| In this paper, the zirconia ceramics were prepared by spark plasma sintering equipment, the technological parameter of zirconia ceramics by SPS was optimized by orthogonal test method. The effect of the content of yttrium oxide stabilizer and the powder size on the microstructure and properties of zirconia ceramics were studied. And the relationship between grain size, stress induced phase variable and fracture toughness were researched. The experimental results are showed as follow:1. The sintering temperature is the main factor affecting the performance of zirconia ceramic samples, followed by sintering time and sintering pressure. The best sintering process of 3mol% yttrium oxide stabilized zirconia powder is:1400℃×10min×15MPa. Uniform tetragonal phase morphology and grain distribution are obtained through the best process parameters, and the hardness, fracture toughness are 1429.45HV,5.65MPa·m0.5, respectively.2. The content of four kinds of yttrium oxide stabilizers (1.5mol%,3mol%,5mol% and 8mol%) were tested. The results show that the performance of zirconia ceramic is the best when the content of yttrium Stabilizer is 3mol%. Under the certain sintering process conditions, when the grain size is between 301.9nm-444.8nm, the grain size of zirconia ceramics increased gradually with the decrease of particle size. With the increase of grain size of zirconia ceramics, cause the fracture toughness increases in the end. When the particle size of the powder is 301.9nm, the fracture toughness reaches the maximum, which is 7.06 MPa·m0.5.3. Under a certain stress, the stress induced phase transformation of zirconia ceramics can be induced, and the content of stress induced phase transformation increases with the increase of sintering temperature and grain size, cause the fracture toughness increase. Grain size (X) is the main factor affecting the content (Y) of stress induced phase, and both of them approximately assume the linear increasing relationship, Y=12.57X-0.05. With the increase of grain size, the fracture toughness (Z) decreases firstly and then increases, and the relation between them is close to parabola, Z=1.84X2-1.31X+3.44. |
