AISI 321 austenitic stainless steel was treated using rf plasma carbonitriding with the intention of use low-cost orthopedic implant material in biomedical applications. The treatment process was carried at low workin...AISI 321 austenitic stainless steel was treated using rf plasma carbonitriding with the intention of use low-cost orthopedic implant material in biomedical applications. The treatment process was carried at low working gas pressure of 0.075 mbar in nitrogen-acetylene gaseous mixture to form a superficial carbonitrided layer. The samples were treated using rf inductively coupled at a fixed plasma-processing power of 500 W and for a processing time varied from 4 to 20 minutes. The microstructural, mechanical and tribological properties of the untreated and treated samples were studied. The surface hardness is improved by rf plasma carbonitriding to a maximum of 1468 HV0.1 for plasma-processing time of 16 min. To evaluate the biocompatibility performance, the blood was cultured in RPMI media to test the adhesion of blood cells on the untreated and treated samples. It has been found that the blood adhesion on the treated samples is enhanced with increasing the plasma-processing time. The contact angle of the carbonitrided surfaces is decreased to lower values compared to that of the untreated surface. Furthermore, the carbonitrided layer in-vitro corrosion was tested in Ringer’s solution. A degradation in the corrosion resistance was observed for the sample carbonitrided at low plasma processing time of 4 min. However, the corrosion resistance increased to a maximum value at a plasma-processing time of 8 min then gradually decreased with further increase of plasma processing time.展开更多
AISI 316 austenitic stainless steel was carbonitrided using rf plasma with purpose of using low-cost orthopedic implant materials in biomedical applications besides the manufacturing requests. The plasma treatment pro...AISI 316 austenitic stainless steel was carbonitrided using rf plasma with purpose of using low-cost orthopedic implant materials in biomedical applications besides the manufacturing requests. The plasma treatment process was accomplished at low working gas pressure of 0.075 mbar in nitrogen-acetylene gaseous mixture. The plasma-processing time was fixed at 10 min while the plasma-processing power was varied from 450 to 650 watt. The effect of plasma treatment power on the structure, tribological, mechanical, electrochemical and biocompatibility of AISI 316 has been investigated. The structural results demonstrated the formation of nitrogen and carbon solid solutions, chromium nitride, iron carbide and iron nitride phases in the treated samples. The microhardness of the treated layer increases with increasing the processing power to reach a maximum value of approximately 1300 HV0.1 at 600 W which represents more than 6-folds increase in microhardness in comparison with the untreated matrix. The wear and corrosion resistance of the treated AISI 316 were enhanced compared to the untreated one. The friction coefficient was reduced from nearly 0.5 for the untreated substrate to nearly 0.3 for the carbonitrided sample. The surface energy and wettability of the carbonitrided samples were augmented as the plasma-processing power increased. Furthermore, the numbers of grown mesenchymal stem cells are higher for carbonitrided samples compared to the untreated one. The formation of nitrogen and carbon solid solution, chromium nitride, iron nitride and iron carbide hard phases after carbonitriding process is responsible for achieving good mechanical, tribological, biocompatibility and electrochemical properties for AISI 316 alloys.展开更多
文摘AISI 321 austenitic stainless steel was treated using rf plasma carbonitriding with the intention of use low-cost orthopedic implant material in biomedical applications. The treatment process was carried at low working gas pressure of 0.075 mbar in nitrogen-acetylene gaseous mixture to form a superficial carbonitrided layer. The samples were treated using rf inductively coupled at a fixed plasma-processing power of 500 W and for a processing time varied from 4 to 20 minutes. The microstructural, mechanical and tribological properties of the untreated and treated samples were studied. The surface hardness is improved by rf plasma carbonitriding to a maximum of 1468 HV0.1 for plasma-processing time of 16 min. To evaluate the biocompatibility performance, the blood was cultured in RPMI media to test the adhesion of blood cells on the untreated and treated samples. It has been found that the blood adhesion on the treated samples is enhanced with increasing the plasma-processing time. The contact angle of the carbonitrided surfaces is decreased to lower values compared to that of the untreated surface. Furthermore, the carbonitrided layer in-vitro corrosion was tested in Ringer’s solution. A degradation in the corrosion resistance was observed for the sample carbonitrided at low plasma processing time of 4 min. However, the corrosion resistance increased to a maximum value at a plasma-processing time of 8 min then gradually decreased with further increase of plasma processing time.
文摘AISI 316 austenitic stainless steel was carbonitrided using rf plasma with purpose of using low-cost orthopedic implant materials in biomedical applications besides the manufacturing requests. The plasma treatment process was accomplished at low working gas pressure of 0.075 mbar in nitrogen-acetylene gaseous mixture. The plasma-processing time was fixed at 10 min while the plasma-processing power was varied from 450 to 650 watt. The effect of plasma treatment power on the structure, tribological, mechanical, electrochemical and biocompatibility of AISI 316 has been investigated. The structural results demonstrated the formation of nitrogen and carbon solid solutions, chromium nitride, iron carbide and iron nitride phases in the treated samples. The microhardness of the treated layer increases with increasing the processing power to reach a maximum value of approximately 1300 HV0.1 at 600 W which represents more than 6-folds increase in microhardness in comparison with the untreated matrix. The wear and corrosion resistance of the treated AISI 316 were enhanced compared to the untreated one. The friction coefficient was reduced from nearly 0.5 for the untreated substrate to nearly 0.3 for the carbonitrided sample. The surface energy and wettability of the carbonitrided samples were augmented as the plasma-processing power increased. Furthermore, the numbers of grown mesenchymal stem cells are higher for carbonitrided samples compared to the untreated one. The formation of nitrogen and carbon solid solution, chromium nitride, iron nitride and iron carbide hard phases after carbonitriding process is responsible for achieving good mechanical, tribological, biocompatibility and electrochemical properties for AISI 316 alloys.
