Silica-Free Zirconia-Based Primary Slurry for Titanium Investment Casting

In the present study, a zirconia-based primary slurry free from silica (S-0) was prepared by replacing the colloidal silica sol binder in the commercial zirconia-based slurry (S-6.4) with an aqueous polymer binder. The results of X-ray diffraction (XRD), scanning electron microscopy (SEM), and line scan analyses from the surface of cast samples show that the thickness of reaction layer has been decreased from 10 to 6 mu m in the samples S-6.4 and S-0, respectively. Also, the microhardness tests obtained from the sample surfaces show a 80 mu m decrease in the surface-hardened layer.