Influence of Ceramic Filter on Surface Defects in Investment Casting

M.R. Alizadeh¹ , Y. Miladi²

Section:Research Paper, Product Type: Journal-Paper
Vol.8 , Issue.1 , pp.32-35, Mar-2021

Online published on Mar 31, 2021

Copyright © M.R. Alizadeh, Y. Miladi . This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
 

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Abstract :
Although casting in vacuum atmosphere can reduce some metallurgical defects, surface defects in investment casting in vacuum induction melting (VIM) furnace are usual and inevitable. As a result, if the cleanliness of ingot and crucible are not controlled, these defects will elongate the time of finishing process or even worse, will cause the reject of casting parts. In this investigation the effects of ceramic filter on preventing inclusions to the mold cavity is studied. To perform this study practically, eight firs nozzle vanes from the gas turbine of MS5002D are cast in VIM furnace. The alloy was cobalt base super alloy FSX-414 and the pouring temperature was 1485 °C. The filter used in all of the melts made from zirconia. The mesh of filter was 10 ppi, and its thickness was 20 mm with diameter of 90 mm. The crucible was made from Alumina. The results showed in four molds the filter remained in the gate of pouring cup but in the others it floated on the top of the melt. Finally, the fluorescence inspection test uncovered that in the latter group which filter was not floated, the percentages of the surface defects were lower and reached to minimum 0.4 percent. In addition, the scanning electron microscope (SEM) images demonstrated that the inclusions were almost aluminum and its oxide which may relate to the reaction between melt and crucible walls.

Key-Words / Index Term :
ceramic filter, surface defects, investment casing, super alloy

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