Effect of Deposition Time on Microstructures and Growth Behavior of ZrC Coatings Prepared by Low Pressure Chemical Vapor Deposition with the Br2-Zr-C3H6-H2-Ar System

摘要

ZrC coatings were deposited on graphite substrates by low pressure chemical vapor deposition(LPCVD) with the Br_2-Zr-C_3H_6-H_2-Ar system. The effects of deposition time on the microstructures and growth behavior of ZrC coatings were investigated. ZrC coating grew in an island-layer mode. The formation of coating was dominated by the nucleation of ZrC in the initial 20 minutes, and the rapid nucleation generated a fine-grained structure of ZrC coating. When the deposition time was over 30 min, the growth of coating was dominated by that of crystals, giving a column-arranged structure. Energy dispersive X-ray spectroscopy showed that the molar ratio of carbon to zirconium was near 1:1 in ZrC coating, and X-ray photoelectron spectroscopy showed that ZrC was the main phase in coatings, accompanied by about 2.5mol% ZrO_2 minor phase.