阅读说明：本技术 一种铝合金轮毂的表面处理方法及铝合金轮毂 (Surface treatment method of aluminum alloy hub and aluminum alloy hub ) 是由 李志广 韩鹏 魏庆旺 宋亚飞 舒永锋 张健 李健 杨广浩 刘裕 熊彬羽 于 2019-10-14 设计创作，主要内容包括：本申请涉及一种铝合金轮毂的表面处理方法及铝合金轮毂。所述铝合金轮毂的表面处理方法包括对所述铝合金轮毂的表面进行第一预处理、渗氮、抛光、第二预处理、喷涂透明粉和固化的步骤,其中所述渗氮步骤包括对经所述预处理后的铝合金轮毂表面在500～520℃下进行40～48h的气体等温渗氮,其中,氨的分解率控制为20～50％。本发明的铝合金轮毂,通过上述对铝合金表面进行渗氮处理的表面处理方法获得了更强的美观性,尤其是良好的光泽度,以及优异的耐腐蚀性能。(The application relates to a surface treatment method of an aluminum alloy hub and the aluminum alloy hub. The surface treatment method of the aluminum alloy hub comprises the steps of carrying out first pretreatment, nitriding, polishing, second pretreatment, transparent powder spraying and curing on the surface of the aluminum alloy hub, wherein the nitriding step comprises carrying out gas isothermal nitriding on the surface of the pretreated aluminum alloy hub for 40-48 hours at 500-520 ℃, and the decomposition rate of ammonia is controlled to be 20-50%. According to the aluminum alloy hub, the surface treatment method for nitriding the surface of the aluminum alloy is adopted to obtain stronger aesthetic property, particularly good glossiness and excellent corrosion resistance.)

1. A method of surface treating an aluminum alloy wheel hub, the method comprising: and carrying out first pretreatment, nitriding, polishing, second pretreatment, transparent powder spraying and curing on the surface of the aluminum alloy hub, wherein the nitriding step comprises carrying out gas isothermal nitriding on the surface of the pretreated aluminum alloy hub for 40-48 h at 500-520 ℃, and the decomposition rate of ammonia is controlled to be 20-50%.

2. The surface treatment method of an aluminum alloy hub as recited in claim 1, wherein the nitriding step further comprises maintaining the temperature of the aluminum alloy hub at the same temperature after the isothermal nitriding by the gas, wherein the decomposition rate of ammonia is controlled to be 18 to 25% 15 to 20 hours before the maintaining; and controlling the decomposition rate of ammonia to be 30-40% 50-55 h after heat preservation.

3. The surface treatment method of an aluminum alloy hub as recited in claim 2, wherein the nitriding step further comprises performing nitrogen-removing treatment at 550 ℃ to 570 ℃ for 2 to 4 hours after the heat preservation.

4. The method of surface treatment of an aluminum alloy hub as set forth in claim 1, wherein the nitriding step includes:

performing gas isothermal nitriding on the surface of the aluminum alloy hub for 45 hours at 510 ℃, wherein the decomposition rate of ammonia is controlled to be 20-50%;

carrying out heat preservation for 70 hours at 510 ℃, wherein the decomposition rate of ammonia is controlled to be 18-25% in the first 20 hours, and the decomposition rate of ammonia is controlled to be 30-40% in the last 50 hours; and

and carrying out nitrogen removing treatment for 2h at 560 ℃.

5. The surface treatment method of an aluminum alloy hub as recited in any one of claims 1 to 4, wherein the first and second pretreatment steps respectively comprise: the method comprises the following steps of pre-cleaning, pre-degreasing, main degreasing, twice water washing, acid washing, twice pure water washing, passivation, pure water washing, sealing, twice pure water washing and drying, wherein the passivation adopts chromium-free passivation and uses a zirconium-titanium system agent or a silane system agent.

6. The surface treatment method for the aluminum alloy hub as claimed in any one of claims 1 to 4, wherein the step of spraying the transparent powder is carried out under an electrostatic voltage of 30 to 80kv, a powder discharge amount of 35 to 80% and a total gas amount of 3.5 to 5.0m³And/h, carrying out electrostatic spraying under the condition that the gun distance is 180-250 mm, preferably, the transparent powder is acrylic powder, polyurethane powder or epoxy resin powder, and the thickness of the transparent powder is 80-100 mu m after the curing step.

7. An aluminum alloy hub obtained by subjecting the hub to surface treatment by the surface treatment method according to any one of claims 1 to 6.

