用铸渗工艺对消失模铸件件进行表面合金化的研究

利用干砂消失模铸造工艺，对铸铁件表面合金化铸渗机理进行了研究，通过建立数学模型，对铸渗过程中铁水传输进行了理论分析，给出了铸渗量与浇口的大气压力、铁水静压力、渣液阻力及附加压力的关系，提出了铸渗量大小主要取决于铸渗孔道半径的新观点，用正交试验对合金涂层中合金粉粒度，合金粉加入量、溶剂加入量及涂层中聚苯乙烯泡沫加入量等进行了考证，得出最佳工艺配方为：合金粉粒度75－100目，泡沫加入量30％－50％（ψ（B））；溶剂加入量4％，在配制涂料时，适当加入一定量泡沫珠粒，有利于母液透，这与理论推导结果相符，易获得3mm以上合金层厚度，合金层具有珠江体基体及大量M7C3碳化物，并且有高硬度及高抗磨性。

Surface alloying of iron castings produced by EPC method using casting infiltration process

The mechanism of surface alloying of iron castings produced by means of dry sand evaporative pattern casting (EPC) using casting infiltration was studied in this paper. The transfer of molten iron during casting infiltration was analyzed theoretically through establishing a mathematic model and the relationship between amount of casting infiltration and gate pressure, static pressure of molten iron, dreg resistance and additional pressure was investigated. A new point of view indicating that the amount of casting infiltration depends on the radius of casting infiltration hole was proposed. The grain size and added amount of alloying powders and EPC foam were examined in light of orthogonal experiments. The optimum combination of parameters was obtained as well. The powder grain size and the amount of added foam are 75~100 mesh and 30vol%~50 vol% respectively, and the amount of added solvent is 4%. An amount of foam granule can be added and this is beneficial to the infiltration of master melt and can gain an alloy layer with a thickness more than 3 mm. The experimental data are in agreement with the theoretically deduced results. The alloy layer has pearlite matrix and a lot of M 7C 3 carbide leading to a high hardness and good wear resistance.