【作者】 罗洪峰；

【导师】 陈维平；

【作者基本信息】 华南理工大学 ， 材料加工工程， 2014， 博士

【摘要】 铝液熔蚀-磨损常见于铝合金熔炼、成形及热浸镀铝生产中，不仅造成部件使用寿命的降低，而且可能会造成铝液的污染，使铝及其合金产品性能的下降，甚至报废。本文采用自制高温金属熔蚀-磨损试验装置研究了不同金属材料在铝液中的熔蚀-磨损特性，提出铝液熔蚀-磨损工况下材料设计原则，在此基础之上，设计制备新型耐铝液熔蚀-磨损合金铸铁并与304不锈钢进行复合。采用750℃×24h静态铝液浸没试验研究了QT350、HT300、高铬铸铁、合金HT、Q235、H13、Cr13、SKH51、W、Mo、Nb、Ta和Zr在铝液中的熔蚀行为。结果表明：Zr因在铝液中熔解度大而完全熔解，其余金属材料与铝液发生互扩散形成金属间化合物。钢铁中碳以石墨形式存在时，具有阻隔铝液腐蚀金属的作用，其效果与石墨形态、大小和分布有关；以碳化物形式存在时，其耐铝液熔蚀性能不如石墨，但远较铁基体优异，对基体具有保护作用。钢铁中石墨或碳化物的数量越多、间隙越小则其耐铝液熔蚀性能越好。难熔金属与铝液形成的金属间化合物和金属基体的结合强度很差，无法起扩散屏障作用，但难熔金属在铝液中的熔解度很小，因而具有优异的耐铝液熔蚀性能。为了研究金属材料在铝液中的熔蚀-磨损行为，研制了高温金属熔蚀-磨损试验机，该设备实现了金属液熔蚀-磨损工况的模拟，并具有金属液用量少、载荷施加准确及摩擦力准确传递与测量的特点，为研究材料在熔融金属中的熔蚀-磨损机理，开发新型耐高温金属液熔蚀-磨损材料提供了技术支持。采用自制高温金属熔蚀-磨损试验装置研究了QT350、HT300、高铬铸铁、Q235、H13、Cr13、SKH51、W、Mo在750℃铝液中的熔蚀-磨损行为。结果表明：金属材料在铝液中熔蚀-磨损所形成的金属间化合物的相组成与其在铝液中的熔蚀所形成的金属间化合物的相组成相同。由于铝液熔蚀形成的脆硬金属间化合物在摩擦磨损的切削作用下与金属基体分离形成磨粒对金属基体产生犁削，金属材料在铝液中的磨损机制以磨粒磨损为主。熔蚀-磨损交互作用量占熔蚀-磨损总量的比例均在95%以上，熔蚀与磨损的交互作用造成材料损伤急剧增大。在金属材料铝液熔蚀-磨损行为研究基础上，提出了铝液熔蚀-磨损工况下材料设计原则：以铸铁为基体，加入足够数量的碳化物形成元素如Cr、W，以在基体中获得具有较好耐铝液熔蚀性能并在熔蚀-磨损过程中起支撑作用的高硬度碳化物，此外，加入少量其它合金元素如Mo、V等改善材料的组织与性能。在铝液熔蚀-磨损工况下材料设计原则提出的基础上，以高铬铸铁为基体，添加W、Mo、V、B合金元素，成功研制一种新型耐铝液熔蚀-磨损合金铸铁。结果表明：与H13钢相比，新型合金铸铁耐铝液熔蚀性能提升3倍以上，耐铝液熔蚀-磨损性能提升12倍以上。为使新型合金铸铁可用于大尺寸部件的制备，利用瞬时液相扩散连接成功制得304不锈钢/新型合金铸铁复合材料。研究了连接温度、保温时间及连接压力对接头组织和力学性能的影响。当连接温度为1080℃，连接压力为6MPa，保温时间为6min时，获得了具有良好组织和力学性能的接头，接头的拉伸强度超过新型合金铸铁的拉伸强度，剪切强度达317.5MPa。更多还原

