Study On Ultrasonic Assisted High-frequency Induction Cladding Of Nickel Composite

With the development of modern science and technology, human beingshave been deep into the inner earth and the outer space. Many mechanicalcomponents need to work under high temperatures, high pressures, corrosion andother kinds of harsh conditions, which makes them easier to be failure. Most ofthe failure incidents are caused by corrosion and wear of the surface. Soimproving surface properties of mechanical components can prolong the servicelife of the equipments, improve their work efficiency and reduce energyconsumption.Induction cladding is a useful method of surface cladding technologies. Ithas drawn more and more attention for its advantages such as fast heating,smooth surface, flexible operation and so on. Induction cladding is thedeveloping trend of surface cladding technologies.We use ultrasonic-assisted high frequency induction cladding method in thiswork. A SiC-Ni60composite coating on the surface of cylindrical45steelsamples was fabricated in order to improve the performance of the45steel byusing both ultrasonic and SiC nano-particles. A coating with uniform chemicalcomposition, little residual stress and refined grains was obtained.The metallographic microscope, scanning electron microscope and X-raydiffraction were used to test and analyze the microstructure, chemicalcomposition, phase composition and surface structure of the coating. The micro-hardness tester, wear resistance testing machine and electro-chemicalworkstation were applied to test the performance of the coating. Theexperimental results are:A good metallurgical bond was formed between the45steel and the SiC-Ni60cladding layer. The cladding layer was mainly composed of Cr7C3and Fe-Ni inter-metallic phases. The dendrite crystals were nickel-based solid solutionswith other compounds. Most of the Cr gathered around the grain boundaries in aform of compounds. Nickel-iron compounds, nickel-boron compounds and Crcompounds contributed to the good wear resistance of the cladding layer.After adding nano SiC particles in Ni60powder, the Vickers hardness of thecladding layer was nearly2times of that of45steel. Compared with traditionalNi60cladding coating, The Vickers hardness had a41%increase. So nano SiCparticles can obviously improve the micro-hardness of the cladding layer.The average wear width and friction coefficient of SiC-Ni60cladding layerwere219.3μm and0.348, respectively, but for Ni60cladding layer, they were254.7μm and0.413. The wear scar width of SiC-Ni60cladding layer was more narrow and shallow comparing with Ni60cladding layer under the sameexperimental condition. So the wear resistance of the SiC-Ni60coating is betterthan that of the Ni60cladding layer.The corrosion resistance of45steel can be significantly improved bycladding Ni60on its surface. After adding the nano SiC powder, the corrosionresistance of Ni60coating does not change much, indicating that SiC has littleeffect on the corrosion resistance of the cladding layer. In conclusion, by usingultrasound and adding nano SiC particles, the comprehensive performances ofthe cladding layer can be improved.