Protective tube for thermocouple and method of producing same
Abstract
Abstract A protective tube for a thermocouple for measuring the temperature of molten metal, comprising two layers, an inner layer being made of a silicon nitride or sialon ceramic having a bending strength of 50 kg/mm 2 or more, a density of 90% or more based on a theoretical density and a thermal shock temperature ΔT of 400° C. or more, and an outer layer being formed on the silicon nitride or sialon ceramic and containing BN and SiO 2 . The silicon nitride of sialon ceramic comprises 70 weight % or more of Si 3 N 4 having 65 weight % or more of an α-phase content, 20 weight % or less of one or more oxides of elements of Group IIIa of the Periodic Table, 20 weight % or less of Al 2 O 3 , and optionally 15 weight % or less of AlN or AlN solid solution, and the outer layer is composed mainly of BN-SiO 2 -Al 2 O 3 -Y 2 O 3 . This protective tube is produced by coating ceramic powder comprising BN and SiO 2 before sintering. This protective tube can enjoy an extremely long life.
Inventors
- 👤 Kiyoshi Furushima
- 👤 Kazunori Haratoh
- 👤 Hideshige Matsuo
Bibliographic Details
Claims Analysis
Total Claims: 7References Cited (Backward Citations)
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| 3.5 Years (Year 4) | 1992-01-10 | 1992-07-11 | 1993-01-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-01-10 | 1996-07-11 | 1997-01-10 | $3760.00 | Window Closed / Lapsed |
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