【Abstract】 Some parts such as sink roll used in hot dip aluminizing and tube used in squeeze castingare not only corroded by molten aluminum, but also worn by other contact materials. The partin such condition must be replaced after a certain time of use. Moreover, molten aluminumwill be contaminated because of dissolution of the part into molten aluminum, which willmake the capability of product made of aluminum worse, or even scrapped.In this paper, the corrosion–wear characteristics of metals in molten aluminum have beenidentified by a self-made high temperature test rig, design principle of corrosion–wearresistant materials in molten aluminum has been proposed, and a new alloy cast iron with highcorrosion-wear resistance in molten aluminum has been prepared and synthesized.Corrosion of QT350, HT300, high chromium cast iron, alloy grey cast iron, Q235, H13,Cr13, SKH51, W, Mo, Nb, Ta and Zr in molten aluminum have been investigated by750℃×24h static molten aluminum immersion test under the same experimental conditions. Theresults show that: Except Zr is completely dissolved in molten aluminum, other chosen metalsenable mutual diffuse with molten aluminum, and intermetallic layers are formed. For ironbased materials, C in form of graphite or carbides plays a role of barrier to molten aluminum.The corrosion resistance in molten aluminum of graphite is better than carbides. Moreover,the barrier effect of graphite to molten aluminum is related to its shape, size and distribution.As the gap between graphits or carbides is smaller, the corrosion resistance in moltenaluminum of iron based materials is better. The intermetallic compound layer formed betweenrefroctory metals and molten aluminum cannot play a role of barrier for poor bond strengthbetween intermetallic compound layer and refroctory metals, but the corrosion resistance inmolten aluminum of refroctory metals is excellent because of small solubility of refroctorymetals in molten aluminum.Since the existing high temperature test apparatus have a lot of deficiencies inperformance and structure, such as over consumption of molten metal, uncertaintyload and the lack of friction coefficient measurement, a self-made high temperature test righas been developed. The new device has characteristics such as less consumption of liquidmetal for the use of lift type heating furnace, accurate loading for the use of flexible wire rope hanging weight loading, accurate transmission and measurement of friction for the use ofspecial suspension mechanism. The device can accurately simulate corrosion-wear behave ofmetals in different molten metal, and can provide technical supporting for the research aboutcorrosion-wear mechanism of metals.Corrosion-wear characteristics of QT350, HT300, high chromium cast iron, Q235, H13,Cr13, SKH51, W and Mo in molten aluminum were investigated by self-made hightemperature test rig. The results show that: The intermetallic compound layer that formedbetween chosen metals and molten aluminum in the process of corrosion-wear is as same asthe layer formed in the process of corrosion. The intermetallic compound layer formedbetween metals and molten aluminum is cut from metal matrix and separated to abrasive toproduce plowing on the metal substrate. The wear mechanism of cast irons in moltenaluminum is mainly abrasive wear. The synergistic amounts between corrosion and wear ofmetals are more than95%and the synergistic effect between corrosion and wear leads torapidly increased weight loss of metals.On the basis of the research results about the corrosion-wear characteristics of metals inmolten aluminum, design principle of corrosion–wear resistant materials in molten aluminumhas been proposed: by adding carbide forming elements such as Cr and W, high hardnesscarbides with good corrosion resistance in molten aluminum are formed in cast iron matrix,and play a role of bearing in the process of corrosion-wear in molten aluminum. Moreover,other alloy elements such as Mo and V are added into cast iron matrix in order to obtainperfect organization and performance.On the basis of design principle of corrosion–wear resistant materials in moltenaluminum, a new alloy cast iron with high corrosion-wear resistance in molten aluminum hasbeen successfully developed by adding W, Cr, Mo, V alloying elements into high chromiumcast iron. The corrosion resistant in molten aluminum of new alloy cast iron is more than3times than H13steel, and the corrosion-wear resistant in molten aluminum of it is more than12times than H13steel.In order to prepare large size parts, new alloy cast iron and304stainless steel have beensuccessfully synthesized by transient liquid phase diffusion bonding technology. Underparameters as follows: bonding temperature1080℃, holding time6min and bonding pressure 6MPa, the tensile strength of joint is bigger than new alloy cast iron, and the shear strength ofjoint is317.5MPa.更多还原