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Metal Casting Technologies : September 2007
CONCLUSIONS The experiments demonstrated that a skin of lamellar graphite forms on the surface of compacted graphite iron castings. Conditions of slow cooling rates and small undercooling promote flake graphite growth by impurity adsorption along the prism faces. Skin transition seems to happen as a result of the imbalance between spheroidizing, primary and gaseous elements; skin freezes off because diffusion slow down and lack of active surface elements as the casting solidifies. Wedge shaped formation of the skin seems to be caused by presence of a thermal gradient along the specimen height. The overlay of different potential causes leading to graphite morphology change at the mold metal interface increases the complexity of flake skin examination. ● Dr. Flavia Duncan was awarded "Best Technical Paper" for this research paper addressing the causes of flake skin in compacted graphite iron (CGI). The award was presented to Duncan by the World Foundrymen Organization (WFO) at the 11th GIFA International Foundry Trade Fair in Dusseldorf, Germany. Jörg Kroker, a native of Germany, studied chemistry at Philips University in Marburg, Germany. He received the Master of Science degree in 1984, subsequently specialized in the field of organometallic chemistry, and received the doctoral degree in 1986. Jörg accepted a post-doctoral appointment at the University of Michigan in Ann Arbor, MI in 1987. In 1988 he joined BASF to work in Ludwigshafen, Germany and at various sites in the USA in the areas of carbon fiber manufacturing, textile auxiliaries, waterborne polymers and automotive OEM coatings. Jörg joined Ashland Specialty Chemical in 1999 and held R&D positions of increasing responsibility addressing metal casting consumables. Prior to his current role as Global Technology Director for Ashland Water Technologies he served as Global Technology Director for Casting Solutions. ACKNOWLEDGMENTS Thanks to Ben Carr and Mark Hysell for producing the molds and castings used in the experiments, to Becky King for assisting with sample preparation, to Steve Johnston and Jesus Benavente Jr. for the simulation work, and to Ralph Showman for the interesting discussions that much added to the quality of this work. Supercharge Your Green Sand System Green sand systems work harder and last longer with TRUBOND®. These sodium bentonite grades mull in quickly and undergo a controlled hydration to develop a stronger, more elastic adhesive. TRUBOND delivers excellent green compressive and hot strength properties and maintains its working bond in repetitive exposure to high heat loads and metal temperatures. SODIUM BENTONITE Unimin Australia Limited Tel.: +613 9586 5400 Fax: +613 9586 5411 E-mail: firstname.lastname@example.org ® TRUBOND is a registered trademark. All rights reserved. ©2003 Worldwide: www.metalcaster.com REFERENCES  A.Sahn, E.Abele and H.Schulz - Mat.-wiss. u. Wekstofftech. 33, 501-506 (2002).  C.H.Hsu, S.C.Lee, Y.H.Shy and W.T.Chiou - Mater. Sci. Eng. A282, 115-122 (2000).  SAE, J1887 (2002).  M.Gastel, U.Reuter, H.Schulz, H.M.Ortner - Fresenius J. Anal. Chem., 365, 142-146 (1999).  S.Skvarenina and Y.C.Shin - Int. J. Mach. Tool. Manu., 46, 7-17 (2006).  S.L.Gertsman and A.E.Murton - AFS Transactions v.58, 595- 603 (1950).  U.S. Pat. No. 5,337,799 (1994). U.S. Pat. No. 6,767,130 (2004).  S.V.Subramanian, D.A.R.Kay and G.R.Purdy - AFS Transactions v.90, 589-603 (1982).  J.T.Su, C.T.Chow and J.F.Wallace - AFS Transactions v.90, 565-574 (1982).