Study On (MgO,Y₂O₃)-PSZ Oxygen Probe Material Used In Molten Steel

Oxygen probe is a new kind of equipment for instantaneous detecting of oxygen in the metallurgy process, which is fast, in time and accurate. It is the key point to produce high grade of steel products.As an oxygen probe material, the (MgO,Y₂O₃)-PSZ ceramic is mainly investigated in this article to introduce the detecting of molten steel containing small quantity oxygen.Several domestic and foreign-made oxygen probes were studied by XRD and SEM. The result is that the main phase of the material is monoclinic, and its contents of the probes made abroad are 85.5%～86.6%, while the oxygen probes made domestically are higher than them by 5 to 8 percent. The optimal content of monoclinic has not been known.The (MgO,Y₂O₃)-PSZ powder which had different Y₂O₃ contents was produced by the solvent drying technique. The grains distribute concentratedly.The compacting and sintering process of (MgO,Y₂O₃)-PSZ was studied. It is found that the comparative density of the material sintered at 1600℃is 97%,the satisfactory density for the material of zirconia tubes. The bending strength and thermal shock resistance of (MgO,Y₂O₃)-PSZ ceramic containing 2.0mol% Y₂O₃ sintered at 1600℃is optimal.The data of thermal expansion curve of the (MgO,Y₂O₃)-PSZ material was recorded by the dilatometer which was made by ourselves. The conclusion is that the thermal expansion coefficient is increasing with the addition of Y₂O₃, because the tetragonal phase is increasd. Accompanied by the shrinkage of the volume the monoclinic structure transforms to tetragonal phase when the temperature is elevating. Thus the thermal expansion coefficient begins reduced at 1100℃and is 0 at some temperature. The temperature field and stress field of the zirconia tube were simulated by the ANSYS analysis software. The highest temperature and stress gradient are at the contacting area of ZrO₂ and Al₂O₃ tube, and the second highest stress gradient is at the bottom of ZrO₂ tube. That is to say, the most dangerous part when the ZrO₂ is inserting into the steel is the contacting part of ZrO₂ and Al₂O₃ tube, and the senond dangerous area of it is the the bottom of ZrO₂ tube.