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Two-section gas nitridation method for surfaces of aluminum and aluminum alloy

A technology of aluminum alloy surface, gas nitriding, applied in metal material coating process, coating, solid diffusion coating and other directions, can solve the problems of difficult to obtain nitride layer, high resistance of aluminum alloy, increase the difficulty of nitriding, etc. To achieve the effect of good quality of the infiltration layer, uniform thickness, and low requirements for nitriding equipment

Inactive Publication Date: 2013-02-13
JIANGSU UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] But this method often requires pre-sputtering before nitriding to eliminate the oxide film
At the same time, the temperature is high, and some even reach 650°C, which causes local melting of the aluminum alloy and because of the high resistance of AlN, in the ordinary DC glow discharge nitriding, with the thickening of the AlN layer, in order to maintain the discharge process, it must be changed Process parameters, thus increasing the difficulty of nitriding, etc.
[0010] In order to obtain a better nitriding effect, many researchers have improved the process and equipment, and successively proposed enhanced plasma ion nitriding, laser-induced plasma nitriding Nitrogen, ECR (electron cyclotron resonance) microwave plasma nitriding, radio frequency (high frequency) plasma nitriding, etc., but the above-mentioned nitriding processes of aluminum and its aluminum alloys have in common: high equipment requirements, high production costs, and complicated operations Difficult to control, it is difficult to obtain an ideal and uniform nitride layer for large-sized and complex-structured workpieces

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0041] The workpiece material is 1050 pure aluminum, and its chemical composition is aluminum Al 99.50%, Si0.25%, Cu0.05%, Mg0.05%, and a very small amount of Zn, Mn, etc. First, the pure aluminum workpiece is treated to remove the surface oxide film, which is specifically completed by the following steps:

[0042] 1) Pretreatment, chemical degreasing, hot water washing, cold water washing, acid etching and water washing are carried out on the surface of pure aluminum workpieces sequentially. Among them, chemical degreasing and acid etching are treated according to the existing general industrial pure aluminum surface treatment methods. Let me repeat.

[0043] 2) For the first zinc immersion, prepare the zinc immersion solution first, and prepare according to the proportion relationship of dissolving the following quality compounds in 1 liter of water:

[0044] Zinc oxide ZnO 10 g,

[0045] Sodium hydroxide NaOH 50g,

[0046] Potassium Sodium Tartrate KNaC 4 ...

Embodiment 2

[0061] The workpiece material is 5050 aluminum alloy, its chemical composition and content (wt%) are: Si0.4, Fe0.7, Cu0.2, Mn1.1, Mg1.4, Zn0.25, other 0.15, and the balance is aluminum. First, the aluminum alloy workpiece is treated to remove the surface oxide film, which is specifically completed by the following steps:

[0062] 1) Pretreatment, chemical degreasing, hot water washing, cold water washing, acid etching and water washing are carried out on the surface of the aluminum alloy workpiece in sequence. Let me repeat.

[0063] 2) For the first zinc immersion, prepare the zinc immersion solution first, and prepare according to the proportion relationship of dissolving the following quality compounds in 1 liter of water:

[0064] Zinc oxide ZnO 20 g,

[0065] Sodium hydroxide NaOH 60g,

[0066] Potassium Sodium Tartrate KNaC 4 h 4 o 6 70g,

[0067] Dip the above-mentioned cleaned workpiece into the prepared zinc dipping solution at room temperature fo...

Embodiment 3

[0081] The workpiece material is 2A12 aluminum alloy, its chemical composition and content (wt%) are: Cu4.3, Mg1.6, Mn0.6, Si0.4, and the balance is aluminum. First, the aluminum alloy workpiece is treated to remove the surface oxide film, which is specifically completed by the following steps:

[0082] 1) Pretreatment, chemical degreasing, hot water washing, cold water washing, acid etching and water washing are carried out on the surface of the aluminum alloy workpiece in sequence. Let me repeat.

[0083] 2) For the first zinc immersion, prepare the zinc immersion solution first, and prepare according to the proportion relationship of dissolving the following quality compounds in 1 liter of water:

[0084] Zinc oxide ZnO 30 g,

[0085] Sodium hydroxide NaOH 70g,

[0086] Potassium Sodium Tartrate KNaC 4 h 4 o 6 90g,

[0087] Dip the above-mentioned cleaned workpiece into the prepared zinc dipping solution at room temperature for the first dipping zinc, a...

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Abstract

The invention relates to a two-section gas nitridation method for the surfaces of aluminum and aluminum alloy. The method comprises a surface oxidation film removing step and a surface nitridation treatment step. The step 1 comprises the following steps of: pre-treating; primarily galvanizing zinc; washing by water; removing zinc; secondarily galvanizing zinc; and drying after water washing. The step 2 comprises the following steps of: exhausting in a furnace, wherein the ammonia resolution ratio is less than 10%; primarily heating to 570-590 DEG C, wherein the ammonia resolution ratio is 15-25%; carrying out one-section nitridation, wherein the furnace temperature is 580-640DEG C, and the ammonia resolution ratio is kept at 15-25%; secondarily heating to 620-640 DEG C, wherein the ammonia resolution ratio is 40-55%; carrying out two-section nitridation, wherein the temperature is 620-640DEG C, and the ammonia resolution ratio is 40-55%; and denitriding, wherein the furnace temperature is 580-640DEG C, and the ammonia resolution ratio is controlled at 70-80%. The two-section gas nitridation method has the advantages that compact oxidation films on the surfaces of aluminum and the aluminum alloy can be effectively eliminated, the nitrogen atom can be preferably infiltrated, the nitridation treatment can be carried out by a common gas nitridation furnace, and the two-section gas nitridation method is low in production cost, simple and easy to operate, wide in adaptability, and good in infiltration layer quality.

Description

[0001] technical field [0002] The invention relates to a heat treatment process for aluminum alloys, in particular to a two-stage gas nitriding method for the surface of aluminum and aluminum alloys. Background technique [0003] Aluminum and aluminum alloys are widely used in engineering structures and machine manufacturing, especially in the automotive industry, because they have high specific strength and small specific gravity, which can reduce the weight of engineering structures and complete machines without reducing safety and stability. At the same time, aluminum and aluminum alloys also have good machinability. However, with the development of industrial technology, the lower hardness, lower wear resistance and corrosion resistance of aluminum and aluminum alloys make it unable to meet the harsh service conditions such as high relative movement between components, high mass flow and high corrosion. requirements. [0004] At present, the commonly used surface st...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C8/24C23C8/02
Inventor 纪嘉明卢章平吴晶
Owner JIANGSU UNIV
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