A kind of nickel-free one-component high corrosion resistance environmental protection black phosphating liquid

Abstract

The invention discloses highly corrosion-resistant environment-friendly black phosphatizing liquid without nickel single component. Each liter of the treatment liquid consists of the following raw materials: 25-50g of main film forming agent, 5-25g of film forming aid, 0.1-3g of accelerant, 60-80g of grain refiner, 0.5-2g of stabilizer, 0.05-1g of blackening agent and 0.1-0.5g of blackening aid. The phosphatizing liquid disclosed by the invention can form a black phosphatized film on a steel surface by a one-step process. The phosphatized film has high blackness and high corrosion resistance, is uniform and avoids stripping; a copper sulfate spot test can reach 40min which is much longer than the national standard (2min); the phosphatizing liquid does not contain toxic and harmful substances such as nickel, nitrite and the like and causes little environmental pollution.

Description

technical field [0001] The invention mainly relates to the field of surface chemistry, in particular to a nickel-free single-component high-corrosion-resistant and environment-friendly black phosphating solution. Background technique [0002] Phosphating is a commonly used metal surface treatment technology. In principle, it belongs to chemical conversion film treatment. It is mainly used for phosphating on steel surfaces. Non-ferrous metals (such as aluminum and zinc) can also be phosphating. Phosphating is a process in which chemical and electrochemical reactions form a phosphate chemical conversion film, and the formed phosphate conversion film is called a phosphating film. The purpose of phosphating is mainly to provide protection for the base metal and prevent the metal from being corroded to a certain extent; it is used as a primer before painting to improve the adhesion and anti-corrosion ability of the paint film layer; it can reduce friction in the metal cold proces...

AI Technical Summary

Problems solved by technology

The black film phosphating process of steel can be roughly divided into two types: one is a one-step method, that is, direct phosphating without pre-dipping, and the existing one-step black phosphating is mostly manganese salt high-temperature phosphating, but the film layer It is prone to problems such as coarse crystallization and more phosphating solution sediment, and the adjustment is more complicated, and the process operation temperature is high, generally at 90-98°C, which consumes a lot of energy

The other is a two-step method, that is, pre-soaking and then phosphating. The blackening agent in the pre-soaking solution is mostly composed of selenite. The disadvantage of this process is that the pre-blackening treatment solution is unstable and easy to fall off. Membrane, this will cause problems such as the solution is easy to change, the solution repetition rate is reduced, and selenous acid is a toxic substance, and the price is relatively expensive, which has caused problems such as waste liquid treatment and recovery.

[0003] At present, the domestic black phosphating treatment generally has the disadvantage of poor corrosion resistance. Generally, it will rust after being placed indoors for a few days to dozens of days, and the copper sulfate solution will change color in about one minute (tested according to the national standard GB6807-86). Moreover, the blackness of the phosphating film is poor, and it is easy to remove the film, which is far from meeting the high-quality requirements of modern industrial products. Now, the market of high-corrosion-resistant black phosphating solution is basically monopolized by foreign companies, so how to improve the quality of black phosphating film Corrosion resistance, improving blackness, enhancing the bonding force of the film layer, breaking the monopoly of foreign companies on the domestic market, has become an urgent topic to be solved in domestic black phosphating treatment technology