Investigation on the electrical properties of vacuum cold sprayed SiC-MoSi ₂ coatings at elevated temperatures

SiC-MoSi ₂ composite powders was prepared by wet milling with MoSi ₂ powders and SiC loose grinding ball in alcohol solution. Vacuum cold spray (VCS) process was used to deposit SiC-MoSi ₂ electric conducting composite coatings. The microstructure of the VCS SiC-MoSi ₂ composite coatings were characterized by scanning electron microscopy. The electrical resistance of the coatings was measured using a four-point probe method. The effects of the deposition parameters on the electrical resistivity of the composite coatings were investigated. The electrical properties of the coatings at elevated temperatures in air and Ar gas atmospheres were also explored. The results show that the electrical resistivity of SiC-MoSi ₂ coatings decreases with increasing He gas flow rates ranged from 3 to 6 L/min. The electrical resistivity increases with the increase in heat treatment temperature due to "pesting" behavior of MoSi _2. The electric conductive property of the VCS SiC-MoSi ₂ coating is significantly improved after heat treatment at 1000 °C for 3 h in Ar protective atmosphere without oxidation. A minimum resistivity of the heat treated coating is 0.16 Ω • cm.