Xiaoyang Xu

Synthesis of refractory cordierite from calcined bauxite, talcum and quartz

A cordierite was synthesized from calcined bauxite, talcum, and quartz. The properties and microstructure of the cordierite sintered samples were characterized by Archimedes’ method, thermal dilatometry, X-ray diffraction (XRD), scanning electron microscopy (SEM), and so on. The experimental results showed that calcined bauxite could broaden the range of synthesizing temperature from 1300 °C to 1420 °C and get pure cordierite. The bulk density and linear thermal expansion coeffi cient of the sample synthesized at 1420 °C for 2 h were 1.97 g·cm−3 and 2.1×10−6 °C−1, respectively. The XRD analysis showed that the major crystalline phase was α-cordierite with almost no glassy matters, the SEM images illustrated a small vent hole and the size were 5–100 μm, the well-grown hexagonal and granular cordierite grains had the sizes distributed among 0.1–8 μm, and providing high mechanical strength and lower linear thermal expansion coeffi cient.

Effect of MnO2 on properties of SiC-mullite composite ceramics for solar sensible thermal storage

For improving the properties of SiC-mullite composite ceramics used for solar sensible thermal storage, MnO2 was introduced as sintering additive when preparing. The composite ceramics were synthesized by using SiC, andalusite, α-Al2O3 as the starting materials with non-contact graphite-buried sintering method. Phase composition and microstructure of the composites were investigated by XRD and SEM, and the effect of MnO2 on the properties of SiC composites was studied. Results indicated that samples SM1 with 0.2 wt% MnO2 addition achieved the optimum properties: bending strength of 70.96 MPa, heat capacity of 1.02 J·(g·K)-1, thermal conductivity of 9.05 W·(m·K)-1. Proper addition of MnO2 was found to weaken the volume effect of the composites and improve the thermal shock resistance with an increased rate of 27.84% for bending strength after 30 cycles of thermal shock (air cooling from 1 100 °C to RT).

Research and development of cadmium sulphoselenide red pigment

Cadmium sulphoselenide was synthesized continuous substitution solid solution and the only known pigment to yield bright red color on ceramic decoration. Encapsulated cadmium sulphoselenide pigments could yield abundant hues from yellow to red with high opacity at high temperature. The color generation has a linear function relation with the substitution rate. The encapsulation formation process of zirconium silicate encapsulated cadmium sulphoselenide was shown. Insufficient encapsulation efficiency and potential hazard to human and environment had limited the industrial application of cadmium sulphoselenide red pigment. Ink-jet printing decoration required fine size cadmium sulphoselenide red pigment on ceramic decoration. The review mainly focused on the synthesis techniques and industrial application of cadmium sulphoselenide red pigment.