Cadmium Electroplating (Nadcap Accredited)
Electroplated cadmium is a robust and versatile metallic coating. Cadmium is a soft white metal that, when plated onto steel, cast iron, malleable iron, copper, and powdered metal, functions as a "sacrificial coating," corroding before the substrate material. To enhance the corrosion protection of cadmium plating, chromate conversion coatings can be applied over the plated metal, yielding the familiar gold color as seen in the above picture. Other colors, such as olive drab are also available.
Cadmium plating offers an exceptional bonding surface for adhesives, such as those increasingly used in aircraft manufacturing, and is the preferred coating for salt-water environments. Additional advantages of cadmium plating include: low electrical resistance; outstanding conductivity; superior solderability; favorable galvanic coupling with aluminum; and excellent natural lubricity, which results in prevention of galling and a low coefficient of friction. Furthermore, the corrosion products of cadmium are less significant that those of other plated coatings such as zinc. These characteristics are especially useful in applications where components will be repeatedly disassembled and reassembled, such as in scheduled maintenance of aircraft. Thus cadmium plating continues to be critical to the aerospace industry . Cadmium plated surfaces resist mold or bacteria growth.
In some limited applications, zinc-nickel alloy plating may be an acceptable alternative to cadmium plating. Please contact Chem Processing for more information about this substitution.
Cadmium plating is not recommended for spaceflight applications due to its propensity to sublimate, outgas and spontaneously form whiskers in a vacuum. See NASA's NPSL page on cadmium plating for more information.
Chem Processing Inc. Cadmium Plating Capabilities:
- AS 9100 certified and Nadcap accredited cadmium plating
- Aerospace OEM approvals, including UTC Aerospace Systems, Rockwell Collins, Eaton Aerospace, Woodward, L3 and Honeywell
- Plating thickness range of 0.0001 to 0.0010 in.
- Rack and barrel plating available
- Clear hexavalent chromium, yellow dichromate and olive drab chromate conversion coatings available
- Application of Zinc Phosphate onto cadmium as a painting pre-treatment (for QQ-P-416 Type III supplementary treatment)
- Precision masking for selective surface plating
- In-house salt spray testing
- Thickness analysis on a Fischer Technology XDL-B X-Ray fluorescent spectrometer
- ASTM A165
- ASTM B766
- ISO 4521
- SAE AMS 2400
- SAE AMS 2401
- PN 13.08 (UTC Aerospace Systems/Hamilton Sundstrand)
- M-032-P (Mercury Marine)
- Most Major OEM Specifications
Typical Cadmium Applications:
- Aerospace: corrosion protection on flight-critical components and galvanic coupler for mating stainless steel parts aluminum airframes
- Transportation: disc brake components, radiator hose fittings and door latches
- Electronics: connectors, relays and chassis
- Consumer Products: window hardware and home construction products
- Formed Products: shaped or formed pre-plated parts
- Marine: fasteners and components cyclically exposed to fresh and salt water
Functional Properties: Cadmium vs. Zinc
Cadmium retains its original appearance longer than zinc , and is superior to zinc in marine and industrial environments. Due to Cadmium's lubricity, it is also preferred for moving parts, as well as parts that are made out of cast iron. Its corrosion products are also considered less problematic relative to moving parts. Plated cadmium's upper useful service temperature limit is 450F, while zinc's is 250F.
While cadmium plating offers engineering properties that have yet to be matched by a single finish, it is toxic. For this reason, Chem Processing, Inc. incorporates state-of-the-art environmental controls and redundant containment systems at its facility. CPI is also actively involved in the development of viable alternatives to cadmium plating.