Abstract
A chopped ZrO2 fiber (ZrO2 (f)) reinforced CaO-based integral ceramic mold was successfully fabricated by stereolithography (SLA) and tert-butyl alcohol (TBA)-based gel-casting, and the effect of chopped ZrO2 (f) content on properties of the ceramic mold was investigated. The results show that the ZrO2 (f) content had a significant effect on the viscosity of CaO-based ceramic slurry, which directly affects the filling ability of slurry in complex structures of the integral mold. The tiny structures of the ceramic mold cannot be filled completely with a ZrO2 (f) content exceeding 3 vol %. The sample fabricated with 3 vol % fiber content showed a harmonious microstructure and exhibited an excellent comprehensive performance with 25 °C bending strength of 22.88 MPa, an 1200 °C bending strength of 15.74 MPa, a 1200 °C deflection of 0.86 mm, and a sintering shrinkage of 0.40%, which can meet the requirements of casting very well.
Highlights
CaO has long been considered an attractive refractory for application in metallurgical and ceramics industries because of the global abundant sources of high-purity limestone, as well as its advantages of high melting temperature, low vapor pressure, and excellent thermodynamic stability [1,2,3,4,5]
CaO was studied as a potential ceramic core material for investment casting due to the reaction-resistance to molten active alloy [6,7,8], easy dissolution compared to common ceramic core materials, such as fused silica or alumina [9,10,11], and its approximating the thermal expansion coefficient of superalloys [12]
Tert-butyl alcohol (TBA) is selected as solvent, on the one hand because it can effectively avoid the hydrolysis of CaO powder, and on the other hand because of its high saturation vapor pressure and low surface tension force: the green body can be dried with a small shrinkage and deformation [19]
Summary
CaO has long been considered an attractive refractory for application in metallurgical and ceramics industries because of the global abundant sources of high-purity limestone, as well as its advantages of high melting temperature, low vapor pressure, and excellent thermodynamic stability [1,2,3,4,5]. Cracking often occurs during the pre-sintering of the RIFT process In this stage, 2the integrity of the ceramic mold can be only maintained by the particle packing effects because the gel networks were burnt the slender may broken were by gravity andTherefore, the thinbe only maintained byoff. The slender structures may be broken by stress gravity and the may beMoreover, broken by the integral ceramic mold always has slightly poor mechanical properties, a lager deflection, the stress caused by pyrolysis of the resin prototype. The unacceptable drawbacks for investment casting of ceramic mold can be slightly poor mechanical properties, a lager deflection, and sintering shrinkage. CaO-based integral ceramic molds are fabricated sintering temperature unlike the silica or alumina fibers. Of chopped reinforced porous CaO ceramic mold is discussed
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