Riedel-de Haen Aktiengesellschaft

Bernd Schonfeld

Rudolf Hirschberg

Karl Franz

Chlorofluoroferrates(II,III) are manufactured by fusing alkali metal halides or ammonium halides with an iron(III) halide and metallic iron. The starting materials used are, in particular, (a) an alkali metal chloride or ammonium chloride, (b) an alkali metal fluoride or ammonium fluoride, (c) anhydrous iron(III) chloride and (d) iron powder. The reaction is carried out a temperature of 300.degree. to 900.degree. C. The chlorofluoroferrates, which have a markedly lower hygroscopicity compared with customary chloroferrates, are particularly suitable for use as active fillers for grinding wheels.

Chlorofluoroferrate(II,III), a process for its manufacture, its use and

Filter phosphors consist of phosphor particles coated with a filter material. A phosphor which shows a red emission when excited by cathode rays may be coated with red iron oxide by producing a thin layer of pyrite on the phosphor particles and thereafter converting the said layer into hematite. Thus, the surface of the phosphor particles is evenly coated with a uniform, dense pigment layer of extreme adherence. The filter phosphors thus obtained are used in cathode ray tubes and especially in color picture tubes.

Process for the preparation of a red emitting phosphor coated with red

In grinding disks, toxic lead chloride and antimony sulfide may be replaced by non-toxic alkali metal chloroferrates (II,III) produced by melting together alkali metal chloride, anhydrous ferric chloride and iron powder.

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Bad Nenndorf, Germany

Bernd Schonfeld