The Preparation Of ZrO₂and Co-Cr-Mo Alloy/ZrO₂Sintering Behavior Research

ABSTRACT:Zirconia ceramic material is an ideal alternative material to artificial joints under high load conditions. The preparation of high purity, small particle size, narrow particle size distribution, and good sintering performance zirconia powder, is an important step to obtain high performance bio ceramic materials. Co-Cr-Mo alloy is the perfect metallic material of artificial joints.But the metal debris between Co-Cr-Mo alloy and acetabular is the main reason leading to loosening of the artificial joint. By using zirconia ceramic ball head can solve this problem and Getting a good interface bonding of Co-Cr-Mo alloy/ZrO2joint, is the key to solve this problem.The5Y-TZP powder was prepared by co-precipitation and the Co-Cr-Mo alloy/ZrO2joint was prepared by co-sintering. The influence of co-precipitation process parameters on the powder particle size, and morphology was studied. The influence of sintering temperature and particle size of5Y-TZP powder on the sintering character, mechanical properties and microstructure of zirconia ceramic was also studied. And the influence of green density and sintering temperature on the mechanical properties and microstructure of Co-Cr-Mo alloy/ZrO2joint was studied. The results show that:The optimal process of5Y-TZP presoma was:the precipitant was buffer solution of ammonia-ammonium chloride with2wt%PEG, reverse setting was used,the pH was10, the concentration of Zr4+was0.8mol/L, the reaction temperature was50℃. By using ultrasonic dispersion washing, we could obtain not only smaller5Y-TZP powder, but also help to reduce the number of washes and organic consumption. By using microwave drying method, we could obtain better dispersion, powder size smaller5Y-TZP powder. After calcining at600℃, we could obtain nanoscale primary particle size, average particle size of1.71μm and tetragonal phase5Y-TZP.The relative density and the shrinkage ratio of5Y-TZP increased with sintering temperature. At1450℃, the relative density reached98%. At the same temperature, the relative density increased with the reducing of the particle size of the powder. After sintering at1400℃, we could obtain the small grain size and uniform size of5Y-TZP by using microstructure analysis,. The flexural strength of5Y-TZP ceramic increased with the sintering temperature increased. At1400℃, the bending strength reached717MPa.Low porosity Co-Cr-Mo alloy shrinked faster than high porosity Co-Cr-Mo alloy, so we could control the shrinkage of Co-Cr-Mo alloy by means of control porosity to make Co-Cr-Mo alloy and ZrO2have similar shrinkage behavior. Interface bonding strength increased with the temperature increased. Interface bonding strength of high porosity Co-Cr-Mo alloy/ZrO2was greater than the interface bonding strength of low porosity Co-Cr-Mo alloy/ZrO2at the same temperature. The interface bonding strength of high porosity Co-Cr-Mo alloy/ZrO2had reached35.06MPa at1400℃2h. The porosity and crack of Co-Cr-Mo alloy/ZrO2interface decreased with the increased of sintering temperature and Co-Cr-Mo alloy porosity. At the same time on the longitudinal-section perpendicular to the Co-Cr-Mo alloy/ZrO2interface there was a1-2μm elements diffusion region.