Precise Chemical Polishing of Aluminum Alloys for UHV Wall

Chemical polishing (CP) is advantageous for low-cost polishing of metallic objects with complex shapes. But conventional CP has not been sufficiently developed to be applied to materials used in ultrahigh vacuum (UHV) and extremely high vacuum (XHV) systems. Therefore, we developed a CP process optimized for application to UHV and XHV materials that uses a solution of phosphoric and nitric acids and an additional cleaning process. Using this optimized CP process, the degree of outgassing of chemically polished aluminum is comparable to the outgassing achieved with special extrusion and ethanol lathing processes. This optimized CP process can be used for regular surface treatment of aluminum alloys used in both UHV and XHV chambers and related equipment.