Why the use of nickel alloys is recommended as wire in arc spray process
Arc Spray is a sub-category of arc spray process. It is a method metallization; this means depositing a layer of substrate metal over a surface in order to protect, decorate or add new properties to the surface.
How is arc spraying performed?
The metalizing wire which is also known as arc spray wire is used in metalizing operations as a means to feed the material into plasma or arc in order to be sprayed onto the surface. The wires are made from a nickel-based alloy (Incoloy and Inconel) which are a lot resilient as compared to the traditional bases and cost a fraction of their value.
To coat a surface with a given material, first of all, the coating material is fed into a container in either powdered or wire form into a container. These materials are then heated using an electrical arc until they melt down completely or partially. After this, they are sprayed over the surface in micrometer-sized particles using the arc to propel them through the gun.
The equipment used in the process
Any arc spraying system consists of following things.
- Spray gun: It is the most important part as it melts and accelerates the particles that are to be sprayed.
- Media Supply: The substance used to generate an arc or plasma jet. Usually, a gas or a liquid is used.
- Feeder: It is used to store the powder or arc spray wires of the substance that is to be sprayed.
- Control panel and power supply: These are used to control the process and supply the energy respectively.
- Robot: It is used to hold the torch which is too dangerous for a human being to handle directly.
Why are the alloys such as Inconel or incoloy used?
Inconel and Incoloy are alloys made using nickel and various other elements which provide it extreme durability against oxidation, corrosion against acid and bases. This level of ruggedness cannot be matched by the traditionally used metals such as aluminium.
Another advantage that these wires have over the generic ones is wire feeding. Other wires used for the process of wire feeding can cause excessive wear and tear of the machines and might even jam the equipment. In addition to this, these wires are made for the purpose of metallizing and provide a perfect finish whereas the generic wires can cause kinks and visible weld joints which make the surface look unfinished and even compromise the integrity.
What is the difference between arc-spray, thermal spray and plasma spray?
All these techniques are used for the purpose of metallization. The difference is the method used to propel the particles and melt the wires. These different methods are used as they create different temperatures which are suitable for different kind of metallizing wires.
Where is the Arc-spray process used?
The arc spraying technique is used to coat structural materials. These arc spray wire coatings provide protection against high temperatures, corrosion, and wear & tear. Apart from protection, the substance sprayed could also be used to alter the appearance or electrical properties of the surface. The technique with slight alterations can be used to create porous structures and used as a coating for medical implants.