Pressure assisted master sintering surface of Co, Cu and Fe powder mixture

The master sintering curve (MSC) is an empirical model to predict densification during sintering or hot pressing. In the MSC, the sintering curves plotted at various heating paths converge into a single densification curve, once the right activation energy was found. That makes it possible to determine the dominant densification mechanism of the specimen made of two or more different kinds of powder. As a practical application of the MSC, the Co, Cu and Fe based metallic powder was used because it is one of the most common soft metal bonds of the diamond tool industry. The effective activation energy of sintering was found to be 294 kJ/mol. It suggests that the dominant densification mechanism for the powder mixture was diffusion of Cu into Fe since the effective activation energy was in good agreement with that of Cu solute in Fe solvent from literature. Four data sets having different heating rates merged onto a single curve when the density was plotted as a logarithmic function of Θ, the integral of temperature function over time. Thus, density versus Θ profile can be used to predict the final density of the Co, Cu and Fe based metallic powder at a given pressure regardless of heating history. The study was also extended to a range of pressures from 9.8 MPa to 39.2 MPa to generate the pressure assisted master sintering surface (PMSS).

In the master sintering curve (MSC), the sintering curves with different heating paths converged into a single densification curve, once the right activation energy was found. That activation energy estimated by the empirical model of the MSC enabled us to determine the dominant densification mechanism of the specimen made of two or more different kinds of powder.Figure optionsDownload as PowerPoint slideHighlights
► We could predict the densification of complex powder mixtures by the MSC model.
► We detected the densification mechanism by estimating the activation energy.
► Using the PMSS model, one can specify the heating schedule of powder mixtures.