3Y-TZP dip-coated with Zn-containing calcium silicate layers: development and characterization

Abstract

Coating layers based on Ca3Si3O9, Ca2ZnSi2O7, and ZnSiO4 on 3Y-TZP ceramics were obtained by the dip coating process, using SiO2-CaO-P2O5-ZnO glass suspensions with Zn contents in the range of 0-20 mol%. The influence of the Zn content in the dip coating slips, the slip solid loading, and the 3Y-TZP surface porosity on the layer formation rate was studied. The Zn content of the dip coating slips as well as the slip solid loading greatly affected the slip viscosity, and consequently the liquid entrainment mechanism at the initial stage. The low dissolution rate of 20 mol% Zn-containing slips decreased the dip coating slip viscosity, whereas the lower stability of 10 mol% Zn-containing slips increased the slip viscosity. A significant increase in the initial layer thickness was produced either by using 10 mol% Zn-containing slips or by increasing the slip solid loading. The casting rate for longer immersion times was markedly accelerated by increasing the 3Y-TZP surface porosity. Sintered layers based on ZnSiO4 having the lowest thickness values were produced using the glass containing 20 mol% Zn. On the other hand, the 0 and 10 mol% Zn-containing glass produced thicker sintered layers mainly composed of Ca3Si3O9 and Ca2ZnSi2O7, respectively.