Investigation of the Properties of Shell Molds for Investment Casting quasi-high-entropy alloys

Abstract

The performance of ceramic shell molds for investment casting prepared using fused quartz was evaluated. The quartz raw material was obtained from the Aktas deposit in Kazakhstan. The developed shell molds were intended for the precision casting of high-alloy materials. Fused quartz was produced by melting natural quartz at 1750 °C, followed by rapid cooling to obtain an amorphous structure. X-ray diffraction (XRD) analysis confirmed the absence of crystalline SiO₂ phases and revealed a broad diffuse halo characteristic of amorphous silica. The ceramic slurry was prepared using fused quartz as the refractory filler and 15A silica sol as the inorganic binder. The ceramic shell molds were fabricated using a five-layer dipping process with controlled intermediate drying, followed by firing at 800 °C. The developed shell molds exhibited a high gas permeability of 143 conventional units, exceeding that of the reference shell system based on quartz sand. The residual compressive strength reached 35.75 ± 1.10 MPa, indicating sufficient mechanical integrity during molten metal pouring. Experimental casting of a Fe–Cr–Mn–Co–Ni–Nb–Mo alloy revealed no visible evidence of significant mold–metal interaction, burn-on, metal penetration, or other macroscopic surface defects under the investigated casting conditions. The ceramic shell molds maintained their structural integrity during pouring and cooling, demonstrating satisfactory performance for high-temperature investment casting.