Effect of Deposition Temperature on Microstructures and Properties of MoSi2 Coatings Prepared by Low Pressure Chemical Vapor Deposition

MoSi2 coatings were prepared on Mo substrates by low pressure chemical vapor deposition￡¨LPCVD￡ using SiCl4 and H2 as source gases, in the temperature range from 1000 o 1300 Effect of deposition temperature on the microstructures, phase composition, deposition process, deposition rates, hardness and the bonding strength between coatings and Mo matrix were studied. It is indicated that the MoSi2 coatings deposited in the temperature range from 1100 o 1200 re compact consisting of single MoSi2 phase. The deposition rates, hardness and the bonding strength increase with the increase of temperature￡ however above 1200 cracks and Si phase appear in the coating, the deposition rates, hardness and the bonding strength decrease. The deposition process is mainly controlled by the reaction between Si and Mo below 1100 while above 1100 he diffusion of Si in MoSi2 coatings becomes the controlling step.