Thermoelement comprising a graphite/boron carbide thermocouple

US4732620A · kind A · utility

Assignee

• Elektroschmelzwerk Kempten GmbH · DE

Inventors

• Klaus Hunold · Kempten, DE
• Alfred Lipp · Bad Wörishofen, DE
• Klaus Reinmuth · Durach, DE
• Peter Arnold · Earby, GB

Key dates

• Filing date: Mar 14, 1986
• Grant date: Mar 22, 1988
• Expiry date: Mar 14, 2006

Classification

• Technology area (CPC G): Physics
• CPC primary: G01K7/06
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

The invention is an improved theroelement which comprises a graphite/boron carbide thermocouple, the arms of which are constructed as a tube and a rod, arranged concentrically inside the tube, which are electrically connected at one end. One of the arms of the thermocouple consists essentially of boron carbide formed from self bonding boron carbide by pressureless sintering. Prefabricated sleeves of high-purity, boron-oxide-free hexagonal boron nitride are used between the arms of the thermocouple as spacers. Only the end of the arm of the thermocouple constructed as a rod is secured in an electrically conductive connecting piece and the arm is freely mobile in the direction towards the cold junction. As the material for the arm of the thermocouple constructed as a rod, there can be used, for example, boron carbide having a coarse-grained structure and a density of from 60 to 80% TD, which has been manufactured from boron carbide powder having bimodal particle size distribution by means of extrusion, followed by pressureless sintering at from 2000.degree. to 2250.degree. C. The thermoelement can also be manufactured in one operation by means of pressureless sintering of the boron c…