Transport phenomena in some solids under hipping pressure

The effects of pressure in hot isostatic press (HIP) on the transport pheno mena have been studied on the following three systems; (1) Fe-WC, (2) Ba(Zr ,Ti)O-3 and (3) amorphous SiO2-crystalline SiO2. In these cases, mass trans ports were suppressed by hipping pressure. In the Fe-WC system, WC grains r eacted with surrounding Fe. and the pressure appears to suppress the diffus ion. In the case of (2), thin plates of Ba(Zr,Ti)O-3, having different comp ositions, were piled to make a functionally graded material (FGM). To suppr ess the diffusion between the plates, hipping pressure of 200 MPa was appli ed at 900 degreesC, and then the temperature was raised to 1200 degreesC. T he hipped compact revealed a flat temperature dependence of dielectric cons tant, which was ca. 2000 over the temperature range of 25-120 degreesC. The grain growth was also suppressed by the hipping pressure. In the case of ( 3), the crystallization of amorphous SiO2 was suppressed under the conditio ns of 1200 degreesC, 200 MPa and 30 min to prepare the amorphous-crystallin e composite of SiO2. (C) 2001 Elsevier Science B.V. All rights reserved.