大中型球墨铸铁件冒口发热保温覆盖剂的补缩效率试验研究

Experimental Study on Feeding Efficiency of Exothermic Insulating Covering-Agent for Risers of Large and Medium-Sized Ductile Iron Castings

简述了大中型球墨铸铁冒口覆盖剂的性能要求,提出了新的冒口补缩效率表征和测试方法,通过实际生产试用对新型大中型球墨铸铁件冒口发热保温覆盖剂和国内外2家著名公司同类产品进行了系统的对比研究。结果表明:大中型球墨铸铁件冒口新型发热保温冒口覆盖剂的发热反应起燃温度、起燃时间、发热速度、发热量和生产成本等得到综合平衡,具有低成本和环境友好的特点;新型覆盖剂中氟盐含量低,冒口根部未见石墨球粗大或球化不良缺陷,对球铁铸件表层的石墨球形态影响很小;新型覆盖剂可使大中型球墨铸铁件的冒口相对补缩效率高达50%,优于对比测试的国内外2家著名公司的同类产品,能较好地满足高端装备大中型球墨铸铁件生产要求;新建立的“冒口相对补缩效率”新指标反映了冒口缩沉总体积和形状(即冒口安全高度)的综合影响,比传统的“冒口补缩效率”更能准确地表征冒口的实际补缩能力和效果。

The performance requirements of covering-agents for large and medium-sized ductile iron riser are briefly described in the paper,and a new characterization and testing methods for riser feeding efficiency is proposed,which is carried out the systematically research and comparison with the new-type of large and medium-sized ductile iron riser exothermic insulating covering agent and congener product from two well-known companies at home and abroad by mean of practical production trials.It can be seen from the test results that:the newtype of exothermic insulating covering agent for the riser of large and medium-sized ductile iron castings achieves a comprehensive balance of ignition temperature,ignition time,heat release speed,heat release value,and production cost for exothermic reaction,with the characteristics of low cost and environmental friendliness.The new covering agent has a low fluorine salt content,and there are no defects such as coarse graphite balls or poor spheroidization at the root of the riser,which has little effect on the morphology of graphite balls on the surface of ductile iron castings.The relative feeding efficiency of new covering-agent is up to 50% for the risers of large and medium-sized ductile iron castings,which is superior to similar products from two well-known companies that have been compared and tested,and can better meet the production requirements of large and medium sized ductile iron castings of high-end equipment.The relative feeding efficiency of the riser which was newly established indicates the comprehensive impact on the total volume and shape of the riser sinking(i.e.the safety height of the riser),and more accurately characterizes the actual feeding capacity and effect of the riser than the traditional feeding efficiency of the riser.