Due to the sensitivity of nanopowders and the challenges in controlling the grain size and the density during the sintering of ceramics, a systematic study was proposed to evaluate the densification and the microstructure of ZnO ceramics using spark plasma sintering technique. Commercially available ZnO powder was dried and sintered at various parameters (temperature (400–900 °C), pressure (250–850 MPa), atmosphere (Air/Vacuum) etc.). High pressure sintering is desirable for maintaining the nanostructure, though it brings a difficulty in obtaining a fully dense ceramic. Whereas, increasing the temperature from 600 to 900 °C results in fully densified ceramics of about 99% which shows to have big impact on the grain size. However, a high relative density of 92% is obtained at a temperature as low as 400 °C under a pressure of 850 MPa. The application of pressure during the holding time seems to lower the grain size as compared to ceramics pressed during initial stage (room temperature).

中文翻译：

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工艺参数对放电等离子烧结纯氧化锌陶瓷致密化和微观结构的影响

由于纳米粉末的敏感性以及陶瓷烧结过程中控制晶粒尺寸和密度的挑战，提出了一项系统研究，以使用放电等离子烧结技术评估ZnO陶瓷的致密化和微观结构。市售的 ZnO 粉末在各种参数（温度（400-900°C）、压力（250-850 MPa）、气氛（空气/真空）等）下干燥和烧结。高压烧结对于维持纳米结构是可取的，尽管它给获得完全致密的陶瓷带来了困难。而将温度从 600 °C 提高到 900 °C 会导致陶瓷完全致密化约 99%，这表明对晶粒尺寸有很大影响。然而，在 850 MPa 的压力下，在低至 400 °C 的温度下获得了 92% 的高相对密度。