Combustible gas detecting element
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsYoshihiko Nakatani, Masayuki Sakai
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Abstract
Combustible gas detecting element for detecting the existence of combustible gas such as methane, ethane, propane iso-butane and hydrogen. The element comprises .alpha.-Fe.sub.2 O.sub.3 containing a small amount of sulfate ion (SO.sub.4.sup.--). By using a precipitation process with urea as a precipitant for preparing the above .alpha.-Fe.sub.2 O.sub.3, remarkably high stability and reliability can be released. Addition of quadrivalent metal of Sn, Zr or Ti to the .alpha.-Fe.sub.2 O.sub.3 greatly enhances the gas sensitivity to those gases. Furthermore the sensitivity to carbon monoxide was also enhanced by adding cadmium (Cd) and/or gold (Au).
Claims10
A combustible gas detecting element comprising:
- a sintered body of .alpha.-Fe.sub.2 O.sub.3 containing 0.005 to 10 weight percent of sulfate ions;
- and
- a pair of spaced apart electrodes attached to said sintered body of .alpha.-Fe.sub.2 O.sub.3 for applying an electric current to said sintered body,
- whereby the presence of a combustible gas may be detected as a change in electrical resistance between said pair of electrodes.
A combustible gas detecting element comprising:
- a sintered body of .alpha.-Fe.sub.2 O.sub.3 containing 0.005 to 10 weight percent of sulfate ions, and at least one additive selected from the group consisting of the dioxides of tin, zirconium and titanium, the total amount of said at least one additive being 0.1 to 50 mole percent;
- and
- a pair of spaced apart electrodes attached to said sintered body for applying an electric current to said sintered body,
- whereby the presence of a combustible gas may be detected as a change in electrical resistance between said pair of electrodes.
A combustible gas detecting element comprising:
- a supported sintered film of .alpha.-Fe.sub.2 O.sub.3 containing 0.005 to 10 weight percent of sulfate ions;
- and
- a pair of spaced apart electrodes attached to said sintered film of .alpha.-Fe.sub.2 O.sub.3 for applying an electric current to said sintered film,
- whereby the presence of a combustible gas may be detected as a change in electrical resistance between said pair of electrodes.
Dependencies are inferred from the claim text.