Surface treatment of metal parts is of vital importance in modern industry, not only to improve the physical and chemical properties of the parts, but also to enhance their aesthetics and durability. Common surface treatment processes include oxidation and electroplating. In this paper, we will discuss in detail the principles and characteristics of these Anodising vs plating and their selection methods in different applications.
Anodising
Anodising treatment is a chemical or electrochemical methods in the metal surface to generate a layer of oxide film process. This oxide film can significantly improve the corrosion resistance, wear resistance and decorative effect of the metal.
Types of Anodising
Anodic Oxidation
Mainly used for aluminium and its alloys, it generates a film of aluminium oxide on the surface of aluminium through an electrolytic process. This oxide film has high hardness, good insulation and strong corrosion resistance, and is commonly used in aerospace, automotive and electronic products.
Chemical Oxidation
Applied to metals such as iron and copper, it does not require an electric current and generates an oxide film directly through chemical treatment. Compared to anodising, chemical oxidation produces a thinner film, but still provides basic protection.
Advantages of Oxidation
- Strong corrosion resistance: the oxide film can effectively isolate the metal from the external environment, preventing oxidation and corrosion.
- High hardness: especially after anodic oxidation of aluminium alloy, the hardness of the oxide film is close to corundum (aluminium oxide), which improves the wear resistance of the parts.
- Good insulation: the anodic oxidation film has excellent insulation properties and is suitable for electronic products.
- Highly decorative: Oxidation treatment can achieve various colours by dyeing process to meet different aesthetic needs.
Disadvantages of oxide treatment
- Limited to specific metals: Oxidation treatment is mainly applicable to aluminium and its alloys, the effect on other metals such as steel, copper is relatively poor.
- Film brittleness: although the hardness of the oxide film is high, but brittle, easy to crack when subjected to a large impact.
Electroplating
Electroplating is the process of depositing a layer of metal or alloy on the metal surface through electrolysis. Plating layer can not only beautify the metal surface, but also significantly enhance its corrosion resistance, wear resistance and electrical conductivity.
Types of electroplating treatment
- Zinc plating: Widely used for steel products to prevent steel from rusting by electroplating a layer of zinc, commonly used in the automotive, construction and home appliance industries.
- Nickel plating: nickel plating layer is bright and beautiful, with excellent abrasion resistance and corrosion resistance, commonly used in electronics, machinery and decorative products.
- Chrome plating: with extremely high hardness and wear resistance, it is widely used in automotive parts, tools and moulds.
- Silver plating and gold plating: mainly used in electronic components and decorations, providing excellent conductivity and aesthetics.
Advantages of plating treatment
- Wide range of application: It is applicable to almost all metals and their alloys, including steel, copper, aluminium, etc.
- Multifunctionality: according to different plating materials, it can achieve a variety of functions, such as anti-corrosion, wear-resistant, conductive and so on.
- Good decorative effect: the plating layer is bright as a mirror, which can significantly enhance the appearance of metal products.
Disadvantages of electroplating treatment
- Environmental issues: improper treatment of electrolyte and wastewater used in electroplating process will cause environmental pollution.
- Complicated process: The electroplating process involves several steps, including pretreatment, plating, post-treatment, etc., and requires strict control of the process parameters.
- Higher cost: Compared with oxidation treatment, the cost of electroplating treatment is higher, especially silver and gold plating and other precious metals plating.
How to choose between Anodising vs plating
In the choice of oxidation and plating treatment, need to consider the characteristics of the metal material, the use of parts of the environment, performance requirements and cost and other factors.
Selection of metal materials
- Aluminium and aluminium alloy: anodic oxidation treatment is preferred, which can significantly improve its corrosion resistance and decorative effect.
- Iron and steel: zinc plating is commonly used to prevent rust; chrome plating is chosen when high wear resistance is required.
- Copper and copper alloy: nickel plating is suitable to enhance its antioxidant and decorative properties.
Depending on the environment of use
- Highly corrosive environment: such as marine environment, should choose plating treatment with high corrosion resistance, such as zinc plating or nickel plating.
- High abrasion environment: such as mechanical parts, should choose chrome plating treatment with high abrasion resistance.
- High aesthetic requirements: such as decorative and electronic products, choose silver plating or gold plating to enhance the quality of its appearance.
Based on performance requirements
- Corrosion resistance: oxidation treatment and electroplating treatment can enhance the corrosion resistance of metal, but the effect is different for different metals, which needs to be selected according to specific materials.
- Wear resistance: anodic oxidation is suitable for aluminium alloys, and chrome plating is suitable for steel.
- Conductivity: When high conductivity is required, silver plating or gold plating should be chosen.
Selection according to cost
- Economy: Chemical oxidation is low cost and suitable for cost-sensitive projects.
- High Performance Requirements: Despite the higher cost of electroplating, it provides superior performance and is suitable for demanding applications.
Case Study
Aerospace parts
Aerospace parts require high corrosion resistance and high strength, and anodized aluminium alloy parts are usually used to improve their service life and performance.
Automotive parts
Automotive parts such as chassis and exhaust systems are often galvanised to prevent rust and improve durability, while exterior parts such as emblems and decorative strips are selected for chrome-plated treatment to improve aesthetics and wear resistance.
Electronic products
The connectors and wire terminals in electronic products are often silver-plated or gold-plated to ensure excellent conductivity and corrosion resistance.
Conclusion
Oxidation and electroplating are two important processes for surface treatment of metal parts, each with its own characteristics and scope of application. In practical application, it is necessary to reasonably select the appropriate surface treatment process according to the specific material, use of the environment, performance requirements and cost factors, in order to achieve the best results. Through in-depth understanding of the principles and characteristics of these two processes, can better guide the actual production and application, to enhance the comprehensive performance of metal parts.
