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Nitriding method of aluminum and aluminum alloy surface

A technology of aluminum alloy surface and surface oxidation, applied in metal material coating process, coating, solid-state diffusion coating and other directions, can solve the problems of high equipment requirements and production cost, difficult to obtain nitride layer, complicated operation, etc. The nitriding equipment requirements are not high, the quality of the nitriding layer is good, and the adaptability is wide.

Inactive Publication Date: 2015-10-07
JIANGSU UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0018] The above-mentioned nitriding process of aluminum and its aluminum alloys requires high equipment requirements and production costs, complicated operation and difficult control, and it is difficult to obtain an ideal and uniform nitrided layer for large-sized and complex-structured workpieces.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0047] 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:

[0048] 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.

[0049] 2) For the first zinc immersion, first prepare a zinc immersion solution, and dissolve the following compounds in 1 liter of aqueous solution:

[0050] Zinc oxide ZnO 10 g,

[0051] Sodium hydroxide NaOH 50g,

[0052] Potassium Sodium Tartrate KNaC 4 h 4 o 6 50g,

[0053] At room temperature (5-35...

Embodiment 2

[0065] 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:

[0066] 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.

[0067] 2) For the first zinc immersion, first prepare a zinc immersion solution, and dissolve the following compounds in 1 liter of aqueous solution:

[0068] Zinc oxide ZnO 20 g,

[0069] Sodium hydroxide NaOH 60g,

[0070] Potassium Sodium Tartrate KNaC 4 h 4 o 6 70g,

[0071] Dip the above-mentioned cleaned workpiece into the prepared zinc dipping solution at room temperature for the first dipping of zinc for 60 seconds.

[0072]...

Embodiment 3

[0083] 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:

[0084] 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.

[0085] 2) For the first zinc immersion, first prepare a zinc immersion solution, and dissolve the following compounds in 1 liter of aqueous solution:

[0086] Zinc oxide ZnO 30 g,

[0087] Sodium hydroxide NaOH 70g,

[0088] Potassium Sodium Tartrate KNaC 4 h 4 o 6 90g,

[0089] Dip the above-mentioned cleaned workpiece into the prepared zinc dipping solution at room temperature for the first dipping zinc, and the dipping time is 70s.

[0090] 3) Water washin...

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Abstract

The invention relates to a surface nitridation method of aluminium and aluminium alloy, comprising the following steps: 1, removing surface oxide-films; 2, conducting surface nitridation treatment, wherein the step 1 comprises 1) pretreating, 2) conducting a first zinc immersion, 3) washing, 4) removing zinc, 5) conducting a secondary zinc immersion, and 6) washing and drying; and the step 2 comprises 1) exhausting in the furnace and controlling the ammonia dissociation rate below 10%, 2) heating up in the furnace to 580-640 DEG C and controlling the ammonia dissociation rate between 30-45%, 3) nitriding at the furnace temperature of 580-640 DEG C for 10-50 h and keeping the ammonia dissociation rate between 30-55% in the nitriding process, and 4) denitriding at the furnace temperature of 580-640 DEG C for 0.5-1h and controlling the ammonia dissociation rate between 60-70%. According to the invention, the surface dense oxide-films of aluminium and aluminium alloy can be effectively removed, the infiltration of nitrogen atoms is benefited, and nitridation treatment can be conducted by using a common gas nitriding furnace, thus the production cost is low, the operation is simple, the adaptability is wide, and the infiltrated layer has good quality.

Description

technical field [0001] The invention relates to a heat treatment process for aluminum alloys, in particular to a surface nitriding method for aluminum and aluminum alloys. Background technique [0002] Aluminum alloy has the advantages of high specific strength, good electrical and thermal conductivity, good corrosion resistance, and good plasticity and formability. It has become the most widely used metal material in industry besides steel. Electricity, electricity, electronics, automobiles, machinery manufacturing, construction, packaging and other industries are important basic materials for the development of the national economy. However, with the development of industry, higher and higher requirements are put forward for the performance of materials. Therefore, strengthening aluminum alloys to meet service conditions has become the focus of aluminum alloy research. [0003] Nitriding the aluminum alloy to form AlN compound on its surface can effectively improve th...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C23C8/24C23C8/02
Inventor 纪嘉明吴晶周博李春平
Owner JIANGSU UNIV