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石灰石砂作为一种造型材料在锕水的作用下分解为CaO 和CO_2,在金属铸型界面上产生一系列复杂的物理化学反应,其结果会导致铸钢件产生气孔。本文研究了石灰石砂的发气性与颗粒大小及加热温度的关系。高于1100℃发气率几乎与粒度无关,而加热温度对发气性却有极大的影响。1克石灰石砂总发气量约为210-250毫升。本文讨论了气孔的成因。气核产生于金属/铸型界面上的渣相中,并在其中长大。当气体压力足够大时,气体就极易侵入液态金属成为气孔。本文还研究了铸型背压与透气性的关系。型砂透气性加大可以显著减少背压,防止气孔的产生。
As a modeling material, limestone sand decomposes into CaO and CO_2 under actinide water and produces a series of complex physico-chemical reactions at the metal mold interface, which can result in pores in steel castings. In this paper, the relationship between the gasification of limestone sand and the particle size and heating temperature was studied. Gas rates above 1100 ° C are almost independent of particle size, whereas heating temperatures have a significant effect on gas evolution. 1 g of limestone sand total gas output of about 210-250 ml. This article discusses the genesis of stomata. Gas nuclei originate in and grow in the slag phase on the metal / mold interface. When the gas pressure is large enough, the gas can easily invade the liquid metal to become pores. The paper also studied the relationship between mold back pressure and breathability. Increased sand permeability can significantly reduce the back pressure to prevent the production of stomata.