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

Abstract

SiC-TiC composite powders were synthesised through carbothermal reduction under an argon atmosphere by using silica sol, starch, and TiO 2 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 -20 wt. %. The morphological characteristics of the powder samples with 5 -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. %.

SYNTHESIS AND MECHANISM OF SiC-ZrC COMPOSITE POWDERS BY CARBOTHERMAL REDUCTION METHOD

“…The amounts of silica sol, ZrO 2 , and starch were adjusted to yield an SiC/ZrC molar ratio of 7:3 in the expected synthesis product. In addition, the Thermogravimetry and Differential Thermal Analysis (TG-DTA) curve of a single starch raw material shows that starch de-composes under high-temperature conditions and argon atmosphere, resulting in a mass loss of up to 78.2 % [26]. Therefore, in this study, the amount of starch was determined according to the actual mass loss rate during the synthesis reaction.…”