Carbon dioxide (CO₂) is commonly used in welding as a shielding gas, particularly in the Gas Metal Arc Welding (GMAW) process, also known as Metal Inert Gas (MIG) welding. In this context, CO₂ is often used either in its pure form or mixed with other gases, such as argon. The main purpose of using CO₂ in welding is to protect the weld pool from contamination by atmospheric gases like oxygen, nitrogen, and water vapor, which can cause defects in the weld.