8. The utility model provides an aluminum alloy wheel hub, aluminum alloy wheel hub has the aluminum alloy base member and the coating on the aluminum alloy base member surface, its characterized in that, the top layer of aluminum alloy base member is the nitriding layer that thickness is 0.45 ~ 0.60mm, the coating is in by the passivation layer and the transparent polymer layer that stack gradually on the aluminum alloy base member surface constitute.

9. The aluminum alloy hub of claim 7 or 8, wherein the passivation layer has a thickness of 1-9 μm.

10. The aluminum alloy hub of claim 7 or 8, wherein the transparent polymer layer is acrylic, polyurethane or epoxy, and the transparent polymer layer has a thickness of 80-100 μm.

Technical Field

The invention relates to the field of metal surface treatment, in particular to a surface treatment method of an aluminum alloy hub and the aluminum alloy hub.

Background

The appearance and the corrosion resistance of the wheel have great influence on the whole automobile, and as the demand of people on the individuation of the automobile continuously rises, the individuation wheel also becomes the target continuously pursued by each automobile factory.

Chinese patent application CN 105538051 a discloses an aluminum alloy hub polishing process. The polishing process comprises descaling, rough grinding, fine grinding and polishing. However, the traditional polishing process has poor appearance and cannot meet the individual requirements of people on automobiles.

The chinese patent application CN 103510139 a discloses an anodic oxidation treatment process for the surface of an aluminum alloy hub. The technological process of the method comprises the steps of polishing the aluminum alloy hub, carrying out alkaline etching treatment, carrying out anodic oxidation treatment in a dilute sulfuric acid solution to form an oxide film, and finally carrying out normal-temperature sealing. However, after the surface of the aluminum alloy hub is subjected to anodic oxidation treatment, the corrosion resistance of the aluminum alloy hub is still difficult to meet the requirements.

Disclosure of Invention

In view of the above, the main object of the present invention is to provide a surface treatment method for an aluminum alloy hub, which can further improve the appearance and corrosion resistance.

To this end, the first aspect of the present invention provides a surface treatment method for an aluminum alloy hub, the method comprising: and carrying out first pretreatment, nitriding, polishing, second pretreatment, transparent powder spraying and curing on the surface of the aluminum alloy hub, wherein the nitriding step comprises carrying out gas isothermal nitriding on the surface of the pretreated aluminum alloy hub for 40-48 h at 500-520 ℃, and the decomposition rate of ammonia is controlled to be 20-50%.

According to one embodiment of the invention, the nitriding step further comprises the step of carrying out heat preservation on the aluminum alloy hub at the same temperature after the isothermal nitriding by the gas, wherein the decomposition rate of ammonia is controlled to be 18-25% 15-20 h before the heat preservation; and controlling the decomposition rate of ammonia to be 30-40% 50-55 h after heat preservation.

According to an embodiment of the present invention, the nitriding step further comprises performing nitrogen-removing treatment at 550-570 ℃ for 2-4 hours after the heat preservation.

According to one embodiment of the invention, the nitriding step comprises:

performing gas isothermal nitriding on the surface of the aluminum alloy hub for 45 hours at 510 ℃, wherein the decomposition rate of ammonia is controlled to be 20-50%;

carrying out heat preservation for 70 hours at 510 ℃, wherein the decomposition rate of ammonia is controlled to be 18-25% in the first 20 hours, and the decomposition rate of ammonia is controlled to be 30-40% in the last 50 hours; and

and carrying out nitrogen removing treatment for 2h at 560 ℃.

Generally, in the nitriding process, the higher the nitriding temperature is, the higher the nitriding speed is, and the thickness of a nitriding layer can be increased. However, too high a nitriding temperature may cause deformation of the workpiece. The thicker the nitrided layer, the better its corrosion resistance, but too thick a nitrided layer may result in poor powder adhesion. Under the process conditions, the aluminum alloy hub with good appearance and excellent corrosion resistance is obtained.

According to one embodiment of the invention, the first and second pre-treatment steps respectively comprise: the method comprises the following steps of pre-cleaning, pre-degreasing, main degreasing, twice water washing, acid washing, twice pure water washing, passivation, pure water washing, sealing, twice pure water washing and drying, wherein the passivation adopts chromium-free passivation and uses a zirconium-titanium system agent or a silane system agent.

