Control Mechanism And Thermal Fatigue Properties Of Interface And Microscopic Structure In WCp/steel Substrate Surface Composite By SPS

The ceramics particle reinforced surface composite has advantages not only in ductility but also toughness, modulus, hardness and so on. This composite can meet the wear-resistance requirements. It is a great candidate for replacing tradition metal materials in some working condition. However, there is thermal fatigue of quench heat shock in some complex wear working condition; it means that the surface composite must have thermal fatigue resistance. Recently, tungsten carbide particles reinforced steel substrate surface composite is developed greatly, and it is expected to be applied in many industries, such as metallurgy, machinery and so on. The thermal fatigue property becomes a difficult thing because of the organization and structure. The surface composites were successfully fabricated by new fabrication process, and then we can study the thermal fatigue property easy.The composite is fabricated by spark plasma sintering (SPS) technique and interface vacuum remelting in optimal. By this fabrication method, the microstructure of composite is controllable and flawless. The matrix of composite is lamellar and ferrite in the. Then we can control the distribution of the particle. The extreme processing parameters be applied on processing different composites, it order advantages to study the fatigue performance of composite. The interface reaction zone between particle and matrix increase are study by the remelting temperature.The thickness of interface reaction zone between particle and matrix increase with remelting temperature. The interface reaction product, Fe3W3C, was formed as follows, the reaction would happened in the tungsten carbide particles by heat and formation W、C and W2C. Then the W2C would react with the Fe to produce Fe3W3C. Then the W and C would reaction with Fe to produce Fe3W3C. The diffusion and the decomposition reaction in the tungsten carbide would play an important role. But the heat is the most important things in the diffusion and the decomposition reaction. We can get a function for the diffusion: The diffusion distances will follow with the temperature. And the thickness of interface reaction zone between particle and matrix increase with temperature. The result shows that the interface reaction happened when the matrix was in solid state through the DSC.The composites processed by different parameters are investigated by thermal shock. The cracks initiate and propagate in the composite because of the thermal expansive coefficient difference between matrix and particle and the brittleness of particle. The thermal fatigue performance of composite with pearlite is better than the composite with ferrite matrix. The crack is easier to propagate nearby the interface between substrate and composite, and the crack initiate on the interface reaction zone between particle and matrix.