DESIGN OF MIXTURE EXPERIMENTS OF Al2O3 -TiB2 -TiC COMPOSITES: PART 1 -PREDICTION OF RELATIVE DENSITY AND FLEXURAL STRENGTH

Ten minutes after spark plasma sintering of 10 different mixtures at 1700°C, 47 MPa, their relative density and flexural strength were analyzed in Minitab. Different regression models were obtained for each property. The behavior of relative density and flexural strength was explained by two quadratic models RD<sub>Q</sub> and FS<sub>Q</sub>, which were adequate with a statistical significance level of p = 0.05. Based on the models RD<sub>Q</sub> and FS<sub>Q</sub>, contour plots were made in the Al<sub>2</sub>O<sub>3</sub>-TiB<sub>2</sub>-TiC simplex for a visual representation of the predicted results. These contour plots show the zones corresponding to values of relative density > 99%, and flexural strength > 500 MPa. Combining these zones, it was possible to determine the region of the Al<sub>2</sub>O<sub>3</sub>-TiB<sub>2</sub>-TiC simplex, which simultaneously correspond to the relative density and flexural strength of sintered samples greater than 99%, and 540 MPa, respectively. The RD<sub>Q</sub> and FS<sub>Q</sub> models were additionally tested at three new points, revealing that additionally experimental values fit well into the predicted by Minitab intervals. Therefore, the RDQ and FSQ models can be used for the relative density and flexural strength prediction of Al<sub>2</sub>O<sub>3</sub> -TiB<sub>2</sub> -TiC composites sintered as described.