Main advances in preparation technology of zirconia hollow microspheres
Zirconia hollow microspheres have attracted more attention because of their excellent performance,which combines the advantages of the properties of zirconia and hollow structural materials,such as low thermal conductivity,ablation resistance,and chemical corrosion resistance.Zirconia hollow microspheres is an important feedstock for preparing thermal barrier coatings.The thermal barrier coating prepared by zirconia hollow microspheres has the characteristic of excellent insulation and corrosion resistance.The performance of the coating is determined by the characteristics of the powder.The preparation of high quality zirconia hollow spherical powder has become a hot topic in the industry.In this work,the research status of the preparation technology of zirconia hollow spherical powder is analyzed,and the main preparation approaches are introduced,including templating,solvothermal,spray drying,and plasma sintering.In addition,the characteristic of these approaches is briefly summarized.Templating method contributes to obtaining hollow zirconia spheres with perfect morphology.However,some problems such as difficulty both in template synthesis and subsequent template removal,which can cause the material waste and damage to hollow particles.For solvothermal method,the reaction conditions are relatively harsh,and it also involves cumbersome process,such as separation,washing and drying process,which makes it difficult to batch preparation of hollow microspheres.The spray drying method is an effective approach for batch preparation of hollow microspheres.However,the hollow microspheres prepared by spray drying possesses have low strength and become easy to be damaged during application.Importantly,it is considered that the hollow microspheres prepared by spray drying combined with plasma sintering process have the advantages of high sphericity,good fluidity,and controllable particle size distribution,which are more conductive to preparation of coatings.
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