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24 pages, 7954 KiB

Open AccessArticle

The Effect of Incorporating Juncus Fibers on the Properties of Compressed Earth Blocks Stabilized with Portland Cement

by Reda Sadouri, Hocine Kebir and Mustafa Benyoucef

Appl. Sci. 2024, 14(2), 815; https://doi.org/10.3390/app14020815 - 18 Jan 2024

Cited by 1 | Viewed by 850

Abstract

This study investigates the impact of incorporating Juncus fibers (JF) into compressed earth blocks (CEBs) stabilized with varying Portland cement contents, aiming to enhance local construction materials’ performance and reduce housing costs. CEB composites were produced with soil stabilized using different cement contents [...] Read more.

This study investigates the impact of incorporating Juncus fibers (JF) into compressed earth blocks (CEBs) stabilized with varying Portland cement contents, aiming to enhance local construction materials’ performance and reduce housing costs. CEB composites were produced with soil stabilized using different cement contents (4%, 8%, and 12% by weight) and JF reinforcement (0 to 0.2% by weight), compressed at 10 MPa with a hydraulic press. After 28 days of drying, the CEBs underwent diverse experimental characterizations to assess their physical, mechanical, thermal, and durability properties. The results revealed that incorporating JF led to a reduction in unit weight, ultrasonic pulse velocity (up to 36%), and dry compressive strength (approximately 17%). Higher fiber content correlated with increased water absorption and an increased capillarity coefficient. Thermal conductivity analysis indicated improved thermal performance, decreasing from 0.4350 W/m·K (12% cement without fibers) to 0.2465 W/m·K (4% cement with 0.2% JF). Despite the decrease in mechanical strength, CEBs with lower cement (4%) and higher fiber content (0.2%) demonstrated satisfactory durability (abrasion and erosion) and thermal insulation properties. This research suggests the potential of this material as a promising composite for the building materials industry. The findings contribute valuable insights into sustainable construction materials and have implications for cost-effective housing solutions. Full article

(This article belongs to the Special Issue Processing, Properties and Applications of Composite Materials)

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22 pages, 14540 KiB

Open AccessArticle

Additive Friction Stir Deposition of AA7075-T6 Alloy: Impact of Process Parameters on the Microstructures and Properties of the Continuously Deposited Multilayered Parts

by Yousef G. Y. Elshaghoul, Mohamed M. El-Sayed Seleman, Ashraf Bakkar, Sarah A. Elnekhaily, Ibrahim Albaijan, Mohamed M. Z. Ahmed, Abdou Abdel-Samad and Reham Reda

Appl. Sci. 2023, 13(18), 10255; https://doi.org/10.3390/app131810255 - 13 Sep 2023

Cited by 5 | Viewed by 1438

Abstract

In the aircraft industry, the high-strength aluminum alloys AA7075 and AA2024 are extensively used for the manufacture of structural parts like stringers and skins, respectively. Additive manufacturing (AM) of the AA7075-T6 aluminum alloy via friction stir deposition to build continuously multilayered parts on [...] Read more.

In the aircraft industry, the high-strength aluminum alloys AA7075 and AA2024 are extensively used for the manufacture of structural parts like stringers and skins, respectively. Additive manufacturing (AM) of the AA7075-T6 aluminum alloy via friction stir deposition to build continuously multilayered parts on a substrate of AA2024-T4 aluminum has not been attempted so far. Accordingly, the present work aimed to explore the applicability of building multilayers of AA7075-T6 alloy on a substrate sheet of AA2024-T4 alloy via the additive friction stir deposition (AFSD) technique and to optimize the deposition process parameters. The experiments were conducted over a wide range of feed rates (1–5 mm/min) and rotation speeds (200–1000 rpm). The axial deposition force and the thermal cycle were recorded. The heat input to achieve the AFSD was calculated. The AA7075 AFSD products were evaluated visually on the macroscale. The microstructures were also investigated utilizing an optical microscope and scanning electron microscope (SEM) equipped with an advanced EDS technique. As well as the presence phases, the mechanical performance of the deposited materials in terms of hardness and compressive strength was also examined. The results showed that the efficiency of the deposition process was closely related to the amount of heat generated, which was governed by the feeding rate, the rotational speed, and the downward force. AA7075 defect-free continuously multilayered parts were produced without any discontinuity defects at the interface with the substrate at deposition conditions of 1, 2, 3, and 4 mm/min and a constant 400 rpm consumable rod rotation speed (CRRS). The additively deposited AA7075-T6 layers exhibited a refined grain structure and uniformly distributed fragment precipitates compared to the base material (BM). The gain size decreased from 25 µm ± 4 for the AA7075-T6 BM to 1.75 µm ± 0.41 and 3.75 µm ± 0.78 for the AFSD materials fabricated at 1 and 4 mm/min deposition feeding rates, respectively, at 400 rpm/min. Among the feeding rates used, the 3 mm/min and 400 rpm rod rotation speed produced an AA7075 deposited part possessing the highest average hardness of 165 HV ± 5 and a compressive strength of 1320 MPa. Full article

