Electroless nickel-phosphorus plating method for austenitic stainless steel surface

Abstract

The invention provides an electroless nickel-phosphorus plating method for an austenitic stainless steel surface. Cleaned austenitic stainless steel is activated, a nickel layer is activated after assistant nickel layer electroplating, then electroless nickel-phosphorus plating is conducted, and finally hardening heat treatment is conducted. The thickness of electroless plated layers is increased,the adhesive force is improved, all the plated layers are well integrated mutually and are not liable to fall off, and thus the product quality is greatly improved; and due to the fact that the nickel content and the phosphorus content of the austenitic stainless steel surface are increased, the hardness and the corrosion resistance of the austenitic stainless steel surface are greatly improved.

Description

technical field [0001] The invention relates to the field of surface treatment of austenitic stainless steel, in particular to a method for chemically plating nickel and phosphorus on the surface of austenitic stainless steel. Background technique [0002] Austenitic stainless steel has a dense passivation film on the surface, so it has excellent corrosion resistance and is widely used. However, there are often some defects on the surface of austenitic stainless steel that destroy the uniformity of the passivation film, such as inclusions, chromium-poor regions, grain boundaries, dislocations, etc. The passivation film in these places is relatively weak, and some active anions such as Cl-, SCN- etc. are easy to enter the surface of austenitic stainless steel from the defect, destroying its passivation film, so that the corrosion resistance of austenitic stainless steel is greatly weakened; the hardness of austenitic stainless steel is low, and its wear resistance is not good...

AI Technical Summary

Problems solved by technology

However, there are often some defects on the surface of austenitic stainless steel that destroy the uniformity of the passivation film, such as inclusions, chromium-poor regions, grain boundaries, dislocations, etc. The passivation film in these places is relatively weak, and some active anions such as Cl-, SCN- etc. are easy to enter the surface of austenitic stainless steel from the defect, destroying its passivation film, so that the corrosion resistance of austenitic stainless steel is greatly weakened; the hardness of austenitic stainless steel is low, and its wear resistance is not good enough. Defects also limit the application fields of austenitic stainless steel. Therefore, the hardness and corrosion resistance of austenitic stainless steel must be improved in order to make it have a wider application field, such as gaskets used in high-speed rail, ships, etc., not only Requires extremely high corrosion resistance and strong hardness

The electroless nickel-plating phosphorus alloy coating has good acid, alkali and salt corrosion resistance. The introduction of nickel can enhance the hardness and corrosion resistance of austenitic stainless steel. For example, 304 stainless steel has a nickel content of more than 8%, and 316 stainless steel The nickel content is more than 10%. However, in some special fields, such as gaskets used in high-speed rail, ships, etc., the hardness and corrosion resistance of 304 stainless steel and even 316 stainless steel are still far from meeting the requirements. Traditional chemical plating Although nickel-phosphorus can increase the nickel content to a certain extent, the improvement is limited. Therefore, it is urgent to improve the traditional electroless nickel-phosphorus plating process to obtain austenitic stainless steel with high nickel content on the surface and the coating does not fall off, so as to achieve sufficient hardness and corrosion resistance. Corrosion ability