GB778298A - - Google Patents

Abstract

778,298. Ceramic compositions: compressionmoulding machines. GLOBE-UNION, Inc. Dec. 18, 1953 [Dec. 26, 1952], No. 35305/53. Classes 22 and 87(2). [Also in Group XXXVI] A composite dielectric plate comprises' a plurality of adjacent areas of different ceramic composition which are fired together and are united by the intermingling consequent upon the firing, the areas being arranged side by side and extending without overlapping, through the thickness of the plate. The adjacent areas may be chosen to have differing dielectric constants, differing temperature coefficients of dielectric constant or desirable piezo-electric properties. The composite plate may be produced in the manner shown in Figs. 1 and 2. A filler shoe, having two compartments 12 and 14 which are filled with different respective powdered compositions, is passed over an opening 18 thereby filling the opening with the compositions as shown in Fig. 2. The powder is then compacted between upper and lower punches 22, 24 to form a pellet which is subsequently fired to form a unitary ceramic plate having two regions of differing electrical properties. Fig. 4 (not shown) illustrates a modified filler shoe comprising three compartments whereby a plate having three separate areas may be produced. Materials which may be used in the preparation of the ceramic bodies comprise titanates of barium, calcium, strontium, lead and magnesium, zirconates of barium and magnesium, heavy-grade titanium dioxide, barium carbonate, steatite talc, a mixture of rare-earth oxides prepared from commercial didymium carbonate, and ball clay. Reference has been directed by the Comptroller to Specification 696,185 [Group XXXVI].