Research On Making Of WC-Co Substrate Diamond Thin Film Coated Tools And Their Cutting Testing

CVD diamond thin film is considered the most promising new type of tool coated material in the 21st century because of its high hardness, high thermal conductivity, low friction coefficient, low thermal expansion coefficient, and many other excellent performance.Which is widely used to machine difficult materials such as high-silicon aluminum alloy, metal composite materials, engineering ceramics, fiber reinforced plastic, etc. Diamond coated cutting tools are prepared by depositing a diamond thin film oncemented carbide substrate with Chemical Vapor Deposition (CVD) method. Diamond coated cutting tools have unique combination of excellent physical properties, such ashigh hardness and toughness, good thermal conductivity, outstanding wear and chemical resistance and low friction coefficient. The coated technology is relatively simple and cheap, and can be applied to the cutting tools with complex shape, such as milling cutters, twist drills and taps etc., by depositing the diamond film on the substrate material directly, so that they can be employed to machine difficult-to-cut materials with high efficiency.In this paper, which mainly researches some key technological issues regarding on the deposition process of diamond coated cutting tools with complex shape and their application in machining, Firstly, the dynamics model of the diamond thin film deposition was studied, and the deposition process is optimized based on the inspect results and data of the diamond deposition experiments conducted in the lab. Pretreatment methods suitable for cemented carbide substrate with complex shape are investigated, the pretreatment parameters of the conventional two-step pretreatment process are optimized, and the optimal process parameters are obtained.A novel combined pretreatment of Murakami's reagent, acid etching and microwave plasma decarburization is developed based on the study.Secondly, Diamond coated inserts with different pretreatment processes and coating type areprepared on the cemented carbide inserts with complex chip-breaking groove (SCMT120408-HR). Morphology and quality of different sections of diamond coated inserts, such as cutting edge, rake face, flank face, and the cross-section etc. are inspected using SEM and Raman. The effect of pretreatment and deposition process on the diamond morphology and quality is analyzed. The adhesive strength between the diamond film and the substrate, tool wear of different coating type and the surface roughness of the workpiece is investigated through the cutting test of glass fiber. Thirdly, Diamond coated PCB router bits with high uniformity and adhesive strength are prepared on the substrate of cemented carbide (YG6) PCB router bits (STARBIDE455060,Φ6.35mm), by optimizing pretreatment and process and rebuilding the deposition apparatus. The cutting performance and the adhesive strength of diamond coated PCB router bits are evaluated by milling GFRP plank.