Influence of Bismuth Oxide as a Sintering Aid on the Densification of Cold Sintering of Zirconia

TL;DR

This study demonstrates a novel single-step cold sintering process for zirconia using bismuth oxide as a sintering aid, achieving high density at significantly lower temperatures than traditional methods.

Contribution

It introduces a combined approach utilizing water vapor and Bi2O3 to enhance densification of zirconia at reduced sintering temperatures.

Findings

Achieved >80% density at 900°C

Developed a single-step process combining water vapor and Bi2O3

Reduced sintering temperature compared to traditional methods

Abstract

Zirconia (ZrO2) has emerged as a promising technical ceramic, both as high temperature structural material and thermal barrier coating material, etc. The traditional synthesis of ZrO2 with spark plasma sintering (SPS) usually requires a sintering temperature as high as 1200C. General interest in lowering the sintering temperature to reduce energy consumption and thermal stresses has led to research on two promising routes, cold sintering via temperature-dependent chemical reactivity and sintering aids, which facilitates mass transport and improves densification. Here we combine both by developing a single-step sintering process benefitting from both water vapor through the in-situ conversion of Zr(OH)4 to ZrO2 and liquid phase Bi2O3 as a sintering aid. The resultant ZrO2 has a relative density above 80 percent with a sintering temperature as low as 900C.