Building ceramics covered with willemite crystalline glaze were prepared with roller kiln at low temperature in short time. The effects of the content of CoO (colorant) on the non-isothermal crystallization performance of willemite crystalline glaze were studied, while the mechanism of amorphous crystallization of the crystalline glaze was revealed by using Kissinger method and water quenching & rapid cooling treatment. The blue color of the crystalline glazed gradually deepened, while the area proportion, diameter and crystal phase content of the crystalline glaze increased first and then decreased with increasing content of CoO. All the three parameters reached the maximum values when the content of CoO was 0.6 wt.%. The mechanism of amorphous crystallization of the willemite crystalline glaze was the surface crystallization synergistically with volume crystallization. The addition of an appropriate content (0.6 wt.%) of CoO is beneficial to reducing the crystallization activation energy, improving Avrami exponent, enhancing the small angle branching ability, and effectively promoting the amorphous crystallization process of the crystalline glaze. However, the excessive content (1.0 wt.%) of CoO would actually weaken the amorphous crystallization of the crystalline glaze, leading to decrease in integrity of the petals and diameter size of the flower-shaped crystal patterns. Finally, building ceramics covered with the willemite crystalline glaze with a integral flower-shaped pattern structure, crystal pattern diameter size of 2.8 mm and bright blue color (b^* value of-50.2), were obtained with roller kiln at a relatively low temperature and quick firing process (the ferro firing temperature of 1165 ℃ and firing time of 70 min).

Al₂O₃-AlN composite ceramics have a wide range of applications in the field of electronic information. In order to ensure their service safety and reliability, the post-treatment reinforcement technique under the thermochemical deformation control was used to enhance mechanical properties of the composite ceramics. Non-contact in-situ deformation measurements, SEM-EDS, XRD and indentation tests were used to study thermochemical deformation behavior, phase-microstructure evolution and the prestress reinforcement mechanisms of the Al₂O₃-AlN composite ceramics. It is indicated that flexural strength of the Al₂O₃-AlN composite ceramics first increased and then decreased with increasing post-treatment temperature. Specifically, flexural strength of the sample post-treated at 1100 ℃ reached a maximum value of (519.23±23.87) MPa, which is 15% higher than that of the untreated sample. Meanwhile, thermal conductivity of the composite ceramics was not reduced by the post-treatment. The post-treatment process caused localized surface oxidation of AlN in the composite ceramics, accompanied by the volume expansion. Subsequently, residual compressive stress was produced on surface of the composite ceramics through the external and internal thermochemical deformation mismatch, which is favorite to the increasement of crack propagation resistance and the effective enhancement of mechanical strength of the composite ceramics. However, when the post-treatment temperature exceeds 1200 ℃, pores and microcracks were formed on the surface oxide layer, leading to a decrease in the mechanical strength of the composite ceramics.

Si₃N₄ ceramics have great application prospects in the fields of heat dissipation and packaging of electronic components, because of their excellent chemical stability, mechanical and thermal properties. In order to prepare Si₃N₄ ceramics with excellent bending strength and thermal conductivity, Y₃Si₂C₂-MgO binary composite sintering additive was used in this work. The effects of Y₃Si₂C₂ content and high temperature soaking time on relative density, mechanical properties and thermal conductivity of Si₃N₄ ceramics were systematically studied. The optimization mechanisms of mechanical/thermal properties of the Si₃N₄ ceramics were explained based on their microstructure and phase composition analyses. Thermal conductivity and bending strength of the Si₃N₄ ceramics, prepared after high temperature soaking for 4 h and 12 h, increased first and then decreased with increasing content of Y₃Si₂C₂. The bending strength of the Si₃N₄ ceramics prepared by high temperature soaking for time for 4 h is mainly dependent on relative density, while that of the Si₃N₄ ceramics prepared by high temperature soaking for time for 12 h is related to the microstructure uniformity and Si₃N₄ grain size. The prolonging of holding time is conducive to eliminating pores and increasing grain size, resulting in enhanced densification and increased thermal conductivity. Si₃N₄ ceramics, with relative density of 99.0%, thermal conductivity of (106.80±2.64) W·m^-1·K^-1 and bending strength of (590.21±25.69) MPa, were prepared by using gas pressure sintering, at 1900 ℃ for 12 h, with the addition of 1.5 mol % Y₃Si₂C₂. Such Si₃N₄ ceramics has excellent comprehensive mechanical/thermal properties, which is conducive to improving the service safety and reliability of Si₃N₄ ceramic packaged electronic components.