Layered double hydroxides (LDHs) are a class of naturally occurring inorganic minerals that are composed of divalent and trivalent metal cations. In this study, three different sized NiAl-LDH ...nanoplatelets were synthesized by varying crystallization time during the microemulsification process. The layered structure and three-dimensional size of nanoplatelets were confirmed by transmission electron microscopy (TEM) and atomic force microscopy (AFM). As lubricant additives, their tribological properties in base oil were evaluated by use of a ball-on-disk reciprocating tribometer under three different loads: 50, 100, and 150 N (which created peak Hertz pressures of 1.74, 2.16, and 2.47 GPa). Under contact pressures of up 2.16 GPa, not only did the coefficient of friction (COF) decrease by about 10% after nano-LDHs were added but also the wear performance improved substantially. These improvements resulted from a protective tribolayer formation on the contact interface, as revealed by detailed surface and structure analytical studies. In particular, cross-sectional TEM images revealed that the larger size nanoplatelets (NiAl-24h), rather than the smaller ones (NiAl-6h) showed the best and most stable tribological performance. This was mainly because of their higher degree of crystallinity, which in turn resulted in the formation of a tribofilm with far superior mechanical properties during sliding. Owing to the simple synthetic method and superior tribological properties as oil-based additives, nano-LDHs hold great potential for use in demanding industrial applications in the future.
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IJS, KILJ, NUK, PNG, UL, UM
High performance materials with low friction and high vibration-absorbing properties play a vital role in stable operation of water-lubricated ship stern bearings. Therefore, a TPU composite material ...reinforced by WS2 and UHMWPE was prepared. After friction and vibration tests, it was found that WS2 reduced the coefficient of friction of TPU matrix with its excellent lubricating properties, and after adding UHMWPE, the coefficient of friction continued to drop to 0.07 and became more stable during the whole friction process. The synergistic effect of WS2 and UHMWPE effectively reduced the friction and amplitude of the composite and made the composite present the best tribological and vibration-absorbing performance. This research provided a basis for the design of new water-lubricated ship bearing materials.
•A novel composite material for water-lubricated bearings reinforced by WS2 and UHMWPE was prepared.•WS2 significantly reduced the COF and wear rate of the composite and weakened the friction-induced vibration behaviour.•UHMWPE minimized the COF and stabilised the friction process, and further improving the tribological and damping properties of the composite.•The composites modified with 4 % WS2 and 10 % UHMWPE exhibited the best friction-reducing and vibration-absorbing performances.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In the field of aviation and aerospace engineering, the application of high-entropy alloys (HEAs) is inevitably needs to withstand the damage of both wear and adhesion in vacuum. Herein, the vacuum ...tribological behavior of a high performance Co21Cr21Fe21Ni21V14.5C1.5 HEAs (C12) were investigated. In this study, the hardness and compressive strength, significantly improved for Co21Cr21Fe21Ni21V14.5C1.5 (1200 °C, C12) HEA compared to the CoCrFeNiV (C0) base alloy. The focus was put on the effect of C element and sintering temperature at 1000 ℃ and1200 ℃ (C10 and C12) on the microstructure and vacuum tribological mechanisms of the alloy. It was found that the friction coefficient of the C12 alloy under air can be minimized to lower than 0.37. The wear rate of C12 alloy ((1.31–2.67)× 10−4 mm3/Nm) is 2–4 times lower than that of C10 alloy (2.91–8.31)× 10−4 mm3/Nm). The wear-resistance of Co21Cr21Fe21Ni21V14.5C1.5 alloy at sinter temperature 1200 °C (C12) is significantly higher than that of alloy sinter temperature at 1000 °C (C10). Therefore, C12 alloy exhibited optimal vacuum tribological properties. This work provides helpful guidance for material design and wear resistance in the field of space tribology.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this study, (AlCoCrFeNi)1-x(WC)x high-entropy alloy composites with different WC weight ratios (x = 0, 10, 30, 50 wt%) were prepared using the gas atomization method and a vacuum hot-pressing ...sintering technique. The phase compositions, microstructures, and tribological properties in a wide temperature domain of the (AlCoCrFeNi)1-x(WC)x composites were evaluated over a wide temperature range. The results showed that an increase in the WC weight fraction promoted the diffusion of Fe, Co, and Ni from the body-centered cubic (BCC) and face-centered cubic (FCC) phases to generate η-carbide phases containing WC. This hindered the transformation of the BCC phase to the FCC+σ phase, resulting in a decrease in the FCC content and an increase in the BCC phase. The BCC phase further decomposed into the A2+B2 phase by spinodal decomposition. At the same time, the coupling strengthening effect of the η-carbide, BCC, and WC phases resulted in a significant increase in the hardness of the (AlCoCrFeNi)1-x(WC)x composites.
The characterization of the tribological properties of the (AlCoCrFeNi)1-x(WC)x composites over a wide temperature range showed that the friction coefficient decreased with the addition of WC. In addition, the (AlCoCrFeNi)1-x(WC)x composites showed good tribological properties and wear resistance at high temperatures, i.e., the wear rate of the composites decreased significantly. This can be attributed to the formation of an oxide film on the worn surface.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The stability of a titanium alloy screw implant in a spinal internal fixation system is primarily influenced by its tribological properties. We integrated laser texturing and anodic oxidation ...technology to fabricate surface micro/nanostructures on titanium alloys. The tribological properties of titanium alloys against bone were investigated by mimicking the progress of screw implantation. The results demonstrated that surface structure reduced the dynamic friction of the titanium alloy under dry conditions and increased the static friction under wet conditions. The low sliding friction in the dry state facilitated the initial implantation of the titanium alloy screws. Conversely, the high static friction in the wet state prevents post-implantation loosening of the titanium alloy screw and enhances its stability within bone tissue.
