等离子喷涂碳化硼涂层相组成和电学性能研究

Influence of Spraying Distance on Phase Composition and Electronic Property of Plasma Boron Carbide Coating

采用大气等离子喷涂，在不同喷涂距离下制备了碳化硼涂层，研究了喷涂距离对碳化硼涂层的显微结构、相组成和电导率的影响．用EDS和XPS分析了涂层的相组成；扫描电镜观察涂层的显微结构；标准四探针法测量涂层的电导率．结果表明，喷涂距离不仅会影响碳化硼涂层的显微结构，而且会改变碳化硼涂层的相组成；等离子喷涂碳化硼涂层的表面电导率随温度的增加而增加，表现出明显的半导体特性；涂层表面电导率同相组成和显微结构密切相关，涂层中B_2O_3相含量越高，气孔率越大，则涂层的电导率越低．

Boron carbide coatingS were deposited under atmospheric pressure by plasma spray at differentspraying distance. Their microstructure and phase composition were studied through EPMA, EDSand XPS. Their dc conductivity was measured by standard four-probe. The results show that thesuitable spraying distance causes dense B4C coating; the longer the spraying distance, the seriousoxidation of B4C powder is, the spraying distance may severely effect the phase composition. Theplasma spray boron carbide coatings possess semiconductor properies. The conductivity increaseswith temperature. The phase composition and B/C ratio determined by the spraying distance,can effect the conductivity of boron carbide coating.