Anodizing is an Electrolytic process through which a layer of oxide is produced on the surface of the part to improve the properties of corrosion resistance. It improves adhesion properties of bonding, wear and tear resistance. Anodizing can be done on highly corrosive metals and the anodizing process creates an oxide on the surface of the part which prevents the metals from corroding. Based on the characteristic of a metal, different types of aqueous solutions are used. Anodizing on Aluminum and Aluminum alloys are done with Tartaric Sulphuric Acid or Chromic Acid whereas for Steel and Titanium metal parts, anodizing is done with Boric or Sulphuric Acid.
To improve the traceability of the part/product and to make the metal active and to bring the grains on the surface, Etching is carried out on the parts. Marking is done through either chemical or non- chemical means like electro chemical etch marking, ink jet marking, marking with pens and Tagging on to Steel, Aluminum and Aluminum Alloy products and precise etching is done from a mixed acids on Titanium parts.
To improve the corrosion resistant property and for aesthetic, Moly Coat and Painting is done either using solvent based paint or water based paint. Application of paint can be done using conventional spray or electrostatic or electrophoretic processes. Once the painting of the part or product is carried out, it is marked for with a batch number for traceability.
Passivation and Salt Spray are standardized and popular corrosion test methods, used to check corrosion resistance of materials and surface coatings. Once the passivation is done by using a light coat of a protective material, such as metal oxide which creates a shell, it has to then undergo a corrosive attack in order to evaluate (mostly comparatively) the suitability of the coating for use as a protective finish. This corrosive attack is done by a Salt Spray test and the appearance of corrosion products (rust) is evaluated after a pre-determined period of time. Test duration depends on the corrosion resistance of the coating; generally, the more corrosion resistant the coating is, the longer the period of testing before the appearance of corrosion/ rust.
NADCAP accredited Cadmium Plating is a robust and versatile metal coating process which is widely accepted in the Aerospace industry. Some of the main functions of Plating are to decorate objects, for corrosion inhibition, to improve solderability, to harden, to improve wearability, to reduce friction, to improve paint adhesion, to alter conductivity, to improve IR reflectivity, and for radiation shielding.
Imparting residual compressive stresses in the surface layers of metallic components is one of the ways to improve their fatigue strength characteristics. Shot peening is employed for imparting residual stresses by means of cold work by shooting tiny steel balls on the surface from a certain height with pressure to enhance the compressive strength of the material. In this process compressive stress is induced to considerably reduce the risk of fatigue cracks during this operation.