Plating on Aluminum

Because of the properties of the substrate surface, plating on aluminum is technically demanding and requires advanced pretreatment techniques. This article explains the fundamentals, focusing on plating applications for components used in extreme environments such as those encountered in rocket nozzles and semiconductor manufacturing equipment.

Why Is Plating on Aluminum Difficult?

This is because the oxide film that naturally forms on the surface hinders coating adhesion. This is a major cause of delamination during operational testing in high-temperature, high-pressure environments. Because conventional cleaning alone is insufficient, zincate treatment (zinc displacement treatment), which forms a zinc coating while removing the oxide film, is commonly used as a pretreatment.

This is an important process for preventing the oxide film from re-forming, but it is difficult to control, and only a limited number of companies can perform it. Surface treatment for extreme environments, including plating on a range of difficult-to-plate substrates such as titanium and copper alloys, presents significant technical barriers and is a specialized field that only a limited number of companies can handle.

Main Applications and Industries Served

This technology is essential in industries that require extreme reliability.

Rocket Nozzles and Space Equipment

For aerospace components, aluminum alloys may be selected to reduce weight and surface-treated to provide corrosion resistance, electrical conductivity, and wear resistance. To withstand ultra-high temperatures and pressures during combustion, the surface is treated to provide heat resistance, corrosion resistance, and wear resistance.

Adhesion must be maintained under ultra-high temperatures and pressures, and uniform coating thickness must also be ensured. High-quality processing enables long-term stable operation in harsh space environments.

Semiconductor Manufacturing Equipment Components

Aluminum is widely used for chamber components and similar parts because it offers a balance of low weight, machining accuracy, and cost. To improve resistance to plasma and corrosive gases and prevent contamination, a functional coating is formed. Because such environments are highly sensitive to particulate contamination, both clean processing facilities and consistent coating quality are subject to stringent requirements.

Applicable Plating Types

The main types of plating that can be applied to aluminum, along with their properties and applications, are summarized below.

Anodizing is a surface treatment that differs from plating and forms an oxide film through electrolysis. It is included here for reference as a typical surface treatment for aluminum. Because the appropriate process varies depending on alloy composition, shape, and application, request a technical review from a specialist with advanced expertise.

Quality and Technical Requirements for Plating

Zincate treatment is required for proper surface preparation. Depending on the required specifications, it is also important to confirm that appropriate inspection systems are in place for coating thickness measurement, adhesion testing, visual inspection, and cleanliness control. In the space and semiconductor industries, production systems with stringent cleanliness controls, including particle control, are essential.

Key Points When Requesting Plating Services

When requesting a quote or technical consultation, provide the following information.

• Substrate type (alloy designation, such as the 1000 or 5000 series)
• Drawings, dimensions, and required coating thickness specifications
• Expected service environment and required properties, such as heat resistance, corrosion resistance, and conductivity
• Required cleanliness standards for plating facilities
• Track records and quality control systems of prospective plating shops

To ensure consistent quality, a comprehensive evaluation of each plating shop’s track record and quality control system is essential. The “3 Recommended Functional Plating Shops by Industry and Component Type” page summarizes each company’s areas of expertise and provides criteria for identifying a plating shop suited to your needs.