Mechanical and thermal properties of SiO2/S composite coating prepared by APCVD

Three series of SiO2/S composite coatings were prepared on HP40 alloy substrates by atmospheric pressure chemical vapor deposition (APCVD). The morphologies, components and chemical structures were analyzed by means of scanning electronic microscope (SEM), energy dispersive spectroscopy (EDS) and Raman spectroscopy, respectively. Thermal shock properties, thermal stability properties, microhardnesses and tensile strengths of three samples were performed. The results show that the particles of SiO2/S composite coating reduce with the increase of sulfur content. However, thermal shock cycles by water quenching from 900 °C increase with the increase of sulfur content. The microhardness and thermal stability property reduce with the decrease of sulfur content, and the microhardness of SiO2/S composite coating can reach HV0.1890. There are a small amount of sulfur losses for three samples after thermal stability tests. The tensile strength of SiO2/S composite coating can reach 39.5 MPa. SiO2/S composite coating prepared on HP40 alloy substrate can meet the needs of ethylene cracking production.