Testing the New Ablation Method
Ablation’s ability to achieve fine microstructure and better mechanical properties could enhance the possibilities for casting alloys.
DAVID WEISS, ECK INDUSTRIES, MANITOWOC, WISCONSIN, USA; JOHN GRASSI, ALOTECH LLC LTD., BROOKLYN, OHIO, USA; AND BEN SCHULTZ AND PRADEEP ROHATGI, UNIVERSITY OF WISCONSIN-MILWAUKEE, MILWAUKEE, WISCONSIN, USA
测试新的消融铸造法
铸型消融法可以实现细的微观组织和更好的机械性能，这给铸造合金带来 更多的机遇。
DAVID WEISS, ECK INDUSTRIES, MANITOWOC, WISCONSIN, USA; JOHN GRASSI, ALOTECH LLC LTD., BROOKLYN, OHIO, USA; AND BEN SCHULTZ AND PRADEEP ROHATGI, UNIVERSITY OF WISCONSIN-MILWAUKEE, MILWAUKEE, WISCONSIN, USA
S
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, evaporation and sublimation, ablation cast-
ing erodes away the sand and binder of a sand mold. In this emerging casting method, a sand mold is sprayed with a liq- uid and/or gas solvent directly after pouring. As the solvent dissolves (or ablates) the sand mold, it facilitates rapid heat removal to solidify the molten alloy quickly (Figs. 1a and 1b). Te rapid solidification enhances the mechanical proper- ties 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 cast-
ing technology, researchers studied its ability to produce aluminum metal matrix composites (MMCs) compared to conventional sand casting.
Testing With MMCs Te manufacture of aluminum silicon carbide brake
rotors for high volume applications via conventional sand casting can be difficult due to the settling of the silicon car- bide particles. Te particles are heavier than molten alumi- num and difficult to machine due to their high hardness. A hybrid MMC incorpo-
rating 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 aluminum, along with graphite particles, which are less dense than aluminum. Te two particle
Fig. 1a. In the beginning of the ablation process, a solvent erodes the surface of the core package.
类
似冬季累积起的冰川在夏季由于融化、侵 蚀、蒸发和升华等造成的冰雪消融，消融铸 造会侵蚀型砂和粘结剂。在这种新的铸造方法中，浇注完 成后，马上向铸型喷洒液态或固态溶剂。溶剂会溶解掉砂 型，促进熔融金属的散热，使其快速凝固（图1a和b）。 快速凝固会改善合金的机械性能。该方法已经成功用 于传统的铝合金商业生产，并且通过对比发现该方法并 不逊色于其它镁合金铸造新方法。
为了进一步发掘消融法可能给铸造技术带来的潜在好 处，研究者对比了消融铸造与传统砂型铸造生产铝基复 合材料。
采用铝基复合材料的测试
由于碳化硅颗粒的沉淀，用传统砂型铸造方法大批量 生产铝-碳化硅复合材料制动片很困难。碳化硅颗粒比 熔融的铝液重，并且硬度高难以加工。
现在正在开发一种在铝合金基体中加入碳化硅和石墨 颗粒的金属基复合材料， 用来生产带有碳化硅颗粒 的复合材料熔体。该熔 体比铝液重很多，而在其 中加入石墨颗粒后，就 变得比铝液稍重。这两 种颗粒相互阻碍彼此的运 动，实现悬浮。石墨的加
图1a 消融开始时，溶剂侵蚀 组芯表面.
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FOUNDRY-PLANET.COM | MODERN CASTING | CHINA FOUNDRY ASSOCIATION Spring 2012
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