| 摘要 |
PURPOSE: To improve the resistance to spalling and erosion by forming the upper nozzle with an unfired magnesia-carbon brick using a boron-modified phenolic resin excellent in oxidation resistance at high temps. as a binder. CONSTITUTION: The magnesia and carbon as the brick material and an additive are mixed, and 0.5-10wt.% boron-modified phenolic resin contg. 10-50wt.% B is added along with a binder such as pitch, tar and phenolic resin. The admixture is kneaded, press-formed and dried at 30-700 deg.C to obtain the upper nozzle brick. Although the boron-modified phenolic resin can be used alone as a binder, the resin is preferably used jointly with common novolac resin and resol-type phenolic resin from the viewpoint of economy and formability. Further, the unfired upper nozzle is ordinarily used without being impregnated. |
