Ouzhan Trade (Shanghai) Co., Ltd.

Surface treatment

First of all, we need to know why the product needs surface treatment, what is the function, and what problem it solves.

First of all, the surface treatment method of artificially forming a surface layer on the surface of the substrate material that is different from the mechanical, physical and chemical properties of the substrate. The purpose of surface treatment is to meet the product's corrosion resistance, wear resistance, decoration or other special functional requirements.

Many customers will ask us why we need surface treatment, what is the function, and what is the reason for adding this process?

Ouzhan technical staff: Surface treatment is to remove all kinds of foreign matter (such as oil, rust, dust, old paint film, etc.) attached to the surface of the object, and provide a good substrate suitable for the coating requirements to ensure that the coating film has good protection. Corrosion performance, decorative performance and some special functions, the surface of the object must be pretreated before painting. The work done by this kind of treatment is collectively referred to as pre-painting (surface) treatment or (surface) pretreatment.

The surface treatment enhances the durability and abrasion resistance of the product. On the original basis, it increases the use time and saves a lot of time, cost and money.

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 and nickel plating.

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(2) Oxidation

In the electrolyte solution, the workpiece is the anode. The process of forming an oxide film on the surface under the action of external current is called anodization, such as the anodization of aluminum alloy.
The oxidation treatment of steel can be done by chemical or electrochemical methods. The chemical method is to put the workpiece in an oxidizing solution, and rely on chemical action to form an oxide film on the surface of the workpiece, such as blueing of steel.

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FOLDING CHEMISTRY

This method has no current action, and uses the interaction of chemical substances to form a coating on the surface of the workpiece. The main methods are:

(1) Chemical conversion membrane 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 of metal surfaces.

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(2) Electroless plating

In the electrolyte solution, the surface of the workpiece is catalytically treated without the effect of external current. 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.

FOLDING HEAT PROCESSING

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 aluminum.

(3) Hot stamping
The process of heating and pressing the metal foil to cover the surface of the workpiece to form a coating layer is called hot stamping, such as hot stamping aluminum 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.

FOLDING VACUUM METHOD

This method is a process in which materials are vaporized or ionized and deposited on the surface of the workpiece under high vacuum to form a coating. The main method is.

(1) Physical vapor deposition (PVD)

Under vacuum conditions, the process of vaporizing metal into atoms or molecules, or ionizing them into ions, is directly deposited on the surface of the workpiece to form a coating, which is called physical vapor deposition. The deposited particle beam comes from non-chemical factors, such as evaporation 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)

Under low pressure (sometimes normal pressure), the process in which gaseous substances form a solid deposition layer on the surface of the workpiece due to chemical reactions is called chemical vapor deposition, such as vapor deposition of silicon oxide and silicon nitride.

OTHER METHODS OF FOLDING

Mainly mechanical, chemical, electrochemical, and physical methods. The main methods are:

Painting

The idle spraying or brushing method is the process of applying paint (organic or inorganic) on the surface of the workpiece to form a coating, called painting, such as painting, painting, etc.

Impact plating

The process of forming a coating layer on the surface of the workpiece with mechanical impact is called impact plating, such as impact galvanizing.

Laser surface treatment

The process of irradiating the surface of the workpiece with laser to change its structure is called laser surface treatment, such as laser quenching and laser remelting.

Superdural technology

The technology of preparing super-hard film on the surface of the workpiece by physical or chemical methods is called super-hard film technology. Such as diamond film, cubic boron nitride film and so on.

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ELECTROPHORESIS AND ELECTROSTATIC SPRAYING

1. 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. Electrostatic spraying

Under the action of a DC high-voltage electric field, the atomized negatively charged paint particles are directed to fly onto the positively-charged workpiece to obtain a paint film, which is called static spraying.