According to one embodiment of the invention, the step of spraying the transparent powder comprises spraying the transparent powder at an electrostatic voltage of 30-80 kv, a powder spraying amount of 35-80% and a total gas amount of 3.5-5.0 m³And h, performing electrostatic spraying under the condition that the gun distance is 180-250 mm. Preferably, the transparent powder is acrylic powder, polyurethane powder or epoxy resin powder, and the thickness of the transparent powder is 80-100 μm after the curing step. The transparent powder is more preferably acrylic powder.

The invention provides an aluminum alloy hub, which is provided with an aluminum alloy matrix and a coating on the surface of the aluminum alloy matrix, and is characterized in that the surface layer of the aluminum alloy matrix is a nitriding layer with the thickness of 0.45-0.60 mm, and the coating is formed by sequentially laminating a passivation layer and a transparent polymer layer on the surface of the aluminum alloy matrix.

According to an embodiment of the present invention, the passivation layer has a thickness of 1 to 9 μm. Depending on the agent used, the passivation layer may consist of zirconium and titanium, or zirconium and silane.

According to one embodiment of the present invention, the transparent polymer layer is acrylic, polyurethane or epoxy resin, and the thickness of the transparent polymer layer is 80 to 100 μm.

According to the aluminum alloy hub, the surface treatment method for nitriding the surface of the aluminum alloy is adopted to obtain stronger aesthetic property, particularly good glossiness and excellent corrosion resistance.

Drawings

Fig. 1 is a schematic flow chart of a surface treatment method of an aluminum alloy hub according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention and the accompanying drawings, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

The invention provides a surface treatment method for nitriding the surface of an aluminum alloy hub.

The base material of the aluminum alloy hub that can be used in the surface treatment method of the present invention is not particularly limited, and examples thereof include, but are not limited to, magnesium aluminum alloys, aluminum manganese series aluminum alloys, and the like.

The surface treatment method of the present invention is further explained with reference to fig. 1. Before the nitriding process is carried out, the aluminum alloy hub matrix is firstly pretreated. The pretreatment process comprises the following steps: the method comprises the following steps of pre-cleaning, pre-degreasing, main degreasing, twice water washing, acid washing, twice pure water washing, passivation, pure water washing, sealing, twice pure water washing and drying. Impurities and an oxidation layer on the surface of the matrix are removed through the steps, and a passivation layer is formed on the surface through passivation treatment, so that the surface of the aluminum alloy is prevented from being oxidized, and the corrosion resistance of the surface of the aluminum alloy is improved. The passivation may be chromium-free passivation, and for example, a zirconium titanium system agent and a silane system agent may be used, but not limited thereto. After passivation, a compact and firm passivation film can be formed, so that the corrosion and oxidation of the surface of the aluminum alloy are prevented, and the corrosion resistance of the metal surface is improved.

And nitriding the aluminum alloy hub matrix after pretreatment. The nitriding treatment in the invention can adopt gas isothermal nitriding. In particular, the nitriding treatment may generally comprise gas isothermal nitriding, holding and nitriding steps. Wherein the nitriding temperature is 500-520 ℃, and the nitriding time is 40-48 h. And (3) performing heat preservation on the aluminum alloy hub at the same temperature after the isothermal nitriding by the gas, wherein the heat preservation time can be about 65-75 h, and preferably 70 h. Wherein the decomposition rate of ammonia is controlled to be 18-25% 15-20 h before heat preservation, and then the decomposition rate of ammonia is increased to 30-40%. And raising the nitrogen removing temperature to 560 ℃ for nitrogen removing treatment 2-4 h before the end. The thickness of the nitriding layer is 0.45-0.6 mm.

The nitriding process equipment in the invention can use a shaft type nitriding furnace, a bell jar furnace or a box type furnace, etc., but is not limited thereto.

And (4) nitriding the aluminum alloy hub matrix, and then polishing. The polishing process may use mechanical lapping and polishing.

And after polishing the aluminum alloy hub matrix, spraying transparent powder and curing. One example of the process of spraying the transparent powder is electrostatic spraying. The process conditions of electrostatic spraying can be as follows: electrostatic voltage is 30-80 kv, powder discharging amount is 35-80%, and total gas amount is 3.5-5.0 m³The distance between guns is 180-250 mm. The transparent powder can be acrylic powder, polyurethane powder or epoxy resin powder, and the thickness of the powder is 80-100 mu m, preferably 100 mu m. The curing temperature of the transparent powder is different according to different materials. The curing temperature of the acrylic powder may be, for example, about 177 ℃, and the curing time may be, for example, about 17 min.

The reagents used in the present invention are all commercially available.