Cu-1%Cr(mass fraction)and Cu-1%Cr-5%carbon nanotube(CNT)(mass fraction)nanocomposite powders were produced by mechanical alloying and consolidated by hot pressing.Then,nanocomposites were hot-rolled by the order of 50...Cu-1%Cr(mass fraction)and Cu-1%Cr-5%carbon nanotube(CNT)(mass fraction)nanocomposite powders were produced by mechanical alloying and consolidated by hot pressing.Then,nanocomposites were hot-rolled by the order of 50%reduction at 650°C.The structure and microstructure were investigated by X-ray diffractometry(XRD)and scanning electron microscopy(SEM).Relative density,microhardness,thermal stability,electrical and wear properties were evaluated.Compared to the Cu-Cr sample,the relative density of Cu-Cr-CNT sample is greatly improved from 75%to near full density of 98%by hot rolling.Although electrical conductivity and microhardness increase in both Cu-Cr and Cu-Cr-CNT nanocomposites after hot rolling,the effect of hot rolling on the enhancement is more prominent in the presence of CNTs.The microhardness and electrical conductivity of hot-rolled Cu-Cr-CNT nanocomposite approach HV 175 and 68%(IACS),respectively.Also,hot rolling is more effective on thermal stability improvement of Cu-Cr-CNT nanocomposite compared to Cu-Cr composite.However,after hot rolling,both the friction coef?cient and wear loss of the Cu-Cr sample display higher reduction than those of Cu-Cr-CNT nanocomposite owing to different wear mechanisms.After hot rolling,friction coefficient and wear loss of Cu-Cr sample display variation of 25%and 62%,respectively.展开更多
In the present work, a new biocompatible composite was fabricated by hot-press sinter-bonding of polytet- rafluoroethylene （PTFE）-hydroxyapatite composite. Furthermore, the wear properties of this composite were stu...In the present work, a new biocompatible composite was fabricated by hot-press sinter-bonding of polytet- rafluoroethylene （PTFE）-hydroxyapatite composite. Furthermore, the wear properties of this composite were studied by computer-controlled pin-on-disk type tribometer in reporting volume loss per distance. The investigation was performed in three different fractions of hydroxyapatite （10, 20 and 30 wt%）. In order to improve the bonding between hydroxyapatite and PTFE, and thus to increase the wear properties of the composite, the effect of adding silane-coupling agent was investigated. Furthermore, to simulate the environment of human body, some of the wear tests were carried out in the ringer＇s solution. It was found that the wear resistance is improved at high load. Moreover, an optimum fraction of hydroxyapatite （20 wt%） was found in which the best wear resistance is achieved, especially at dry sliding condition. At last, the roles of the factors such as wear load, ringer＇s solution, and silane-coupling agent are described with respect to their influences on the Lancaster wear coefficient.展开更多
基金the financial support of University of Tehran for this researchfinancial supports of Iran Nanotechnology Initiative Council
文摘Cu-1%Cr(mass fraction)and Cu-1%Cr-5%carbon nanotube(CNT)(mass fraction)nanocomposite powders were produced by mechanical alloying and consolidated by hot pressing.Then,nanocomposites were hot-rolled by the order of 50%reduction at 650°C.The structure and microstructure were investigated by X-ray diffractometry(XRD)and scanning electron microscopy(SEM).Relative density,microhardness,thermal stability,electrical and wear properties were evaluated.Compared to the Cu-Cr sample,the relative density of Cu-Cr-CNT sample is greatly improved from 75%to near full density of 98%by hot rolling.Although electrical conductivity and microhardness increase in both Cu-Cr and Cu-Cr-CNT nanocomposites after hot rolling,the effect of hot rolling on the enhancement is more prominent in the presence of CNTs.The microhardness and electrical conductivity of hot-rolled Cu-Cr-CNT nanocomposite approach HV 175 and 68%(IACS),respectively.Also,hot rolling is more effective on thermal stability improvement of Cu-Cr-CNT nanocomposite compared to Cu-Cr composite.However,after hot rolling,both the friction coef?cient and wear loss of the Cu-Cr sample display higher reduction than those of Cu-Cr-CNT nanocomposite owing to different wear mechanisms.After hot rolling,friction coefficient and wear loss of Cu-Cr sample display variation of 25%and 62%,respectively.
文摘In the present work, a new biocompatible composite was fabricated by hot-press sinter-bonding of polytet- rafluoroethylene （PTFE）-hydroxyapatite composite. Furthermore, the wear properties of this composite were studied by computer-controlled pin-on-disk type tribometer in reporting volume loss per distance. The investigation was performed in three different fractions of hydroxyapatite （10, 20 and 30 wt%）. In order to improve the bonding between hydroxyapatite and PTFE, and thus to increase the wear properties of the composite, the effect of adding silane-coupling agent was investigated. Furthermore, to simulate the environment of human body, some of the wear tests were carried out in the ringer＇s solution. It was found that the wear resistance is improved at high load. Moreover, an optimum fraction of hydroxyapatite （20 wt%） was found in which the best wear resistance is achieved, especially at dry sliding condition. At last, the roles of the factors such as wear load, ringer＇s solution, and silane-coupling agent are described with respect to their influences on the Lancaster wear coefficient.