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•Contact normal load between screw and bone was determined utilizing the classical model proposed by Hagiwara and Ohashi.•Laser texturing and anodic oxidation technology to fabricate surface micro/nanostructures on titanium alloys.•Tribological properties of titanium alloys against bone were investigated by mimicking the progress of screw implantation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The interfacial compatibility issue of boron nitride (BN) nanofillers in epoxy resin (EP) matrix is one of the major challenges plaguing the efficient application of composites. Herein, inspired by ...phenol-amine green chemistry, microwave-assisted ball milling was used to synthesize tannic acid (TA) and polyethyleneimine (PEI) functionalized boron nitride (TA/PEI@BN). Characterization indicated that TA/PEI grafted on BN via both non-covalent and covalent interactions, which improved the interfacial compatibility and cross-linking properties of TA/PEI@BN within the EP. Meanwhile, the introduction of 0.25 % TA/PEI@BN reduced the average friction coefficient and wear rate of the EP composite coating by 17 % and 50 %, respectively. The characterization of the friction interface showed that TA/PEI@BN could exhibit a "sliding complementary repair" effect during friction. This work presents a novel, green, and scalable method for realizing the surface functionalization of BN, beneficial for the further application of high-performance epoxy matrix composites.
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•TA/PEI functionalized BN (TA/PEI@BN) was synthesized by microwave-assisted ball milling.•Microwave-assisted ball milling had a facilitating effect on the cross-linking reaction of TA and PEI.•TA/PEI@BN has good interfacial compatibility in epoxy resins.•TA/PEI@BN/EP composite coatings have improved tribological properties.•The frictional wear process of epoxy composite coatings was modeled.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Technological advancements in functionally graded materials.•Comparison of various homogenization schemes.•Review on analysis of functionally graded structures.•Suggested future scope in the ...analysis of functionally graded structures.•Review on various fabrication methods of functionally graded materials along their mechanical and tribological performance.
This paper discourses an overview of the recent advancements in functionally graded materials (FGMs) research. The paper also disseminates on the key researches that are carried out in the scientific community on the development of manufacturing and modelling of functionally graded materials. The rationale of the current work is to emphasize the selection of materials, processing techniques and analytical modelling and applications of FGMs. Alongside, challenges involved in developing these materials towards various aspects of scientific and technological fields will be addressed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
CoCrFeNiMn high-entropy alloy (HEA) matrix composites with different mass fraction of Cr3C2 are produced by spark plasma sintering. The composites are composed of HEA's face-centered-cubic and Cr7C3 ...phases. When addition of Cr3C2 increases, the hardness and yield strength of composites increase. The friction coefficients at room temperature (RT), 200 and 800 °C exhibit a decreasing tendency with the increase of Cr3C2 content. The wear rates decrease from RT to 800 °C when adding 10% Cr3C2 in CoCrFeNiMn HEA. The wear mechanisms of CoCrFeNiMn HEA matrix composites are governed by abrasion and adhesive wear from RT to 400 °C, and change to oxidation wear above 400 °C. Combined the mechanical and tribological properties, CoCrFeNiMn-10% Cr3C2 composite possesses the best comprehensive properties.
•The CoCrFeNiMn high entropy alloy matrix composites with different Cr3C2 content are produced by spark plasma sintering, and the Cr3C2 decarburizes forming Cr7C3 phase with improving stability, hardness and wear resistance.•The hardness and strength of the CoCrFeNiMn high entropy alloy matrix composites increase with the increasing of the Cr3C2 content.•The wear resistance improves significantly from room temperature to 800 °C as 10% Cr3C2 is added in the CoCrFeNiMn high entropy alloy matrix.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This work aims to investigate the effects of load condition induced and nanosilica-rich tribofilm that tribo-sintered on the steel counterbody on the tribological performance of the PEEK-based ...composite. It reveals that high load condition is favourable for encapsulating the detached nanosilica and promoting the formation of even, thick, and robust tribo-sintered tribofilm, which possesses outstanding lubricating ability and long lifetime. Transfer film tribo-sintered at 8 MPa and 4 m/s reduces the COF by 29.6% and specific wear rate by 43.7%, respectively. Morphologies analysis shows that high load condition promotes the coating of polymeric debris and crushing of accumulated nanosilica on counterbody surface, which benefits the embedding of nanosilica into the sintered tribofilm that significantly reduces the severe friction and wear.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Introducing wear-resistant layers or constructing microtextures is normally employed to improve the wear resistance of materials. However, single role of the wear-resistant layer or microtexture ...still could not effectively address the wear issue of titanium alloys. In this study, a sinusoidal nitriding layer is directly fabricated on the Ti6Al4V surface by one-step laser irradiation. Chemical composition and microstructure analysis indicate that the nitriding layer contains TiN and α-Ti phases, and it is metallurgically bonded to the heat-affected zone. Friction wear tests show a 96.9 % reduction in wear rate with dry sliding and 99.6 % with oil lubrication, without exhibiting groove orientation dependence. The wear mechanism is discussed by scrutinizing the morphology of the wear scars and their corresponding cross-sections.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
