Exploration on Preparation Process of High-Strength Fiber-Reinforced Shell for Investment Casting

Abstract

The use of fibers as additives to increase the strength of investment casting shell has yielded some significant results. Here, polypropylene fiber of length 6 mm was added to the shell by airflow placement fiber method, and the three different processes [the conventional method, preimmersion silica sol method, and preimmersion slurry method (PSM)] were used to prepare fiber-reinforced shell based on better fiber dispersion; the strength of shell with 0.2–1.0 wt% fiber addition was tested and compared. The experimental results show that the green strength and fired strength of shell with 0.4–0.6 wt% fiber addition reached the maximum in the three processes. The shell prepared by PSM exhibited a higher strength than the other two methods with the same amount of fiber addition; the maximum green strength was 36.9% higher than the strength of fiber-free shell. Combined with the surface morphology of placement fiber and fracture surface morphology of shell, the factors affecting shell strength and interface bonding characteristics were analyzed.