Use of ferrous and non- ferrous material is unavoidable in the industry due to its availability, strength, durability, work-ability and ability to recycle. Automobiles, bridges, house- hold appliances, power generation equipment’s, railways, engines etc. are manufactured using ferrous and non -ferrous materials by adjusting metal properties in terms of hardness, flexibility, resistance to corrosion, weight to strength ratio etc.
Loss of metal due to various types of corrosion processes is a perennial problem in the industry. Thousands of dollars are wasted due to loss of metal (corrosion) and also thousands of dollars are invested in protecting the metal from corrosion. This in turn increases the life span of manufactured items, avoids the probable risk of accident.
Use of different types of fasteners, nuts, bolts, clips are necessary to manufacture different articles. The adequate strength required for the articles is provided by different sizes of fasteners, nuts and bolts. Fasteners are subjected to failure due to atmospheric corrosion, hydrogen embrittlement, temperature variations and bi- metallic corrosion.
Different types of phosphating systems and also painting systems with different types of resins, film thickness varying from few microns to few millimeters are used to protect the main structure. However higher film thickness of any coating is a limiting factor for fasteners.
Different types phosphating, blackodizing, zinc plating followed by passivation layers are used to improve the corrosion protection of fasteners. However, zinc plating has limitations in terms of corrosion protection and possibility of hydrogen embrittlement. Adverse effect on environment due to use of hazardous chemicals also needs to be considered while using such coatings.
Zinc aluminum flake coating is developed with the extensive research to provide protection against all types of corrosion for fasteners, brake disc etc with a very thin film of 6~10 microns. Zinc aluminum flakes with water or solvent based, binders free from hexavalent chromium (environmentally friendly) and adequate additives to improve different properties are widely used in the industry. Even at low film thickness zinc aluminum flake coating provides excellent protection against corrosion considering different environmental cycles. Zinc aluminum flake coating also helps in preventing bi metallic corrosion.
