| Cubic boron nitride has a number of attractive physical and chemical properties, such as low density, high thermal conductivity, and very high hardness that only less than diamond. Moreover, thermal stability and chemical stability of the c-BN are better than diamond. The c-BN is resistant to oxidation even up to the 1000℃at the atmosphere, especially it does not react with molten ferrous materials while diamond will do. Thus, c-BN is very suitable for processing materials with high hardenss and great tenacity, such as harden quenching steel, high speed tools steel, bearing steel, titanium alloy, and so on. It is comprehensively applied to produce various tools or superabrasive against abrasion in the field of auto manufacture, mechanical processing, precision processing, stone materials processing, constructional materials, aviation, new materials processing, and so on.The range and field of application for c-BN is restricted due to the bad processing property of c-BN superhard material. As an abrasive material, which is used to manufacture various tools or superabrasive coats, the processing of c-BN is mainly produced by means of PVD, CVD, resin bond, vitrified bond, metal bond, electroplating and brazing, et al. The efficiency of c-BN produces prepared by using PVD, CVD processing is low. When the c-BN is prepared to be a coat or a wearable component by means of sinter processing, c-BN would be knocked down which was operated as the function of wearability. The lifespan of c-BN coat with electroplated processing is short, and it contaminates the environment in processing. In the production prepared by brazing, the alloy bonding can be formed in the interface between filler substrate and c-BN. But the filler freezes to be molten structure, which decreases its own wearability and makes c-BN to be uneven in the substrate.In this paper, the design of bionic structure is adopted. The c-BN/Cu-based composite materials are prepared by SPS that use the c-BN grain as strengthened phase and the CuNiSnTi alloy as substrate. Then, the effects of c-BN volume percentage on the density, compactablitiy and wearability of the c-BN/Cu composite materials are investigated. Also, the influence of abrasion versus load on wear resistance of composite materials is studied. Through the orthogonal polynomial regress equations, the technical factors are designed to research the influence of sintering temperature, pressure and the keeping time on compactablitiy and wearablitiy. At last, the inherited arithmetic is adopted to optimize the technical factors.Experiments indicate that CuNiSnTi active alloy exhibit a good wettability on c-BN. During the process of SPS, titanium atoms in active alloys segregated preferentially to the surface of the c-BN to form TiN and TiB2 by reaction between titanium atoms and nitride and boron atoms, strong chemical joining was formed in the interface between c-BN and active alloy.The c-BN/Cu composite materials (the volume percentange of c-BN being 20%-30%) prepared by SPS have good compactness which is more than 95%. Moreover, the density and compactness decrease gradually with the increase of c-BN volume percentage. The high hard and wearable c-BN grains are embedded in Cu-based active alloy to resist the grit together, which result in a good wearablity. With the volume percentage of c-BN raise and abrasion versus load increased, the abrasion weight of the c-BN/Cu composite materials is enhanced.Orthogonal polynomial regression design process is adopted to plan craft parameter. The effects of craft parameter on compactablitiy and wearablitiy of composite materials are studied by means of regression equations. The regression equations shows, at the sintering temperature of 700℃~800℃, the pressure of 20~40 Mpa and the keeping time of 3~5 min, the compactablitiy and wearablitiy of composite materials increase with the keeping time extended and sintering temperature raise. Moreover, the compactablitiy and wearablitiy of composite materials firstly increase and then decrease with the increase of pressure. Meanwhile, pressure and sintering temperature affect each other.The inherited arithmetic is adopted to optimize the regress equations, which achieve the most optimized factors of SPS: the axes stress being 28~33 Mpa, the sintering temperature being 780~800℃and the keeping time being 4.6~5 min. These values are consistent with the experimental ones on the whole. The error between optimized and experimental value for the compactablitiy is less than 1% while it is less than 10% for the wearablitiy. |
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