Microstructure evolution and fracture behavior of heat treated enamel coating: Experiment and finite element analysis

Abstract

The enamel coating (CaO-BaO-MgO-SiO 2 -Al 2 O 3 ) is prepared and performed isothermal oxidation at 900 °C. With the increase of oxidation time, the microstructure and phase evolution of enamel coating are analyzed. Meanwhile, the fracture toughness of heat treated enamel coatings are characterized using the micro-cantilever bending method. The experimental result indicates that the heat treatment can promote the precipitation of oval crystal particles from the enamel itself. With increase of crystallinity, the fracture toughness of heat treated enamel coatings increases from 2.35 to 4.20 MPa·m 1/2 . In addition, finite element method (FEM) with inserting global cohesive elements is adopted to estimate the fracture of micro-cantilever for enamel including elliptical crystals. Both load-displacement curves and failure modes from FEM analyses agree well with those from experiments. Meanwhile, the fracture mechanisms including crack deflection, crack bridging, intergranular and transgranular fracture of the enamel can be revealed. • With the increase of oxidation time, the microstructure evolution and phase of enamel coating are analyzed. • The crystallization of SiO 2 -Al 2 O 3 -CaO-BaO-MgO based enamel coating can improve its fracture toughness. • Finite element method (FEM) with inserting global cohesive elements can simulate the authentic fracture process of enamel coating including crystals. And, this method aids in understanding the fracture behavior of glass-ceramic coating.