To make detectable the temp./oxygen concn. by a convenient method, without using complicated electric wirings or measuring circuits by constituting a detector for detecting signals from a specified ceramic sintered compact.
E.g., 6 sheets of ceramic sintered compact 1 formed in specified dimensions, contg. zinc oxide 80 mol% or more, are adhered onto an alumina board 3 with an inorg. adhesive 2 to form the furnace atmosphere detector. The sheets of sintered compact 1 are made by sintering in the air (O concn. 20%) at temps. of 950°C, 960°C, 970°C, 980°C, 990°C, respectively. The furnace atmosphere detector is set in an electric furnace set e.g. at 970°C, the surface of each sintered compact 1 is visually seen after completion of the sintering process. In this time voids or cracks appear on the sintered compact surface at 950°C, 960°C, 970°C, and if no change appears on the sintered compact at 980°C, 990°C, the furnace temp. is lower than 980°C and higher than 970°C. When the temp. must be known at a more fine resolution, the furnace temp. can be estimated at an accuracy within about 2°C from the change of the crystal grain size.
SUZUKI YASUTAKA
YAMADA SEIICHI
CHIBA AKIO
TAKAHASHI KEN
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