The sand systems containing sodium silicate binder have excellent casting quality and eco-friendly advantages. However, the poor collapsibility of sodium silicate bonded sand (SSBS) makes it difficult for foundries to recycle used sand. Thus, many investigations have been performed recently to improve the collapsibility of SSBS. In this study, the powder breakdown additives alumina (Al₂O₃), silicon carbide (SiC) and boron nitride (BN) were used as modifiers to further improve the collapsibility of ester-hardened sodium silicate bonded ceramic sand (SSBCS) on the basis of modified sodium silicate, and the specific parameters were optimized by orthogonal experiments. The results of orthogonal experiment showed the optimum additive amount of Al₂O₃, SiC and BN were 0.4%, 0.3% and 0.1% of ceramic sand, and the addition of modifiers effectively increased the 1h tensile strength and further reduced the residual strength of the SSCBS. The experimental results indicated that the difference of the linear expansion coefficient between the modifiers, the new phase AlN formed by the modified sand sample and the phases Na₃PO₄, Na₄B₂O₅ formed by the unmodified sand sample effectively accelerated the generation of many coarse pores and very big cracks on the bonded bridge in the process of heating at 950 °C and cooling, thereby resulting in the improvement in the collapsibility of SSBCS.

含有硅酸钠粘合剂的砂体系具有出色的铸造质量和环保优势。但是，硅酸钠粘结砂（SSBS）的易碎性使铸造厂难以回收用过的砂。因此，最近已经进行了许多研究来改善SSBS的可折叠性。在这项研究中，粉末分解添加剂氧化铝（Al ₂ O ₃），碳化硅（SiC）和氮化硼（BN）被用作改性剂，以进一步提高酯硬化的硅酸钠粘结陶瓷砂（SSBCS）的可湿性。改性硅酸钠的基础，并通过正交试验优化了具体参数。正交试验结果表明，Al ₂ O ₃的最佳添加量SiC和BN分别为陶瓷砂的0.4％，0.3％和0.1％，添加改性剂可有效提高1h拉伸强度并进一步降低SSCBS的残余强度。实验结果表明，改性剂，改性砂样形成的新相AlN和未改性砂样形成的Na ₃ PO ₄，Na ₄ B ₂ O ₅相之间的线性膨胀系数的差异有效地促进了生成。在950°C加热和冷却的过程中，粘结桥上会出现许多粗大的孔洞和非常大的裂纹，从而改善了SSBCS的塌陷性。