Studies On The Fabrication And Toughening- Strengthening Mechanisms Of Al₂O₃ Whiskers-reinforced ZrO₂ Composites

Tetragonal polycrystalline zirconia?TZP?is a widely used ceramic material with excellent mechanical properties,special crystal structure and excellent biocompatibility.It is often used in the manufacture of structural components and tools,3C intelligence,terminals and smart wearable products,as well as biological materials.However,TZP materials still have its disadvantages,such as large brittleness and poor resistance to hydrothermal aging.Therefore,it is necessary to improve the comprehensive properties from the perspective of raw material components and preparation processes to achieve its deeper application and development.The fracture toughness of TZP materials can be greatly improved by the introduction of alumina whiskers?Aw?,but the existing research still has many problems such as complicated whisker introduction process,poor dispersion,single length to whisker aspect ratio,etc.The related discussion of the TZP stabilizer system has restricted the industrial development of the alumina whisker toughened zirconia composite material?TZP/Aw?.In this context,this paper is devoted to the studies of the effects of alumina whiskers on the densification process,microstructure evolution process and mechanical properties of zirconia matrix in different stabilizer systems under different aspect ratios and good dispersion conditions.This research expands and enriches the cognitive level of TZP/Aw composite materials from the perspective of theory and application.In this study,the dispersion process and morphology of alumina whiskers were explored through the optimized process route of“De-agglomeration/De-impurity/Dispersion”.On the basis of comprehensive application of steric hindrance effect and electric double layer theory,the good dispersion of alumina whiskers in TZP matrix and the precise regulation of aspect ratio were realized.Secondly,by optimizing the sintering process,alumina whisker toughening ceria-stabilized tetragonal polycrystalline zirconia material?Ce-TZP/Aw?with different aspect ratios was prepared,and its densification behavior and microstructure were determined.Evolution and mechanical properties were studied.The results show that the presence of alumina whiskers will reduce the sintering performance of Ce-TZP matrix.When the whisker aspect ratio is larger,the inhibition is more obvious.With the decrease of whisker aspect ratio,the grain growth of composite matrix tendency is weakened;the effect of whisker aspect ratio on the fracture toughness,bending strength and phase transition of the material has the same trend.When the aspect ratio of whisker is about 12,the toughness and strength are optimal.The results are 11.4±0.2 MPa·m^1/2 and 475±12 MPa,respectively,which indicates that the stress-induced phase transition is the main toughening mechanism of Ce-TZP/Aw composites.Based on the above research,three different aspect ratio alumina whiskers optimized by morphology were used to prepare 3Y-TZP/Aw and 12Ce-TZP/Aw composites,and different stabilizer systems were further studied under the influence of alumina whisker on the sintering process and strengthening and toughening effect of TZP matrix.The results show that compared with 12Ce-TZP/Aw,3Y-TZP/Aw does not produce liquid phase due to the introduction of alumina whiskers during sintering,and stress-induced phase transition does not occur when 3Y-TZP/Aw is broken.The toughening mechanism is mainly caused by crack deflection,bridging and whisker extraction caused by alumina whiskers.Therefore,the toughness increases with the decrease of the aspect ratio of whiskers,up to 9.35±0.36MPa·m^1/2.The effect is obvious.The studies of this subject deepens the understanding of TZP ceramic materials with different stabilizer systems,expands and enriches the basic theory of strengthening and toughening modification of oxide whisker as a second relative on TZP ceramics.The processing technology of the whisker material and the preparation process of the composite material are optimized.Therefore,this studies have great scientific significance and application value.