Surface treatment method of die-cast aluminum alloy
2021-08-23
Die-casting aluminum alloy uses a metal smelting process, that is, casting, so it has advantages that other products do not have, such as low density, but relatively high strength, close to or surpassing high-quality steel, good plasticity, etc., so it can be processed Various profiles, excellent electrical conductivity, thermal conductivity and corrosion resistance make it widely used in industry. Then, let’s take a look at some related knowledge, including the information on the surface treatment method of die-cast aluminum alloy.
According to the different methods used, surface post-treatment technologies can be divided into the following categories.
(1) Electrochemical method
This method uses electrode reaction to form a coating on the surface of the workpiece. The main methods are:
1. Electroplating
In the electrolyte solution, the workpiece is the cathode. The process of forming a coating on the surface under the action of an external current is called electroplating. The plating layer can be metal, alloy, semiconductor or containing various solid particles, such as copper plating, nickel plating, etc.
2. Oxidation
In the electrolyte solution, the workpiece is the anode, and under the action of external current, the process of forming an oxide film on the surface is called anodic oxidation. The aluminum oxide film is formed on the surface of the aluminum alloy.
3. Electrophoresis
As an electrode, the workpiece is put into the conductive water-soluble or water-emulsified paint, and forms a circuit with the other electrode in the paint. Under the action of the electric field, the coating solution has been dissociated into charged resin ions, the cations move to the cathode, and the anions move to the anode. These charged resin ions, together with the adsorbed pigment particles, are electrophoresed to the surface of the workpiece to form a coating. This process is called electrophoresis.
(2) Chemical methods
This method has no current action, and uses the interaction of chemical substances to form a plating layer on the surface of the workpiece. The main methods are:
1. Chemical conversion film treatment
In the electrolyte solution, the metal workpiece has no external current action, and the chemical substance in the solution interacts with the workpiece to form a coating on its surface, which is called chemical conversion film treatment. Such as bluing, phosphating, passivation, and chromium salt treatment on the metal surface.
2. Electroless plating
In the electrolyte solution, the surface of the workpiece is catalytically treated, and there is no external current effect. In the solution, due to the reduction of chemical substances, the process of depositing certain substances on the surface of the workpiece to form a coating is called electroless plating, such as electroless nickel, Electroless copper plating, etc.
(3) Thermal processing method
This method is to melt or thermally diffuse the material under high temperature conditions to form a coating on the surface of the workpiece. The main methods are:
1. Hot dip plating
The process of putting a metal workpiece into molten metal to form a coating on its surface is called hot-dip plating, such as hot-dip galvanizing and hot-dip aluminum.
2. Thermal spraying
The process of atomizing the molten metal and spraying it on the surface of the workpiece to form a coating is called thermal spraying, such as thermal spraying zinc and thermal spraying ceramics.
3. Hot stamping
The process of heating and pressing the metal foil on the surface of the workpiece to form a coating layer is called hot stamping, such as hot stamping copper foil.
4. Chemical heat treatment
The process in which the workpiece is in contact with chemical substances and heated, and a certain element enters the surface of the workpiece at a high temperature is called chemical heat treatment, such as nitriding and carburizing.
5. Surfacing
By welding, the process of depositing the deposited metal on the surface of the workpiece to form a welding layer is called surfacing, such as surfacing welding with wear-resistant alloys.
(4), vacuum method
This method is a process in which materials are vaporized or ionized and deposited on the surface of the workpiece in a high vacuum state to form a coating.
The main method is.
1. Physical vapor deposition (PVD) vaporizes metals into atoms or molecules under vacuum conditions, or ionizes them into ions, and deposits them directly on the surface of the workpiece to form a coating. The process is called physical vapor deposition, which deposits particle beams. It comes from non-chemical factors, such as evaporative plating, sputtering plating, ion plating, etc.
2. Ion implantation
The process of implanting different ions into the surface of the workpiece under high voltage to modify the surface is called ion implantation, such as boron injection.
3. Chemical vapor deposition (CVD) is a process in which gaseous substances form a solid deposition layer due to chemical reactions on the surface of the workpiece under low pressure (sometimes normal pressure), called chemical vapor deposition, such as vapor deposition of silicon oxide, silicon nitride, etc. .
(5), spraying
Spraying is a coating method in which spray guns or disc atomizers are used to disperse into uniform and fine droplets by means of pressure or centrifugal force and apply to the surface of the object to be coated. It can be divided into air spraying, airless spraying and electrostatic spraying.
1. Air spraying
Air spraying is a coating technology widely used in paint coating construction at present. Air spraying is the use of compressed air to flow through the nozzle hole of the spray gun to form negative pressure. The negative pressure causes the paint to be sucked in from the suction tube and sprayed through the nozzle to form a paint mist. The paint mist is sprayed on the surface of the painted parts to form a uniform paint. Membrane.
2. No air spraying
Airless spraying uses a booster pump in the form of a plunger pump, a diaphragm pump, etc. to pressurize the liquid paint, and then transports it to an airless spray gun through a high-pressure hose, and finally releases the hydraulic pressure at the airless nozzle and sprays it after instantaneous atomization. On the surface of the object to be coated, a coating layer is formed. Since the paint does not contain air, it is called airless spraying, or airless spraying for short.
