Microstructure And Mechanical Properties Of Laser Cladding Sn/Ni Coating On Turbine Bushes

Tin-based pasteurized alloys are widely used in oil film bearings,such as steam turbine bearing pads,because they have good abrasion resistance,antifriction,mosaic properties,and compliance.During the start and stop of the steam turbine,the main shaft of the steam turbine will damage the oil film established between the main shaft and the bearing shell,causing wear between the main shaft and the bearing shell,causing the bearing shell to wear or even fall off.According to this problem,a laser-based cladding technology is used to prepare a tin-based Babbitt cladding layer on the surface of No.45 and Q235 steel substrates,and the connection between the tin-based Babbitt alloy and the bearing bush is increased by a nickel-based transition layer.To avoid the wear and tear of the tin-based bearing bush produced by the traditional process,it has a broad prospect in the thermal power equipment manufacturing industry.Babbitt cladding layer on the surface of No.45 steel.The phase composition of the cladding layer was a hard-spot particle Sn Sb phase,an antifriction phase Cu5Sn6,and a soft matrix phase?-Sn.Through the experiments on the hardness and friction and wear properties of the cladding layer,it is found that the hardness of the cladding layer is significantly higher than that of the cast tin-based Babbitt alloy,and the friction performance is also better than that of the cast tin-based Babbitt alloy.The wear mechanism of the cladding layer is mainly the surface Fatigue and abrasive wear with furrows.A layer of nickel-based alloy is cladding between No.45 steel substrate and tin-based Babbitt cladding layer to increase the bonding strength between the cladding layer and the substrate.The research shows that the nickel-based transition layer diffuses to the tin-based cladding layer,and the combination of nickel and tin,antimony,and copper in the tin-based alloy forms a more complex Nix Sny phase,and inhibits the formation of the brittle phase Cu5Sn6.The substance improves the bonding strength between the cladding layer and the substrate,and improves the microhardness of the cladding layer.At the same time,it also enhances the wear resistance of the tin-based Babbitt alloy cladding layer,and the wear mechanism of the cladding layer mainly manifests Fatigue and wear on the surface,accompanied by a little bit of corrosion.By controlling the laser power,three tin-based Babbitt cladding layers were prepared on the Q235 steel plate using 800 W,1000W,and 1200 W laser power,respectively.The change of laser power did not change the phase composition of the cladding layer,but changed the size of the hard spot particles Sn Sb phase in the cladding layer.The Sn Sb phase of the cladding layer prepared with 1000 W laser power had a smaller grain size and distribution.Evenly.The average friction coefficients of the three cladding layers were 0.592,0.257,and 0.526,respectively.In terms of wear mechanism,the pitting of the three cladding layers has caused pitting.The former wear mechanism is mainly adhesive wear and accompanied by oxidation,and the latter two are abrasive wear,and furrows are generated on the wear surface.