Effect of Rice Husk on Fired Ceramic Shell Strength

Abstract

In recent years, ceramic shell mould for investment casting process is often associated to defects due to its brittle properties. The defects would originate from cracking mechanism yielded from the ceramic brittleness. In this work, the improvement of ceramic shell mould by reinforcement technique was studied and analyzed. Rice husk consisting high percentage of silica content with the ability to withstand high temperature during casting process was studied as the reinforcing component as to impede cracking mechanism. Higher Modulus of Rupture (MOR) value of ceramic shell reinforced by rice husk fiber as compared to the non-reinforced ceramic shell MOR value was obtained. Nonetheless, presence of the fused silica phase from rice husk fiber was also found to lead the formation of a new phase of zircon (ZrSiO4). These two factors were found to influence the ceramic shell composition and indirectly enhanced the ceramic shell strength performance.

Toughening of Ceramic Shell Mould with Rice Husk Fiber (CSm-RH) to Improve Strength Property and Mould Performance

“…In relation to this fact, higher silica content allow the mould to be operated at higher temperature. Nonetheless, new phase of zircon (ZrSiO4) was found initiated from fused silica phase based-RH fiber as reported elsewhere [24]. Ceramic shells composition are found to be influenced by these factors and eventually enhanced their mechanical strength.…”

“…The CSm was prepared by slurry coating followed by alumina and zircon sand coating via rainfall sanding technique by sprinkle it after wax pattern immersion in the modified slurry. The steps were repeated up to 5 layers with a controlled drying and finally subjected to dewaxing and sintering for final CSm matrix consolidation [24][25][26]. The surface modification of RHs and surface fracture of composites shell mould was characterized via Scanning Electron Microscopy (SEM, Jeol JFM-6380 LA, Japan).…”

“…In fact, a study has proved the addition of fly ash RH to slurry composition makes the slurry more hardened [4,21]. Indeed, highest MOR value indicates the possibility of SiO2 bonding in the fired CSm structure as supported by [24], proved that the existence of RHs fiber are not only purposely as reinforced agent in green body but existed SiO2 is indirectly influence the properties of fired CSm. Fig.…”

Technological Properties of Ceramic Slurries Based on Silicon Carbide with Poly(vinyl alcohol) Addition for Shell Moluds Fabrication in Precision Casting Process

“…When strength of ceramic shell is not sufficient enough at high casting temperatures, there is a risk of bulging and cracking in a contact with the molten metal [4]. The mold should also be permeable to gases passing through the shell mold.…”