Dry Ice particle blasting is similar in some aspects to sand, plastic bead or soda blasting where a media is accelerated in a pressurized airstream (or other inert gas) to impact the surface to be cleaned or prepared, but the unique difference with Dry Ice blasting is the media that impacts the surface is solid carbon dioxide (CO2) particles which sublimate (vaporise) upon impact with the surface.
The combined impact energy dissipation and extremely rapid heat transfer between the pellet and the surface cause instantaneous sublimation of the solid CO2 into gas. This gas expands almost eight hundred times the volume of the pellet in a few milliseconds in what is effectively a ‘micro-explosion’ at the point of impact. Because of this vaporising it does not generate any secondary waste. All that remains to be collected is the contaminant.
The kinetic energy associated with Dry Ice blasting is a function of the particle mass density and impact velocity. Since CO2 particles have a relatively low hardness, the process relies on high particle velocities to achieve the required impact energy.
Unlike other blast media, the CO2 particles have a very low temperature around -100 degrees Fahrenheit, which provides a unique thermodynamically induced surface. Because of the temperature differential between the Dry Ice particles and the surface being treated, a phenomenon known as ‘fracking’ or thermal shock can occur. As a material’s temperature decreases, it becomes embrittled, enabling the particle impact to disintegrate the coating.