3. Electrostatic spraying
According to the different methods used, surface post-treatment technologies can be divided into the following categories.
(1) Electrochemical method
This method uses electrode reaction to form a coating on the surface of the workpiece. The main methods are:
1. Electroplating
In the electrolyte solution, the workpiece is the cathode. The process of forming a coating on the surface under the action of an external current is called electroplating. The plating layer can be metal, alloy, semiconductor or containing various solid particles, such as copper plating, nickel plating, etc.
2. Oxidation
In the electrolyte solution, the workpiece is the anode, and under the action of external current, the process of forming an oxide film on the surface is called anodic oxidation. The aluminum oxide film is formed on the surface of the aluminum alloy.
3. Electrophoresis
As an electrode, the workpiece is put into the conductive water-soluble or water-emulsified paint, and forms a circuit with the other electrode in the paint. Under the action of the electric field, the coating solution has been dissociated into charged resin ions, the cations move to the cathode, and the anions move to the anode. These charged resin ions, together with the adsorbed pigment particles, are electrophoresed to the surface of the workpiece to form a coating. This process is called electrophoresis.
(2) Chemical methods
This method has no current action, and uses the interaction of chemical substances to form a plating layer on the surface of the workpiece. The main methods are:
1. Chemical conversion film treatment
In the electrolyte solution, the metal workpiece has no external current action, and the chemical substance in the solution interacts with the workpiece to form a coating on its surface, which is called chemical conversion film treatment. Such as bluing, phosphating, passivation, and chromium salt treatment on the metal surface.
2. Electroless plating
In the electrolyte solution, the surface of the workpiece is catalytically treated, and there is no external current effect. In the solution, due to the reduction of chemical substances, the process of depositing certain substances on the surface of the workpiece to form a coating is called electroless plating, such as electroless nickel, Electroless copper plating, etc.
(3) Thermal processing method
This method is to melt or thermally diffuse the material under high temperature conditions to form a coating on the surface of the workpiece. The main methods are:
1. Hot dip plating
The process of putting a metal workpiece into molten metal to form a coating on its surface is called hot-dip plating, such as hot-dip galvanizing and hot-dip aluminum.
2. Thermal spraying
The process of atomizing the molten metal and spraying it on the surface of the workpiece to form a coating is called thermal spraying, such as thermal spraying zinc and thermal spraying ceramics.
3. Hot stamping
The process of heating and pressing the metal foil on the surface of the workpiece to form a coating layer is called hot stamping, such as hot stamping copper foil.
4. Chemical heat treatment
The process in which the workpiece is in contact with chemical substances and heated, and a certain element enters the surface of the workpiece at a high temperature is called chemical heat treatment, such as nitriding and carburizing.
5. Surfacing
By welding, the process of depositing the deposited metal on the surface of the workpiece to form a welding layer is called surfacing, such as surfacing welding with wear-resistant alloys.
(4), vacuum method
This method is a process in which materials are vaporized or ionized and deposited on the surface of the workpiece in a high vacuum state to form a coating.
The main method is.
1. Physical vapor deposition (PVD) vaporizes metals into atoms or molecules under vacuum conditions, or ionizes them into ions, and deposits them directly on the surface of the workpiece to form a coating. The process is called physical vapor deposition, which deposits particle beams. It comes from non-chemical factors, such as evaporative plating, sputtering plating, ion plating, etc.
2. Ion implantation
The process of implanting different ions into the surface of the workpiece under high voltage to modify the surface is called ion implantation, such as boron injection.
3. Chemical vapor deposition (CVD) is a process in which gaseous substances form a solid deposition layer due to chemical reactions on the surface of the workpiece under low pressure (sometimes normal pressure), called chemical vapor deposition, such as vapor deposition of silicon oxide, silicon nitride, etc. .
(5), spraying
Spraying is a coating method in which spray guns or disc atomizers are used to disperse into uniform and fine droplets by means of pressure or centrifugal force and apply to the surface of the object to be coated. It can be divided into air spraying, airless spraying and electrostatic spraying.
1. Air spraying
Air spraying is a coating technology widely used in paint coating construction at present. Air spraying is the use of compressed air to flow through the nozzle hole of the spray gun to form negative pressure. The negative pressure causes the paint to be sucked in from the suction tube and sprayed through the nozzle to form a paint mist. The paint mist is sprayed on the surface of the painted parts to form a uniform paint. Membrane.
2. No air spraying
Airless spraying uses a booster pump in the form of a plunger pump, a diaphragm pump, etc. to pressurize the liquid paint, and then transports it to an airless spray gun through a high-pressure hose, and finally releases the hydraulic pressure at the airless nozzle and sprays it after instantaneous atomization. On the surface of the object to be coated, a coating layer is formed. Since the paint does not contain air, it is called airless spraying, or airless spraying for short.
3. Electrostatic spraying
Electrostatic spraying is a spraying method that uses a high-voltage electrostatic electric field to make negatively charged paint particles move in the opposite direction of the electric field and adsorb the paint particles on the surface of the workpiece.
