Cadmium Electroplate

APTICOTE 900 is an electrolytic process that can deposit protective cadmium coatings on to a variety of base materials to produce a degree of corrosion protection unmatched by other sacrificial coating systems.

APTICOTE 900 out-performs coatings based on zinc or aluminium in aggressive corrosion situations, including atmospheric, saline and alkaline conditions.

How it works

Cadmium provides corrosion protection by its unique 'sacrificial' action. When applied as a coating on steels or other structural metals, it corrodes preferentially and the substrate remains undamaged, even if the coating is scratched. Normally, the cadmium coating is applied with a thickness between 5 and 25µ and its own corrosion rate is less than one fiftieth of that of steel.

Features

• Superb corrosion protection (> 2,000hrs salt spray)
• Low friction (0.15 vs steel)
• Ductile, self-healing
• Small volume growth when oxidising
• No final grinding
• Can be chromate passivated for enhanced corrosion protection

Benefits

• Provides prolonged corrosion protection to your key components
• Prevents galvanic corrosion between steel fasteners and aluminium
• Reduces the tightening torque of fasteners and allows repeated dismantling
• Prevents jamming of fasteners or delicate mechanisms
• Accommodates your manufacturing tolerances without finishing
• Helps guarantee the safety of highly stressed components

Why is Apticote 900 better than other cadmium plating?

The answer is precise process control, bespoke jigging and racking, rigorous quality systems and comprehensive NDT inspection systems. Poeton have made major investments in plating plant, electrical supply systems, operator training and quality inspectors, so that the coating is right first time, be it on single large items or on batch components.

De-embrittlement

Like many electroplating processes, cadmium deposition could involve hydrogen absorption into the substrate. Highly stressed parts should be heat-treated after coating to minimise embrittlement. The heat- treatment conditions depend on the material, and users should provide a comprehensive specification. For metals with a tensile strength above 1100MPa, specialised pre-treatment and coating procedures are required.

For normal, bright cadmium plate, you should specify Apticote 900N. For a low-embrittlement, a duller variety, you should specify Apticote 900L.

Health and Safety

There are restrictions on the use of cadmium plating for certain applications, and any plated part should not be welded or similarly heated without the use of effective breathing apparatus. (Cadmium oxide fumes are harmful.)

There are very stringent conditions imposed on the plating process itself, and Poeton are proud to say that the Apticote 900 technique is zero-effluent, with all cadmium residues being returned to the bath.

Applications

Cadmium plating can be used in aeronautical, aerospace, mining, military & defence, offshore and nuclear applications. Cadmium can also be used on SAFETY devices in road vehicles, agricultural vehicles, rolling stock & vessels. The use of cadmium on electrical contacts in any sector of use is also not restricted.

Chromate Passivation

After electroplating, and heat treatment if required, a chromate conversion coating is usually applied, giving the coating its well known iridescent green/brown appearance. Such a treatment can double the corrosion resistance, and a thin conversion coating can maintain a bright as-plated finish and does not appreciably affect the electrical conductivity of the surface, nor its solderability. Additional protection can be provided by a clear lacquer coating.

Sizes

Poeton can cadmium plate parts up to 3 metres long.

More information about Cadmium Plating

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