislava Vukušić, Alenka Vesel, Matej Holc, Mario Ščetar, Anet Režek Jambrak and Miran Mozetič
Materials 2018, 11(3), 372; https://doi.org/10.3390/ma11030372 - 03 Mar 2018
Cited by 18 | Viewed by 4059
Abstract
This investigation was focused on the influence of long-living neutral reactive oxygen species on the physico-chemical properties of acryl-coated polypropylene foils for food packaging. Reactive species were formed by passing molecular oxygen through a microwave discharge and leaking it to a processing chamber [...] Read more.
This investigation was focused on the influence of long-living neutral reactive oxygen species on the physico-chemical properties of acryl-coated polypropylene foils for food packaging. Reactive species were formed by passing molecular oxygen through a microwave discharge and leaking it to a processing chamber of a volume of 30 L, which was pumped by a rotary pump. The density of neutral O-atoms in the chamber was tuned by adjustment of both the effective pumping speed and the oxygen leak rate. The O-atom density was measured with a catalytic probe and was between 3 × 1018 and 5 × 1019 m−3. Commercial foils of biaxially oriented polypropylene (BOPP) coated with acrylic/ poly(vinylidene chloride) (AcPVDC) were mounted in the chamber and treated at room temperature by O atoms at various conditions, with the fluence between 1 × 1021 and 3 × 1024 m−2. The evolution of the surface wettability versus the fluence was determined by water contact angle (WCA) measurements, the formation of functional groups by X-ray photoelectron spectroscopy (XPS), and the morphology by atomic force microscopy (AFM). The WCA dropped from the initial 75° to approximately 40° after the fluence of a few 1022 m−2 and remained unchanged thereafter, except for fluences above 1024 m−2, where the WCA dropped to approximately 30°. XPS and AFM results allowed for drawing correlations between the wettability, surface composition, and morphology. Full article
(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)
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15 pages, 6073 KiB  
Article
Tribological and Wear Performance of Nanocomposite PVD Hard Coatings Deposited on Aluminum Die Casting Tool
by Jose Mario Paiva, German Fox-Rabinovich, Edinei Locks Junior, Pietro Stolf, Yassmin Seid Ahmed, Marcelo Matos Martins, Carlos Bork and Stephen Veldhuis
Materials 2018, 11(3), 358; https://doi.org/10.3390/ma11030358 - 28 Feb 2018
Cited by 35 | Viewed by 6256
Abstract
In the aluminum die casting process, erosion, corrosion, soldering, and die sticking have a significant influence on tool life and product quality. A number of coatings such as TiN, CrN, and (Cr,Al)N deposited by physical vapor deposition (PVD) have been employed to act [...] Read more.
In the aluminum die casting process, erosion, corrosion, soldering, and die sticking have a significant influence on tool life and product quality. A number of coatings such as TiN, CrN, and (Cr,Al)N deposited by physical vapor deposition (PVD) have been employed to act as protective coatings due to their high hardness and chemical stability. In this study, the wear performance of two nanocomposite AlTiN and AlCrN coatings with different structures were evaluated. These coatings were deposited on aluminum die casting mold tool substrates (AISI H13 hot work steel) by PVD using pulsed cathodic arc evaporation, equipped with three lateral arc-rotating cathodes (LARC) and one central rotating cathode (CERC). The research was performed in two stages: in the first stage, the outlined coatings were characterized regarding their chemical composition, morphology, and structure using glow discharge optical emission spectroscopy (GDOES), scanning electron microscopy (SEM), and X-ray diffraction (XRD), respectively. Surface morphology and mechanical properties were evaluated by atomic force microscopy (AFM) and nanoindentation. The coating adhesion was studied using Mersedes test and scratch testing. During the second stage, industrial tests were carried out for coated die casting molds. In parallel, tribological tests were also performed in order to determine if a correlation between laboratory and industrial tests can be drawn. All of the results were compared with a benchmark monolayer AlCrN coating. The data obtained show that the best performance was achieved for the AlCrN/Si3N4 nanocomposite coating that displays an optimum combination of hardness, adhesion, soldering behavior, oxidation resistance, and stress state. These characteristics are essential for improving the die mold service life. Therefore, this coating emerges as a novelty to be used to protect aluminum die casting molds. Full article
(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)
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10 pages, 5957 KiB  
Article
Comparison of SF6 and CF4 Plasma Treatment for Surface Hydrophobization of PET Polymer
by Matic Resnik, Rok Zaplotnik, Miran Mozetic and Alenka Vesel
Materials 2018, 11(2), 311; https://doi.org/10.3390/ma11020311 - 21 Feb 2018
Cited by 38 | Viewed by 7013
Abstract
The fluorination of the polymer polyethylene terephthalate in plasma created from SF6 or CF4 gas at various pressures was investigated. The surface was analysed by X-ray photoelectron spectroscopy and water contact angle measurements, whereas the plasma was characterized by optical emission [...] Read more.
