Effect of P/Al Molar Ratio and Curing Conditions of CBAPC Binder on Flexural Strength and Moisture Resistance of Artificial Sand Core

摘要

CBAPC (chemically bonded aluminum phosphate ceramic) binders have various advantages, including superior corrosion resistance and strength at high temperature. They are also a non-toxic and eco-friendly material. We investigated an inorganic binder based on CBAPC using artificial sand for casting. The CBAPC binders were synthesized with various P/Al molar ratios from 2.0 to 6.0. Specimens were prepared by mixing the artificial sand and CBAPC binder, and then heat-treating at 260 °C for 10 min. The prepared CBAPC binders were characterized using TGA/DSC, XRD, FT-IR, and FE-SEM. The artificial sands (Esperal 40, Cps 1) were characterized by XRF, grain size analysis, and FE-SEM. The ultimate flexural strengths obtained for the artificial sands (Esperal 40, Cps 1) were 6.40 and 6.36 MPa, respectively, under the conditions P/A1=4.5, curing temperature=260 °C, and curing time=10min. The CBAPC_4.5 had higher thermal stability at low temperature than the samples with other P/Al molar ratios. The AIH_2P_3O_(10) -2H_2O structure formed at 260 °C exhibited high mechanical strength and moisture resistance with improved flexural strength. The effect on the surfaces of the CBAPC_4.5 coated artificial sands depended on the curing temperature and curing time. We confirmed that the P/Al molar ratio and curing conditions strongly affected flexural strength.