2019 Volume 91 Issue 4 Pages 195-200
In Europe, SiC that is around 90% is used generally as a raw material of carbon and silicon. SiC is effective for improving the properties of molten metal such as reduction of chill depth and improvement of graphite shape, etc. Suggested theories for explaining its effects include the deoxidation theory by SiC and graphite nuclei theory by Cn molecular. European cast engineers think that SiC that is around 90% pure is the most effective for improving the properties of molten metal. As for dendrite, T. Benecke reports that the dendrite arm space becomes short when SiC is added. In this study, we therefore aimed to change SiC purity, investigate the influence of SiC purity on the graphite nodule count (hereafter GNC) and eutectic graphitization ability (hereafter EGA), and review the functions of SiC in spheroidal graphite cast iron. The following results were obtained.
As the purity of SiC increases, the dissolved speed of SiC becomes fast and the slag generation amount reduces. EGA and GNC also increase. When SiC is more than 95% pure, it is effective for refining the dendrite arm space. The higher the purity is, the higher is its effects, Moreover, the dendrite refining effect of SiC helps increase the graphite nuclei site between dendrite arm space and the GNC. Like SiC, Zr-type inoculant is also effective for refining dendrites. When the (a) dendrite refining effect of SiC that is more than 95% pure and (b) graphite nucleation ability of other inoculants such as Zr, Al, and Ba are combined, GNC increases remarkably..
