High-entropy alloy matrix solid-lubricating composites(HSLCs)are promising anti-wear and friction-reduced materials to meet the demands of complicated engineering applications.Here we present a strat-egy to develop HS...High-entropy alloy matrix solid-lubricating composites(HSLCs)are promising anti-wear and friction-reduced materials to meet the demands of complicated engineering applications.Here we present a strat-egy to develop HSLCs by using the coupled high-entropy phases of(BCC+FCC+L2_(1))with near-equal volume fraction as the matrix material,instead of using the usual single phase-dominated high-entropy phases,which can preserve the intrinsic strength and deformability of the matrix while activating adap-tive wear protection during sliding.This enables a low coefficient of frictions of 0.23-0.31 and wear rates within the order of 10^(-6)-10^(-5) mm^(3) N m^(-1) for the(CrFeNi)_(83)(AlTi)_(17)-Ag-BaF_(2)/CaF_(2) HSLC between room-temperature and 800℃,considerably outperforming the reported HSLCs and conventional alloy matrix solid-lubricating composites.At low and moderate temperatures,the synergistic Ag-BaF_(2)/CaF_(2) lubricat-ing films eliminate the surface stress concentration upon wear,thus suppressing three-body abrasion and surface roughening during the groove multiplication process.At elevated temperatures,the high-entropy composite tribo-layers provide the friction interface with strong and deformable stress shielding,which avoids the oxidative and adhesive wear triggered by the delamination of the tribo-layer.Developing sim-ilar coupled high-entropy matrix phases may open an avenue for further optimization of the tribological properties of the HSLCs.展开更多
The development of a high‐performance solid‐lubricating composite with excellent self‐lubricity over a broad temperature range in vacuum is significant to solve the frictional problems of spatial mechanisms.In this...The development of a high‐performance solid‐lubricating composite with excellent self‐lubricity over a broad temperature range in vacuum is significant to solve the frictional problems of spatial mechanisms.In this study,the vacuum tribological behaviors of nickel‐matrix/Ag/(Ca,Ba)F2/graphite(0–2 wt%)composites were studied from 25 to 800°C.The results show that the synergistic effects of solid lubricants can significantly improve the tribological properties of the composites in vacuum,with the graphite content contributing considerably.For 2 wt%graphite,a low friction coefficient(0.14–0.25)and the lowest wear rate((0.12–4.78)×10^(-5) mm^(3)∙N^(-1)∙m^(-1))were observed in vacuum over the entire testing temperature range.Moreover,the wear mechanisms were clarified via analysis of the chemical composition and morphologies of the sliding surfaces.展开更多
基金supported by the National Natural Science Foundation of China (Nos.52175197 and 51975557)the Outstanding Youth Fund of Gansu Province (No.20JR5RA571)the Youth Innovation Promotion Association CAS (No.2022425).
文摘High-entropy alloy matrix solid-lubricating composites(HSLCs)are promising anti-wear and friction-reduced materials to meet the demands of complicated engineering applications.Here we present a strat-egy to develop HSLCs by using the coupled high-entropy phases of(BCC+FCC+L2_(1))with near-equal volume fraction as the matrix material,instead of using the usual single phase-dominated high-entropy phases,which can preserve the intrinsic strength and deformability of the matrix while activating adap-tive wear protection during sliding.This enables a low coefficient of frictions of 0.23-0.31 and wear rates within the order of 10^(-6)-10^(-5) mm^(3) N m^(-1) for the(CrFeNi)_(83)(AlTi)_(17)-Ag-BaF_(2)/CaF_(2) HSLC between room-temperature and 800℃,considerably outperforming the reported HSLCs and conventional alloy matrix solid-lubricating composites.At low and moderate temperatures,the synergistic Ag-BaF_(2)/CaF_(2) lubricat-ing films eliminate the surface stress concentration upon wear,thus suppressing three-body abrasion and surface roughening during the groove multiplication process.At elevated temperatures,the high-entropy composite tribo-layers provide the friction interface with strong and deformable stress shielding,which avoids the oxidative and adhesive wear triggered by the delamination of the tribo-layer.Developing sim-ilar coupled high-entropy matrix phases may open an avenue for further optimization of the tribological properties of the HSLCs.
基金This work was supported by the National Natural Science Foundation of China(Nos.51675510 and 51975558)the Open Foundation for the State Key Laboratory of Solid Lubrication(No.LSL‐1808).
文摘The development of a high‐performance solid‐lubricating composite with excellent self‐lubricity over a broad temperature range in vacuum is significant to solve the frictional problems of spatial mechanisms.In this study,the vacuum tribological behaviors of nickel‐matrix/Ag/(Ca,Ba)F2/graphite(0–2 wt%)composites were studied from 25 to 800°C.The results show that the synergistic effects of solid lubricants can significantly improve the tribological properties of the composites in vacuum,with the graphite content contributing considerably.For 2 wt%graphite,a low friction coefficient(0.14–0.25)and the lowest wear rate((0.12–4.78)×10^(-5) mm^(3)∙N^(-1)∙m^(-1))were observed in vacuum over the entire testing temperature range.Moreover,the wear mechanisms were clarified via analysis of the chemical composition and morphologies of the sliding surfaces.