Sintering and densification

Sintering and Densification. Recall from Section 2.2.2.4 that sintering is the consolidation of particles during heat treatment, and that it is controlled by the reduction in free energy of the system that accompanies surface area elimination during densification. Since the thermodynamics of sintering have already been described, we... 

Silica membranes have also been studied by several investigators for use in gas separation and membrane reactors. They arc thermally very sublc up to about 500°C. Sintering and densification temperatures of silica membranes depend on the water/alkoxide ratio in the sol-gel process for making the membranes (Langlct et al., 1992]. Crystallization of amorphous silica particles in the membranes takes place at temperatures around 1,000°C [Larbot et al., 1989]. However, pore growth can gradually... 

Silicate ceramics are well suited for structural applications because of their strength, which originates in the partially ionic, strong silicon-oxygen bonds in the tetrahedral orthosilicate anion. This structural unit appears in naturally occurring minerals and clays, which are fashioned into ceramic pieces through sintering and densification processes. 

In-pile self-diffusion of uranium in stoichiometric UO2 and UC has been measured by Hoh and Matzke 3J6). The diffusion coefficients obtained at a nominal irradiation temperature of 900°C and a fission rate of 1 x 10 //cm indicated that radiation-enhanced diffusion was higher by a factor of 10 to lO than determined by extrapolation of thermal diffusion coefficients. They suggested that the data are of immediate relevance to the understanding and the prediction of such quantities as in-pile sintering and densification, diffusion-controlled creep, and fission gas behavior in the outer zones of the fuel. 

The other point to emphasize is that for many years the aim of sintering has been to make dense ceramics. The terms sintering and densification were almost used interchangeably. Today, there are many uses for porous ceramics and these materials must also be sintered. The aim is then different and the process must change accordingly. Most of the time we assume that the material we are sintering is single phase, so we make some assumptions that will not necessarily be valid for multiphase materials that also need to be sintered. 

Sintering and Densification (I)—Conventional Sintering Technologies Self-interstitial... 

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