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Through the phosphorus electroless nickel plating process operating characteristics and summarize the status of research and application analysis, design based on TC4 titanium alloy electroless plating solution of phosphorus studied bath composition and operating conditions and other factors on Ni-P deposition rate and phosphorus content of the law , on the basis of the orthogonal test , get the best low phosphorus electroless Ni-P alloy process recipe is: nickel sulfate 19g / L, sodium hypophosphite 25g / L, acetic acid 19g / L, lactic acid 21g / L, sodium tetrafluoroborate 3g / L, sodium dodecyl sulfate 2mg / L, pH 7.4 ± 0.2, temperature 85 ± 2 ℃. For technical questions titanium activation , through the existing high phosphorus leaching zinc formulation process improvement study , get good adhesion of phosphorus coating , dip zinc activation process is : HF (40%) 40ml / L ~ 80ml / L, ZnSO 4 · 7H 2 O 15g / L ~ 20g / L, a dip zinc 2min, except in 1:1 nitric acid faded 20s, the second dip zinc 1min. Use mechanical agitation and ultrasonic dispersed combination of methods, to achieve the third phase SiC (1μm ~ 5μm) particles added was prepared phosphorus Ni-P-SiC composite coating . Using scanning electron microscopy and energy dispersive spectroscopy incidental , X-ray diffraction, micro hardness tester and salt spray chamber , etc. on the coating surface morphology , chemical composition , phase structure , hardness and corrosion resistance characterization. Ni-P coating surface smooth, flat , dense , with a silver-white metallic luster ; average particle size of 10μm, the average thickness of 45μm, the deposition rate is 25.68μm / h, a phosphorus content of 2.56wt%, plated hardness 750.20HV; coating structure is crystalline nickel-phosphorus supersaturated substitutional solid solution ; heat treatment at 400 ℃ coating hardness reached the maximum 1120.45HV; coating has good resistance to neutral salt spray corrosion , 120h salt spray corrosion coating surface did not change significantly , capable of matrix alloy play a protective role . Ni-P-SiC composite coating phosphorus content of 2.98wt%, is crystalline nickel-phosphorus supersaturated solid solution structure , SiC coating is added does not affect the organizational structure ; plated hardness than Ni-P alloy coating high- 350HV, 400 ℃ heat treatment , the hardness of the highest value 1974.26HV, this is due to Ni 3 P solid solution strengthening phase fully dispersed precipitates , on the other SiC particles on Ni-P alloy from the strengthening effect due. Phosphorus composition process recipe with a recipe and process parameters controlled scientific, production and application of technical and economic feasibility and value .
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