Thin film high temperature silicide thermocouples
First Claim
1. A method of preparing a metal silicide thermoelement for a thermocouple, said method comprising the steps of:
- providing a silicon base layer extending from a thermocouple measurement junction to a thermocouple reference junction;
applying a transition metal silicide film over said base layer between said measurement junction and said reference junction; and
heat treating said metal silicide film under an oxidizing gas atmosphere to form a continuous SiO2 overlayer on said film, said atmosphere having a partial pressure of oxidizing gas sufficient to oxidize silicon atoms from said metal silicide film to SiO2 but insufficient to oxidize transition metal atoms from said metal silicide film, whereby silicon atoms from said metal silicide film which are oxidized to SiO2 are replaced in said film by silicon atoms from said silicon base layer.
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Accused Products
Abstract
A high temperature resistant and corrosion resistant thermoelement for a thermocouple formed of a silicon base layer, a conductive thin film of a silicide of a transition metal such as titanium or molybdenum which is stable at temperatures in the range from 800° C. to at least 1000° C., preferably to at least about 1500° C., and an oxygen diffusion limiting silica overlayer, and a method of forming such a thermoelement by depositing a conductive transition metal silicide film over a silicon base layer and heat treating the film in an oxidizing gas atmosphere having a partial pressure of oxidizing gas sufficient to oxidize silicon atoms from the transition metal silicide to form a continuous SiO2 overlayer, but insufficient to oxidize transition metal atoms from the transition metal silicide, in which silicon atoms from the transition metal silicide layer which are oxidized to form the SiO2 overlayer are replaced by silicon atoms from the silicon base layer.
38 Citations
20 Claims
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1. A method of preparing a metal silicide thermoelement for a thermocouple, said method comprising the steps of:
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providing a silicon base layer extending from a thermocouple measurement junction to a thermocouple reference junction; applying a transition metal silicide film over said base layer between said measurement junction and said reference junction; and heat treating said metal silicide film under an oxidizing gas atmosphere to form a continuous SiO2 overlayer on said film, said atmosphere having a partial pressure of oxidizing gas sufficient to oxidize silicon atoms from said metal silicide film to SiO2 but insufficient to oxidize transition metal atoms from said metal silicide film, whereby silicon atoms from said metal silicide film which are oxidized to SiO2 are replaced in said film by silicon atoms from said silicon base layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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- 11. A high temperature and corrosion resistant thermocouple comprising a first conductive thermoelement extending between a measurement junction and a reference junction and a dissimilar second conductive thermoelement extending between said measurement junction and said reference junction, said first and second thermoelements having different electrical resistivities and being in electrical communication with each other only at said measurement junction and at said reference junction, wherein at least one of said first and second thermoelements comprises a conductive transition metal silicide film disposed on a silicon base layer and covered by an oxygen diffusion limiting SiO2 overlayer, said at least one thermoelement being stable at temperatures up to at least about 1,000°
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20. A high temperature and corrosion resistant thermocouple comprising a first conductive thermoelement extending between a measurement junction and a reference junction and a dissimilar second conductive thermoelement extending between said measurement junction and said reference junction, said first and second thermoelements having different electrical resistivities and being in electrical communication with each other only at said measurement junction and at said reference junction, wherein at least one of said first and second thermoelements comprises a conductive transition metal silicide film produced by
providing a silicon base layer extending from said measurement junction to said reference junction; -
applying a transition metal silicide film over said base layer between said measurement junction and said reference junction; and heat treating said metal silicide film under an oxidizing gas atmosphere to form a continuous SiO2 overlayer on said film, said atmosphere having a partial pressure of oxidizing gas sufficient to oxidize silicon atoms from said metal silicide film to SiO2 but insufficient to oxidize transition metal atoms from said metal silicide film, whereby silicon atoms from said metal silicide film which are oxidized to SiO2 are replaced in said film by silicon atoms from said silicon base layer.
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Specification