Abstract
In most surface treating methods of metal casting molds, refractory materials glazed on the mold surfaces onto which lamp black produced by incomplete combustion of acetylene is spread. These methods, however, result in the appearance of chill layers due to accelerated cooling, and aggravation of the working environment. We developed the following new treating method which can be substituted for the conventional methods described above. Material properties characteristic to grey cast iron consisting of iron matrix and free graphite are made use of in this method. Namely, a porous surfaec layer of metal casting mold consisting mainly of flaky graphite is formed by electrolysis, corroding the original mold surface. Then, binder penetration and sintering are performed to strengthen the surface layer. Appearance of chill layers in the casting can be prevented by elevating the mold preheating temperature. A satisfactory casting result can be obtained with this new method.
