Protective ceramic device for immersion pyrometer
AssigneeRDC Controle Ltee
InventorClaude Allaire
Life of this patent
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Abstract
An elongated protective device for an immersion pyrometer. The device comprises a self-supporting inner sheath made of a ceramic material having virtually no open pores and a protective, crack-free outer ceramic casing at least partially surrounding the inner sheath. The inner ceramic sheath has an interior cavity extending from an open end of the sheath internally to a closed end for receiving a thermocouple element. The thermocouple element is then positioned within the cavity with the hot junction of the thermocouple element contacting the closed end of the ceramic sheath. The device provides good corrosion, shock and oxidation resistance for pyrometers when immersed into molten metals and by-products at high temperatures.
Claims17
An elongated protective device for an immersion pyrometer having an open end for insertion of a thermocouple element and a closed end for immersion into a fluid whose temperature is to be sensed, said device comprising:
- a self-supporting inner sheath made of a ceramic material of 0 to 2% porosity having an open end, a closed end having an outer closed end surface, outer sidewalls extending from said outer closed end surface to said open end and an elongated cavity extending internally from said open end to near said closed end for receiving a thermocouple element;
- and
- a crack-free protective outer ceramic casing covering said inner sheath, at least over said outer sidewalls of said inner sheath, formed from a uniform layer of a refractory castable material comprising a blend of refractory cementitious material particles and a bonding phase intimately bonded to said inner sheath by heating such that no interfacial crack is observable between the inner sheath and the outer casing when viewed at 10.times.magnification.
A thermocouple having a temperature sensing element enclosed within a protective device, said protective device comprising:
- a self-supporting inner sheath made of a ceramic material of 0 to 2% porosity having an open end, a closed end having an outer closed end surface, sidewalls extending from said outer closed end surface to said open end and an elongated cavity extending internally from said open end to near said closed end for receiving a thermocouple element;
- and
- a crack-free protective outer ceramic casing covering said inner sheath at least over said outer sidewalls of said inner sheath, formed from a uniform layer of a refractory castable material comprising a blend of refractory cementitious material particles and a bonding phase intimately bonded to said inner sheath by heating such that no interfacial crack is observable between the inner sheath and the outer casing when viewed at 10.times.magnification.
A process of producing a protective device for a thermocouple element of an immersion pyrometer, comprising:
- forming an inner sheath of ceramic material of 0 to 2% porosity, said sheath having an open end, a closed end having an outer closed end surface, outer sidewalls extending from said outer closed end surface to said open end and an elongated cavity extending internally from said open end to near said closed end for receiving a thermocouple element;
- forming an outer protective casing around said inner sheath, at least over said outer sidewalls of said inner sheath, by casting a uniform layer of a refractory castable material comprising a blend of refractory cementitious material particles and a bonding phase;
- heating said inner sheath and outer casing at an elevated temperature that causes an intimate bond to form between said outer casing and said inner sheath such that no interfacial crack is observable between the outer casing and the inner sheath when viewed at 10.times.magnification;
- and
- cooling said inner sheath and outer casing to form said protective device.
Dependencies are inferred from the claim text.