Back to results
US 4,952,902 AGranted
Thermistor materials and elements
AssigneeTDK Corporation
InventorsYukio Kawaguchi, Tohru Kineri
Life of this patent
Estimating the term…
Abstract
A thermistor material comprising, in sintered form, (A) a matrix comprising aluminum oxide, silicon oxide, or the oxide of an element belonging to Group 2A in the Periodic Table, and (B) a conductive path forming substance comprising silicon carbide and/or boron carbide, wherein the volume ratio of silicon carbide to the matrix is up to about 1.24 is stable at elevated temperatures of 400.degree.-800.degree. C.
Claims12
A thermistor material in the form of a sintered body comprising
- (A) a matrix comprising at least one oxide selected from the group consisting of oxides of aluminum, of silicon, and of the elements magnesium, calcium, strontium and barium, and
- (B) a conductive path forming substance comprising at least one carbide selected from the group consisting of silicon carbide and boron carbide, wherein the volume ratio of silicon carbide to the matrix is up to about 1.24, and wherein the weight ratios of the matrix, silicon carbide and boron carbide are within the region defined by boundary lines joining corner coordinates (x, y, z) on a triangular plot, where x, y, z are the weight percent respectively of Al.sub.2 O.sub.3, SiC and B.sub.4 C, when the matrix is Al.sub.2 O.sub.3 and the corner coordinates are (95,0,5), (5,0,95), (50,50,0) and (95,5,0) or by the corner coordinates (Ay.rho.m/.rho.a, Ay, Az) when the matrix is different from Al.sub.2 O.sub.3, where .rho.m is the theoretical density of the matrix, .rho.a is the theoretical density of Al.sub.2 O.sub.3, and A is a value such that A.times..rho.m/.rho.a+Ay+Az=100, and the variables x, y, z have the preceding values specified for the corner coordinates when the matrix is Al.sub.2 O.sub.3.
Dependencies are inferred from the claim text.