(This article belongs to the Special Issue Processing, Properties and Applications of Composite Materials)

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13 pages, 2913 KiB

Open AccessArticle

Thermochemical Analysis of Hydrogenation of Pd-Containing Composite Based on TiZrVNbTa High-Entropy Alloy

by Ivan Savvotin, Elena Berdonosova, Artem Korol, Vladislav Zadorozhnyy, Mikhail Zadorozhnyy, Evgeniy Statnik, Alexander Korsunsky, Mikhail Serov and Semen Klyamkin

Appl. Sci. 2023, 13(16), 9052; https://doi.org/10.3390/app13169052 - 8 Aug 2023

Cited by 2 | Viewed by 1003

Abstract

The microcalorimetric hydrogen titration technique combined with conventional volumetric measurements has been used to reveal peculiarities of the hydrogenation of the single-phase TiZrVNbTa equiatomic high-entropy alloy. The alloy has been produced in the form of microfibers by the pendent drop melt extraction technique. [...] Read more.

The microcalorimetric hydrogen titration technique combined with conventional volumetric measurements has been used to reveal peculiarities of the hydrogenation of the single-phase TiZrVNbTa equiatomic high-entropy alloy. The alloy has been produced in the form of microfibers by the pendent drop melt extraction technique. Palladium coating of the fibers has been applied to enable first hydrogenation at room temperature without additional activation. An analysis of the obtained data allows us to evaluate the dependence of hydrogenation enthalpy on the hydrogen concentration in the alloy. Three concentration ranges, presumably related to the formation of the hydrogen solid solution, monohydride and dihydride phases, have been identified, and the corresponding ΔH values of about −100, −80 and −60 kJ/mol H₂, respectively, have been determined. Full article

(This article belongs to the Special Issue Processing, Properties and Applications of Composite Materials)

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27 pages, 12482 KiB

Open AccessArticle

Deep Drawing Behaviour of Steel–Glass Fibre-Reinforced and Non-Reinforced Polyamide–Steel Sandwich Materials

by Wei Hua, Mohamed Harhash, Gerhard Ziegmann, Adele Carradò and Heinz Palkowski

Appl. Sci. 2023, 13(11), 6629; https://doi.org/10.3390/app13116629 - 30 May 2023

Cited by 2 | Viewed by 1173

Abstract

Thermoplastic-based fibre metal laminates (FMLs) have gained increasing interest in the automotive industry due to their forming potential—especially at higher temperatures—into complex components compared to thermoset-based ones. However, several challenges arise while processing thermoplastic-based FMLs. One the one hand, forming at room temperature [...] Read more.

Thermoplastic-based fibre metal laminates (FMLs) have gained increasing interest in the automotive industry due to their forming potential—especially at higher temperatures—into complex components compared to thermoset-based ones. However, several challenges arise while processing thermoplastic-based FMLs. One the one hand, forming at room temperature (RT) leads to early failure modes, e.g., fracture and delamination. On the other hand, warm forming can extend their forming limits, although further defects arise, such as severe thickness irregularities and wrinkling problems. Therefore, this study focuses on developing different approaches for deep drawing conditions to deliver a promising, feasible, and cost-effective method for deep-drawn FML parts. We also describe the defects experimentally and numerically via the finite element method (FEM). The FMLs based on steel/glass fibre-reinforced polyamide 6 (GF-PA6/steel) are studied under different deep drawing conditions (temperatures, punch, and die dimensions). In addition, mono-materials and sandwich materials without fibre reinforcement are investigated as benchmarks. The results showed that the best deep drawing condition was at a temperature of 200 °C and a die/punch radius ratio of 0.67, with a gap/thickness ratio of ≤2.0. The FEM simulation via Abaqus 6.14 was able to successfully replicate the anisotropic properties and wrinkling of the GF-PA6 core in an FML, resembling the experimental results. Full article

