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
A comparative evaluation of the friction and wear behaviors of 40CrNiMoA steel and Inconel 718 alloy sliding against Si_(3)N_(4) counterparts was conducted over a large temperature range from room temperature(RT)to 80...A comparative evaluation of the friction and wear behaviors of 40CrNiMoA steel and Inconel 718 alloy sliding against Si_(3)N_(4) counterparts was conducted over a large temperature range from room temperature(RT)to 800℃.The temperature‐dependent tribological properties associated with the resulting chemical mitigation and structural adaptation of the solid sliding surface were clarified by surface/interface characterizations.The results revealed desirable performance in reducing friction and wear at elevated temperatures,which was associated with the resulting oxide composite filmʹs adaptive lubricating capability,whereas severe abrasive wear occurred at room/ambient temperatures.The oxidative‐abrasive differentials for the two alloys were further discussed by considering the combined effect of temperature and stressed‐shearing conditions.展开更多
Graphene has been shown to be a promising solid lubricant to reduce friction and wear of the sliding counterparts,and currently is reported to only function below 600℃.In this study,its potential as a lubricant above...Graphene has been shown to be a promising solid lubricant to reduce friction and wear of the sliding counterparts,and currently is reported to only function below 600℃.In this study,its potential as a lubricant above 600℃ was studied using a ball-on-disc tribo-meter and a rolling mill.Friction results suggest that a reduction up to 50%can be obtained with graphene nanoplatelets(GnP)under lubricated conditions between 600 and 700℃ when compared with dry tests.and this friction reduction can last more than 3 min.At 800 and 900℃,the friction reduction is stable for 70 and 40 s,respectively,which indicates that GnP can potentially provide an effective lubrication for hot metal forming processes.Hot rolling experiments on steel strips indicate that GnP reduces the rolling force by 11%,7.4%,and 6.9%at 795,890,and 960℃,respectively.These friction reductions are attributed to the easily sheared GnP between the rubbing interfaces.A temperature higher than 600℃ will lead to the gasification of the residual graphene on the strip surface,which is believed to reduce the black contamination from traditional graphite lubricant.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The research received great support from the National Natural Science Foundation of China(Nos.51575505 and 51675508)The work is also funded by Australian Research Council(ARC)Discovery Project(DP)(No.150103718).
文摘A comparative evaluation of the friction and wear behaviors of 40CrNiMoA steel and Inconel 718 alloy sliding against Si_(3)N_(4) counterparts was conducted over a large temperature range from room temperature(RT)to 800℃.The temperature‐dependent tribological properties associated with the resulting chemical mitigation and structural adaptation of the solid sliding surface were clarified by surface/interface characterizations.The results revealed desirable performance in reducing friction and wear at elevated temperatures,which was associated with the resulting oxide composite filmʹs adaptive lubricating capability,whereas severe abrasive wear occurred at room/ambient temperatures.The oxidative‐abrasive differentials for the two alloys were further discussed by considering the combined effect of temperature and stressed‐shearing conditions.
基金This work was supported by the Australian Research Council Discovery Project(No.DP190103455)and the Linkage Project(No.LP160101871).
文摘Graphene has been shown to be a promising solid lubricant to reduce friction and wear of the sliding counterparts,and currently is reported to only function below 600℃.In this study,its potential as a lubricant above 600℃ was studied using a ball-on-disc tribo-meter and a rolling mill.Friction results suggest that a reduction up to 50%can be obtained with graphene nanoplatelets(GnP)under lubricated conditions between 600 and 700℃ when compared with dry tests.and this friction reduction can last more than 3 min.At 800 and 900℃,the friction reduction is stable for 70 and 40 s,respectively,which indicates that GnP can potentially provide an effective lubrication for hot metal forming processes.Hot rolling experiments on steel strips indicate that GnP reduces the rolling force by 11%,7.4%,and 6.9%at 795,890,and 960℃,respectively.These friction reductions are attributed to the easily sheared GnP between the rubbing interfaces.A temperature higher than 600℃ will lead to the gasification of the residual graphene on the strip surface,which is believed to reduce the black contamination from traditional graphite lubricant.
