| Laser cladding metal surface has a dilution rate control, extensive material system, combined with high strength, heat distortion is small. Furthermore, a ceramic material mixed with the metal composite coating consisting of, a metal good plasticity and toughness and excellent wear and corrosion properties of high-temperature ceramic materials combined to develop wear-resistant protective coating provides a broad space.With the application and use of nano-ceramic particles value continues to increase, nano-ceramic particles emerged a lot of preparation, this paper introduces a precipitation method using nano-alumina particles in the production process. In an aqueous medium, 0.3 M of Al C l3 as aluminum salts, water bath heated to 40 ~ 50 ℃, with 1.0 M of Na2CO3 solution as a precipitating agent(PEG1500 precipitation reaction initially charged as a surfactant), dropping by optimizing the way, after obtaining a white precipitate, aging 24 h, washing filter press at 450 ℃ high temperature dehydration 1.5 h. Finally, after two pulverized to give a particle size in the nano-alumina particles of 50 nm or less.Then, this paper iron substrate surface using laser cladding technology, 316 L stainless steel surface was prepared Al2O3/Fe-Cr-Mo composite coating; were prepared on the surface of Q235 Si C /316 L composite coating. By optical microscopy(OM), scanning electron microscopy(SEM), X-ray energy dispersive spectroscopy(EDS), X-ray diffraction(XRD), such as testing the cladding microstructure and strengthening mechanism is analyzed. Al2O3/Fe-Cr-Mo composite coatings, the occurrence of partial decomposition of Al2O3 generated between iron aluminide. Si C/316 L composite coating, micron Si C partially decomposed residual phase of Si C. Nano-Si C complete decomposition occurs, generate a new phase of strengthening carbides M7C3 and Fe Si, new and enhanced silicide phases, so that cladding organized by columnar grain into cellular crystals. The use of micro-hardness, friction and wear testing machine, tensile testing and other analysis of the distribution of the cladding layer hardness, friction and wear properties and tensile mechanical properties. Al2O3/Fe-Cr-Mo composite coatings, 8wt.% Al2O3 the appropriate dosage. Compared with the micro-Al2O3, in the amount of the same, nano-Al2O3 mixed with the metal powder is more uniform, fine organization, hardness, high tensile strength, and exhibits excellent wear resistance. Al2O3 ceramics reinforced by intermetallic phase transition between Fe3 Al compound and the substrate has a high bonding strength, excellent wear resistance of composite coating which is the main reason. Si C/316 L composite coating, cladding layer hardness up to 527 HV, than 316 L cladding was increased by 132%, compared with micron Si C cladding layer hardness 100 HV or more, the minimum friction coefficient and wear volume, It has excel ent wear resistance. |
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