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Hot dipping aluminium and aluminium alloy inactivation process of plating

A hot-dip aluminum and aluminum alloy technology, applied in hot-dip plating process, metal material coating process, coating and other directions, can solve the problems of high solvent price, toxic and expensive fluoride salt components, and achieve the process flow Simple, easy to operate, low cost effect

Inactive Publication Date: 2003-01-22
HUAZHONG UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] (1) The melting point of the solvent salt film is lower than the melting point of the plating solution, so the selection of solvent components is relatively harsh;
[0005] (2) The solvent salt film is easy to absorb moisture, and must be fully dried before plating, otherwise it is easy to produce missed plating and pinholes, which will damage the surface quality and corrosion resistance;
[0006] (3) The solvent price is high, even expensive, and the fluorine salt component is toxic;
[0007] (4) The molten salt covered on the surface of the plating solution is easy to age during production, and the melting point rises;
[0008] (5) It is difficult to clean the molten salt attached to the surface of the workpiece after plating

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] Embodiment 1. Carbon steel Q235, 760×13×1.5mm. With 20% NaOH and 0.5% Na 2 CO 3 The resulting solution was degreased at 90°C for 20 minutes. with 20%H 2 SO 4 Add a small amount of corrosion inhibitor solution, pickle at 70°C for 15 minutes, wash with water, soak in 3% dilute hydrochloric acid solution for 5 minutes, and wash with water. Immerse in a passivator solution (0.4% CrO 3 +0.1%K 2 MnO 4 +0.4%NaNO 2 + water), treated at room temperature for 2 min, washed with water, and dried. Preheat at 150°C for 15 minutes. Immerse in pure aluminum plating solution at 730°C for 5 minutes, lift out of the furnace at a speed of 6m / min, and cool in air to obtain a smooth, flat, seamless, and void-free aluminum coating. The total thickness of the coating is 132 μm, and the thickness of the intermediate alloy layer is 78 μm.

Embodiment 2

[0033] Embodiment 2. Iron casting, 80*35*5mm, its chemical composition is 3.24%C, 1.82%Si, 1.01%Mn, 0.06%P, 0.08%S, and the surface of the casting is treated by sandblasting. Oil was removed with 20% NaOH aqueous solution at 100°C for 15 min. with 25%H 2 SO 4 Add a small amount of corrosion inhibitor solution, pickle at 70°C for 10 minutes, wash with water, soak in 3% dilute hydrochloric acid solution for 5 minutes, and wash with water. With a passivating agent solution (2% CrO 3 +0.3%NaNO 2 + water), treated at room temperature for 3 minutes, and dried. Preheat at 160°C for 15 minutes, then immerse in pure aluminum plating solution at 760°C for 7 minutes, and lift the furnace at a speed of 4.5m / min. The total thickness of the coating is 116 μm, and the thickness of the intermediate alloy layer is 62 μm.

Embodiment 3

[0034] Example 3. Oil pipe steel 50Mn, φ60×5×110mm. Degreasing and pickling in the same manner as in Example 1. With a passivating agent solution (1.5% CrO 3 +0.2%K 2 MnO 4 + water), treated at room temperature for 1.5 min, washed with water, and dried. Preheat at 180°C for 20 minutes. Immerse in an aluminum-silicon alloy (containing 3% silicon) plating solution at 780°C and keep warm for 10 minutes, and the lifting speed out of the furnace is 7.5m / min. The resulting coating is bright and has no missing plating. The total thickness of the coating is 106 μm, and the thickness of the intermediate alloy layer is 53 μm.

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PUM

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Abstract

The present invention belongs to the field of iron and steel material surface chemical and heat treatment technology. The technological process is that before hot dipping, the workpiece surface is filming treated with the inactivation solution compounded by using CrO3 0.2-5 wt%, K2MnO4 0.05-3 wt%, NaNO2 0.05-6 wt% and water, at room temperature for 0.5-5 min. The present invention features the repeated use of the inactivation solution, good filming effect, simple technological process, low cost and capacity of forming smooth, level plated coating without pinhole and leakage.

Description

technical field [0001] The invention belongs to the technical field of surface chemical heat treatment of iron and steel materials, and in particular relates to hot-dip aluminum plating and aluminum alloy of carbon steel parts, alloy steel parts, stainless steel parts and cast iron parts. Background technique [0002] Hot-dip aluminum or aluminum alloy on the surface of steel is one of the commonly used and effective measures for steel protection. It has long been known by people. Hot-dip aluminum or aluminum alloy steel parts have been widely used in petroleum, chemical, metallurgy, machinery, light Industry, transportation, construction, electric power, communication, aviation and other fields. [0003] There are many processes for hot-dip aluminum plating of steel and aluminum alloys, mainly including gas protection method and solvent method. At present, hot-dip plating with gas protection method is mainly used in foreign countries, such as Sendzimir method, improved Sen...

Claims

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Application Information

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IPC IPC(8): C23C2/02C23C2/12C23C22/24
Inventor 李华飞
Owner HUAZHONG UNIV OF SCI & TECH
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