| 摘要 |
A thermocouple is disposed inside the closed end of a tubular sheath made of sintered ceramic refractory material comprising by weight between 3% and 15% of TiO2 between 0.8% and 25% of Cr2O3 between 40% and 95% of MgO the sum of these constituents being at least 75%, and not more than 15% of Fe2O3, the remainder if any being less than 7.5% of Al2O3, less than 2% of SiO2, less than 1% of CaO, the material having a homogeneous mineralogy on a macroscopic scale and microscopically comprising an intimate, intergrown mixture of periclase crystals and mixed magnesium spinel crystals, there being substantial direct mineralogical bonding between the crystals and at least a major portion of the periclase crystals containing fine exsolved magnesium-spinel crystals and discontinuous microcracks. A refractory buffer layer comprising at least 90% by weight of MgO fills the space between the sheath and the thermocouple. |
