| Partially stabilized zirconia(PSZ) has been widely used to produce structural ceramics components in industry for its excellent physical and chemical properties, such as high strength, good hardness, fine wear resistance et, al. However, as one of the major defects, pores, which are distributed both inside of the body and on the surface, seriously restrict zirconia's service as structural components as well as the field of application.In this paper, experiments of grain composition, additives, moulding process and sintering process were implemented in order to increase density and to conclude an optimized process route to produce densified PSZ with relatively good mechanical properties. It has great directive significance for producing densified zirconia ceramics with fine wear resistance. Conclusions of the experiments would make a contribution to the development of Zirconia's densification theory.Sequential optimization experiments of each process elements were implemented by the evaluation of density. Bending strength, Vickers hardness and Fracture toughness were also measured. Microstructure was observed by SEM and metaloscope. When produced according to the following process route, the zirconia sample could obtain a relative density of 99.67%, a bending strength of 812MPa, a fracture toughness of 10.51MPa·m1/2 and a Vickers hardness of11.35GPa(HV10).Process route optimized:Add CuO, Al2O3, MgO and CeO2 into 3Y-PSZ superfine powders in accordance of mass fraction 0.5%,0.4%,0.4%,1.5%. Add some PVA whose consistency is 5.5%into the powder in accordance of 6ml/100g. The powder and additives are then ball milled for 24 hours and granulated manually. Use 20,80 and 200 meshes to filter the powder into three grades of particle sizes with a mass ration of 6:3:1 correspondingly.5 gram powder is weighed each time to form one sample following the process of:6MPa-5sec-dry pressing combined with 200MPa-10sec-CIP. The samples are sintered according to the following sintering curve:A heating rate of 0.5℃/min on the temperature range of 150-400℃; a heating rate of 2℃/min on the temperature range of 1000-1200℃; a heating rate of 1℃/min on the other heating up sections. Samples would be sintered at 1540℃with a heat preservation of 180min and then cooled to room temperature in air.Investigation of grain composition showed that, the process of grain composition is capable of increase the density of zirconia for the reason of bridging effect. Especially for the powder which is granulated manually.The dope of the four kinds of oxide could remarkably increase the density and mechanical properties of zirconia. Within the designed range of experiment, density of zirconia increases with the increasing of doping amount of Al2O3 and MgO, but decreases when the doping amount of CeO2 and CuO is too high. The content of PVA also affects zirconia's densification.Investigation of forming process indicates that, within a certain range of pressure and hold time, a two-step compacting (dry-pressure combined with CIP) could remarkably promote the densification of zirconia. The density increases at first but decrease in the end with the increasing of pressure. The hold time doesn't show much affection to the densification because the dimensions of the samples are relatively small. Densities of green body and sintered samples showed great pertinence.Densification completed at 1540℃. Both grain particles and pores would grow up if the heating temperature continues rising. Relatively low heating rate on the temperature range of 150-400℃could give PVA enough time to be ejected. Relatively high heating rate on the temperature range of 1000-1200℃could inhibit the CuO related chemical reactions which are bad for the densification.This research has great significance on the densification of zirconia, extending the service life of zirconia ceramics as structural components and expanding the fields of application.
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