ELECTRICAL RESISTOR CONTAINING LEAD RUTHENATE

1329358 Glass incorporating conductive materials AIRCO Inc 23 Sept 1971 [19 Oct 1970] 44413/71 Heading C1M [Also in Division H1] A resistor material comprises lead ruthenate dispersed in matrix of glass or refractory ceramic material. The lead ruthenate is prepared from the sintering reaction of RuO 2 with PbO, PbO 2 , PbCO 3 or Pb(NO 3 ) 2 ; with the use of PbO, extra amounts of PbO may be added to yield a mixture of Pb 2 Ru 2 O 6 and PbO. The glass frit may be a Pb-Al borosilicate or a Pb-Zn- Zr-Mn borosilicate; the first having a composition in wt. per cent of PbO, 60; B 2 O 3 , 30; SiO 2 , 4; N 2 O 3 , 6. For screen printing, the composition is made into a paste by adding for example benzol, pine oil, α or # terpineol, polyvinyl alcohol or ethyl cellulose in butyl carbitol. The lead ruthenate may be formed in situ as part of the firing of the finished glaze film. In described examples a paste is printed on sintered alumina substrates which have been preterminated with a silver conductor film. V 2 O 3 , Sb 2 O 5 , MnO 2 or Fe 3 O 4 may be added to the composition to modify the temperature coefficient of resistance. Volumetric resistors are formed with lead ruthenate mixed with a refractory ceramic material such as particulate Al 2 O 3 or ZrO 2 .