Method of producing homogeneous sintered zno non-linear resistors

Abstract

A method of making a homogeneous ZnO sintered resistor body, having a substantially uniform density, which can exhibit non-linear V-I characteristics by a bulk effect, comprises the steps of: (1) mixing about 75 mole % to about 98 mole % of small, finely divided, solid ZnO and about 2 mole % to about 25 mole % of at least one small, finely divided, solid additive effective to produce non-linear characteristics within the body, preferably one or more oxides selected from the group consisting of TiO.sub.2, Ta.sub.2 O.sub.5, FeO, In.sub.2 O.sub.3, B.sub.2 O.sub.3, Al.sub.2 O.sub.3, SnO.sub.2, Sn.sub.3 O.sub.4, Mo.sub.2 O, SiO.sub.2, BaO, SrO, PbO, NiO, CaO, MgO, Bi.sub.2 O.sub.3, Co.sub.3 O.sub.4, CoO, MnO, MnO.sub.2, Cr.sub.2 O.sub.3, and Sb.sub.2 O.sub.3, with an aqueous binder solution comprising a fugitive organic, water soluble binder, wherein the weight ratio of the aforesaid mixed finely divided solids:binder is between about 100:1 to about 100:10, to provide a slurry; (2) simultaneously drying, mixing and agglomerating the slurried solids into a mass of larger substantially spherical particles containing the finely divided solids and binder; (3) pressing a mass of the agglomerated particles or powder in a uni-axial press, to provide a cohesive pressed green body having a substantially uniform density; and then (4) heating the pressed body, first at a temperature rate increase effective to slowly decompose and remove the fugitive binder from the body and then heating at a temperature of between about 625.degree. to about 1,400.degree. C for a time effective to sinter together the particles of the body.