Application of Response Surface Methodology for Optimization the SPS Sintering Preparation Process of TiB₂ Base Composites with Ni

Abstract

Ni-TiB₂ composites can also maintain high hardness at high temperatures, which has a wide range of application prospects, but due to the low self-diffusion coefficient of TiB₂, dense sintering is more difficult. Adding Ni as the binder phase and using the SPS sintering process can significantly reduce the sintering temperature of the composites and obtain the composites denser and improve the toughness. In this research, we investigated the sintering process of Ni-TiB₂ composites at 5%–15% Ni content, sintering temperatures between 1273 K–1473 K, holding times between 300 s–1200 s, in vacuum environments with 50 MPa of pressure. Using Box-Benhnken (BBD) design and Response Surface Methodology (RSM) were applied to optimize the process parameter variables including sintering temperature, nickel content and holding time, and hardness as a response variable. Based on the statistical model, the predicted optimal sintering process is Ni-10%, sintering temperature is 1433 K and holding time is 930 s. At the optimum process, the hardness and relative density of the composites were 2036 HV and 96.8%. The experimental predictions yielded an optimal average hardness of 2065 HV, an optimal density of 4.56 g/cm³, and an optimal relative density of 96.5%. The experimental results are highly consistent with the model prediction.

Fig. 6 Comparison between experimentally measured and estimated Hv values for the compact with process conditions proposed by RSM.