Preparation method of cadmium coating on surface of steel strip

Abstract

The invention discloses a preparation method of a cadmium coating on the surface of a steel strip. The preparation method comprises the following steps of: carrying out conventional degreasing and deoiling on an austenitic stainless steel cold-rolled steel strip serving as a base material; carrying out conventional washing and drying until no water exists on the surface of the steel strip; carrying out annealing in a total hydrogen protective atmosphere; carrying out plating: electroplating a Zn-In alloy; carrying out ion implantation of Cd; carrying out physical vapor deposition of an In-Sn alloy; and carrying out natural cooling to room temperature. According to the method, a Zn-In / Cd / In-Sn composite coating with the thickness of 10.3-13.5 microns is generated on the surface of the steelstrip, the hardness is 36-42 HV, the surface roughness is 0.015-0.025 microns, and the porosity does not exceed 2 / cm<2>; the surface corrosion area does not exceed 0.08% after the coating is continuously placed in a seawater environment of 30 DEG C for 3600 days; the surface oxidation area does not exceed 0.12% after the coating is continuously placed at high temperature of 300 DEG C for 500 days; and after the coating is continuously placed in a 100 KHz ultrasonic environment for 10,000 hours, the thickness of the coating is not obviously changed, falling and cracking are avoided, heavy metal exposure is avoided, and the requirements of special environments such as oceans and aviation are completely met.

Description

technical field [0001] The invention belongs to the technical field of material surface treatment, in particular to a method for preparing a cadmium coating on the surface of a steel strip. Background technique [0002] Cadmium (Cd) is an important low-melting heavy metal with good plasticity and easy forming. Especially in marine or high-temperature atmospheric environments, it has excellent corrosion resistance and oxidation resistance. After being plated on the surface of steel products, it forms a protective coating to protect the steel base from corrosion. [0003] However, the application of cadmium coating in reality is greatly limited, mainly because: [0004] First, cadmium is a toxic heavy metal element. During the plating process, whether it is its vapor, molten liquid metal or soluble salt, it is highly polluting and extremely harmful to the environment and human body. [0005] Second, in the process of direct cadmium plating on the surface of steel parts, unde...

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Problems solved by technology

[0010] The object of the present invention is to overcome the problems of heavy environmental pollution and poor coating quality in the prior art, and provide a Zn-In / Cd / In-Sn composite coating with a thickness of 10.3-13.5 μm formed on the surface of a steel strip. 36~42HV, surface roughness 0.015~0.025μm, porosity no more than 2 / cm 2 ; After being placed continuously in seawater at 30°C for 3,600 days, the surface corrosion area does not exceed 0.08%; after being placed at a high temperature of 300°C for 500 days, the surface oxidation area does not exceed 0.12%; The preparation method of the cadmium coating on the surface of the steel strip has no obvious change, no shedding and cracks, and no heavy metal exposure, which fully meets the needs of special environments such as marine and aviation.

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