A plasma electrolytic nitrocarburising （PEN/C） process was performed on stainless steel 316L to improve the surface properties for using as medical implants. A bath was optimised to reduce the required voltage to 15...A plasma electrolytic nitrocarburising （PEN/C） process was performed on stainless steel 316L to improve the surface properties for using as medical implants. A bath was optimised to reduce the required voltage to 150 volts. Aqueous urea-based solutions with 10% NH4Cl were prepared with slightly different amounts of Na2CO3 to optimise the electrolyte composition. The surface and the cross-section morphologies were studied by scanning electron microscopy. The microstructure and the chemical composition of samples were investigated by X-ray diffraction （XRD） and energy dispersive X-ray （EDX） techniques. The microstructure of the outer layer of the coatings was found to be a complex oxide containing Cr and Fe. The wear properties of the samples were examined by using a pin on disk wear test with Ringer＇s solution and were compared with their wear properties in the ambient atmosphere. The Ringe（s solution acted as a lubricant, reducing friction coefficient. Hardness and roughness were also studied. The bath with the composition of 10% NH4CI and 3% Na2CO3 exhibited the best tribological properties. The results showed that the tribological properties of treated samples were improved and the wear mechanism was abrasion of the pin.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supported by the Research Committee of Shiraz University under grant No.88-GR-ENG-62,which is gratefully appreciated
文摘A plasma electrolytic nitrocarburising （PEN/C） process was performed on stainless steel 316L to improve the surface properties for using as medical implants. A bath was optimised to reduce the required voltage to 150 volts. Aqueous urea-based solutions with 10% NH4Cl were prepared with slightly different amounts of Na2CO3 to optimise the electrolyte composition. The surface and the cross-section morphologies were studied by scanning electron microscopy. The microstructure and the chemical composition of samples were investigated by X-ray diffraction （XRD） and energy dispersive X-ray （EDX） techniques. The microstructure of the outer layer of the coatings was found to be a complex oxide containing Cr and Fe. The wear properties of the samples were examined by using a pin on disk wear test with Ringer＇s solution and were compared with their wear properties in the ambient atmosphere. The Ringe（s solution acted as a lubricant, reducing friction coefficient. Hardness and roughness were also studied. The bath with the composition of 10% NH4CI and 3% Na2CO3 exhibited the best tribological properties. The results showed that the tribological properties of treated samples were improved and the wear mechanism was abrasion of the pin.
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.
