Thermal Spray Coating and different types of thermal spray coating?

Thermal spray coating refers to a number of processes in which are coated to improve functional performance. Many types of coating methods can be applied by thermal spray processes. Coatings can range in thickness from a thousandth of an inch up to an eighth of an inch. Thermal spray coatings have been used for protecting the parts from wear, abrasion, corrosion, high temperatures, etc.

In the Thermal spray coating processes embrace the deposition of coatings from a high-velocity stream shyly divided particles in a molten state impinging onto the substrate. These types of processes they use fine powdered source material or sometimes metal wire that is molten and broken into fine droplets. The coating gun will add thermal energy to bring the materials to a plastic or molten condition and speed up these materials at high velocities toward the substrate.

There are 5 types of thermal spray coating:-

HVOF (High-Velocity Oxy-Fuel Spraying):

HVOF Gun is a process that makes use of a torch that allows the flame to spread whenever the nozzle is used. This creates rapid speedup which speeds up the particles in the mixture. The end result is an exceptionally thin coating that is evenly applied. Despite being thin, this coating is strong and deposited well. Its resistance to corrosion is better than plasma coatings, but it is not suitable for high temperatures.

Combustion Flame Spraying:-

Combustion flame spraying is an excellent option for surfaces that aren’t designed to handle extreme stress. The coating which results from these process is not strongly attached to the surface because the spraying mechanism is powered by a lower flame velocity. The flame will be generated by the oxygen which is combined with fuel, and it will melt the mixture. this type is popular for low-intensity applications due to its low cost.

Plasma Spraying:-

Plasma spraying uses the plasma torch as the main tool for heating and spraying the coating. After the powder material has been melted down, it is then placed on the product in a manner that is similar to combustion flame spraying. The coatings which result from plasma spraying maybe a few micrometers thick to a few millimeters thick. While the powder is the most widely used material, metals and ceramics are also used. This type of process is highly popular due to its adaptability.

Vacuum Plasma Spraying:-

Vacuum plasma spraying is a controlled environment but utilizes low temperatures. This maintains the vacuum while also reducing damage to the material. A variety of gas combinations can be used for the necessary pressure for spraying. this type is used for items such as car bumpers, the dashboard or housings for door mirrors. This process can also be used for the pre-treatment of polyethylene moldings, which provides adhesion for epoxy adhesives which are water-based.

Twin Arc Spraying:-

This spraying method utilizes a Twin Arc Spray Gunpoint that is created between two wires which are electrically conductive. Melting will occur at the point where the wires connect. The arc allows for heating which in turn creates deposition and melting, similar to this type of spraying which is used with a torch. Compressed air is used for spraying the coatings. This type of spraying is popular due to its cost-effectiveness, and will typically use aluminum or zinc as the base material.