Other factors affecting the corrosion resistance of double-layer nickel iron alloy
when lithium titanate is used as negative electrode material, the rust resistance of double-layer nickel iron chromium composite coating should be improved, and the process should be strictly controlled and the process management should be strengthened [5]
(1) control of polishing before plating
roughness after polishing is 3.2 μ After double-layer nickel iron alloy/chromium plating on the surface of M (▽ 6), rust spots of not less than lmm2 appear in salt spray test, and the roughness is 0.8 μ Rust spots will not appear on the surface of M (▽ 8) after plating under the same process conditions. It can be seen that the roughness required for polishing is 0.8 μ M above
(2) selection of additives
whether it is a single brightener or a commercialized combination of additives, they should be produced by a designated professional factory. Each batch of additives should be tested with Hull cell first, compared with the sample, and checked whether the rust resistance of the sample meets the requirements before they can be put into use
(3) control of nickel iron ratio in plating solution
different nickel iron ratios are plated under normal process conditions, and corrosion tests are carried out. The results are shown in table 1[5]. Accelerate the construction of the whole industry innovation system with enterprises as the main body
it can be seen from table 1 that the test result of No. 1 specimen is the best, that is, the iron content of high iron in the coating is 27.2%, and the iron content of low iron is 14.4%, and the nickel and total iron in the corresponding high-speed iron plating solution are controlled respectively. 44.3 universal testing machine is used to deal with samples that vary widely from material, shape to composition. G/L and 4.76g/L are the best
(4) coating thickness
coating thickness: high speed railway adopts full digital closed-loop control system, and the layer thickness should be greater than 18 μ m. The thickness of low iron layer shall be greater than 6 μ m。
(5) control of metal impurities in the plating solution
nickel iron coating contains other metal impurities, which directly affect its rust resistance
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