(This article belongs to the Special Issue Processing, Properties and Applications of Composite Materials)

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24 pages, 12779 KiB

Open AccessArticle

Stretching and Forming Limit Curve of Steel–Glass Fibre Reinforced and Non-Reinforced Polyamide–Steel Sandwich Materials

by Wei Hua, Mohamed Harhash, Gerhard Ziegmann, Adele Carradò and Heinz Palkowski

Appl. Sci. 2023, 13(11), 6611; https://doi.org/10.3390/app13116611 - 29 May 2023

Cited by 2 | Viewed by 1456

Abstract

This paper focuses on investigating the forming behaviour of sandwich materials composed of steel sheets and glass fibre-reinforced polyamide 6 (GF-PA6), i.e., thermoplastic-based fibre metal laminates (FML). Stretching and forming limit curve (FLC) determination of FML with different cover/core layer thickness ratios at [...] Read more.

This paper focuses on investigating the forming behaviour of sandwich materials composed of steel sheets and glass fibre-reinforced polyamide 6 (GF-PA6), i.e., thermoplastic-based fibre metal laminates (FML). Stretching and forming limit curve (FLC) determination of FML with different cover/core layer thickness ratios at various forming temperatures, i.e., at room temperature (RT), 200 and 235 °C, are the main approaches for characterizing their formability. In addition, the formability of mono-materials and non-reinforced sandwich materials is investigated as a reference. For a successful test and reliable results, several technical issues are considered, such as the suitable lubrication configuration and digital image correlation at elevated forming temperatures. The results revealed that the formability of non-reinforced sandwich materials with different core layer thicknesses exhibited compared formability to their monolithic steel sheet and no remarkable improvement in their formability with increasing the temperature up to 200 °C. Conversely, the formability of FML shows significant improvement (approx. 300%) with increasing temperature with a forming depth of about 33 mm at 235 °C compared to only 12 mm at RT. Full article

(This article belongs to the Special Issue Processing, Properties and Applications of Composite Materials)

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13 pages, 3575 KiB

Open AccessArticle

Novel Highly Dispersed Additive for Proton-Conducting Composites

by Aleksandr I. Aparnev, Anton V. Loginov, Nikolai Uvarov, Valentina Ponomareva, Irina Bagryantseva, Anton Manakhov, Abdulaziz S. Al-Qasim, Valeriy V. Golovakhin and Alexander G. Bannov

Appl. Sci. 2023, 13(8), 5038; https://doi.org/10.3390/app13085038 - 17 Apr 2023

Cited by 1 | Viewed by 1327

Abstract

The proton conductivity and structural properties of (1–x)CsH₂PO₄–xZnSnO₃ composites with compositions of x = 0.2–0.8 were studied. Zinc stannate ZnSnO₃ was prepared by the thermal decomposition of zinc hydroxostannate ZnSn(OH)₆, which [...] Read more.

The proton conductivity and structural properties of (1–x)CsH₂PO₄–xZnSnO₃ composites with compositions of x = 0.2–0.8 were studied. Zinc stannate ZnSnO₃ was prepared by the thermal decomposition of zinc hydroxostannate ZnSn(OH)₆, which was synthesized by hydrolytic codeposition. To optimize the microstructure of ZnSnO₃, thermal decomposition products of ZnSn(OH)₆ were characterized by thermal analysis and X-ray diffraction, Fourier transform infrared spectroscopy, low-temperature nitrogen adsorption, and electron microscopy. The study reveals that the thermolysis of ZnSn(OH)₆ at temperatures of 300–520 °C formed an X-ray amorphous zinc stannate with a high surface area of 85 m²/g possessing increased water retention, which was used as a matrix for the formation of the composite electrolytes CsH₂PO₄–ZnSnO₃. The CsH₂PO₄ crystal structure remained in the composite systems, but dispersion and partial salt amorphization were observed due to the interface interaction with the ZnSnO₃ matrix. It was shown that the proton conductivity of composites in the low-temperature region increased up to 2.5 orders of magnitude, went through a smooth maximum at x = 0.2, and then decreased due to the percolation effect. The measurement of the proton conductivity of the ZnSnO₃–CsH₂PO₄ composites revealed that zinc stannate can be used as a heterogeneous additive in other composite solid electrolytes. Therefore, such materials can be applied in hydrogen production membrane reactors. Full article

