Polycrystalline diamond films have been synthesized on various substrates by hot filament CVD from the mixture gases of methane and hydrogen. The interface layers between CVD diamond films and substrates have been inv...Polycrystalline diamond films have been synthesized on various substrates by hot filament CVD from the mixture gases of methane and hydrogen. The interface layers between CVD diamond films and substrates have been investigated by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). In addition, visible luminescence between 2.0～3.5eV of undoped and boron-doped CVD diamond films has also been studied by cathodoluminescence.展开更多
Diamond films were deposited on high-speed steel substrates by hot filament chemical vapor deposition （HFCVD） method. To minimize the early formation of graphite and to enhance the diamond film adhesion, a WC-Co coa...Diamond films were deposited on high-speed steel substrates by hot filament chemical vapor deposition （HFCVD） method. To minimize the early formation of graphite and to enhance the diamond film adhesion, a WC-Co coating was used as an interlayer on the steel substrates by high velocity oxy-fuel spraying. The effects of methane content on nucleation, quality, residual stress and adhesion of diamond films were investigated. The results indicate that the increasing methane content leads to the increase in nucleation density, residual stress, the degradation of quality and adhesion of diamond films. Diamond films deposited on high-speed steel （HSS） substrate with a WC-Co interlayer exhibit high nucleation density and good adhesion under the condition of the methane content initially set to be a higher value （4%, volume fraction） for 30 min, and then reduced to 2% for subsequent growth at pressure of 3 kPa and substrate temperature of 800 ℃.展开更多
Diamond-coated tools were fabricated using Co-cemented carbide inserts as substrates by the electronically aided hot filament chemical vapor deposition (EACVD). An amount of additive in an acid solution was used to pr...Diamond-coated tools were fabricated using Co-cemented carbide inserts as substrates by the electronically aided hot filament chemical vapor deposition (EACVD). An amount of additive in an acid solution was used to promote the Co etching of the substrate surface. The surface of the WC-Co substrate was decarburized by microwave plasma with Ar-H 2 gas. Effect of the new substrate pretreatment on the adhesion of diamond films was investigated. A boron-doped solution was brushed on the tool surface to diffuse boron into the substrates during diamond deposition. A new process was used to lower the surface roughness of diamond thin films by appropriately controlling deposition parameters. It consists of a composite diamond film chemical vapor deposition procedure including first the deposition of the rough polycrystalline diamond and then the fine-grained diamond. The research results show that the pretreatment including both Co etching in acid solution and Ar-H 2 etching decarburization by microwave plasma is an effective method to enhance adhesive strength. An adequate amount of boron dopant solution can effectively suppress the cobalt diffusion to the surface and avoid the catalytic effect of Co at the high temperature. The composite film CVD process can deposit smooth diamond films with low surface roughness. It is of great significance for improvement of the cutting performances of diamond-coated tools using the above new technology to deposit diamond coatings with the low surface roughness and high adhesive strength on WC-Co substrates.展开更多
Compared with the sintered polycrystalline diamond, the deposited thin film diamond has the great advantage on the fabrication of cutting tools with complex geometries such as drills. Because of their low costs for fa...Compared with the sintered polycrystalline diamond, the deposited thin film diamond has the great advantage on the fabrication of cutting tools with complex geometries such as drills. Because of their low costs for fabrication equipment and high performance on high speed machining non-ferrous metals and alloys, metal-compound materials, and hard brittle non-metals, diamond-coated drills find great potentialities in the commercial application. However, the poor adhesion of the diamond film on the substrate becomes the main technical barriers for the successful development and commercialization of diamond-coated tools. In this paper, diamond thin films were deposited on WC-Co based drills by the electron aided hot filament chemical vapor deposition (EACVD). A new multiple chemical pre-treatment technology including microwave oxidation, reaction in alkaline solution and cleaning by ultrasonic treatment in acid solution was developed and affects on the diamond adhesion strength, nucleation and surface morphology were investigated. At the same time, a special setup to fabricate diamond-coated drills was also developed and then the novel CVD process based on the varied parameters controlling model was presented, therefore the uniform quality and homogenized thickness of diamond coating could be available. From practical utilization viewpoint, the cutting performance of the diamond-coated drill was studied by drilling SiC particle reinforced aluminum matrix composite. The satisfied wear resistance and decrease of torque and thrust led to the long life of this kind of drill. This paper exhibited the meaningful work for the development of cutting tools with complex geometries and further extended the application of diamond material.展开更多
基金This work is supported by the National Natural Science Foundation of China.