The fluorination of the polymer polyethylene terephthalate in plasma created from SF6 or CF4 gas at various pressures was investigated. The surface was analysed by X-ray photoelectron spectroscopy and water contact angle measurements, whereas the plasma was characterized by optical emission spectroscopy. The extent of the polymer surface fluorination was dependent on the pressure. Up to a threshold pressure, the amount of fluorine on the polymer surface and the surface hydrophobicity were similar, which was explained by the full dissociation of the SF6 and CF4 gases, leading to high concentrations of fluorine radicals in the plasma and thus causing the saturation of the polymer surface with fluorine functional groups. Above the threshold pressure, the amount of fluorine on the polymer surface significantly decreased, whereas the oxygen concentration increased, leading to the formation of the hydrophilic surface. This effect, which was more pronounced for the SF6 plasma, was explained by the electronegativity of both gases. Full article
(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)
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Review

Jump to: Editorial, Research

20 pages, 1497 KiB  
Review
Biocompatibility of Plasma-Treated Polymeric Implants
by Nina Recek
Materials 2019, 12(2), 240; https://doi.org/10.3390/ma12020240 - 12 Jan 2019
Cited by 40 | Viewed by 5181
Abstract
Cardiovascular diseases are one of the main causes of mortality in the modern world. Scientist all around the world are trying to improve medical treatment, but the success of the treatment significantly depends on the stage of disease progression. In the last phase [...] Read more.
Cardiovascular diseases are one of the main causes of mortality in the modern world. Scientist all around the world are trying to improve medical treatment, but the success of the treatment significantly depends on the stage of disease progression. In the last phase of disease, the treatment is possible only by implantation of artificial graft. Most commonly used materials for artificial grafts are polymer materials. Despite different industrial procedures for graft fabrication, their properties are still not optimal. Grafts with small diameters (<6 mm) are the most problematic, because the platelets are more likely to re-adhere. This causes thrombus formation. Recent findings indicate that platelet adhesion is primarily influenced by blood plasma proteins that adsorb to the surface immediately after contact of a synthetic material with blood. Fibrinogen is a key blood protein responsible for the mechanisms of activation, adhesion and aggregation of platelets. Plasma treatment is considered as one of the promising methods for improving hemocompatibility of synthetic materials. Another method is endothelialization of materials with Human Umbilical Vein Endothelial cells, thus forming a uniform layer of endothelial cells on the surface. Extensive literature review led to the conclusion that in this area, despite numerous studies there are no available standardized methods for testing the hemocompatibility of biomaterials. In this review paper, the most promising methods to gain biocompatibility of synthetic materials are reported; several hypotheses to explain the improvement in hemocompatibility of plasma treated polymer surfaces are proposed. Full article
(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)
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14 pages, 3745 KiB  
Review
A Mini Review: Recent Advances in Surface Modification of Porous Silicon
by Seo Hyeon Lee, Jae Seung Kang and Dokyoung Kim
Materials 2018, 11(12), 2557; https://doi.org/10.3390/ma11122557 - 15 Dec 2018
Cited by 49 | Viewed by 10687
Abstract
Porous silicon has been utilized within a wide spectrum of industries, as well as being used in basic research for engineering and biomedical fields. Recently, surface modification methods have been constantly coming under the spotlight, mostly in regard to maximizing its purpose of [...] Read more.
