Assessment of pressure-assisted sintering models through sinter-forging tests: A case study of alumina incorporating capillarity forces

Abstract

Pressure-assisted sintering models involve numerous closely correlated parameters that depend on temperatures, porosity, and microstructure development. Consequently, the identification of the model parameters is relatively lengthy and requires experiments to extract the underlying creep behavior (pressure/temperature dependent), shear, bulk sintering moduli that are porosity-dependent, and grain growth. Knowing that certain sintering mechanisms are grain-size dependent, it is very difficult to assess the densification behavior for the case of ceramics. We have already developed a sinter-forging method to assess independently all parameters for ceramics. However, this method implies numerous interruption tests to measure the specimen diameter evolution, and the capillarity forces were neglected. In this study, an instrumented microwave sinter-forging prototype avoiding highly repetitive interruption tests has been developed to record the specimen diameter evolution of submicronic alumina powder samples. The new method includes the effect of the capillarity forces on the identification equations, making the model more realistic for submicronic ceramics. The resulting model was tested on a finite element code for validation and to explore its stability for complex shapes.