Ting Wu

Interface characterization of Cu–Mo coating deposited on Ti–Al alloys by arc spraying

Cu–Mo pseudobinary alloys are promising candidates as electrode materials in CoSb3-based skutterudite thermoelectric (TE) devices for TE power generation. In this study, Cu–Mo coatings were deposited onto Ti–Al substrates by applying a dual-wire electric arc spraying coating technique. The microstructure of the surfaces, cross sections and coating interfaces were analyzed by scanning electron microscopy (SEM) and energy dispersion spectrometry (EDS). Cu–Mo coatings showed a typical banded splat with compact microstructures, and have no coarse pores nor micro-cracks. The thermal shock resistance of the Cu–Mo coating was also investigated to show good combinations with Ti–Al substrates. After 50 thermal shock cycles, there were no cracks observed at the interface. In contrast, the test of the thermal shock resistance of the Cu coating on the Ti–Al substrate was also investigated. Due to a large difference in the thermal expansion coefficients between Cu and Ti–Al alloys, the Cu coating flaked from the Ti–Al substrate completely after 10 thermal shock cycles. The contact resistivity of the Ti–Al/Cu–Mo interface was about 1.6 μΩ⋅cm2 and this value was unchanged after 50 thermal shock cycles, indicating the low electric resistance and high thermal stability of the Cu–Mo/Ti–Al interface.