Analysis of Wettability and Reaction of Molten Cast Iron to Carbides --- Fundamental Study for Wear Resistant Composite Castings

Abrasive wear tests were made on steels, high chromium cast iron, aluminazirconium boride and steels with 16 and 31 vol.% alumina pins to clarify the desireble structuresfor wear resistant materials. A pair of cylindrical specimens of <50^phi> mm x 10mm rotated at 382286rpm在接触与每一个其他的人。A commpressive load of 30kg was applied and silica particles连续fed to the contact surface. the results revealed that fine ceramics，as much as possible，must be dispersed in tough metallic matrix to obtain the superior wear resistance. the wettabilityand interaction of cast iron melt on WC and ZrO2 substrates has been investigated in vacuum，< 10 ^ (- 5) > torr,at 1200 C by the sessile drop method. the wetting angle between cast iron melt and WC was 0while that between the melt and ZrO2 was 105 . This excellent wettability of WC by molten cast ironindicated that metallic carbides could be easily dispersed in molten cast iron. Each of sintered WCand powder of WC， VC， Cr3C2或Mo2C was set in the sand mold cavity和Mgtreated cast iron melt poured in the mold. the solidification structuresmetallographically examined and the distributions of elements分析与EPMA. Both Cr3C2and Mo2C dissolved easily into cast iron melt，and eapecially chromium made the most of melt freeze in brittle white cast iron. On the other hand，WC and VC moderately dissolved in molten cast iron and arose thin reaction zones which were composedmany finer WC or VC particles in Fe-matrix. Though ferritic spheroidal-graphite cast ironstructure developed after these very hard reaction zones. The thickness of hard layers可以controlled by using mixtures of WC/VC and Cr3C2 powders blended at different ratios。

Abrasive wear tests were made on steels, high chromium cast iron, alumina, zirconium boride and steels with 16 and 31 vol.% alumina pins to clarify the desireble structures for wear resistant materials. A pair of cylindrical specimens of <50^phi> mm x 10mm rotated at 382 and 286rpm in contact with each other. A commpressive load of 30kg was applied and silica particles were continuously fed to the contact surface. The results revealed that fine ceramics, as much as possible, must be dispersed in tough metallic matrix to obtain the superior wear resistance. The wettability and interaction of cast iron melt on WC and ZrO2 substrates has been investigated in vacuum, <10^(-5)> torr, at 1200゜C by the sessile drop method. The wetting angle between cast iron melt and WC was 0゜, while that between the melt and ZrO2 was 105゜. This excellent wettability of WC by molten cast iron indicated that metallic carbides could be easily dispersed in molten cast iron. Each of sintered WC and powder of WC, VC, Cr3C2 or Mo2C was set in the sand mold cavity, and Mgtreated cast iron melt was poured in the mold. The solidification structures were metallographically examined and the distributions of elements were analyzed with EPMA. Both Cr3C2 and Mo2C dissolved easily into cast iron melt, and eapecially chromium made the most of melt freeze in brittle white cast iron. On the other hand, WC and VC moderately dissolved in molten cast iron and arose thin reaction zones which were composed of many finer WC or VC particles in Fe-matrix. Though ferritic spheroidal-graphite cast iron structure developed after these very hard reaction zones. The thickness of hard layers can be controlled by using mixtures of WC/VC and Cr3C2 powders blended at different ratios.