Porous silicon has been utilized within a wide spectrum of industries, as well as being used in basic research for engineering and biomedical fields. Recently, surface modification methods have been constantly coming under the spotlight, mostly in regard to maximizing its purpose of use. Within this review, we will introduce porous silicon, the experimentation preparatory methods, the properties of the surface of porous silicon, and both more conventional as well as newly developed surface modification methods that have assisted in attempting to overcome the many drawbacks we see in the existing methods. The main aim of this review is to highlight and give useful insight into improving the properties of porous silicon, and create a focused description of the surface modification methods. Full article
(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)
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24 pages, 2385 KiB  
Review
Superhydrophobic Natural and Artificial Surfaces—A Structural Approach
by Roxana-Elena Avrămescu, Mihaela Violeta Ghica, Cristina Dinu-Pîrvu, Răzvan Prisada and Lăcrămioara Popa
Materials 2018, 11(5), 866; https://doi.org/10.3390/ma11050866 - 22 May 2018
Cited by 64 | Viewed by 8300
Abstract
Since ancient times humans observed animal and plants features and tried to adapt them according to their own needs. Biomimetics represents the foundation of many inventions from various fields: From transportation devices (helicopter, airplane, submarine) and flying techniques, to sports’ wear industry (swimming [...] Read more.
Since ancient times humans observed animal and plants features and tried to adapt them according to their own needs. Biomimetics represents the foundation of many inventions from various fields: From transportation devices (helicopter, airplane, submarine) and flying techniques, to sports’ wear industry (swimming suits, scuba diving gear, Velcro closure system), bullet proof vests made from Kevlar etc. It is true that nature provides numerous noteworthy models (shark skin, spider web, lotus leaves), referring both to the plant and animal kingdom. This review paper summarizes a few of “nature’s interventions” in human evolution, regarding understanding of surface wettability and development of innovative special surfaces. Empirical models are described in order to reveal the science behind special wettable surfaces (superhydrophobic /superhydrophilic). Materials and methods used in order to artificially obtain special wettable surfaces are described in correlation with plants’ and animals’ unique features. Emphasis is placed on joining superhydrophobic and superhydrophilic surfaces, with important applications in cell culturing, microorganism isolation/separation and molecule screening techniques. Bio-inspired wettability is presented as a constitutive part of traditional devices/systems, intended to improve their characteristics and extend performances. Full article
(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)
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28 pages, 5860 KiB  
Review
Surface Texture-Based Surface Treatments on Ti6Al4V Titanium Alloys for Tribological and Biological Applications: A Mini Review
by Naiming Lin, Dali Li, Jiaojuan Zou, Ruizhen Xie, Zhihua Wang and Bin Tang
Materials 2018, 11(4), 487; https://doi.org/10.3390/ma11040487 - 24 Mar 2018
Cited by 91 | Viewed by 7124
Abstract
Surface texture (ST) has been confirmed as an effective and economical surface treatment technique that can be applied to a great range of materials and presents growing interests in various engineering fields. Ti6Al4V which is the most frequently and successfully used titanium alloy [...] Read more.
Surface texture (ST) has been confirmed as an effective and economical surface treatment technique that can be applied to a great range of materials and presents growing interests in various engineering fields. Ti6Al4V which is the most frequently and successfully used titanium alloy has long been restricted in tribological-related operations due to the shortcomings of low surface hardness, high friction coefficient, and poor abrasive wear resistance. Ti6Al4V has benefited from surface texture-based surface treatments over the last decade. This review begins with a brief introduction, analysis approaches, and processing methods of surface texture. The specific applications of the surface texture-based surface treatments for improving surface performance of Ti6Al4V are thoroughly reviewed from the point of view of tribology and biology. Full article
(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)
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