Self-healing environment-friendly type steel normal-temperature blackening agent

Abstract

The invention discloses a self-healing environment-friendly type steel normal-temperature blackening agent which takes a molybdate / sulfur-copper system as a main membrane component and which consists of 12-22g / L of copper nitrate, 14-24g / L of ammonium molybdate tetrahydrate, 8-12g / L of sodium thiosulfate, 18-28g / L of monosodium phosphate, 3-5g / L of oxalic acid, 6-13g / L of nickel sulfate, 3-5g / L of dimethylformamide, 0.5-1g / L of lanthanum oxide, 30-40g / L of aluminum potassium sulfate, 4-10g / L of sodium chloride, 2-6g / L of citric acid, and a surfactant. The blackening agent is high in blackening capability, free of selenium, environment-friendly, low in production cost and simple in process; a steel normal-temperature blackening film layer obtained through blackening has the characteristics that the corrosion resistance and the healing capability are good, a blacking film is free of crack, the film layer is uniform and dark and bright in color, and the adhesion capability and the corrosion resistance are excellent; and the technical indexes of the blackening film layer are that the 3% copper sulfate drop test lasts for 65 seconds (the blackening film layer is not dipped into anti-rust oil), the 3% sodium chloride soaking test lasts for 8 hours, and the binding force is greater than 187 times.

Description

technical field [0001] The invention belongs to the technical field of metal material surface treatment, relates to a normal temperature blackening agent, in particular to a self-healing and environment-friendly normal temperature blackening agent for steel. technical background [0002] Blackening is one of the effective methods for corrosion protection of metal materials. At present, blackening of steel mainly includes high-temperature alkaline blackening, normal temperature blackening, normal temperature non-toxic blackening, black phosphating and black electroplating. The high-temperature alkaline blackening process is simple, and the appearance, adhesion and corrosion resistance of the film are the most ideal among the current methods. However, since this method must be carried out at a high temperature of about 140°C, the reaction time is longer, generally about 40min , so energy consumption is high, efficiency is low, and working conditions are poor. In addition, the...

AI Technical Summary

Problems solved by technology

At present, most selenium-containing blackening agents at room temperature have shortcomings such as low matching between film-forming agents and additives, excessive solution precipitation, and poor bonding between the blackened film layer and the metal substrate. Moreover, due to the high price of selenium-containing oxides , is a highly toxic substance that will pollute the environment and cause great harm to the human body, which greatly limits the development of blackening agents containing selenium at room temperature

Therefore, the development of non-toxic and environment-friendly room temperature steel blackening agent has become an inevitable trend of scientific research and blackening technology upgrading. During the drying process, the blackened film is affected by the stress difference of micro-regions in the film, and the blackened film is easy to crack, resulting in poor gloss, poor bonding force and poor corrosion resistance of the blackened film.

In addition, the existing selenium-free room temperature blackening agents also have disadvantages such as poor stability and difficult maintenance of the solution. Most of the existing researches remain in the laboratory stage, and have not been fully promoted in the domestic and foreign steel surface treatment markets.

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