Chemical pd-plating process for stainless steel surface with excellent anticossive performance in non-oxidant medium

Abstract

The present invention belongs to the field of surface treatment technology, and is especially chemical Pd-plating process for stainless steel surface with excellent anticorrosive performance in non-oxidant medium. The Pd-plated stainless steel is suitable for use in high temperature non-oxidant acidic medium environment. The chemical Pd-plating process includes surface pre-treatment and chemical plating, the surface pre-treatment includes deoiling and acid pickling, and chemical plating uses the plating solution comprising Pd salt Pd(NH3)4Cl2 in 1.5-5g / L accounting in PdCl2, stabilizer NH4Cl in 20-30 g / L, auxiliary complexing agent EDTA in 0-20g / L, surfactant Tween-20 in 0-0.002 ml / L, NH3 .H2O in 80-160 ml / L, reductant NaH2PO2 .H2O in 10-20g / L and water for the rest, of pH 9-10, for 30-60 min at 30-50 deg.c. The chemical Pd-plating process is simple.

Description

Technical field: [0001] The invention belongs to a stainless steel surface anticorrosion treatment process working in the harsh environment of high-temperature non-oxidizing medium (especially acidic medium), and belongs to the field of surface treatment. Background technique [0002] Stainless steel itself has the advantages of strong corrosion resistance and beautiful surface. The surface can form a dense passivation film in oxidizing medium to prevent the infiltration of corrosive medium, so as to achieve the purpose of protecting the substrate. However, in many chemical plants in my country, some stainless steel equipment is used in the harsh environment of high-temperature non-oxidizing media (especially acidic media), and a dense passivation film cannot be formed on the surface of stainless steel, resulting in serious corrosion problems of the equipment. After years of research by scholars at home and abroad, several solutions have been initially found, such as electro...

AI Technical Summary

Problems solved by technology

However, in many chemical plants in my country, some stainless steel equipment is used in the harsh environment of high-temperature non-oxidizing media (especially acidic media), and a dense passivation film cannot be formed on the surface of the stainless steel, resulting in serious corrosion of the equipment.

After years of research by scholars at home and abroad, several solutions have been initially found, such as electrochemical protection technology, and the method of anodic protection is often used in industry, but this technology is not conducive to popularization and use due to its complicated operation and high cost

Another method is to add alloying elements silicon, molybdenum, nickel, rare earth, copper, etc. to the matrix, but such methods involve metallurgy, thermal processing, selection of alloying elements and equipment renewal, which will greatly increase the production cost of stainless steel equipment. Improvement, and cannot be upgraded on the basis of the original equipment

[0003] The electroless palladium plating and electroplating palladium plating processes reported in the current literature and patents are relatively complicated. Electroless palladium plating must go through tedious sensitization and activation steps, and requires a long plating time. The materials are mostly limited to ceramics, glass, and porous. On the surface of stainless steel, the reducing agent is mostly poisonous hydrazine or hydrazine derivatives, and it has not been plated on the surface of general stainless steel.

However, the direct electroplating of palladium on the surface of stainless steel cannot overcome the problem of poor adhesion, so it must be pre-plated with other metals before proceeding.

[0004] The electroless palladium plating process reported in the current literature and patents not only has a long pretreatment time, a long plating time, and a complicated process, but also is mostly used as a catalytic membrane and a high-purity hydrogen permeable membrane. It has not been used for stainless steel in high-temperature non-oxidizing Reports on the use of anti-corrosion medium, such as the Chinese patent "A Surface Treatment Method for Improving the Poisoning Resistance of Lanthanide Alloys by Gas Impurities" (application date December 16, 2004, application number 200410081500.9, publication date July 27, 2005 , Publication No. CN1644759A) the hydrogen storage alloy is pulverized, sieved, and then made of PdCl 2 , NaH 2 PO 4 ·H 2 O, HCl, NH 3 ·H 2 O is formulated as a plating solution, and palladium is electrolessly plated on the surface of the hydrogen storage alloy, so that the hydrogen storage alloy alloy has good resistance to poisoning by gaseous impurities

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