(This article belongs to the Special Issue Processing, Properties and Applications of Composite Materials)

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12 pages, 3371 KiB

Open AccessFeature PaperArticle

The Study of Thermal Stability of Mechanically Alloyed Al-5 wt.% TiO₂ Composites with Cu and Stearic Acid Additives

by Alexey Prosviryakov and Andrey Bazlov

Appl. Sci. 2023, 13(2), 1104; https://doi.org/10.3390/app13021104 - 13 Jan 2023

Cited by 6 | Viewed by 1432

Abstract

In this work, we studied the effect of thermal exposure on the microstructure and mechanical properties of an Al-5 wt.% TiO₂ composite material with additions of 5 wt.% Cu and 2 wt.% stearic acid as a process control agent (PCA), obtained by [...] Read more.

In this work, we studied the effect of thermal exposure on the microstructure and mechanical properties of an Al-5 wt.% TiO₂ composite material with additions of 5 wt.% Cu and 2 wt.% stearic acid as a process control agent (PCA), obtained by mechanical alloying. The composite was processed in a ball mill for 10 h. Composite granules were consolidated by hot pressing at 400 °C. SEM, XRD, and DSC analyses were used to study the microstructure, phase composition, and thermal behavior, respectively. Studies showed that the hot pressing of the material with copper addition leads to the precipitation of Al₂Cu particles from the supersaturated solid solution and a decrease in the microhardness to 233 HV in comparison with the as-milled state (291 HV). In the material with a PCA additive, on the other hand, the microhardness increases from 162 to 187 HV due to the formation of aluminum carbide nanoparticles. In both cases, no reduction reaction products were found. At the same time, the Al-5TiO₂-2PCA material after hot pressing shows a more stable grain structure than the Al-5TiO₂-5Cu material. In addition, the compressive strength at 300 °C of the former material is 1.7 times higher than that of the latter one. Full article

(This article belongs to the Special Issue Processing, Properties and Applications of Composite Materials)

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Review

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42 pages, 7626 KiB

Open AccessReview

Ceramic Matrix Composites for Aero Engine Applications—A Review

by George Karadimas and Konstantinos Salonitis

Appl. Sci. 2023, 13(5), 3017; https://doi.org/10.3390/app13053017 - 26 Feb 2023

Cited by 16 | Viewed by 14426

Abstract

Ceramic matrix materials have attracted great attention from researchers and industry due to their material properties. When used in engineering systems, and especially in aero-engine applications, they can result in reduced weight, higher temperature capability, and/or reduced cooling needs, each of which increases [...] Read more.

Ceramic matrix materials have attracted great attention from researchers and industry due to their material properties. When used in engineering systems, and especially in aero-engine applications, they can result in reduced weight, higher temperature capability, and/or reduced cooling needs, each of which increases efficiency. This is where high-temperature ceramics have made considerable progress, and ceramic matrix composites (CMCs) are in the foreground. CMCs are classified into non-oxide and oxide-based ones. Both families have material types that have a high potential for use in high-temperature propulsion applications. The oxide materials discussed will focus on alumina and aluminosilicate/mullite base material families, whereas for non-oxides, carbon, silicon carbide, titanium carbide, and tungsten carbide CMC material families will be discussed and analyzed. Typical oxide-based ones are composed of an oxide fiber and oxide matrix (Ox-Ox). Some of the most common oxide subcategories are alumina, beryllia, ceria, and zirconia ceramics. On the other hand, the largest number of non-oxides are technical ceramics that are classified as inorganic, non-metallic materials. The most well-known non-oxide subcategories are carbides, borides, nitrides, and silicides. These matrix composites are used, for example, in combustion liners of gas turbine engines and exhaust nozzles. Until now, a thorough study on the available oxide and non-oxide-based CMCs for such applications has not been presented. This paper will focus on assessing a literature survey of the available oxide and non-oxide ceramic matrix composite materials in terms of mechanical and thermal properties, as well as the classification and fabrication methods of those CMCs. The available manufacturing and fabrication processes are reviewed and compared. Finally, the paper presents a research and development roadmap for increasing the maturity of these materials allowing for the wider adoption of aero-engine applications. Full article

(This article belongs to the Special Issue Processing, Properties and Applications of Composite Materials)

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