Chromium-free pre-passivating liquid for hot-galvanized steel pipes

Abstract

The invention belongs to the technical field of metal surface treatment and corrosion protection, and particularly relates to chromium-free pre-passivating liquid for hot-galvanized steel pipes. The chromium-free pre-passivating liquid is prepared from following components in percent by weight: 5%-10% of a film forming agent, 2%-4% of an oxidizing agent, 2%-4% of an organic corrosion inhibitor, 2%-4% of an inorganic rare earth corrosion inhibitor, 0.5%-2% of a water quality stabilizer, 0.5%-2% of a base material wetting agent and the balance water. A preparation method of the chromium-free pre-passivating liquid includes the steps that the film forming agent, the oxidizing agent, the inorganic rare earth corrosion inhibitor and the water quality stabilizer are dissolved in the water, the materials are stirred, then the organic corrosion inhibitor and the base material wetting agent are added, and the materials are evenly stirred. The chromium-free pre-passivating liquid does not contain chromium and other toxic and harmful substances, the high-temperature stability of tank liquor of the chromium-free pre-passivating liquid is good, the appearances of the pre-passivated hot-galvanized steel pipes are bright, the inner walls of the pre-passivated hot-galvanized steel pipes are well resistant to white rust, and the chromium-free pre-passivating liquid can replace chromic anhydridefor pre-passivating.

Description

technical field [0001] The invention belongs to the technical field of metal surface treatment and corrosion protection, and in particular relates to a chromium-free pre-passivation solution for hot-dip galvanized steel pipes. Background technique [0002] Hot-dip galvanizing technology is one of the most basic and extensive methods of steel corrosion protection in the world. Hot-dip galvanizing technology has been widely used in various fields of national economy such as metallurgy, building materials, electric power, transportation, and agriculture. Among them, the hot-dip galvanizing of steel pipes is to dip the processed steel pipes with a clean surface into the zinc solution for hot-dip galvanizing to obtain metal pipe fittings with excellent surface properties. Hot-dip galvanized steel pipes have been applied to all aspects of the national economy. The leading industries include fire-fighting pipes, construction pipes, production material transmission pipes, and agricu...

AI Technical Summary

Problems solved by technology

[0005] However, due to the particularity of the working conditions of the hot-dip galvanized steel pipe water cooling process (the high temperature stability of the pre-passivation solution, the pre-passivation bath must not corrode the iron tank, and the pre-passivation solution must have a high tolerance for zinc ions degree, the pre-passivation solution must have a certain corrosion protection ability for the zinc layer), the relevant research has hardly been reported, and there is no pre-passivation solution that can replace chromic anhydride on the market for hot-dip galvanizing manufacturers to use