Abstract:The Mn-Co spinel coatings was prepared by atmospheric plasma spraying (APS) process, and the effects of different carrier gases and spray distances on the morphology and conductivity of the coatings were studied. The electrical conductivity of the coating was measured by the direct current four-electrode method, and the micro morphology and composition of the coating were characterized by SEM, XRD, XPS and other characterization methods. The results show that the prepared coating is dense, has fewer holes, and is well bonded to the substrate, and the surface is in a state of mixing liquid deposition and micro-melting particles accumulation. At 800°C, the conductivity of the coating under 2 SLPM is 18 S/cm, while the conductivity of the coating under the other carrier gas is only 8 S/cm. The Mn-Co coating prepared with low carrier gas has good conductivity; At 800°C, only the conductivity of the coating with a spray distance of 130 mm exceeds 10 S/cm. Increasing the spray distance has little effect on the conductivity, and the conductivity distribution of each coating is closer. Pyramid-shaped spinel crystal structures of various orientations are formed on the surface of the tested coating, and the intensity of the spinel phase diffraction peak is significantly improved. The peaks in the high-conductivity coating are stronger and sharper; the ratio of divalent and trivalent elements in the high-conductivity coating is closer to 1:2, which is a typical spinel structure and shows higher conductivity. Therefore, increasing the carrier gas flow and appropriately increasing the spraying distance can make the coating more layers are deposited in the molten state.
