A kind of surface rhodium plating method of steel strip

Abstract

A rhodium-plating method on the surface of a steel strip: using ordinary low-carbon cold-rolled steel strips as raw materials, degreasing and degreasing; washing and drying; annealing in a full hydrogen protective atmosphere; plating; naturally cooling to room temperature. The invention generates 2.5~3.5µm Ni-Cu / Ag-Pd / Pt / Rh composite coating on the surface of the steel strip, with a hardness of 70~75 HV, a surface roughness of 0.020~0.030µm, and a porosity of no more than 2 pieces / cm 2 , the specular reflectance is 99.92~99.99%; the resistivity is 0.05~0.09µΩ∙cm, the thermal conductivity is 380~390 W / m∙K; after being placed continuously for 5000 days at room temperature, the surface oxidation area does not exceed 0.05%, and the loss of light does not exceed more than 0.07%; after 5000 hours of continuous storage at 350~400 °C, the surface oxidation area does not exceed 0.07%, and the loss of light does not exceed 0.09%; There is no shedding and cracks, which fully meet the needs of clocks, jewelry, precision instruments and other industries.

Description

technical field [0001] The invention relates to a material surface treatment method, which specifically belongs to a method for plating rhodium on the surface of a steel strip, and is widely used in clocks, watches, jewelry, precision instruments and other industries. Background technique [0002] Rhodium (Rh) is an important precious metal with good ductility, surface properties, electrical conductivity, thermal conductivity, oxidation resistance, etc., and is widely used in clocks, jewelry, precision instruments and other industries. However, since Rh is a rare element in the earth's crust and is expensive, its application is greatly restricted. In order to reduce costs and save consumption, the current practice in the industry is to replace pure metal Rh with Rh-plated steel strips, and to achieve certain performance through Rh plating. [0003] As far as the traditional rhodium plating process for steel strip is concerned, it generally electroplates Cu, Ni, Ag, Rh and o...

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Problems solved by technology

[0011] The purpose of the present invention is to overcome the shortcomings of the prior art such as heavy environmental pollution, large waste of raw materials, poor coating quality and poor stability, and to provide a Ni-Cu coating with a thickness of 2.5-3.5 μm formed on the surface of the steel strip. / Ag-Pd / Pt / Rh composite coating, the hardness is 70~75HV, the surface roughness is 0.020~0.030μm, and the porosity is not more than 2 pieces / cm 2 , the specular reflectance is 99.92~99.99%, and the surface quality of the coating is good

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