Study On Microstructure And Properties Of Ni60/WC Coating Based On Composite Surface Strengthening Technology

Composite surface strengthening technology is to combine two or more kinds of surface strengthening technology, so that to strengthen the surface of the components. This combination is not a mechanical piling up together, but based on the in-depth analysis of the these kinds of technical advantages and disadvantages, understanding these technical characteristics, combining with their advantages, removing their disadvantages, so that they can mix together, to play their respective strengths to make up for its shortcomings that belong to itself when use it dependent.Study on microstructure and properties of Ni60/WC coating based on composite surface strengthening technology. Ni60/WC coating layer was prepared on the surface of 42 Cr Mo steel by oxyacetylene flame spraying, and then was strengthened by electrical contact strengthening technology which created by our team. The experimental scheme is designed based on the whole process of the composite surface strengthening technology, but it is focused on the impact of important technical parameters during the process integration and implementat ion. In the material preparation stage, the thermal analysis of Ni60/WC powders with different WC contents was carried out by TG/DSC thermal analyzer so that to study the thermal state of Ni60/WC from the room temperature to 1300?. In the process integration and implementat ion stage, the paper mainly explores the difference of microstructure and properties of the coating created by the key process parameters changing, such as Ni60/WC coating WC content, coating thickness, current intensity and current intensity, etc. Finally, the thermal shock and wear resistance of the coating were analyzed by thermal shock test and friction wear test after the final forming of the experimental sample.The experimental results show that in TG/DSC thermal analysis, the Ni60/WC powders with different WC contents were stable at a temperature rise to 900?, and there was no increase or weight loss because of chemical reaction or metal melt ing. After 900?, there will be a marked exothermic peak and increasing weight because of the infiltration of foreign elements due to chemical reaction of the coating material in the process of heating. During the process of the research, the primary bonding strength of the coating is provided by the oxygen acetylene flame spraying technology. After electric contact strengthening, the combination of coating and matrix is transformed into a metallurgical bonding, which has a certain area of elements diffusion. The WC content, the coating thickness and the current intensity have a significant effect on the electrical contact strengthening. At the same time, the thermal shock performance of the coating is improved. Coating thickness and current intensity are significant factors for thermal shock, and the WC content in the coating is not so much sensitive to it. In the wear resistance, the wear mechanism of the coating is abrasive wear and the wear resistance of the coating is better than the quenched 42 Cr Mo substrate after electric contact hardening.