Chemical polishing (CP) was selected to develop a practical surface treatment of stainless steel that will be generally used in ultrahigh vacuum (UHV) technology because CP can treat materials wholly in any shape at the final step of parts fabrication process.
Using short samples of SUS304L stainless steel the solution and the polishing condition were optimized from outgassing rate and reproducibility. The polished surfaces were characterized by Auger electron spectroscopy (AES), scanning electron microscopy (SEM), and Atomic force microscopy (AFM).
The chemically polished (CP) chamber was compared with those treated by conventional electrolytic polishing (EP) and glass beads blasting (GBB). In pump-down curves, the outgassing rate of CP samples was the same as that of EP one and 10% of GBB one. At the ultimate pressure at 28°C after 150°C × 20 h baking the outgassing rate of the three chambers with different surface treatments showed a same value, 1 × 10-9 Pa·m·s-1.
The technical purpose to use the CP for UHV material surface treatment is satisfied by this result and the cost of CP is less than that of EP because it doesn't need electricity.
