| 摘要 |
PURPOSE:To measure instantaneously phosphorus concn. with good accuracy by providing an auxiliary electrode of a solid which makes constant the activity of P2O5 on the surface where a solid electrolyte and molten metal contact and measuring oxygen potential with an oxygen concn. cell. CONSTITUTION:A reference electrode 4 which applies the prescribed oxygen potential to the inside surface of the solid electrolyte 3 consisting of stabilized ZrO2 is provided. The outside surface of the solid electrolyte 3 is brought into contact with the molten metal 1 and the auxiliary electrode 2 consisting of the solid which makes constant the activity of P2O5, for example, a mixture composed of MgO and 3MgO.P2O5 is provided on said surface. A quasi-chemical balance zone 10 is formed around the auxiliary electrode 2 so as to make constant [activity of P]<2>X(oxygen partial pressure]<5>. The activity of P in the molten metal is thereupon converted to the oxygen potential and the potential 7 is detected by the molten metal 1 and the reference electrode 4 as the oxygen concn. cell, by which the P concn. is measured. Since the auxiliary electrode consisting of the solid which makes constant the activity of P2O5 is provided, the quick measurement of the phosphorus concn. in the molten metal with high accuracy is made possible. |
