JPS6059059A - Method for preventing corrosion of metallic surface - Google Patents

Abstract

PURPOSE:To prevent the corrosion of a metallic surface and the stripping of a sprayed coating layer and to hinder the progress of the stripping by roughening the metallic surface with an etching soln. and subjecting the roughened surface to preliminary spraying, finish spraying and pore sealing treatment. CONSTITUTION:The surface of a metal such as stainless steel or a Zr alloy is roughened with an etching soln. The roughened surface is subjected to preliminary spraying with an Ni alloy or the like, finish spraying with titania or the like and pore sealing treatment with silicone resin, epoxy resin, bitumen, paraffin or the like. The metallic surface can be thoroughly isolated from a corrosive environment, the stripping of the resulting surface coating layer is effectively prevented, and the progress of the stripping is effectively hindered.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to corrosion inhibition of metal surfaces.

[Technical background of the invention and its problems]

In the past, various studies have been conducted on corrosion prevention measures, including the addition of corrosion inhibitors, PHp14 adjustment, cathodic protection, use of aluminum cladding materials, lining methods for environmental isolation, application of passive treatment, material conversion, etc. Countermeasures such as equipment design changes, process changes, and equipment expansion are being considered. The causes of corrosion in practical equipment include environmental conditions, manufacturing processing conditions,
There are many factors that can be considered, such as the location conditions for equipment installation, stray currents, and the loft in which the equipment's base material is used.As a result, it often takes a long time to take countermeasures and treatments, and as a result, the equipment is often disposable.

Corrosion problems often occur even if they are thoroughly considered at the design stage, and are often discovered during periodic inspections and prompt countermeasures must be taken. In addition, one of the conventional corrosion prevention methods is to roughen the surface by sandblasting and then apply thermal spraying to prevent corrosion, but oxides such as AtzOa used as plastic materials are This causes problems such as the thermal spray coating peeling off from the remaining parts and the surface corroding.

[Purpose of the invention]

Therefore, the present invention was developed in view of the above-mentioned situation, and its purpose is to roughen the surface by replacing the roughening of the surface by the blasting method with a roughening process using an etching solution. After construction, a laminated film is formed through base thermal spraying, finishing thermal spraying, and pore sealing treatment to prevent corrosion of the metal surface and peeling of the thermal spray coating layer and prevent its progression.

[Embodiments of the invention]

Examples are given below to explain the method of the present invention for preventing corrosion on metal surfaces and for preventing peeling and progress of thermal sprayed coatings.

Example (Application example to zirconium alloy) 1st step Skin roughening 2nd step Nickel-based alloy thermal spraying 3rd step Titanium thermal spraying 4th step Sealing treatment with epoxy resin In the 1st step,
The inner surface of the metal hollow tube is roughened by roughening with a mixed aqueous solution (etching solution) of 0.13 CC of sulfuric acid, 2.75 CC of hydrofluoric acid, and 3.66 g/l of ammonium fluoride at 2σC for 160 seconds. This roughening improves the adhesion of the sprayed coating. After washing with water and drying, the second step is base thermal spraying.

The base thermal spray material is selected in consideration of adhesion and corrosion resistance. After base spraying, finish spraying is performed. The finished titania coating has excellent wear resistance and corrosion resistance. As a final step, after finishing thermal spraying, pore sealing treatment is performed using silicone resin, epoxy resin, bituminous material, paraffin, etc. By performing pore sealing treatment after thermal spraying, the film becomes a completely environmentally sealed film. The sealing treatment is carried out while the final thermal spray coating remains active. The pores in the film are formed by the penetration of the sealant through capillary action.The nickel-based gold film to be sealed often has a lower corrosion potential than the base material, so it must be completely isolated from the environment. Particular attention must be paid to hole treatment.

As shown above, the method for preventing and inhibiting metal surface corrosion and thermal spray coating layer peeling of the present invention consists of four steps: roughening treatment, base thermal spraying, finishing thermal spraying, and sealing treatment.
All steps cannot be omitted. In the present invention,
The first step, which is pre-treatment, has the effect of increasing the adhesion strength by roughening the surface, and since no plastic material is used, it has the effect of preventing the peeling of the sprayed coating layer, and the sealed thermal sprayed coating prevents corrosion of the metal surface. It is completely isolated from the environment, and prevents the synergistic effect of surface roughening treatment and thermal spray coating from abrasion and peeling of the surface coating layer, and prevents the progress of the process.

〔Effect of the invention〕

The present invention is characterized by the discovery of the above-mentioned combination out of many combinations of surface treatment methods, and is extremely effective in preventing the corrosion of stainless steel and zirconium alloys and the peeling and progression of the surface coating layer. It is effective and gets an A rating.

Claims (1)

[Claims] A first step of roughening the metal surface using an etching solution, a second step of base thermal spraying with a nickel-based alloy, and a third step of performing finishing thermal spraying for primary corrosion protection. A method for preventing corrosion of a metal surface, comprising a fourth step of performing a sealing treatment using a sealing agent.