PROCEDIMENTO PER LA FABBRICAZIONE DI PARTICELLE MAGNETICHE IN PARTICOLARE PER L OTTENIMENTO DI INCHIOSTRI MAGNETICI

摘要

1460695 Magnetic particles INTERNATIONAL BUSINESS MACHINES CORP 24 Feb 1975 [15 April 1974] 7594/75 Heading C1A [Also in Division C7] Magnetic particles suitable for use in making magnetic inks are produced by a method comprising evaporating substantially pure iron in an inert, low pressure, ambient atmosphere under conditions such that the evaporated iron aggregates to form discrete particles, collecting the particles and thereafter exposing the particles to an oxidizing atmosphere. Iron of 99À999% purity is preferred and the oxidation is preferably carried out by means of air at room temperature and pressure. The preferred inert atmosphere is pure argon at a pressure in the range 0À1 to 1À0 mm. of mercury.