The present disclosure relates to electron beam physical vapor deposition, and more particularly, to nanoparticle or “fluff” mitigation.
Electron Beam Physical Vapor Deposition (EBPVD) is a form of physical vapor deposition in which a target material is bombarded with an electron beam given off by a charged tungsten filament under high vacuum. The electron beam causes atoms from the target to transform into the gaseous phase. These atoms then condense into solid form, coating a workpiece in the vacuum chamber, and within a line of sight, with a thin layer of the material.
Running the EB-PVD process under lower vacuum (higher pressure) conditions results in faster deposition rates and improved coating of surfaces with limited line-of-sight to the targets that generate the vapor flux. However, nanoparticle formation can occur under these conditions, likely due to condensation of vapor in the gas phase. These nanoparticles can have several undesirable effects, including clogging or damage of pumping systems, accumulation in and damage to the electron beam gun systems, and obscuring of viewports. Mitigations of these effects is necessary for an economic, operationally efficient coating process.