Metal Surface Treatment Processes

3. Micro-arc oxidation (MAO)

Micro-arc oxidation is a process that applies high voltage to electrolyte solutions, usually alkalescent solutions, to form the ceramic surface film, which is the result of synergistic effect of physical discharge and electrochemical oxidation.

 

 Advantages

1. Micro-arc oxidation can make metal parts have good texture and anti-fingerprint.

2. Micro-arc oxidation can be used for metal parts made of a wide range of base materials such as Al, Ti, Zn, Zr, Mg, Nb and their alloys.

3. The pre-treatment of micro-arc oxidation is simple, and the metal parts after the micro-arc oxidation surface treatment feature in corrosion resistance, excellent weather abilities and good heat dissipation.

 

Disadvantages

Currently, the micro-arc oxidation process can not make metal parts have many colors and the micro-arc oxidation process which can make metal parts have black and gray colors is more mature; it is difficult to make metal parts have bright colors;

costs of micro-arc oxidation processes are mainly affected by high power consumption, which makes the micro-arc oxidation process one of the processes with high costs.

   
4. Electroplating

Electroplating is a technology that utilizes electrolysis to form a layer of metal film on the metal’s surface so as to prevent corrosion and to improve wear resistance, conductivity, light reflection and appearance of metal parts.

Process: pre-treatment, nonhydrogen basic copper, non cyanide copper tin and chrome plating

 

 Advantages

1. The plating layer can make metal parts have high glossiness and metal appearance with high quality.

2. Electroplating can be used for metal parts made of base materials such as SUS, Al, Zn, Mg, etc., which have relative low costs compared with PVD.
 

Disadvantages

Electroplating is not very environmentally friendly and brings greater risks of environmental pollution.

 

5. Powder spraying

Powder spraying is a process that uses powder spraying equipment (electrostatic spraying machines) to spray powder paint on the surface of the workpiece; under the influence of static electricity, powder will be evenly adsorbed on the surface of the workpiece to form a powder coating; after being leveled and solidified through high temperature baking, powder coatings form different kinds of final coatings due to various types of powder paint.

 

 Process: electrostatic precipitation, spraying, low temperature leveling and baking

 

Advantages

1. Powder spraying can make metal parts have rich colors.

2. Powder spraying has low costs and is suitable for housings of architectural furniture products and heat sinks.

3. Powder spraying has high utilization rates with 100 percent and is environmental friendly. 

4. Powder spraying has good performance in covering defects of metal parts.

5. Powder spraying can be used to imitate the effects of the wood grain.

Disadvantages

Currently, powder spraying is not widely used for electronic products.