Wear behavior and mechanism of plasma nitrided steel oscillating against a heat-treated and an untreated aluminum bronze alloy were investigated using an Optimol SRV tribometer.The influence of heat treatment on the m...Wear behavior and mechanism of plasma nitrided steel oscillating against a heat-treated and an untreated aluminum bronze alloy were investigated using an Optimol SRV tribometer.The influence of heat treatment on the mechanical properties of the alloy was evaluated.Furthermore,the wear debris was also examined to understand the wear mechanisms.The results show that a 220-230μm nitrided layer,which was harder than the substrate,was obtained on the steel surface.The tensile strength and hardness of the alloy are found to be significantly improved by the heat treatment associated with low impact toughness.The heat treatment of the alloy did not obviously decrease the friction coefficient of the nitrided steel-bronze couple.However,the wear loss of the nitrided steel increased when it mated with the treated bronze by a severe three-body abrasion.The nitrided steel was mainly damaged by fatigue spalling.Under plane contact conditions,the wear debris was mainly generated from the bronze part and can escape from the interface before being oxidized,leading to the phase structure of all the debris being copper rather than copper oxides.展开更多
Tungsten heavy alloys(WHAs) produced by powder technology are widely used for the mechanical manufacturing, electronic and defense components, etc.Tribological properties of these alloys need to be improved to meet th...Tungsten heavy alloys(WHAs) produced by powder technology are widely used for the mechanical manufacturing, electronic and defense components, etc.Tribological properties of these alloys need to be improved to meet the severe service conditions demanded. Carburization is a promising way to resolve this problem. In this work, microstructure and tribological properties of the carburized 95W–3.5Ni–1.0Fe–0.5Co heavy alloy were investigated in comparison with those of the untreated alloy. Results show that the carburized layer consists of a porous, outer WC layer and a modified W grain layer surrounded by Fe_6W_6C and Co_6W_6C at 970℃, regardless of the carburizing time. The depth of the carburized layer linearly increases in a relatively short time and slightly increases during the subsequent period. Surface roughness increases with carburizing time. Carburization can stabilize friction coefficient and effectively improve the wear resistance of the tungsten heavy alloy due to its significantly increased hardness and non-deformability, but the porous structure in the WC layer has a negative influence on its wear resistance. The carburized layer is damaged in the porous WC layer in the form of the spalling of WC particles where there are some microcracks and micropores, accompanied with peeling due to the solid tribofilm being pushed away.展开更多
基金Project(9140A18070114JW16001)supported by the Advanced Research Fund of Department of Defense,ChinaProject(2014M562171)supported by the China Postdoctoral Science Foundation
文摘Wear behavior and mechanism of plasma nitrided steel oscillating against a heat-treated and an untreated aluminum bronze alloy were investigated using an Optimol SRV tribometer.The influence of heat treatment on the mechanical properties of the alloy was evaluated.Furthermore,the wear debris was also examined to understand the wear mechanisms.The results show that a 220-230μm nitrided layer,which was harder than the substrate,was obtained on the steel surface.The tensile strength and hardness of the alloy are found to be significantly improved by the heat treatment associated with low impact toughness.The heat treatment of the alloy did not obviously decrease the friction coefficient of the nitrided steel-bronze couple.However,the wear loss of the nitrided steel increased when it mated with the treated bronze by a severe three-body abrasion.The nitrided steel was mainly damaged by fatigue spalling.Under plane contact conditions,the wear debris was mainly generated from the bronze part and can escape from the interface before being oxidized,leading to the phase structure of all the debris being copper rather than copper oxides.
基金financially supported by the Advanced Research Fund of Department of Defense, China (No. 9140A18070114JW16001)Guangdong Natural Science Foundation (No. 2015A030310170)
文摘Tungsten heavy alloys(WHAs) produced by powder technology are widely used for the mechanical manufacturing, electronic and defense components, etc.Tribological properties of these alloys need to be improved to meet the severe service conditions demanded. Carburization is a promising way to resolve this problem. In this work, microstructure and tribological properties of the carburized 95W–3.5Ni–1.0Fe–0.5Co heavy alloy were investigated in comparison with those of the untreated alloy. Results show that the carburized layer consists of a porous, outer WC layer and a modified W grain layer surrounded by Fe_6W_6C and Co_6W_6C at 970℃, regardless of the carburizing time. The depth of the carburized layer linearly increases in a relatively short time and slightly increases during the subsequent period. Surface roughness increases with carburizing time. Carburization can stabilize friction coefficient and effectively improve the wear resistance of the tungsten heavy alloy due to its significantly increased hardness and non-deformability, but the porous structure in the WC layer has a negative influence on its wear resistance. The carburized layer is damaged in the porous WC layer in the form of the spalling of WC particles where there are some microcracks and micropores, accompanied with peeling due to the solid tribofilm being pushed away.