FASTENER S not only need good looking, RUST AND CORRSION is a serious issue for Fasteners,too. Fasteners typically come into contact with other metals and environments that can lead to corrosion and oxidation, so it’s important to choose a finish that will extend the life and performance of that fastener and corresponding joint. Rust damage can cause breakdowns due to load-bearing structural elements having been weakened through corrosion. For this reason it is extremely important to select the right type of surface treatment for fasteners.
The standard finish for different types of steel fasteners is electroplated with a clear RoHS compliant (trivalent) chromate passivation, and diffiient kinds of state-of-art Ceramic Coated which are often designed to pass 500- and 1,000- hour salt spray tests per ASTM B117 test standard.
Refer to the chart below for other options. You'll find all of the popular platings and finishes at ABS METAL
Finish | Color | For Use On (Material) | Corrosion Resistance | Characteristics |
|---|---|---|---|---|
| Zinc (electroplated) |
White to blue grey | All metals | Good | Most common used plating. Good rust-resisting qualities, appearance and low cost. |
| Chromate | Yellow, olive drab, black, blue/white | Zinc & cadmium plated parts | Very good | A secondary dipping process after plating increasing corrosion resistance, adding color or brilliance. |
| Black Oxide | Black | Ferrous metals and stainless steel | Fair | A chemical discoloration which does not add to part thickness. Usually combined with an oil dip. Rust resistance comes from the oil only. |
| Phosphate & Oil | Charcoal grey or black | Steel | Good | Zinc or manganese phosphate used with a rust-inhibiting oil dip. Low cost. |
| Iridite | Olive drab, green, black, red, blue, bronze | All metals | Good | Applied on top of zinc or cadmium plating as a die for color and additional corrosion protection. |
| Nickel | Silver | All metals | Very good | Hard stable finish, relatively expensive and sometimes hard to apply. |
| Chromium | Bright blue/white | All metals | Very good | Hard lustrous finish adds wear resistance and is very expensive. |
| Hot Dip Zinc (galvanizing) |
Dull grey | All metals | Very Good | Parts are dipped in pure zinc. Gives maximum corrosion protection. Adds a thick irregular coating. Size must be adjusted to allow for thickness of coat. |
| Passivating | Bright - etched | Stainless steel | Excellent | Parts are dipped in nitric acid which removes iron particles and brightens the finish. Produces a passive corrosion-resistant finish. |
the plating process needs Preventing hydrogen embrittlement
Most Common Types of Ceramic Coated are following :
Dacromet
The Dacromet coating is a mixture of zinc & aluminum powder, chromate, and organic dissolvent with sticky material. It has good performance of anti-corrosion after coating on metal parts and baked under 300°C temperature. Dacromet has an excellent anti-rust performance, almost 7 times than the electric galvanizing.
Ruspert
As new processing of metal surface treatment, the Ruspert coating provides high performance of corrosion resistance. This coating includes 3 layers: the first layer is metallic zinc plating； the second layer is chemical conversion film and the third layer is baked ceramic surface coating. With this coating, a 500 to 1000 hours salt spray test result can be guaranteed.
Another advantage of the Ruspert coating is that it can be coated in various colors, such as blue, grey, silver, red, etc. This coating can also be combined with other coatings to achieve more customized requirements.