Study On Microstructure And Mechanical Properties Of Surface Coating Remanufacturing Of Medium Carbon Alloy Wear Resistant Steel

To make the large ball mill lining board meet the high requirements on the service life under the circumstances of metallurgy, mining conditions. From two aspects to consider, one is the chemical composition, organization and structure of ball mill lining plate itself, namely internal factors; the other is wear surface corrosion parts of large ball mill for its easy to wear-out failure are coated by the application of remanufacturing technology, namely external factors. This paper is based on these two aspects, the wear of medium carbon alloy steel plate regarded as the substrate is selected by the metal material PANDAT thermodynamic analysis software, the WC-lOCo-xCr (x=2,3,4,5) of ceramic coating on the surface of the base material were prepared by HVOF technology. The microstructure, phase structure and morphology of coating parts were characterized and analyzed by optical microscope, SEM and XRD, at the same time, mechanical properties of coating was tested by the electronic universal testing machine, microhardness tester and friction wear testing machine and the corrosion resistance of coating under the condition of water simulation test was tested by the electrochemical workstation. The results show that:(1) Carbon alloy wear resistant steel was selected which regard as the base material, namely ZG42SiMnCr2MoCe. The Organization of ZG42SiMnCr2MoRe steel is martensite+eutectic carbides, the secondary dispersion carbide+a small amount of retained austenite, its hardness is higher than 55 HRC, toughness is higher than 42J/cm2 (Charpy notch specimen).(2) The WC-10Co-xCr (x=2,3,4,5) ceramic composites have uniform particle size distribution, particle high sphericity and the spherical porous surface which easy to form a high quality dense coating, the between of coating and the substrate is mainly mechanical bonding, WC experienced a certain degree of decarburization in the spraying process, the main phase of ceramic coating is WC phase and a small amount of W2C and trace CoCr phase. The organization of WC-10Co-xCr(x=2,3,4,5) ceramic composite coating prepared by thermal spraying is uniform and compact, no large pore and crack; the lowest porosity, WC-10Co-3Cr coating, is 1.0% and the highest porosity, WC-10Co4Cr coating,is 5.0%.(3) The microhardness of ceramic composite coating which prepared was higher than substrate material whose microhardness is 55.7 HRC, among them, the average microhardness of WC-10Co-2Cr coating is 70 HRC, WC-10Co-3Cr coating is 68 HRC, WC-10Co-4Cr coating is 61.4 HRC, WC-10Co-5Cr coating is 66 HRC. The bonding strength of coating is higher than the bonding adhesive which its bonding strength is70Mpa. The wear resistance of the substrate was significantly improved by the WC-10Co-xCr (x=2,3,4,5) ceramic coating under the conditions: sliding speed of 370r/min, the load 400g conditions. And the wear resistance of WC-10Co-2Cr coating was the best. The main wear mechanism of WC-10Co-xCr (x=2,3,4,5) coating is abrasive wear.(4) The WC-lOCo-xCr (x=2,3,4,5) coating has excellent corrosion resistance, among them, the WC-10Co-3Cr coating is better than the other three kinds of coating and its corrosion potential is the largest, about-0.460V, the corrosion current density is the smallest, about 1.703 10-4A cm-2.