Low-temperature environment-friendly chromium-free phosphating-film-removing agent

Abstract

A low-temperature environment-friendly chromium-free phosphating-film-removing agent is composed of sodium hydroxide with the concentration of 180-220 g / L, a chelating agent with the concentration of 2-5 g / L, a cationic quaternary ammonium salt with the concentration of 5-8 g / L, a surfactant with the concentration of 3-6 g / L, and water employed as a solvent. The prepared phosphating-film-removing agent solves the problem that high-strength fasteners need acid pickling, and helps to substantially reduce the hydrogen-embrittlement rupture risk of high-strength parts. After being used, the phosphating-film-removing agent does not generate waste gases, does not pollute atmosphere, and generates less waste liquid which is simple in processing technology and low in processing cost. The phosphating-film-removing agent helps to realize the purpose of degreasing and removing phosphating films in one step, and helps to reduce the process flow.

Description

technical field [0001] The invention relates to a dephosphating film agent, in particular to a low-temperature, environment-friendly, chromium-free dephosphating film agent. Background technique [0002] The functions of anti-friction phosphating on the surface of parts are mainly anti-friction, lubrication, anti-rust and so on. For example, for fasteners, the production process is: raw material reformation → cold heading forming → thread processing (thread rolling or thread rolling) → heat treatment → surface treatment → sorting and packaging. Raw material reformation is to transform the purchased steel with fixed specifications into wire rods of different specifications required for production. Before the reformation, the material needs to be phosphating to improve the lubricating performance of the material surface, improve the service life of the reformed mold and the surface quality of the reformed material At the same time, the phosphating film on the surface of the m...

AI Technical Summary

Problems solved by technology

[0005]1. The risk of hydrogen embrittlement caused by pickling is very high. For high-strength parts, it is easy to cause delayed fracture. The fracture of DCI11 engine main bearing cap bolts and Cummins engine cylinder head bolts is Due to hydrogen embrittlement, it caused tens of millions of compensation, which greatly affected the Dongfeng brand;

[0006]2. Great harm to personal safety, serious water and air pollution;

[0007]3. The waste gas and waste liquid treatment process is complicated and expensive;

[0008]4. Degreasing is required before pickling, which leads to low production efficiency and high cost;

[0009]5. Chromate high-temperature dephosphorization requires high temperature and high energy consumption, and because it contains hexavalent chromium ions, there are problems in sewage treatment and environmental protection, and enterprises cannot use;

[0010]6. Due to the serious corrosion of equipment by strong acid and chromium-containing wastewater, and the generated wastewater needs special pipelines for classified discharge, it is impossible to realize in-line production with heat treatment equipment , special phosphorus removal equipment is expensive

[0013]2. High-temperature chromate method: Pass Cr6+ at high temperature in a solution containing 50 g / L of Cr6+ The strong oxidizing properties of the ions remove the phosphating film; the process formula is: chromic acid with a content of 50 g / L dephosphorizes the surface of the part at 70-80 ° C, and the reaction time is 15 minutes; this method The disadvantage is that the concentration of Cr6+ is high, which brings many difficulties to environmental protection, and this method has high processing temperature, high energy consumption and high cost;

[0014] The above methods for removing phosphating film all require special equipment to implement the process