Verfahren zur Metallisierung

摘要

A method of simultaneously coating a plurality of articles with one or more metals comprises heating the coating metal to its sublimation temperature but below its melting point at a pressure not exceeding 10-13 mm Hg and moving the articles in the vapour to expose all their surfaces. In forming electric resistors ceramic rods preheated to 300 DEG C. are tumbled in a revolving hollow drum in a vacuum chamber containing an Ni or Cr alloy filament heated to 1170-1220 DEG C. To maintain the composition of the vapour constant a filament is heated for only ten minutes and resistances of 1000 ohm/sq. cm. formed. To produce lower resistances several coatings using several filaments are deposited. The rods are cooled for 10 minutes before removal from the chamber and may then be aged to vary their temperature coefficients of resistance by heating in air to 275 DEG C. for 8 hours. Their final resistance may be adjusted by removing parts of the metal layer e.g. by grinding a helical groove in the coating. Conductive caps having pigtail wire leads may be added to each end and the rod encased in a glass or epoxy resin capsule.