thermo chemical clean

[traytown]

We are tyring to clean surface oxides from nickel nased superalloys using thermochemical cleaning ovens using cf4.
We are struggling to remove fully the oxide films using a 1000c fro 1 hour cycle . Any ideas?

 

[TVP]

Do you know what the ratio of H₂ : CF4 is? I would guess that there is insufficient concentration of HF present in the crack for removing the scale. Also, does your process have some way of removing the water and byproducts prior to Ar gas glow?

 

[traytown]

CF4 0.80 ltr/min Hydrogen flow 5 ltr/min for an hour @ 1000cnot sure there is amy water to ermove as the prior argon purge will remove any atmospheric water?

 

[btrueblood]

The HF formed in the decomposition of the CF4, and excess H2, react with the oxides on the part to yield water. Pulling a vacuum on the system prior to argon purge would help remove byproducts (but that is very tough duty for a vacuum pump).