Investigation of phase Transformation and Tougning Mechanism of Zirconla/Metal Functional Matrix by Grinding

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The functional matrix is the most miracle composite as the future industrial materials. But, there are only a few data in the manufacturing process. Here, the grinding characteristics are investigated for the new product of zirconia/nickel composite. Especiaaly, the influences to its strength characteristics of these composites by the toughening mechanism and surface characteristics induced by grinding are cleared. In zirconia/nickel composite, the bending strength increase with the large constituent rates of zirconia. Because the particle size of nickel is larger than that of zirconia, the crack transmitted in nickel particle on the fracture. Then, the toughening may be due to crack transmission by a lot of zirconia particles. The monoclinic phase increase with the increase of nickel contents. In cooling process of composites, the martensite transformation is induced by the compressive stress of zirconia by the large shrinkage of nickel.The surface roughness and the monoclinic phase o … More n the ground surface increase with the large grits sizes of diamond abrasive grain. The increment rate of monoclinic phase decreases with the large contents of zirconia. Furthermore, in the rich zirconia composite, the bending strength and the monoclinic phase increase with the large size of abrasive grains. On the other hand, the surface roughness increase with the low wheel speed. The monoclinic phase and the bending strength increase with the high wheel speed. This is due to the increase of martensite transformation by the impact force in the high wheel speed. On the contrary, in over 50% nickel composites, the monoclinic phase decrease and the bending strength increase with the high wheel speed in the composites over 50% nickel.The residual stress is measured on the polished sample after grinding with SD140/170 wheel. The part of zirconia is filled by the residual compressive residual stress. These residual stresses and the monoclinic phase increase with the large centents of nickel. But, the 100% nickel reside the tensile residual stress in it. This is due to the martensite transformation on the ground surface. In other word, the volume expansion by the phase transformation of zirconia induced the compressive residual stress in nickel. Less