Papers by Author: Yan Xiang Wang

Abstract: The effects of microstructure on strength, toughness and corrosion resistance of reactionformed silicon carbide and heat treatment on the properties of reaction-formed silicon carbide have been investigated in this paper. The results show strength and corrosion resistance of reaction-formed silicon carbide decrease with increasing Si content. Fracture toughness shows no rule with free Si content. The average SiC grain size and bonding area of SiC grain increase during heat treatment at 1850°C. The strengths of the samples after heat treatment decrease compared with that of the samples before heat treatment due to the pores in the heat treatment bodies.

Abstract: Gelcasting is a novel ceramic forming process for fabricating products of complex-shaped ceramics. In this contribution, the gelcasting process is applied to manufacture green body of microwave ceramic components for resonators, oscillators and antennas. Calcined powders, dispersant and organic monomers are mixed together by ball-milling to acquire high solid loading slurry with low viscosity. After addition of initiator and catalyst, the slurry is cast into a non-pours mold and then polymerized. The slurry is thus solidified in situ and the green bodies with the desired shapes are obtained. The dried body is rather strong and can be machined so as to get more precise or complex-shaped components. Then the green bodies are sintered at high temperature. The microwave properties (εr, Q, τf) and microstructures of the ceramics prepared by gelcasting are compared with those of die-pressed ones.

Abstract: Sr(Bi1-xSmx)8Ti7O27 ceramics were prepared by Sm2O3-substitution for Bi2O3 through solid-state reaction route. The dielectric properties of the sintered bodies such as er, Q and tf were investigated. The ceramics were characterized by SEM, XRD, DTA and TG, which behaved high dielectric constant of 128 ~154 at the frequency of 10 GHz.