Papers by Author: Xia Wan Wu

Abstract: The crystallization and sintering of the Li2O-Al2O3-SiO2 glass powder compacts were studied. Results showed the relative densities of the sintered compacts with lower crystallization temperatures were higher than those with higher crystallization temperatures. A small amount of residual glass in the crystallized compact was good for sintering and densification. Compared with the heat treatment time, the heat treatment temperature was an important factor for the crystallization and sintering of glass powder compacts. The crystallized compacts with a small amount of residual glass should be sintered at a relatively higher heating rate under the prerequisite of keeping sintered compacts from deformation.

Abstract: In order to reduce the raw materials cost, lower the sintering temperature of 3Y-TZP optical fiber ferrules, the 3Y-TZP/ LAS glass ceramics composites were prepared and their properties were investigated in this paper. The results showed that the sintering temperatures and thermal expansion coefficients of the 3Y-TZP/LAS glass ceramics composites were lowered with the increase of glass content. The flexural strength of the composites were decreased with the increase of glass content, but the flexural strength of the composite with 15% weight glass was higher than 400MPa. The LAS glass powder added into the composites was crystallized and b-spodumene s.s was precipitated. during sintering. The b-spodumene s.s. having lower thermal expansion coefficient and higher strength was beneficial to reduce thermal expansion coefficients and keep higher strengths of the composites .

Abstract: (Ag1-xNax)(Nb1-yTay)O3 (ANNT) dielectric ceramic material with perovskite structure was prepared through a wet chemical synthetic method. The precursor solution for the material was obtained from the citric acid solutions of different metal oxides or nitrates with exact molar ratio by a sol-process. The precursor solution thus prepared was then heated under an infrared lamp to evaporate the solvent. This period showed a self-propagating combustion behavior. Ceramic powder was obtained after the residue was calcined at a certain temperature. It is proved that ANNT sintered at 1040°C was finely grained. The obtained ceramic showed excellent high frequency dielectric properties with considerable high dielectric constant and rather low dissipation factor under 1MHz.

Abstract: Effect of Co2O3 on microstructure and dielectric properties of Mg2TiO4-Mg2SiO4 microwave ceramic with low permittivity and high Q value was studied. Co2O3 acts and results in decreasing of the sintering temperature and densification of the ceramic material. As a result, the dielectric loss decreases and quality factor Q increases. Mg2+ is replaced partially with Co2+ in Mg2TiO4 to form (Mg,Co)2TiO4. It is demonstrated that the system with 2.4 wt% Co2O3 possesses better dielectric properties.