RAW MATERIAL AND METHOD OF OBTAINING RAW MATERIAL Russian patent published in 2013 - IPC C04B35/468 C04B35/632 

FIELD: chemistry.

SUBSTANCE: invention relates to obtaining raw material for making ceramic articles with a positive temperature coefficient of resistance (PTC ceramics) by injection moulding. Ceramic filler, which is converted to a PTC ceramic after firing, is mixed with a thermoplastic-based matrix. A granular material is obtained, which is used for injection moulding. The matrix and filler are mixed in a roller mill. The method is realised using tools with a low degree of wear such that material containing less than 10 ppm metallic impurities caused by wear is obtained. To this end, the surfaces of tools which might come into contact with the filler have a hard tungsten carbide-based coating. The basic materials used to obtain the ceramic are BaCO₃, NiO₂, MnSO₄ and Y₂O₃, as well as at least one of the compounds SiO₂, CaCO₃, SrCO₃, Pb₃O_4.

EFFECT: obtaining raw material with low content of impurities, which enables to preserve the necessary electrical properties in the moulded article.

5 cl, 3 dwg