“We are manufacturing cameras for astronomy. We want to use the indium sealing for vacuum chamber. We need the vacuum chamber to keep tight for several years (possibly 5 to 10 years). We are looking forward to your answer.”
No problem, indium can be (and has been) used for long-term vacuum seals. The design of the seal groove is important, as well as the flange material. If you are using stainless steel or nickel flanges you shouldn’t have any compatibility issues with indium – even long term. If you want to use a different material for your flanges, contact me at firstname.lastname@example.org or email AskUs@indium.com to discuss the application/solution with one of our Technical Support Engineers.