Characterization and boriding of ductile cast iron with boric acid based alternative boriding powder mixture

In this thesis, alternative boronizing mixture is used for boronizing of cast iron instead of high cost and patented imported boronizing mixtures. The aim of the study was to improve the surface quality of DIN GGG 70 quality spheroidal graphite cast iron material by boronizing process. According to literature, boronizing of this cast iron was not encountered. Boronizing process was applied by box (solid) boring method at 850, 900, 950 oC for 4, 8, 12 hours using alternative boronizing mixture. Unlike the alternative mixture, the commercial Ekabor®-II powder mixture was also used for boronizing process at 900oCfor 4 hour. The microstructural (optical microscope and SEM), chemical (XRD, EDS) and mechanical (microhardness, surface roughness and abrasion test) properties of the samples boronized with alternative domestic boronizing mixture and industrial Ekabor®-II imported boronizing mixtures were examined. In addition, the thickness of boride layers were calculated by means of the empirical and regression analyzes, and the required activation energy for boron diffusion was calculated using diffusion equations and analyzes. As a result of XRD analysis, only Fe2B phase was observed in samples boronized with alternative domestic mixture but Fe2B + FeB phases were observed in samples boronized with commercial product Ekabor®-II. Keywords: Spheroidal Graphite Ductile Cast Iron, Boronizing, Kinetic Analysis Hardness, Wear