The Process

 

 

These are 3mm dry ice pellets rapidly subliming on the lid of a Clean Surface blast unit.

Dry ice, which is pure solid carbon dioxide, is made by decompressing liquid CO2 to create CO2 snow. The snow is then compacted and extruded through a die plate to form solid CO2 pellets.

Dry ice is unstable above minus 78.6 °C, but instead of melting into CO2 liquid it sublimes directly into CO2 gas. It is this sublimation process that creates the cleaning effect when dry ice is used as a blasting medium.

During blasting the pellets are accelerated to speeds between 200 and 300 m/s with compressed air. They break up as they travel through the blaster system and arrive at the work surface as fast moving pinhead sized particles. The particles embed themselves in the pores of any surface deposits and very quickly sublime into a much larger volume of CO2 gas. The expansion factor varies with temperature, but gas of at least 500 times the volume of the solid particle is generated within the surface deposit, which blows it apart and breaks its bond with the substrate material.

Powered by Pacific LANWorks Pte Ltd © 2007 | All Rights reserved