Investigation on Nano-Fused Silica in Silica-Based Ceramic Cores for Investment Casting

Abstract

In this work, nanofused silica and its effect on mechanical and chemical behavior of injection moulded silica-based ceramic cores were investigated. In order to simulate casting process condition, the sintered samples at 1180 °C were also heated up to 1500 °C. Flexural strength test was carried out on both sintered and heat treated samples. Phase evolution and microstructure were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the samples with 0.5 wt.% nanofused silica content had an optimal comprehensive properties for investment casting. The flexural strength of sintered samples with 0.5 wt.% nanofused silica at room temperature and at 1500 °C for 30 min were 30.3 MPa and 24.4 MPa, respectively, and the creep deformation at 1500 °C was 0.8 mm. The addition of nanofused silica was favorable for cristobalite transformation and the samples had a good leachability for the micro-cracks introduced by crystallization.

Enhanced properties of silica-based ceramic cores by controlled particle sizes of cristobalite seeds

“…82-0512) and mullite (JCPDS No. 79-1276) were detected, which was in agreement with the previous report [23]. The content of cristobalite in the sintered samples was determined to be 26%, based on the K method [24], which was exhibited in Figure 2(b).…”

Effect of Pre-Added Cristobalite Content on the Properties of Silica-Based Ceramic Cores

“…82-0512) and mullite (JCPDS No. 79-1276) were also observed in agreement with previous report [11,12]. As the contents of pre-added cristobalite increasing, the peaks of cristobalite became sharper while the background decreased, demonstrating the increasing amount of crystallization.…”

“…This phase transformation introduced considerable micro-cracks into ceramic core which was confirmed by the SEM morphology (shown in Fig. 3f) [1,11]. Fig.…”