Comparison of different surface treatment processes

Aug 29, 2025

In the manufacturing of precision sheet metal parts and metal components, surface treatment technology is a key link in improving product weather resistance, aesthetics, and service life. Among them, powder coating, anodizing, and galvanizing are the three most widely used processes, but their performance characteristics and applicable materials are significant.

The Core Principles And Technical Characteristics Of The Three Processes

1. Powder coating:
Powder spraying uses thermosetting powder coatings (such as epoxy resin and polyester resin) as raw materials. The powder is charged by an electrostatic spray gun, adsorbed on the surface of the metal workpiece, and then cured at a high temperature of 180-220 ℃ to form a uniform coating.

Technical features: It can achieve various appearance effects such as matte, highlight, texture, etc; Strong adaptability to workpiece shape and even coverage of complex structures.

2. Anodizing:
Anodizing is only applicable to aluminum and aluminum alloys. By placing the workpiece as an anode in an electrolyte solution (such as sulfuric acid or oxalic acid) and applying current, a dense aluminum oxide film is formed on the surface.
Technical features: The oxide film is an extension of the natural color of the metal, with a delicate texture; The film has high hardness and excellent wear resistance.

3. Galvanization:
Galvanizing is the process of forming a zinc coating on the surface of steel workpieces through methods such as electrolysis, hot dipping, and zinc infiltration. Common processes include galvanizing (cold galvanizing), hot-dip galvanizing (hot-dip galvanizing), and mechanical galvanizing.
Technical features: Only applicable to steel materials; Hot dip galvanizing has a thick coating and strong adhesion, while electroplating galvanizing is easier to achieve precise control.

Comprehensive comparison of key performance dimensions

performance metrics	powder coating	Anodizing (aluminum alloy)	Galvanized (steel)
Applicable Material	Most metals such as steel, aluminum alloy, zinc alloy, etc	Only aluminum and aluminum alloys	Only steel (including cast iron and carbon steel)
corrosion resistance	Medium (indoor environment 5-10 years without rust; outdoor requires weather resistant powder, such as PVDF coating, with a lifespan of over 15 years)	Excellent (unsealed hole: resistant to neutral salt spray for more than 500 hours; After sealing the hole: resistant to neutral salt spray for more than 1000 hours, suitable for humid and marine environments)	Good (Electroplated galvanizing: resistant to neutral salt spray for 200-500h; hot-dip galvanizing: resistant to neutral salt spray for 1000-2000h, suitable for outdoor and industrial corrosive environments)
wear resistance	Medium (coating hardness HB20-50, easy to scrape and peel off, not suitable for frequent friction scenarios)	Excellent (oxide film hardness HV300-1000, hard oxidation can be used for mechanical moving parts such as cylinder walls)	Poor (zinc coating hardness HB30-50, easy to wear, requires passivation treatment to improve surface hardness)
Appearance and color	Rich (customizable in any color, texture, smooth coating, diverse visual effects)	Single (mainly metallic in color, can be dyed but with low color saturation, soft luster, and a metallic matte texture)	Single (electroplated zinc: silver white/blue white/color zinc; hot-dip galvanized: silver gray, rough appearance, no texture optional)
heat resistance	Medium (Long term temperature resistance of 120-180 ℃, special high-temperature resistant powder can reach 250 ℃, easily softened and discolored beyond temperature)	Excellent (melting point of oxide film 2050 ℃, long-term temperature resistance above 300 ℃, short-term ability to withstand high temperature of 500 ℃, no softening risk)	Poor (zinc melting point 419 ℃, long-term temperature resistance below 120 ℃, more prone to oxidation, blackening, and peeling)
adhesion	Good (requires phosphating/passivation pretreatment first, adhesion level reaches level 0, and the coating is not easy to peel off)	Excellent (metallurgical bonding between oxide film and substrate, no risk of delamination, able to withstand mechanical deformation such as bending and stretching)	Good (hot-dip galvanizing has strong adhesion and can withstand impact; electroplated galvanizing has weak adhesion and is prone to bending and cracking)
environmental friendliness	High (solvent-free emission, recyclable powder, recovery rate of over 95%, compliant with EU RoHS standards)	Medium (electrolyte solution needs to be treated to avoid heavy metal pollution, some processes contain chromate sealing, and environmental protection is limited)	Low (electroplating zinc contains harmful substances such as cyanide and chromate, and the cost of wastewater treatment is high; hot-dip galvanizing produces zinc smoke, which needs to be collected and treated)