high-velocity solution plasma spray (HVSPS) process. Graded coatings were formed by reactions between the Si(OH) 4 sprayed liquid precursor and the C/C substrate; these reactions were promoted by the high temperature of the plasma torch. The morphologies, microstructures, and chemical compositions of the coatings were investigated by X-ray diffraction, Raman spectroscopy, Fourier-transform infrared spectroscopy, and scanning electron microscopy/energy-dispersive X-ray spectroscopy. By altering the deposition time, the coating thickness was controlled, therefore demonstrating SiC formation and realizing graded SiO 2 /SiC coatings.