文摘Polycrystalline diamond films have been synthesized on various substrates by hot filament CVD from the mixture gases of methane and hydrogen. The interface layers between CVD diamond films and substrates have been investigated by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). In addition, visible luminescence between 2.0～3.5eV of undoped and boron-doped CVD diamond films has also been studied by cathodoluminescence.
基金Project(1343-74236000005) supported by the Innovation Foundation for Postgraduates of Hunan Province, ChinaProject(ZKJ2008001) supported by the Open Fund for Valuable Instruments of Central South University, ChinaProject(2008112048) supported by the Open Fund of State Key Laboratory of Metallurgy, China
文摘Diamond films were deposited on high-speed steel substrates by hot filament chemical vapor deposition （HFCVD） method. To minimize the early formation of graphite and to enhance the diamond film adhesion, a WC-Co coating was used as an interlayer on the steel substrates by high velocity oxy-fuel spraying. The effects of methane content on nucleation, quality, residual stress and adhesion of diamond films were investigated. The results indicate that the increasing methane content leads to the increase in nucleation density, residual stress, the degradation of quality and adhesion of diamond films. Diamond films deposited on high-speed steel （HSS） substrate with a WC-Co interlayer exhibit high nucleation density and good adhesion under the condition of the methane content initially set to be a higher value （4%, volume fraction） for 30 min, and then reduced to 2% for subsequent growth at pressure of 3 kPa and substrate temperature of 800 ℃.
文摘Diamond-coated tools were fabricated using Co-cemented carbide inserts as substrates by the electronically aided hot filament chemical vapor deposition (EACVD). An amount of additive in an acid solution was used to promote the Co etching of the substrate surface. The surface of the WC-Co substrate was decarburized by microwave plasma with Ar-H 2 gas. Effect of the new substrate pretreatment on the adhesion of diamond films was investigated. A boron-doped solution was brushed on the tool surface to diffuse boron into the substrates during diamond deposition. A new process was used to lower the surface roughness of diamond thin films by appropriately controlling deposition parameters. It consists of a composite diamond film chemical vapor deposition procedure including first the deposition of the rough polycrystalline diamond and then the fine-grained diamond. The research results show that the pretreatment including both Co etching in acid solution and Ar-H 2 etching decarburization by microwave plasma is an effective method to enhance adhesive strength. An adequate amount of boron dopant solution can effectively suppress the cobalt diffusion to the surface and avoid the catalytic effect of Co at the high temperature. The composite film CVD process can deposit smooth diamond films with low surface roughness. It is of great significance for improvement of the cutting performances of diamond-coated tools using the above new technology to deposit diamond coatings with the low surface roughness and high adhesive strength on WC-Co substrates.
文摘Compared with the sintered polycrystalline diamond, the deposited thin film diamond has the great advantage on the fabrication of cutting tools with complex geometries such as drills. Because of their low costs for fabrication equipment and high performance on high speed machining non-ferrous metals and alloys, metal-compound materials, and hard brittle non-metals, diamond-coated drills find great potentialities in the commercial application. However, the poor adhesion of the diamond film on the substrate becomes the main technical barriers for the successful development and commercialization of diamond-coated tools. In this paper, diamond thin films were deposited on WC-Co based drills by the electron aided hot filament chemical vapor deposition (EACVD). A new multiple chemical pre-treatment technology including microwave oxidation, reaction in alkaline solution and cleaning by ultrasonic treatment in acid solution was developed and affects on the diamond adhesion strength, nucleation and surface morphology were investigated. At the same time, a special setup to fabricate diamond-coated drills was also developed and then the novel CVD process based on the varied parameters controlling model was presented, therefore the uniform quality and homogenized thickness of diamond coating could be available. From practical utilization viewpoint, the cutting performance of the diamond-coated drill was studied by drilling SiC particle reinforced aluminum matrix composite. The satisfied wear resistance and decrease of torque and thrust led to the long life of this kind of drill. This paper exhibited the meaningful work for the development of cutting tools with complex geometries and further extended the application of diamond material.
