TiC/Ti_(2)AlC core-shell structure reinforced Ti-based composite coating was prepared by laser cladding technology.The effect of Ti_(2)AlC content on the microstructure and mechanical behavior of the coating was studi...TiC/Ti_(2)AlC core-shell structure reinforced Ti-based composite coating was prepared by laser cladding technology.The effect of Ti_(2)AlC content on the microstructure and mechanical behavior of the coating was studied.The results showed that the reinforced phase was mainly TiC/Ti_(2)AlC MAX phase core-shell structure at 20%Ti_(2)AlC content.According to the synthesis mechanism,Ti_(2)AlC nucleated on TiC through the diffusion of Al atoms to further generate the core-shell structure.The friction and wear test results showed that the wear resistance of the coating was significantly improved under the load distribution effect of the core-shell structure.The friction coefficient decreased to 0.342,and the wear rate reached 8.19×10^(−5)mm^(3)/(N·m),which was only 47.07%of TC4 substrate.展开更多
Increasing environmental concerns about limiting harmful emissions has necessitated sulfur-and phosphorus-free green lubricant additives.Although boron-containing compounds have been widely investigated as green lubri...Increasing environmental concerns about limiting harmful emissions has necessitated sulfur-and phosphorus-free green lubricant additives.Although boron-containing compounds have been widely investigated as green lubricant additives,their macromolecular analogs have been rarely considered yet to develop environmentally friendly lubricant additives.In this work,a series of boron-containing copolymers have been synthesized by free-radical copolymerization of stearyl methacrylate and isopropenyl boronic acid pinacol ester with different feeding ratios(S_(n)-r-B_(m),n=1,m=1/3,1,2,3,5,9).The resulting copolymers of S_(n)-r-B_(m)(n=1,m=1/3,1,2,3,5)are readily dispersed in the PAO-10 base oil and form micelle-like aggregates with hydrodynamic diameters ranging from 9.7 to 52 nm.SRV-IV oscillating reciprocating tribological tests on ball-on-flat steel pairs show that compared with the base oil of PAO-10,the friction coefficients and wear volumes of the base oil solutions of S_(n)-r-B_(m)decrease considerably up to 62%and 97%,respectively.Moreover,the base oil solution of S_(1)-r-B_(1)exhibits an excellent load-bearing capacity of(850±100)N.These superior lubricating properties are due to the formation of protective tribofilms comprising S_(n)-r-B_(m),boron oxide,and iron oxide compounds on the lubricated steel surface.Therefore,the boron-containing copolymers can be regarded as a novel class of environmentally friendly lubricating oil macroadditives for efficient friction and wear reduction without sulfur and phosphorus elements.展开更多
基金Project(52365020) supported by the National Natural Science Foundation of ChinaProject([2022]06) supported by the Special Fund for Special Posts of Guizhou University,China+2 种基金Project([2024]03) supported by the Guizhou University Fund,ChinaProject(ZK[2023]78) supported by the Guizhou Provincial Basic Research Program(Natural Science),ChinaProject(BQW[2024]011) supported by the Guizhou Province Science and Technology Foundation,China。
文摘TiC/Ti_(2)AlC core-shell structure reinforced Ti-based composite coating was prepared by laser cladding technology.The effect of Ti_(2)AlC content on the microstructure and mechanical behavior of the coating was studied.The results showed that the reinforced phase was mainly TiC/Ti_(2)AlC MAX phase core-shell structure at 20%Ti_(2)AlC content.According to the synthesis mechanism,Ti_(2)AlC nucleated on TiC through the diffusion of Al atoms to further generate the core-shell structure.The friction and wear test results showed that the wear resistance of the coating was significantly improved under the load distribution effect of the core-shell structure.The friction coefficient decreased to 0.342,and the wear rate reached 8.19×10^(−5)mm^(3)/(N·m),which was only 47.07%of TC4 substrate.
文摘Increasing environmental concerns about limiting harmful emissions has necessitated sulfur-and phosphorus-free green lubricant additives.Although boron-containing compounds have been widely investigated as green lubricant additives,their macromolecular analogs have been rarely considered yet to develop environmentally friendly lubricant additives.In this work,a series of boron-containing copolymers have been synthesized by free-radical copolymerization of stearyl methacrylate and isopropenyl boronic acid pinacol ester with different feeding ratios(S_(n)-r-B_(m),n=1,m=1/3,1,2,3,5,9).The resulting copolymers of S_(n)-r-B_(m)(n=1,m=1/3,1,2,3,5)are readily dispersed in the PAO-10 base oil and form micelle-like aggregates with hydrodynamic diameters ranging from 9.7 to 52 nm.SRV-IV oscillating reciprocating tribological tests on ball-on-flat steel pairs show that compared with the base oil of PAO-10,the friction coefficients and wear volumes of the base oil solutions of S_(n)-r-B_(m)decrease considerably up to 62%and 97%,respectively.Moreover,the base oil solution of S_(1)-r-B_(1)exhibits an excellent load-bearing capacity of(850±100)N.These superior lubricating properties are due to the formation of protective tribofilms comprising S_(n)-r-B_(m),boron oxide,and iron oxide compounds on the lubricated steel surface.Therefore,the boron-containing copolymers can be regarded as a novel class of environmentally friendly lubricating oil macroadditives for efficient friction and wear reduction without sulfur and phosphorus elements.
