Interface Reaction between DD6 Single Crystal Superalloy and Ceramic Core

The interfacial reaction between alloys and ceramic materials is an important factor to influence the quality and service performance of the turbine blade. In this paper, three typical height sections of 120mm, 160mm and 210mm were selected, and the interface reactions between DD6 single crystal superalloy and silica based ceramic cores were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS). The results showed that the infiltration degree of the melt alloy increases with the increase of reaction time. The thickness of the reaction layer could be over 0.3mm when the reaction time increased up to 70min. The main reasons of forming the infiltration layer were the infiltration of the Al element and the interfacial reaction between the Al element and the ceramic core. There formed an aluminum deficient layer on the metal surface because of the interface reaction between the alloy and the ceramic core. The dense layer formed by interfacial reaction on the surface of the core will cause some difficulties for core leaching. Keywords: DD6 single crystal superalloy; Silica based ceramic core; Interface reaction

Effect of the Binder on Properties of Molten Core and Co-Debinding Behavior in Silica-Based Ceramics

The effects of molecular weight of the binder on the properties of molten cores were studied The results showed that the filling parameter had an inverse correlation to molecular weight and was consistent with the Market-Houwink Equation. The surface roughness of the cavity surface deteriorated from 2.468 μm to 11.998 μm as the molecular weight of the binder climbed from 2000 to 6000 due to the presence of residual carbon, which was confirmed by SEM and EDS results. At the debinding stage, the pores that occurred in the ceramic core, were insufficient for the liquid PEG binder to flow out, some of the liquid binder moved to the fringe side. More pores formed as the temperature increased and the rest of the binder flowed out through this channel to flow to the filler. Some of the higher molecular weight PEG binder remained as it could not flow away completely and became residual carbon in the cavity surface.