PERFORATED SHADOW MASK FOR COLOR CATHODE RAY TUBE AND ANNEALING TEHREOF

摘要

An aperture mask comprised of a nickel-iron alloy having a low thermal expansion for a colour CRT is produced by combining a first annealing to produce a low coercive force and mechanical properties desirable for a warm forming operation during which a desired profile of the mask is produced with minimized springback and a second annealing after forming to provide a stress free low coercive force mask also having an oxidized high thermal emissivity surface. The process requires control of the atmospheres and oxidizing potentials in the two annealing steps.