Metal spraying, or metallizing, is the process of coating a surface with metal or alloy using spray equipment. It is used to guard metals from corrosion, employing zinc or aluminum as basic spray materials. It is likewise used on machine parts, tools, and structural steel frames that have corroded. It is also used to hard-face a softer metal to give it more protection against wear and tear. The typical hard-facing materials used in metal spraying include cobalt, nickel with a little amount of chromium, and manganese chrome.
The process begins with the melting of the metal or alloy by means of a flame. The molten metal is then sprayed at high velocity to the surface to be coated using compressed air to propel the molten metal. The thickness of the coating will depend on the number of coatings applied. The common types of metal spraying process include flame, arc, and plasma.
In the flame spray process, the spray material in wire form is melted using a flame such as oxy-acetylene. An electric arc is used in the case of the arc spray process to melt a pair of wire that is metallic or a conductor of electricity. It is also employed in the plasma spray process to heat the material to be sprayed, which is initially in powder form and heated rapidly through a plasma flame to become ready for spraying. The high velocity oxygen fuel (HVOF) process uses oxygen and a fuel gas to create continuous combustion and eventually produce a high-pressure gas that is sufficiently hot to heat and accelerate the velocity of the powder material to its spraying level.
The equipment used is portable, making the process a preference over other metal-coating processes. The portability of the spraying equipment allows it to be mobile and perform spraying jobs on various objects or surfaces that have intricate shapes with ease, regardless of size. The pull-out and replacement of defective equipment on the job can be quickly done also on account of it being handy. Lost production hours due to breakdown can therefore be kept at a minimum.
Metal spraying is a versatile and effective coating process that can be applied to various surfaces, including, among others, metal, glass, and concrete. Its application is thus varied across industries. Even the arts benefit from metal spraying when artists want to create a metallic effect on their masterpieces.