Сферические субмикронные порошки с нано-поликристаллической субструктурой — перспективное сырье для получения мелкозернистой высокоплотной керамики (обзор)

Abstract

The review reflects the unique properties and possible areas of application of submicron non-agglomerating powders from refractory oxides obtained by aerosol-spray pyrolysis. An analysis of the experimental results obtained by researchers at different times convincingly proves the promise of using aerosol nanostructured submicron spherical powders to obtain ceramic materials with a high-density, uniform fine-grained structure without pores. The uniqueness of aerosol powders is due to the presence in the particles of the nano-polycrystalline substructure of a developed network of inter-grain boundaries, which during sintering has a significant impact on the efficiency of diffusion mass transfer and contributes to an increase in the speed and completeness of pores overgrowth. Aerosol powders acquire these properties through the use of ultrasonic spray pyrolysis, where equilibrium physicochemical processes occur in ultra-small local volumes of aerosol droplets, ensuring a high degree of uniformity of the resulting powder. The formed ultrathin substructure of aerosol powders ensures their full sintering at low temperatures, making it possible to obtain high-density ceramic materials with extreme physical and mechanical characteristics. The practical use of nanostructured aerosol powders does not require the use of preliminary preparation operations (grinding-grinding, classification, purification from impurities, etc.) and, unlike ultrafine powders, they are easily molded using traditional methods of powder technology (uniaxial pressing, hot casting, etc.).