Deposition parameters that have great influences on hot filament chemical vapor deposition (HFCVD) diamond films growth on inner hole surfaces of WC?Co substrates mainly include the substrate temperature (t), carbon c...Deposition parameters that have great influences on hot filament chemical vapor deposition (HFCVD) diamond films growth on inner hole surfaces of WC?Co substrates mainly include the substrate temperature (t), carbon content (φ), total pressure (p) and total mass flow (F). Taguchi method was used for the experimental design in order to study the combined effects of the four parameters on the properties of as-deposited diamond films. A new figure-of-merit (FOM) was defined to assess their comprehensive performance. It is clarified thatt,φandp all have significant and complicated effects on the performance of the diamond film and the FOM, which also present some differences as compared with the previous studies on CVD diamond films growth on plane or external surfaces. Aiming to deposit HFCVD diamond films with the best comprehensive performance, the key deposition parameters were finally optimized as:t=830 °C,φ=4.5%,p=4000 Pa,F=800 mL/min.展开更多
Finite element model was developed to analyze thermal residual stress distribution of diamond coating on graded and homogeneous substrates. Graded cemented carbides were formed by carburizing pretreatment to reduce th...Finite element model was developed to analyze thermal residual stress distribution of diamond coating on graded and homogeneous substrates. Graded cemented carbides were formed by carburizing pretreatment to reduce the cobalt content in the surface layer and improve adhesion of diamond coating. The numerical calculation results show that the surface compressive stress of diamond coating is 950 MPa for graded substrate and l 250 MPa for homogenous substrate, the thermal residual stress decreases by around 24% due to diamond coating. Carburizing pretreatment is good for diamond nucleation rate, and can increase the interface strength between diamond coating and substrate.展开更多
The work in this study is focused on investigation of composite nickel coatings. The coatings were deposited on ductile cast iron samples of different composition by electroless method EFTTOM NICKEL with addition of s...The work in this study is focused on investigation of composite nickel coatings. The coatings were deposited on ductile cast iron samples of different composition by electroless method EFTTOM NICKEL with addition of strengthening nanodiamond particles （2-4 nm）, The samples were prepared by casting and austempering. The microstructure, microhardness and wear resistance of the coatings were investigated. The thickness of the coatings was also determined （8-10μm）. Metallographic analyses, SEM （scanning electron microscopic） investigation, microhardness measurements by knoop method, wear resistance tests were carried out. The coatings with and without heat treatment at 290℃, 6 h were tested. Duplication of microhardness value and improvement of the coating＇s properties of heat treated coatings were observed.展开更多
基金Projects(51275302,51005154)supported by the National Natural Science Foundation of China
文摘Deposition parameters that have great influences on hot filament chemical vapor deposition (HFCVD) diamond films growth on inner hole surfaces of WC?Co substrates mainly include the substrate temperature (t), carbon content (φ), total pressure (p) and total mass flow (F). Taguchi method was used for the experimental design in order to study the combined effects of the four parameters on the properties of as-deposited diamond films. A new figure-of-merit (FOM) was defined to assess their comprehensive performance. It is clarified thatt,φandp all have significant and complicated effects on the performance of the diamond film and the FOM, which also present some differences as compared with the previous studies on CVD diamond films growth on plane or external surfaces. Aiming to deposit HFCVD diamond films with the best comprehensive performance, the key deposition parameters were finally optimized as:t=830 °C,φ=4.5%,p=4000 Pa,F=800 mL/min.
基金Project(50323008) supported by the National Natural Science Foundation of China
文摘Finite element model was developed to analyze thermal residual stress distribution of diamond coating on graded and homogeneous substrates. Graded cemented carbides were formed by carburizing pretreatment to reduce the cobalt content in the surface layer and improve adhesion of diamond coating. The numerical calculation results show that the surface compressive stress of diamond coating is 950 MPa for graded substrate and l 250 MPa for homogenous substrate, the thermal residual stress decreases by around 24% due to diamond coating. Carburizing pretreatment is good for diamond nucleation rate, and can increase the interface strength between diamond coating and substrate.
文摘The work in this study is focused on investigation of composite nickel coatings. The coatings were deposited on ductile cast iron samples of different composition by electroless method EFTTOM NICKEL with addition of strengthening nanodiamond particles （2-4 nm）, The samples were prepared by casting and austempering. The microstructure, microhardness and wear resistance of the coatings were investigated. The thickness of the coatings was also determined （8-10μm）. Metallographic analyses, SEM （scanning electron microscopic） investigation, microhardness measurements by knoop method, wear resistance tests were carried out. The coatings with and without heat treatment at 290℃, 6 h were tested. Duplication of microhardness value and improvement of the coating＇s properties of heat treated coatings were observed.
