微波加热硬化水玻璃砂表面涂层的抗湿性研究

Humidity resistance of surface coating of sodium silicate sand hardened by microwave heating

针对微波加热硬化水玻璃砂吸湿性强的特点,以PbO-ZnO系低温玻璃粉作为主要的涂层材料,研究测试了涂层的抗湿性.结果表明:表面涂层后的水玻璃砂样抗吸湿性明显高于普通水玻璃砂样,4h存放强度提高了2.33倍,4h吸水率降低了45.9%.通过SEM和XRD等测试方法,对表面涂层砂样和普通砂样的物相和成分进行了分析:SEM分析表明,表面涂层砂样的表层有涂层材料渗入形成防湿层,防湿层内砂粒表面的粘结桥有许多细小颗粒状物质分布.表面XRD扫描表明:涂层表面出现了3种新的物相,即Al2TiO5,NaAlO2和PbTiO3,它们是表面涂层提高砂样抗湿性的主要原因.

To study the high moisture absorbability of sodium silicate sand hardened by microwave heating process, the PbO-ZnO low-temperature glass powder was used as main coating material, and the humidity resistance of surface coating was measured. The results show that the humidity resist- ance of the sodium silicate sand has significant improvement after the surface coating, and the 4 h storage strength can be increased by 2.33 times, the 4 h water absorption rate can be decreased by 45.9%. Scanning electron microscope （SEM） and X-ray diffraction （XRD） were used to investigate phase and composition of both sodium silicate sand after surface coating and sodium silicate sand. The SEM analysis demonstrate that the sodium silicate sand after surface coating has humidity resistance layer which is formed from coating material infiltration, and the binding bridge of sand surface in the humidity resistance layer has many tiny granule materials. The surface XRD analysis demonstrates that coating surface of sodium silicate sand after coating appears three new kinds of phase： Al2TiO5, NaAIO2, PbTiO3, which are the main reasons for humidity resistance of sodium silicate sand increased by surface coating.