What is the effect when metal particles stick to the inside of the ceramic nozzle?

What is the effect when metal particles stick to the inside of the ceramic nozzle?

• A. They create an arc which is too hot
• B. They cause the cup to crack
• C. They impede the flow of electrons from the base metal to the tungsten electrode
• D. They cause gas turbulence and possible atmospheric contamination

Answer: (D)

Shielding gas coverage is essential to keep the weld protected from the atmosphere. The ceramic nozzle guides that gas around the arc and molten weld. When metal particles stick to the inside of the nozzle, they disturb the smooth gas flow and create turbulence. This breaks the shielding envelope, allowing air—oxygen and other contaminants—to mix with the weld area. The result is atmospheric contamination that can cause porosity and oxide inclusions, weakening the weld. The other ideas don’t fit because debris in the nozzle doesn’t directly change arc temperature, crack the cup, or block electron flow between the base metal and the tungsten; the nozzle’s job is to shield, so disturbances there mainly affect shielding effectiveness.

Shielding gas coverage is essential to keep the weld protected from the atmosphere. The ceramic nozzle guides that gas around the arc and molten weld. When metal particles stick to the inside of the nozzle, they disturb the smooth gas flow and create turbulence. This breaks the shielding envelope, allowing air—oxygen and other contaminants—to mix with the weld area. The result is atmospheric contamination that can cause porosity and oxide inclusions, weakening the weld. The other ideas don’t fit because debris in the nozzle doesn’t directly change arc temperature, crack the cup, or block electron flow between the base metal and the tungsten; the nozzle’s job is to shield, so disturbances there mainly affect shielding effectiveness.