Ni-Cu-P-Ce alloy plating layer and preparation process

Abstract

The invention relates to chemical plating on a surface of a metal material and particularly to a Ni-Cu-P-Ce alloy plating layer used for chemical plating on a surface of a low-carbon steel base material and a preparation process of the Ni-Cu-P-Ce alloy plating layer. The Ni-Cu-P-Ce alloy plating layer adopts a plating liquid composed of 35-40 g / L of nickel sulfate, 0.2-0.4 g / L of copper sulfate, 25-30 g / L of sodium hypophosphite, 8-10 g / L of sodium acetate, 25-30 g / L of trisodium citrate, 22-28 ml / L of lactic acid, 8-10 g / L of butanedioic acid, 0.2-0.4 g / L of cerium nitrate, 8 mg / L of potassium iodide, 1.5 mg / L of thiourea, 0.01 g / L of glycine and 0.2 g / L of ammonium bifluoride. For the adoption of ultrasonic chemical plating, a plating layer material formed by codeposition of Ce, Cu and Ni is obtained; and the material has increased compactness, is a microlithic texture, and is high in hardness and strong in corrosion resistance.

Description

technical field [0001] The invention relates to electroless plating on the surface of metal materials, in particular to an electroless Ni-Cu-P-Ce alloy coating for the surface of a low-carbon steel substrate and a preparation process thereof. Background technique [0002] Rare earth is known as the "treasure house" of new materials. It is one of the most concerned group elements by domestic and foreign scholars, especially material experts. Its value and status are increasingly concerned. Rare earth elements are 15 lanthanide elements with atomic numbers ranging from 57 to 71 in the third subgroup of the periodic table, plus scandium and yttrium, which have similar electronic structures and chemical properties, a total of 17 elements, which are typical metal elements. Metal activity is second only to alkali metals and alkaline earth metals, and is more active than other metals. Rare earth elements have a large atomic radius and special electronic structure, so they have goo...

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Problems solved by technology

Since the mid-1990s, the majority of solid thin film researchers in my country have made many explorations on adding rare earths to the traditional electroless Ni-P alloy plating solution. However, due to the reduction potential of rare earths (between -2.2V and -2.5V Between) is much more negative than the reducing agent sodium hypophosphite in the plating solution. According to the electrochemical theory, the reduction potential of the deposited metal must be higher than that of the reducing agent before it can be reduced and deposited. Therefore, it is difficult for the coating alloy and rare earth to co-deposit

In addition, from an electrochemical point of view, when rare earth elements are added, the electrode system formed is different from that before the addition of rare earth elements, which changes the electronic layer structure of the electrode interface, hinders the deposition of Cu and Ni and interfacial diffusion, and makes Cu The difficulty of reducing deposition with Ni atoms increases, so that the improvement effect of rare earth on the deposition rate is not obvious

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