Which of the following is generally used for melting metal in the metallic gun type of metal spraying process?

Explanation:

Metallic gun type of metal spraying:

• The metallic gun type of metal spraying process is a thermal spraying method where molten metal is applied to a surface to create a protective or decorative coating. The primary function of the process is to melt the metal feedstock and project it onto the target surface. Among the given options, the oxy-acetylene flame is generally used for melting metal in the metallic gun type of metal spraying process. This is due to its ability to achieve high temperatures, which are sufficient to melt most metals used in spraying applications.

Why Oxy-acetylene Flame is Used:

• The oxy-acetylene flame is created by combining oxygen and acetylene gas in a specific ratio. When ignited, this mixture produces a high-temperature flame that can reach temperatures of up to 3,500°C (6,332°F). This temperature is adequate for melting metals like aluminum, zinc, and other alloys commonly used in thermal spraying.

Process Description:

In the metallic gun type of metal spraying process:

• The metal feedstock (typically in the form of wire or powder) is fed into the spray gun.
• An oxy-acetylene flame is used to melt the metal at the tip of the gun.
• Compressed air or another gas is then used to propel the molten metal particles onto the surface being coated.
• Upon impact, these particles solidify, forming a dense and adherent coating.

The oxy-acetylene flame provides a controlled and efficient heat source, ensuring that the metal is melted uniformly and sprayed effectively. This makes it the preferred choice for the metallic gun type of metal spraying process.

Applications:

The metallic gun type of metal spraying process using an oxy-acetylene flame is widely used in various industries, including:

• Corrosion protection: Applying coatings of zinc or aluminum to steel structures to prevent rust.
• Restoration: Repairing worn-out surfaces by adding layers of metal to restore dimensions.
• Decorative purposes: Adding metallic coatings for aesthetic appeal.
• Thermal insulation: Coating surfaces to improve thermal resistance.