Optimization of BaZrO3 sintering by control of the initial powder size distribution; a factorial design statistical analysis

Abstract

A factorial design statistical analysis has been conducted in order to obtain the optimum conditions in the solid state sintering process of barium zirconate bulk materials, optimum with respect to density, closed and open porosities. The optimized heat treatment permits to sinter a 99% dense barium zirconate sample at 1650• C during only 2 h. When the temperature is higher than 1650• C or when the heating time is longer than 2 h, a decrease in density is observed.

Causes of anomalous crystal growth in sintering ceramics after formation of closed pores began

“…Application of the pressure that arises in closed pores in decomposition of barium peroxide should promote such adjustment. This is in agreement with the experiments conducted in [6] in sintering of BaZrO 3 . It was shown that anomalous crystal growth began after the appearance of closed pores, which took place at temperatures above 1650°C or after holding at 1650°C for more than 2 h.…”

“…Attempts are made to exclude it in fabrication of transparent ceramics, ferrites, and ferroelectric ceramics. In some types of ceramics, anomalous crystal growth is especially frequent, for example, in ceramics made of BaMO 3 (M = Ti, Zr) [5,6].…”

Influence of the shaping effect on hardness homogeneity by Vickers indentation analysis

“…After mechanical grinding, a median particle size of 0.6 m (d = 0.5) was obtained. 10 Three different techniques were used to shape the samples (i) the slip casting-the so-called SLIP sample;A powder/water suspension made of (i) solid contents (30 vol.%; 72 wt.%) and (ii) dispersing agent (1 wt.% (PMAADolapix CE64, Zschimmer & Schwarz)) was slip casted in plaster of Paris cylindrical moulds. 11 (ii) the uniaxial pressing-the so-called UNIP sample;This second sample was uniaxially pressed.…”

“…According to previous study of barium zirconate sintering processing, 10 it has been possible to select a specific heating program to obtain a relatively porous body.…”

Slip casting of barium zirconate aqueous concentrated suspensions

“…1 A slight decrease in the final density can be noticed when isotherm temperature is higher than 1650 • C, which is in agreement with previous studies that relate the lowering density to abnormal grain growth. 25 Sintering studies were also conducted by ESEM observations. Fig.…”