Low and Stable Secondary Electron Yields of Alodine-Treated Aluminum Alloys Under Continuous Electron Bombardment

High secondary electron yields of aluminum (Al) alloys limit the performances of high-power microwave devices and even extremely degrade their lifetimes. In this work, a strategy of alodine treatment for Al alloys was proposed to achieve a goal of the secondary electron emission suppression under continuous electron bombardment. It was found that a porous chromate conversion film including the mixture of basic chromium chromate and alumina with a mean pore size of 69.1 nm was formed on the surface of the Al alloy treated by alodine solution. On the basis of the secondary electron yield (SEY) measurement results, this alodine treatment brings about a reduction of maximal SEY of the Al alloy from 1.67 to 1.33 with a ratio of 20.4% and has just a remarkably tiny SEY change within 0.01~0.03 under 240-min continuous electron bombardment.