BLACK OXIDATION (BLACKENING)
Black oxidation or blackening is the very basic coating process applied for fasteners, tools, hardware basically for storage purpose. This will provide a minimal corrosion protection when applied with a protection oil.This is basically a very old process using in engineering sector and the main advantage over other coatings are its minimal surface development. Light greyish to deep black will be the appearance and these coatings are in line with MIL-DTL-13924, AMS 2485, ASTM D769, ISO11048.
ZINC ELECTROPLATING
The major purpose of zinc electroplating is to provide a layer of protection to any metal accessories for example – nuts, bolts, and automotive parts. The application of zinc is that it keeps iron and steel corrosion-free. Not only that but it also helps in making metal components shiny and bright. As mentioned on name electrolysis is the process used for the deposition of zinc on surface of ferric carbon steel products.This will act as both sacrificial and barrier coating. This process will develop a surface layer of minimum 5 microns to a maximum of 35microns based on different classes and variant passivation process. Basically electroplating can provide a minimum of 72hrs salt spray resistance as per ASTM B117 .Parts can be produced with white/blue ,yellow and black surface finish as per ASTM B633,ISO2081
HOT DIP GALVANIZATION
Hot dip galvanizing are mainly used on structures, fasteners etc which are used mainly on outside environments . Coating will have a minimum of 43 micron thickness and due to the development of surface dimensions can get affected . Considering that mostly this process will be selected for the parts having wider tolerance ranges. Mostly on fasteners- nuts will tapped to oversize in-*order to have proper fitment after galvanizing. As hydrogen embrittlement is a concern high tensile fasteners will be processed without using HCL in cleaning process. Also temperature can affect the properties of material and so HDG is not advisable for materials having hardness above 35HRC. It helps in protecting the steel by forming a layer and is also extremely abrasion-resistant.
ZINC NICKEL PLATING
The usage of Zinc nickel plating is an electrolysis process where zinc and nickel will get deposited on metal surface as per ASTM B841,AMS2417. The process combines the coating properties of zinc with the strength, ductility, and corrosion resistance of nickel which develops a clean finish that, in a few cases, is even superior to cadmium. Additionally, it gives extremely long-term cathodic corrosion protection. This can be applied on fasteners ,machined components .As this is a premium coating process service life will be considerably more than other electroplating process.
PHOSPHATING-PARKERIZING
Phosphating-Parkerizing is mostly used as a pre-term method in conjunction with another method of corrosion protection. It is applied to steel and iron components. This is basically a surface reaction process in which metal reacts with an aqueous phosphate solution. It not only helps in corrosion but also in building its resistance. It gives a strong adhesion bonding for subsequent coating too. Additionally this process can provide an minimum level lubricity for applied parts . SEF can offer zinc and manganese based phosphating based on application of parts in compliance with
ELECTROLESS NICKEL PLATING
The electroless plating is metal deposition with a controlled chemical reaction. It does not need any electric current that is generally used in electroplating. The benefits of it include brilliant corrosion resistance to common corrodents. Without heat it provides excellent hardness and wear resistance properties. An affordable process for applications subject to conditions where corrosion is a factor. Additionally with heat treatment surface hardness can be increased for applied ENP coatings.
SPECIAL COATINGS
The special coatings are tailor-made to customers’ demands. These are high-range coating materials for both decorative and functional surfaces. The usage of special coating is done by many industries to protect one’s facilities, grounds, and expensive equipment. These coatings provide extended equipment life cycle, offer non-sticking properties, prevent corrosion, and reduce friction. PTFE and molybdenum disulphide and most commonly used base for these special coatings.