The Preparation Of Spherical Zirconia And Zirconia-Ni Composite Micro-Powders

Zirconia is an important structural and functional material with outstanding physics and chemistry properties. It is one of important raw materials for structural ceramics, functional ceramics, electronic sensors and other high-tech products, and also is one kind of catalysts and catalyst supports. Particularly when compounded with the transition metals, the composite zirconia-metal combines with the dual characters of ceramics and metals, which is more widely used. Therefore, the preparation and application of zirconia and its composite materials with transition metals is continuously a hot research topic for the related researchers.The conventional processes for spherical zirconia are sol-gel, spray pyrolysis, microemulsion method etc. These methods however may not be commercially applied because of the shortcomings such as complexes, severe preparative conditions, high cost, poor dispersivity and wide size distribution of the prepared powders. In addition, the key to prepare metal-ceramic composite materials is to prepare uniformly-distributed metal-ceramic powders which can't be attained by conventional methods. Thus, it is meaningful in reality and theory to develop a novel process for spherical zirconia and its metal composite powders.The fabrication condition and process of spherical zirconia powders prepared by the continuous reaction-precipitation process from raw materials of ZrOCl₂·8H₂O and NH₄HCO₃ have been studied, and the characteristics of the powder such as morphologies, particle size and its distribution were analyzed. The optimised processing conditions for preparing spherical zirconia powders were obtained by optimizing the various factors which would influence the powder capabilities. The manufactured spherical zirconia powders were characterised with 3 to 10μm in size by the Scanning electron microscope(SEM) and a laser particle analyzer, and they had a narrow distribution of particle size with excellent dispersant adequacy. Crystalline phase analysis of powders identified through X-ray diffraction(XRD) and Thermogravimetric and differential scanning calorimetry(TG-DSC) demonstrated that the precursors were transformed to tetragonal zirconia about 500℃, compared with the conventional processs(about 600 ℃), the transition temperature was decreased by approximately 100...