The study of the influence of binder systems in an Y₂O₃-ZrO₂ facecoat material on the investment casting slurries and shells properties

In order to reduce the interaction between the Ti alloys and ceramic shell during the casting, materials with high thermal and chemical inertness were used in investment casting. An investigation was undertaken to analyze the influence of the change of binder systems on the slurries, facecoats and the thermo-chemical properties of the facecoat systems using an Y₂O₃-ZrO₂ filler material. The results showed that, using alumina-sol as the binder in the slurry gave the longest life of around three days followed by that using the commercially available zirconia-sol at around 6h, and the yttria sol based slurry giving a shortest life of around 1.5h. Meanwhile using the alumina-sol can also enhance the facecoat sintering properties. There was no obvious evidence observed that the change of the binder system influenced the facecoat chemical inertness.