A kind of preparation method of lead-tin alloy coating on the surface of steel strip

Abstract

A method for preparing a lead-tin alloy coating on the surface of a steel strip: using an austenitic stainless steel cold-rolled steel strip as a base material, degreasing and degreasing with conventional lye; conventionally washing with water and drying until the surface is free of moisture; Bottom annealing; plating: Cu-Sn alloy electroplating; dual ion implantation of Pb and Sn; physical vapor deposition of In-Cu alloy; natural cooling. The surface of the steel strip of the present invention forms a Cu-Sn/Pb-Sn/In-Cu composite coating with a thickness of 9.2-12.8 µm, a hardness of 37-42 HV, a surface roughness of 0.016-0.026 µm, and a porosity of no more than 2 pieces/cm ² ; After 3600 days of continuous placement in seawater at 30°C, the surface corrosion area does not exceed 0.02%; after 500 days of continuous placement at 300°C, the surface oxidation area does not exceed 0.06%; after 10,000 hours of continuous placement in 100 KHz ultrasonic environment, the coating There was no obvious change in thickness, no shedding and cracks, and no heavy metal exposure was found.

Description

technical field [0001] The invention belongs to the technical field of material surface treatment, in particular to a method for preparing a lead-tin alloy coating on the surface of a steel strip. Background technique [0002] Lead (Pb) is an important heavy metal with low melting point, which has good plasticity and is easy to form. 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 lead plating in reality is greatly limited, mainly because: [0004] First, lead 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 lead plating on the surface of st...

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Problems solved by technology

[0016] The purpose of the present invention is to overcome the problems of heavy environmental pollution and poor coating quality in the prior art, and to provide a Cu-Sn / Pb-Sn / In-Cu composite layer with a thickness of 9.2-12.8 μm on the surface of the steel strip. The coating has a hardness of 37-42HV, a surface roughness of 0.016-0.026μm, and a porosity of no more than 2 pieces / cm 2 ;After being placed continuously for 3600d in 30℃ seawater environment, the surface corrosion area shall not exceed 0.02%; after being continuously placed at high temperature 300℃ for 500d, the surface oxidation area shall not exceed 0.06%; after being continuously placed in 100KHz ultrasonic environment for 10000h, the coating thickness There is no obvious change, no shedding and cracks, and no heavy metal exposure, and the preparation method of the lead-tin alloy coating on the surface of the steel strip fully meets the needs of special environments such as marine and aviation.

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