Investigation of Fused Alumina Based-Mold Facecoats for DZ22B Directionally Solidified Blades

Abstract

The interaction between alloy melt and mold facecoats is the main factor affecting the surface quality of investment casting nickel-based superalloys. An investigation was undertaken to develop suitable refractories as facecoat materials for the directionally solidified blades of DZ22B nickel-based superalloys in order to avoid a sand-burning defect. The wettability and interface reactions between alloy melt and various facecoats were studied by using a sessile drop experiment and the real investment casting method, respectively. The results show that by adding Cr2O3 powder with the amounts of 2 wt.%, 5 wt.% and 10 wt.% in the fused alumina-based facecoats, the wetting angles between the alloy melt and facecoats decreased from 105.40° to 100.37°, 99.96° and 98.11°, respectively, while the sand-burning defect on the casting blade surfaces still formed during the process of directional solidification. However, by adding h-BN powder in the fused alumina-based facecoats, the wetting angles between the alloy melt and facecoats dramatically increased, the sand-burning defect on the casting blade surfaces was effectively inhibited and a metallic luster on the directionally solidified blades could be obviously observed. In this study, the suitable composition of mold facecoats for the investment casting of blades is 2 wt.% h-BN added fused alumina.

Effect of Kaolin/TiO2 Additions and Contact Temperature on the Interaction between DD6 Alloys and Al2O3 Shells

“…The chemical sand adhesion onto the surface of the cast component can reduce dimension accuracy and increase processing cost of the component. How to control the interaction between them has become a focal point for researchers in precision casting technology for DD6 alloys [11][12][13][14][15][16].…”

The Effect of Pulling Speed on the Structure and Properties of DZ22B Superalloy Blades

“…Nickel-based superalloys have been widely used in aero engines and gas turbines to produce turbine blades with excellent high-temperature tensile strength, stress fracture, and creep properties [1][2][3][4][5][6][7]. DZ22B nickel-based superalloy has good casting performance, hightemperature oxidation resistance, and corrosion resistance, and is a common material for directional column crystal blades of aero engines [8][9][10]. However, during the solidification process, the blade is often prone to casting defects such as holes, shrinkage, and hot cracks [11,12].…”