Chromium Decorative and Hard Chrome
Decorative Barrel Chrome Plated Fasteners
Fasteners in the decorative chrome finish are designed to be aesthetically pleasing and durable. Thicknesses range from 0.05 to 0.5 µm, however, they are usually between 0.13 and 0.25 µm.
The chromium plating is usually applied over bright nickel plating and polishing can take place after coating. Chrome plating, nickel chrome, bright chrome, decorative chrome or chromium plating are all ways of describing a thin layer of chromium metal deposited onto the surface of an object that has been coated with a layer of nickel. Unlike zinc which forms a sacrificial layer on steel, nickel is anodic to steel, which means the steel will corrode in preference to the nickel. This is why you see rusty components with perfectly good plating peeling off. In order to prevent this, it’s key to provide a good surface to which you apply the coating and to form a seal around the component. The barrier layer of nickel is what provides the protection. The chrome layer seals the surface of the nickel and prevents the nickel tarnishing and increases its corrosion resistance. The characteristic blue hue comes from the chromium layer making parts appear a cold silver colour whereas the nickel below has a much warmer yellow tint.
Hard chrome plated Fasteners
Hard chrome, also known as industrial chrome or engineered chrome, is used to reduce friction, improve durability through abrasion tolerance and wear resistance, minimize galling or seizing of parts, expand chemical inertness to include a broader set of conditions, primarily oxidation resistance, and bulking material for worn parts to restore their original dimensions. It is very hard, measuring between 65 to 69 HRC.
Hard chrome tends to be thicker than decorative chrome, with standard thicknesses 200 to 600 µm, but it can be thicker for extreme wear resistance