| 摘要 |
PURPOSE:To obtain the titled metallic electrode which can be put in high-temperature flames directly and used stably for a long period by composing it of an Fe-Cr-Al alloy within a specific composition range, and heating a flame inserting part previously in an oxidation atmosphere and forming a protection coating of Al2O3 on the surface. CONSTITUTION:The electrode 4 for a frame sensor is made of the Fe-Cr-Al alloy consisting of 3-8wt% Al, 18-28wt% Cr, and the balance Fe and the flame inserting part of the electrode 4 is heated in an oxidation atmosphere, e.g. in air at about 1,000 deg.C for about 20hr to form the protection coating of Al2O3 on the surface to about 5-100mum thickness. Consequently, good workability is obtained and the long-life flame sensor electrode 4 which is not carburized even in high- temperature reducible flame 3 and used stably also maintains high temperature corrosion resistance and conductivity is obtained. Further, this is usable without trouble even when the Fe-Cr-Al alloy contains a normally contained microelement and a small amount of rare earth element such as Zr, Ti, and Nb for characteristic improvement. |
