The process method that uses modern physics, chemistry, metallurgy, heat treatment and other disciplines to change the condition and properties of the surface of the part and optimally combine it with the core material to achieve predetermined performance requirements is called surface treatment technology.
The role of surface treatment:
Improve surface corrosion resistance and wear resistance, slow down, eliminate and repair material surface changes and damage;
Make ordinary materials obtain surfaces with special functions;
Save energy, reduce costs and improve the environment.
Metal surface treatment process classification
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The main methods of surface quenching include flame quenching and induction heating. Commonly used heat sources include flames such as oxyacetylene or oxypropane.
2. Laser surface strengthening
Laser surface strengthening uses a focused laser beam to hit the surface of the workpiece to heat the extremely thin material on the surface of the workpiece to a temperature above the phase transition temperature or melting point in a very short time, and then cool it in a very short time to harden the surface of the workpiece. strengthen.
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Laser surface strengthening can be divided into laser phase change strengthening treatment, laser surface alloying treatment and laser cladding treatment.
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effect:
Improve the mechanical strength of parts as well as wear resistance, fatigue resistance and corrosion resistance;
Used for surface matting and scale removal;
Eliminate residual stress in castings, forgings, and weldments.
4. Rolling
Rolling is to use hard rollers or rollers to press the surface of a rotating workpiece at room temperature and move along the direction of the generatrix to plastically deform and harden the surface of the workpiece to obtain an accurate, smooth and strengthened surface or surface treatment with a specific pattern. Craftsmanship.
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Application: Parts with relatively simple shapes such as cylindrical surfaces, conical surfaces, and flat surfaces.
5. Brushing
Wire drawing refers to the surface treatment method that forces metal through a mold under the action of external force, compresses the metal cross-sectional area, and obtains the required cross-sectional area shape and size. This is called metal wire drawing process.
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Drawing can be made into straight, random, corrugated, and swirled patterns according to decorative needs.
6. Polishing
Polishing is a finishing processing method for modifying the surface of parts. Generally, it can only obtain a smooth surface and cannot improve or even maintain the original processing accuracy. Depending on the pre-processing conditions, the Ra value after polishing can reach 1.6~0.008μm. .
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Generally divided into mechanical polishing and chemical polishing.
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The two main methods of chemical surface heat treatment are carburizing and nitriding.
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3. Surface conversion coating technology
1. Blackening and phosphating
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Before anodizing, it must undergo pre-processing such as polishing, degreasing, and cleaning, followed by rinsing, coloring, and sealing.
Application: Commonly used for protective treatment of certain special parts of automobiles and aircraft, as well as decorative treatment of handicrafts and daily hardware products.
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4. Surface coating technology
1. Thermal spraying
Thermal spraying is a method of heating and melting metal or non-metallic materials, and continuously blowing compressed gas onto the surface of the workpiece to form a coating that is firmly combined with the substrate, and obtains the required physical and chemical properties from the surface of the workpiece.
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Vacuum sputtering plating principle
According to different processes, vacuum plating can be divided into vacuum evaporation, vacuum sputtering, and vacuum ion plating.
3. Electroplating
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Electroplating is an electrochemical and redox process. Take nickel plating as an example: immerse a metal product in a solution of metal salt (NiSO4) as the cathode, and the metal nickel plate as the anode. After the DC power supply is turned on, a metal nickel plating layer will be deposited on the product.
Electroplating methods are divided into ordinary electroplating and special electroplating.
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Chemical Vapor Deposition (CVD)
Chemical vapor deposition refers to a method in which a mixed gas interacts with the surface of a substrate at a certain temperature to form a thin film of metal or compound on the surface of the substrate.
Because the chemical vapor deposition film has good wear resistance, corrosion resistance, heat resistance, and special electrical and optical properties, it has been widely used in industrial fields such as machinery manufacturing, aerospace, transportation, and coal chemical industry.
