Black phosphating agent for special tool for automobiles and preparation method for black phosphating agent

Abstract

The invention discloses a black phosphating agent for a special tool for automobiles and a preparation method for the black phosphating agent. The black phosphating agent comprises the following raw materials in percentage by mass: 44 to 48 percent of phosphoric acid at the concentration of 85 percent, 11 to 14 percent of nitric acid, 12 to 14 percent of zinc oxide, 1.5 to 2 percent of nickel nitrate, 0.18 to 0.36 percent of reduced iron powder, 0.12 to 0.18 percent of hydrofluoric acid at the concentration of 55 percent and the balance of water. The preparation method comprises the following steps of: adding water in an amount which is 1 / 3 of the calculated amount into a reaction kettle, adding the nickel nitrate into the reaction kettle when the revolving speed is 40 to 60 revolutions per minute, and stirring the solution to fully dissolve the nickel nitrate till the solution is transparent; and adding the phosphoric acid and the nitric acid into the reaction kettle, stirring the solution for 10 to 20 minutes, slowly adding the zinc oxide with stirring till the zinc oxide is reacted and dissolved to transparency, slowly adding the reduced iron powder into the solution till the iron powder is fully reacted and dissolved, adding the hydrofluoric acid and the balance of water into the solution, and continuously stirring the solution for 30 minutes.

Description

Technical field [0001] The invention relates to a phosphating agent, in particular to a black phosphating agent for automobile special tools with fine phosphate film crystals, good wear resistance, corrosion resistance and rust prevention, and a preparation method. Background technique [0002] The process in which steel workpieces are chemically treated in a phosphate solution containing Zn, Mn, and Fe to form a layer of insoluble crystalline phosphate conversion film on the surface is called phosphating. The phosphating film formed by phosphating steel can change the metal surface from a good conductor to a bad conductor, inhibit the formation of micro-batteries on the surface of metal workpieces, and effectively prevent metal corrosion. It has been widely used in automobiles, ships, machinery, and home appliances. , Weapons and aerospace industry. Automobile special metal tools and automobile interior parts must be treated to achieve long-term rust prevention. However, the ex...

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Problems solved by technology

The surface of special metal tools for automobiles and automobile interior parts must also be treated to achieve long-term anti-rust purposes. Although the film layer is wear-resistant, but the crystal is rough, so the current special tools for automobiles use high-temperature alkaline black oxidation treatment process to generate magnetic iron tetroxide on the metal surface, and then dip-coat anti-rust oil, which has the following disadvantages: the oxide film layer It is not wear-resistant and is easily damaged during use; the anti-rust oil dipped on the surface is a soft film that does not dry and is easy to be stained with dust; the surface has poor anti-rust performance