Ablation S
Testing the Limits of
Ablation’s ability to achieve fine microstructure and better mechanical properties could enhance the possibilities for casting alloys. DAVID WEISS, ECK INDUSTRIES, MANITOWOC, WISCONSIN; JOHN GRASSI, ALOTECH LLC LTD., BROOKLYN, OHIO; AND BEN SCHULTZ AND PRADEEP ROHATGI, UNIVERSITY OF WISCONSIN-MILWAUKEE, MILWAUKEE, WISCONSIN
imilar to ablation of ice glaciers, where the snow and ice accumulated in the
winter months is worn away in the summer by melting, erosion, evapora- tion and sublimation, ablation casting erodes away the sand and binder of a sand mold. In this emerging casting method, a sand mold is sprayed with a liquid and/or gas solvent directly after pouring. As the solvent dissolves (or ablates) the sand mold, it facilitates rapid heat removal to solidify the mol- ten alloy quickly (Figs. 1a & 1b). Te rapid solidification enhances
the mechanical properties of the alloy. Te method has been successfully used for conventional aluminum alloys in commercial production and stood up well against other emerging magnesium casting methods in a comparison study. To further explore ablation’s potential benefit to casting technol- ogy, researchers studied its ability to produce aluminum metal matrix composites (MMCs) compared to conventional sand casting.
Testing with MMCs Te manufacture of aluminum silicon
26 | MODERN CASTING December 2011
Fig. 1a. In the beginning of the ablation process, a solvent erodes the surface of the core package.
carbide brake rotors for high volume appli- cations via conventional sand casting can be difficult due to the settling of the silicon carbide particles. Te particles are heavier than molten aluminum and difficult to machine due to their high hardness. A hybrid MMC incorporating both
silicon carbide and graphite particles in the matrix of aluminum alloys is being developed to produce a composite melt with silicon carbide particles, which are more dense than aluminunm, along with graphite particles, which are less dense than aluminum. Te two particle types
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