Nanocrystalline diamond （NCD） film deposition on pure titanium and Ti alloys is extraordinarily difficult because of the high diffusion coefficient of carbon in Ti, the large mismatch in their thermal expansion coef...Nanocrystalline diamond （NCD） film deposition on pure titanium and Ti alloys is extraordinarily difficult because of the high diffusion coefficient of carbon in Ti, the large mismatch in their thermal expansion coefficients, the complex nature of the interlayer formed during diamond deposition, and the difficulty to achieve very high nucleation density. In this investigation, NCD films were successfully deposited on pure Ti substrate by using a novel substrate pretreatment of ultrasonic scratching in a diamond powder-ethanol suspension and by a two-step process at moderate temperature. It was shown that by scratching with a 30-μm diamond suspension for 1 h, followed by a 10-h diamond deposition, a continuous NCD film was obtained with an average grain size of about 200 nm. Detailed experimental results on the preparation, characterization, and successful deposition of the NCD films on Ti were discussed.展开更多
In order to explore the way to improve the adhesion of the calcium phosphate bioceramic coating to Ti substrate, the CaTiO3 coating was fabricated on Ti substrate by laser cladding （LC） using powders of CaCO3 and Ca...In order to explore the way to improve the adhesion of the calcium phosphate bioceramic coating to Ti substrate, the CaTiO3 coating was fabricated on Ti substrate by laser cladding （LC） using powders of CaCO3 and CaHPO4, and then the composition and microstructure of the coatings were investigated. During LC, CaCO3 can hardly react with Ti, and the coating fabricated using CaCO3 powder is mainly composed of the process of CaO, the decomposition product of CaCO3. Moreover, the coating has a loosened structure and part of it has peeled off from the substrate. CaHPO4 reacts vigorously with Ti, and the coating fabricated using CaHPO4 mainly consists of CaTiO3 which is one of the reaction products between Ti and CaHPO4. Chemical bonding is formed at the interface between coating and substrate, which may enhance the adhesion of the CaTiO3 coating to Ti substrate. Furthermore, CaTiO3 dendrite and eutectic of CaTiO3 and Ca2P2O7 are found on the surface of the coating, implying that a transition can be formed between CaTiO3 and some calcium phosphate bioceramic. So CaTiO3 coating fabricated using CaHPO4 can be a potential candidate to improve the adhesion between calcium phosphate coating and Ti substrate. However, there are also pores and cracks existing in the coating, which may degrade the mechanical properties of the coating.展开更多
基金This work was financially supported by the National Natural Science Foundation of China (No. 50572007) and the Foundation forDoctorial Stations of the Ministry of Education of China
文摘Nanocrystalline diamond （NCD） film deposition on pure titanium and Ti alloys is extraordinarily difficult because of the high diffusion coefficient of carbon in Ti, the large mismatch in their thermal expansion coefficients, the complex nature of the interlayer formed during diamond deposition, and the difficulty to achieve very high nucleation density. In this investigation, NCD films were successfully deposited on pure Ti substrate by using a novel substrate pretreatment of ultrasonic scratching in a diamond powder-ethanol suspension and by a two-step process at moderate temperature. It was shown that by scratching with a 30-μm diamond suspension for 1 h, followed by a 10-h diamond deposition, a continuous NCD film was obtained with an average grain size of about 200 nm. Detailed experimental results on the preparation, characterization, and successful deposition of the NCD films on Ti were discussed.
基金Funded by the National Natural Science Foundation of China (50971102)the National Basic Research Program ("973" Program) of China(2007CB613805)the Programme of Introducing Talents of Discipline to Universities (08040)
文摘In order to explore the way to improve the adhesion of the calcium phosphate bioceramic coating to Ti substrate, the CaTiO3 coating was fabricated on Ti substrate by laser cladding （LC） using powders of CaCO3 and CaHPO4, and then the composition and microstructure of the coatings were investigated. During LC, CaCO3 can hardly react with Ti, and the coating fabricated using CaCO3 powder is mainly composed of the process of CaO, the decomposition product of CaCO3. Moreover, the coating has a loosened structure and part of it has peeled off from the substrate. CaHPO4 reacts vigorously with Ti, and the coating fabricated using CaHPO4 mainly consists of CaTiO3 which is one of the reaction products between Ti and CaHPO4. Chemical bonding is formed at the interface between coating and substrate, which may enhance the adhesion of the CaTiO3 coating to Ti substrate. Furthermore, CaTiO3 dendrite and eutectic of CaTiO3 and Ca2P2O7 are found on the surface of the coating, implying that a transition can be formed between CaTiO3 and some calcium phosphate bioceramic. So CaTiO3 coating fabricated using CaHPO4 can be a potential candidate to improve the adhesion between calcium phosphate coating and Ti substrate. However, there are also pores and cracks existing in the coating, which may degrade the mechanical properties of the coating.
