Production process for Sandvik's coated steel strip
We have developed a PVD (physical vapor deposition) process with roll to roll type continuous evaporation coating of full width strip steel. Our process significantly shortens the value chain for bipolar plate production. It also ensures homogenous coating of the whole strip surface and repeated quality from batch to batch.
Complex coatings with multiple-layer options are applied to a strip in motion. The pre-treatment ensures a clean metallic surface, with a good adhesion between the substrate and the coating. All coatings are characterized by very low content of impurities and foreign elements. The coating process also assures close thickness tolerances of the surface layer.
The surface layers consist of metallic elements, for example aluminium (Al), nickel (Ni), cobalt (Co), or tin (Sn). Non-metallic coating in the form of carbon (C) is offered for low temperature fuel cell bipolar plate material.
Environmentally friendly process
Sandvik's coating technology is environmentally friendly, with no discharge to water or air and no toxic residues. The coating process is also energy efficient compared to electroplating, which consumes approximately 60% more energy.
Stainless steel is an environmentally friendly process, as it is manufactured using mainly recycled materials.
Cleaning is important for good adhesion. To avoid harmful defects, the whole area of the strip surface is inspected – both sides.
Coating of metal layers by Sandvik's continuous evaporation coating process.
Automatic X-ray inspection devices measure the thickness and quality of the coating.
4. Testing, slitting and packaging
After coating, the steel strip is inspected and tested (for example tensile, hardness and surface properties). The process is completed by slitting to the required width, control of burr height, width and shape, and finally by packaging and shipment.