Research On The Preparation Of TZP Powder By Ball Milling Reaction

Zirconia ceramics is widely used in structural material, electronic material and refractory. Not only become one of the hot topics in scientific research fields, but also widely use in industrial production, because of its excellent physical and chemical properties. Its main application belows:tetragonal zirconia polycrystal ceramic, zirconia toughened alumina, partially stabilized zirconia ceramic, bioceramic. In the case of 3Y-ZrO2 is one of the tetragonal zirconia polycrystal (TZP) ceramics. Commonly used in harsh environment and severe conditions with excellent mechanical properties, such as high fracture toughness, strength and hardness, good wear resistance. This has prompted considerable attention in the development of synthesis techniques for manufacturing these kinds of ultrafine zirconia powders. There were two traditional methods for preparing the powders, including spray pyrolysis methods, liquid phase methods, vapor phase methods, solid state method etc.With the inherent advantages of the solid phase method, this study used the mechanically activated solid reaction to produce the 3Y-ZrO2 powders. The thermal decomposition of the precursor was analyzed by TG-DTA and the product was presented by XRD,TEM,DLS,BET. The main factors during the process of precursor preparation and the calcining process of the precursor were studied. Systematically discuss the technological parameters, which influences on the average size of the crystallite, the volume fraction of the phase and crystal morphology of the final products. The main contents were as follows:(1)Researched in the factors (such as molar ratio of metal ion and oxalic acid, mass ratio of ball and material, rotational speeds, milling time) during precursor preparation, which influences on the product(such as the average size of the crystallite, the volume fraction of the phase, the crystal morphology)by means of single factor experiment. Orthogonal experiment indicated that the influencing intensity of factors on the average size of the final products was:molar ratio of metal ion and oxalic acid> mass ratio of ball and material> rotational speeds. Take the efficiency and raw materials into consideration. The optimum prepare technology was:the molar ratio of metal ion and oxalic acid was 1:1.5, the mass ratio of ball and material was 10:1, the rotational speeds was 200rpm and the milling time was 1h. The average size of the final products was 14.0nm with distributing uniformity and spherical shape particle size distribution and good dispersion which was prepared in the foregoing conditions. The optimal calcining technology which was researched by TG-DTA thermal analysis was:the calcining temperature was 650℃and calcining time was 2h. When the calcining temperature and holding time was higher, the size of particle grow up and the content of tetragonal phase volume fraction decrease gradually.(2) On the basis of the technology of preparing 3Y-ZrO2 powders by planetary ball milling, this paper carried on the amplification experiments by stirred ball milling. The tests of the 3Y-ZrO2 powder which made by amplification experiments showed that:the average size of the products was about 24.9nm with particle size distribution, good dispersion and the specific area was 32.4608m2/g. The powders with high molding performance, smooth surface and smaller bulk density by spray granulation after milling 24 hours. So mechanical properties is non-ideal during the calcination, it should be improved.(3) The results of calcining the precursor which made by amplification experiments showed that when calcining temperature and holding time was higher, the size of particles grown up and the content of tetragonal phase volume fraction decrease gradually. And the content of monoclinic volume fraction increase gradually. On the basis of the formers researches, we believe that the theoretical explanation of this study is closer to the Garvies'view:the monoclinic zirconia tetragonal zirconia with a large ratio of surface energy than the tetragonal phase. With the growing up size of the powders, the surface energy between the monoclinic phase and tetragonal phase decreased gradually (at a certain temperature and pressure).