Production method for ultrathin steel strip with Cu-Sn/Sn-Au double composite coating

Abstract

The invention relates to a production method for an ultrathin steel strip with a Cu-Sn / Sn-Au double composite coating. The production method comprises the steps that primary annealing is conducted, cold rolling is conducted, Cu-Sn thermal spraying is conducted after uncoiling, striping and burr removing are conducted, secondary annealing is conducted, Sn-Au thermal spraying is conducted, third spraying is conducted, and air cooling and reeling are conducted. The tensile strength of the steel strip produced through the production method is 300 to 350 Mpa, and the elongation rate of the steel strip is 38 to 45%. Bright golden yellow is presented on the surface coating, the surface hardness is 100 o 120 HV, the roughness is 0.1 to 0.2 micrometer, the mirror reflectivity is 94 to 99%, the coating light loss rate is no greater than 0.5% after the steel strip is placed in the normal environment for 720 days, the electric resistance is 14 to 18 Ohm.cm, the heat conductivity is 60 to 75 W / m. DEG C, the surface oxidation area is no greater than 0.1% after the steel strip is maintained for 480 h, the change rate of the hardness value is no greater than 0.3%, and the problems that the cost is high, the pollution is heavy, and the efficiency is low of the traditional technology are solved.

Description

technical field [0001] The invention relates to a production method of a steel strip, in particular to a production method of an ultra-thin steel strip with Cu-Sn / Sn-Au double composite coating. Background technique [0002] Due to its thin thickness, excellent surface properties, electrical conductivity, thermal conductivity and heat resistance, the ultra-thin Au-plated steel strip is widely used in the optoelectronic industry to produce precision semiconductors, electronic chips or special light sources. The market demand great. [0003] At present, the production of Au-plated steel strip is mainly to continuously electroplate Cu, Ni, and Au single metals on the surface of cold-rolled strip steel to form a traditional Cu-Ni-Au composite coating. Although this process has a long history, it has the following problems that are difficult to solve, namely: first, the coating is based on Cu, which is prone to oxidation, resulting in a decrease in the stability of the coating...

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Problems solved by technology

Although this process has a long history, it has the following problems that are difficult to solve, namely: first, the coating is based on Cu, which is prone to oxidation, resulting in a decrease in the stability of the coating.

In addition, once the corrosive medium passes through the cracks and pinholes of the Au layer, passes through the pores of Ni and Cu, and reaches the Fe matrix, since the Fe matrix is ​​the anode of the corroded galvanic couple, it will soon corrode and appear rust spots.

Second, if continuous electroplating is used, highly toxic cyanide needs to be used as the electroplating solution in the process of electroplating Au, which will seriously pollute the environment

The third is that the surface of the steel strip is easily passivated after continuous electroplating, and the comprehensive performance of the obtained composite coating is difficult to control

Fourth, the continuous electroplating process leads to large production energy consumption and more waste liquid

The problem of high cost and poor corrosion resistance of the pure nickel layer on the steel strip is solved, and the obtained double-coated steel plate is mainly used for the manufacture of electrodes

However, since there is no Au-containing composite coating in the steel strip, the surface properties, electrical conductivity, thermal conductivity and heat resistance of the product cannot meet the requirements of the optoelectronics industry.

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