Preparation of diamond coated cutting tool with long life and its machinability against hard work material

在刀具上制备金刚石附着涂层是研制高寿命、高精度难加工材料刀具的迫切研究课题之一。然而，具有高硬度和高热导率的金刚石由于其自身的强sp^3共价键而对大多数基底材料具有低粘附性。建立了金刚石附着涂层技术，并对其切削性能和对难加工材料的切削性能进行了评价。本课题的主要研究成果和结论如下：1.氮化硅刀具上CVD金刚石涂层的制备及其可加工性采用CO-H_2反应体系，采用两段式微波等离子体CVD法在氮化硅基体上制备了金刚石涂层。通过对基底进行仔细的预处理和随后的厚金刚石涂层，形成了从sp^3键到sp^2键的梯度结构。通过a验证了良好的粘附性 关于我们 对Al-20wt%Si合金工件进行了实际切削试验。对金刚石薄膜与基体之间残余应力的X射线分析表明，金刚石薄膜内部应力的松弛是由于梯度结构的形成.硬质合金刀具上CVD金刚石涂层的制备及其可加工性硬质合金基体上附着的金刚石涂层的应用越来越广泛。然而，金刚石薄膜与硬质合金的结合力太弱，难以承受硬切削条件下的大应力。在金刚石涂层之前，对表面层上的钴相进行电化学蚀刻，以将石墨化的碳溶液压入钴中，并通过增加金刚石与基底之间的接触面积来增加附着力。即使在硬切削条件下金刚石膜的附着强度不足，也可以防止金刚石膜的剥离。需要进一步研究以实现更好的依从性。少

The Preparation of adherent diamond coating on tools is one of the urgent subjects to be investigated to develop long life and precise cutting tool for hard work materials. Diamond with high hardness and high thermal conductivity, however, has low adherence against most substrate materials because of its own strong sp^3 covalent bonding. Excellently, adherent diamond coating technique was established in the present paper and its cutting property was evaluated as well as the machinability against hard work materials. The main results and conclusions in the project term were summarized as follows.1. Preparation of CVD diamond coating on silicon nitride tool and its machinabilityAdherent diamond coating was performed on silicon nitride substrate by the two-stage microwave plasma CVD in the CO-H_2 reactant system. A graded structure from sp^3 to sp^2 bonding was formed by a careful pretreatment of the substrate and subsequent thick diamond coating. Excellent adherence was verified by the a … More ctual cutting test against Al-20wt% Si alloy work. Detailed X-ray analysis of the residual stress between diamond film and substrate indicated that the relaxation of inner stress in the diamond film occurred on account of the formation of the graded structure.2. Preparation of CVD diamond coating on cemented carbide tool and its machinabilityAdherent diamond coating on cemented carbide substrate has been desired for its expansion to more versatile application. However, the adherence of diamond film to cemented carbide is too weak to bear the large stress in hard cutting conditions. Prior to diamond coating, electrochemical etching of cobalt phase on the surface layer was carried out to depress the graphitized carbon solution into cobalt and to increase the adherence by increasing contact area between diamond and substrate. Peeling of diamond film was prevented, even though the adherence strength was insufficient under hard cutting conditions. Further investigation is required for better adherence achieved. Less