Molten metal can be sprayed in a manner similar to paint spraying using a high-velocity air pressure ( 70 psi ) wires are connected into an electric arc gun. The intense heat of the arc melts the metal and with high pressure molten metal will be sprayed on the blast cleaned surface.
Both zinc spray and aluminum spray coating provide excellent protection in a wide variety of marine and industrial environment as a general rule, aluminum corrodes less rapidly than zinc in highly acidic condition. While zinc performs better than aluminum in somewhat alkaline conditions. The protection in gas and chemical plant aluminum is better to chose.
The spray galvanizing and spray aluminizing is increasingly displacing painting and hot-dip galvanizing. The advantages of metal coating are:
1.Thickness of coating from 50 mic to 500 microns is possible.
2.Durability of coating is more.
3.Single application to maintain the dft.
4.No drying time.
5.Good abrasion resistance.
6.Site job possible.
7.Coating thickness can be controlled.
Arc sprayed coating are used by industry to protect steel structures from heat corrosion at elevated ( higher ) temperature up to 1000 dig c. The aluminizing is effective for protecting mild steel, low alloys and high carbon steels. The aluminum coating is use full for chimney stacks, exhaust flue gas ducting, rotary kilns, dryers, catalytic crackers, furnance parts and water tube walls etc.,
The spray aluminum coating provide excellent oxidation resistance and also cathodic protection against corrosion, hot gases and condensation products