Effects Of WC/La₂O₃ On The Microstructure And Properties Of Nickel-based Fluxed Alloy

45 steel has been widely used in mechanical fieldas as axial work pieces. With the progress of science and technology, the properties of mechanical parts are required higher and higher. In some demanding environments, the surface with a higher abrasion resistance and corrosion resistance is required. Therefore, the preparation of abrasion or corrosion resistant coatings on the surface of 45 steel has very important practical significance by the thermal spraying technology.In this paper, nickel-based composite coatings are prepared on 45 steel substrate by the method of flame spraying. The microstructure and properties of the coatings before/after remelting containing different WC or La2O3 content are studied using metallographic microscope, X-ray diffractmeter,micro-hardness tester, scanning electron microscope (SEM), electrochemical tester. Furthermore, the effects of the adddition of WC or La2O3 on microstructure and properties of the coatings are discussed which the mechanism is also analyzed.There is mainly mechanical bonding between the smelting layer and substrate, and small amount of metallurgical combination also existing.The coatings are composed of mutual stacking distortion particle and then form layered wave-like structure.The addition of WC into nickel-based alloy increase porosity of coatings, and the hardness and wear resistance of coatings and remelting layers are improved effectively due to the addition of a proper amount of WC. In additon, the close combination of the coating and substrate is occurred after adding rareearth La2O3 powders resulting in the bonding strength increasing.At the same time, corrosion resistance of the smelting layer is also improved obviously.The smelting coating has the best wear resistance under condition of adding 15%wt WC powders to G112 fluxed alloy powders. Under the pressure of 200N, the wear loss of the coatign is 2.36×10-5g/min·mm2 When the rare earth content is 3wt%, the best corrosion resistance is abtained.In the 3.5% NaCl solution, the self corrosion potential is -212.323 mv and the corrosion current density is 1.723A/cm-2.