Liquid sintered silicon carbide

L.S.Sigl. Thermal conductivity of liquid phase sintered silicon carbide. J. Euro. Ceramic Soc., 2003,23, 1115-1122... 

MICROSTRUCTURE OF LIQUID PHASE SINTERED SILICON CARBIDE CERAMICS WITH HIGH FRACTURE TOUGHNESS ... 

Microstructure of Liquid Phase Sintered Silicon Carbide Ceramics... 

A rather different approach has been developed for reaction sintered silicon carbide (RSSC), first developed in the former Soviet Union. In this process a powder preform of mixed graphite and silicon carbide is immersed in a liquid bath of molten silicon. The silicon wets and infiltrates the preform, reacting with the finely-divided graphitic component (carbon black). In the best case, all graphite is reacted and the residual sihcon content is no more than a few percent. The product of the reaction, silicon carbide, firmly bonds the silicon carbide preform powder... 

Due to the tailored properties of liquid phase sintered silicon carbide (LPSSiC) it is used as dewatering elements in the paper machinery and as rings for highly stressed gas seals. It is a price competitive alternative to silicon nitride materials and outperforms alumina and tungsten carbide materials. In addition, LPSSiC is proposed as neutral matrix in ceramic matrix composites containing plutonium to burn the world s stockpiles of military plutonium in thermal or fast reactors [278]. 

Jang, C.-W., Kim, J. S. and Kang, S.-J. L., Effect of sintering atmosphere on grain shape and grain growth in liquid phase sintered silicon carbide, J. Am. Ceram. 

Liquid-Phase>Sintered Silicon Carbide Liquid-phase-sintered SiC (LPS-SiC) is a dualphase SiC ceramic, with typically 95% SiC content and ultrafine microstructure. 

T. Grande, H. Sommerset, E. Hagen, K. Wiik, and M. Einaisud, Effect of Weight Loss on Liquid-Phase-Sintered Silicon Carbide, y./lm.Ceram.5oc., 80(4), 1047-52 (1997). 

H.J. Choi, J.G. Lee, and Y.W. Kim, Oxidation Behaviour of Liquid-Phase Sintered Silicon Carbide with Aluminium Nitride and Rare-Earth Oxides (RerOs, where Re=Y, Er, Yb), J.Am.Ceram.Soc., 85(9), 2281-86 (2002). 

Wang, C.M., Mitomo, M., and Emoto, H., Microstructure of liquid phase sintered superplastic silicon carbide ceramics , J. Mater. Res. 1997, 12, 3266-70. 

Nagano, T., Gu, H., Shinoda, Y., Zhan, D., Mitomo, M., and Wakai, F., Tensile ductility of liquid-phase sintered (3-silicon carbide at elevated temperatures , Mater. Sci. Forum, 1999, 304-6, 507-12. 

Properties of Dense Silicon Carbide. Properties of the SiC structural ceramics are shown in Table 1. These properties are for representative materials. Variations can exist within a given form depending on the manufacturer. Figure 2 shows the flexure strength of the SiC as a function of temperature. Sintered or sinter/HIP SiC is the preferred material for applications at temperatures over 1400°C and the liquid-phase densified materials show best performance at low temperatures. The reaction-bonded form is utilized primarily for its ease of manufacture and not for superior mechanical properties. 

LIQUID PHASE SINTERED o-silicon CARBIDE WITH AIN-RejOj AS SINTERING ADDITIVE... 

Key words a-silicon carbide, liquid phase, sintering, mechanical properties, microstructure... 

Liquid Phase Sintered a-Silicon Carbide with AIN-Re203 as Sintering Additive... 

Rixecker G, Wiedmann I, Rosinus A, et al. High-temperature effects in the fracture mechanical behaviour of silicon carbide liquid-phase sintered with AIN-Y2O3 additives. J.Euro. Ceram Soc., 2001,21 1 013-1 019. 

Silicon carbide (SiC) matrix composites have been fabricated by chemical vapor infiltration (CVl), polymer impregnation and pyrolysis (PIP), and reaction sintering (RS). The RS process can be recognized as an attractive technique, because it offers a high density and good thermal conductivity, compared to those of CVl and PIP process. In general, the fabrication of fiber reinforced SiC matrix composites by reaction sintering involves melt infiltration (Ml) or liquid silicon infiltration (LSI). However, the fabrication of continuous fiber reinforced SiC matrix composites by RS focused in melt infiltration (Ml) such as liquid silicon infiltration (LSl) Vapor silicon infiltration was rarely used for SiC matrix composites. 

RBSC (reaction-bonded silicon carbide) is another example of a material formed by a chemical reaction between a solid and a liquid. In this case liquid silicon and solid carbon are the reactants. The sintering temperature (1410°C) is slightly above the melting point of silicon and because the reaction with carbon is strongly exothermic, the rates are high and thermal stresses may develop. If carefully controlled, however, the product has an acceptable density and high strength. 

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