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Te powder coating to prevent leakage of the role of casting

It is quite a waterproof layer, cut off the channel cavity leakage and Beaufort larvae L channel, which is tellurium powder coating to eliminate the role of defects in the form of leakage. 2 Te layer coating formation mechanism of white paint to form tellurium mechanism of white layer. There are two general argument [21: First chilling effect: Te powder in contact with the molten iron. Absorb large amounts of heat evaporation latent heat of crystallization of liquid metal. Chilling effect of concentration. Thereby casting surface to accelerate cooling. Therefore, the Infiltration casting surface trace tellurium. Play the role of strong anti-graphite, graphite block produced white precipitation. To understand the mechanism. More rational use of tellurium powder coating, we designed an exploratory test, the use of 1400 ℃ high temperature of molten iron and coated sand HT250,[link widoczny dla zalogowanych], the rectangular bar open casting 10x10x70 test block, in which the cavity # l do not brush coated sand tellurium powder coating ; support 2 coated 20 5RESEARCH & DISCUss10N research and discussion is not sand mold cavity half brush, brush the underside of the other half of Te powder coating (: 0.2HIHI), from the brush end into molten iron pouring paint. After natural cooling, metallographic examination, the results shown in Table 2. Table 2 The results of tellurium powder coating Tab. 2Testresultof_rP (! Oating Te paint brush relatively rough surface, there is no clean paint brush Te metallographic examination: (1) found by the # 2 specimen, in the absence of tellurium powder paint brush and b cross-section as a cross-section, and no graphite precipitation, and the matrix are ledeburite. Why is a section similar with the b cross section metallographic it? I believe the reason is: Te atomic number 52, melting point 452c 【= 1390c 【= boiling point, density 6. 27g/cm, is a strong element of anti-graphite _3_. start with the b-side pouring molten iron,[link widoczny dla zalogowanych], b-side of the Te powder melt into the molten iron,[link widoczny dla zalogowanych], with the stream flow to a place, so that a Department alloying good time. (2) from # 2 b the sample also found that the center section out of a small amount of massive cementite aggregation. study the original, I think: Te low melting point, surface solidification of the few not timely and easy segregation of tellurium in the center of the final solidification Suozhi (3) According to the above analysis, I believe that the formation of tellurium powder coating mechanism of white layer is tellurium alloying. When the liquid metal poured into the cavity paint brush with Te and the coating when a direct role in the metal coating layer gathered in the center segregation. the center of white. So Te Te powder coating thickness of content and brushing through tests to find the best value. can not be too thick, not brushing directly to scour the site,[link widoczny dla zalogowanych], including the runner or iron liquid for a long time flows through the site. otherwise it will cause other parts of the white lumps or hard spots. (4) from the # l, # 2 sample surface roughness observed on the surface paint brush with tellurium have more orange peel phenomenon, Te than no paint brush to rough some. I think this is the melting of tellurium powder out from the exigencies of the coating. Therefore, the use of Te powder coating too thick to be careful not too strong, otherwise the casting surface is not smooth,[link widoczny dla zalogowanych], orange peel is serious. 3 Conclusions (1) using Te powder coating is effective against leakage, its role is in the form of whether the use of random surface can achieve the desired effect should be the formation of white layer. The coating can be used as a flexible technology to make up for sand casting process design deficiencies. (2) Te powder coating to form a white cast the mechanism of surface alloying role, such as putting it as a (3), tellurium powder coating can be painted, including the erosion of the gate position directly or iron liquid for a long time through the site, otherwise easily lead to other parts of the white lumps or hard spots. (4) Te powder coating should not be too thick, Otherwise, the phenomenon is also likely to cause orange peel, so that poor surface quality. References 【1] Song Huizong, Huang Naiyu, Zhou Jing one. foundry coatings technology trends 【J1. Foundry Technology, 2000. (5): 28 ~ 32. 【2] Hong Yi. enthalpy change based paint in the chilling of non-ferrous metal casting 【J1. molding material, 2004. (2): 28.f31 Order of Military Sciences. a chilling paint application on the casting 【J1 . molding material, 2004. (2): 41.
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