A colored ceramic body for use in various parts of electronic equipment, comprising at least one of A1.sub.2 O.sub.3 and BeO as a basic component, 0.1 to 5 percent by weight CoO and further additive chosen from the group consisting of MnO.sub.2, Cr.sub.2 O.sub.3, V.sub.2 O.sub.5, Fe.sub.2 O.sub.3 and mixtures thereof, the total amount of CoO and further additive being 1.0 to 10 percent by weight. The ceramic body is dark in color and has excellent electrical, mechanical and thermal characteristics, and maintains an acceptably high volume resistivity even after the body has been heated in a reducing atmosphere.
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of U. S. Ser. No. 864,178, filed Oct. 6, 1969, now abandoned, entitled CERAMIC COMPOSITION, inventor, Masatoshi Sugiura et al.
The present invention is directed to a noise suppressor for electronic signals. The noise suppressor at least includes Aluminum Oxide (Al.sub.2O.sub.3) that is sintered under high temperature, resulting in ceramic Aluminum Oxide (Al.sub.2O.sub.3) for effectively absorbing or suppressing noise, and reshaping the waveform or filtering waveform glitch of the electronic signals.
An aluminous sintered product comprising 70 to 96% by weight of an alumina component and 4 to 30% by weight of additives, said additives including at least the one selected from oxides of elements of the Group 5a of periodic table and at least the one selected from oxides of metals of the iron family and oxides of manganese, titanium, calcium, magnesium, chromium and silica, and said aluminous sintered product exhibiting a volume resistivity of from 1.times.10.sup.7 to 1.times.10.sup.13 .OMEGA.-cm over a temperature range of from 25.degree. to 75.degree. C. and an absolute value of the temperature coefficient of volume resistivity of not larger than 1.8%/.degree.C. under the application of high voltages. The sintered product is used as antistatic part such as conveyer arm, handling jig, tweezers for holding wafers and the like that must not be electrostatically charged in an apparatus for producing semiconductors, and as resistance substrate, electrically conducting material, contact, heater, part in vacuum tubes, and part for electron guns in a CRT such as of TVs and the like.
Ceramics containing 80 wt % or greater of alumina (Al.sub.2O.sub.3), with Mn, Ti, Fe, Si, Ca and Mg, with Mn--Al spinal (MnO.Al.sub.2O.sub.3) crystals and anorthite crystals (CaO.Al.sub.2O.sub.3.2SiO.sub.2) generated by calcination, and having a volume resistivity of 1.times.10.sup.11 .OMEGA.cm or less. Preferably, the ceramics contains a combined weight of 2 11 wt % or greater of Mn, Ti and Fe as the oxides, 0.5 wt % or greater of Mn as manganese dioxide (MnO.sub.2), 0.5 wt % or greater of Ti as titanium oxide (TiO.sub.2), and 0.5 wt % or greater of Fe as iron oxide (Fe.sub.2O.sub.3).
A ceramic body exhibiting black or near-black coloration and having good physical strength has been achieved for a body based on Al.sub.2 O.sub.3, through the addition of SiO.sub.2, TiO.sub.2, and Cr.sub.2 O.sub.3, and fired in a reducing atmosphere. Resistivity of the body can be varied as a function of the amount of TiO.sub.2.
A process for increasing the colorizing effect of known colorizing oxides in an alumina body. The process includes the steps of (a) forming a glass frit containing colorants; (b) mixing the frit and alumina to form a green mixture; and (c) firing the mixture to form a fired ceramic body.
