EFFECTS OF THE AMOUNT OF STARCH AND THE HOLDING TIME ON THE SYNTHESIS OF SiC-TiC COMPOSITE POWDERS

SiC-TiC composite powders were synthesised through carbothermal reduction under an argon atmosphere by using silica sol, starch, and TiO₂ as the raw materials. The influences of the starch dosage and holding time on the synthesis of SiC-TiC composite powder are discussed in detail. The samples were characterised using an X-ray diffractometer (XRD), an integrated thermal analyser (TG-DTA), a scanning electron microscope (SEM), and an energy spectrometer (EDS). The results showed that the SiC-TiC composite powders were completely synthesised after holding at 1550 °C for 3 h when the amount of excess starch was 5 wt% and after holding at 1550 °C for 2 h when the amount of excess starch was 10 wt%-20 wt%. The morphological characteristics of the powder samples with 5 wt%-15 wt% excess starch calcined at 1550 °C for 2 h were mainly flake particles, spherical particles, irregularly shaped particles and elongated whiskers. Conversely, no whiskers were found in the powder samples calcined at 1550 °C for 2 h when the amount of excess starch was 20 wt%.