乙酸铵发泡制备的多孔吸声陶粒的孔结构可控研究

Study on controllable pore structure of porous sound-absorbing ceramsite based on ammonium acetate foaming

多孔陶粒的吸声性能由其孔结构决定,以发泡法制备多孔陶粒时,发泡剂的添加量和升温速率主导着孔结构。为降低多孔陶粒的制备能耗,实现绿色环保多孔吸声陶粒的孔结构调控,以粉煤灰、水泥、生石灰、熟石膏等为原料,以乙酸铵为低温分解发泡剂,在不同升温速率下制备免烧结多孔陶粒,并实现陶粒孔结构可控,从而优化陶粒的吸声性能。通过对多孔陶粒表观孔隙率、微观形貌、孔径大小及分布和吸声性能的研究发现:随着发泡剂用量增加,陶粒表观孔隙率、孔径变大,孔径分布变宽,陶粒的低频吸声性能降低,整体频段吸声性能提升;随着升温速率增大,表观孔隙率增大,孔径变小,孔径分布变得均匀有序,陶粒的低频吸声性能明显提升,升温速率超过20℃/min时,表观孔隙率略微下降。多孔陶粒吸声性能与表观孔隙率呈正相关。陶粒的孔结构存在最优孔径范围(≤2.5μm),最优平均孔径为0.3μm,过大或者过小的孔径均不利于整体吸声性能的优化。

Sound absorption performance of porous ceramsite is determined by its porous structure.Formation of the porous structure of ceramsite is mainly controlled by type of foaming agent and heating rate in the foaming preparation technique.In order to reduce the energy consumption of the preparation of porous ceramsite and realize the control of the pore structure of the green and environmentally friendly porous ceramsite,in this study,sintering-free porous ceramsite with different porous structures were prepared by using fly ash,cement,quick lime and plaster as raw material and using ammonium acetate as low-temperature decomposition foaming agent under different heating rates.Microstructure and sound absorption of the prepared porous ceramsite were discussed.Results demonstrate that with the increase dosage of foaming agent,apparent porosity and pore diameter are increased,accompanied with the broadening range of pore diameter.Moreover,the sound absorption performance in the low-frequency declines,but the sound absorption performance in the whole frequency is improved.In addition,apparent porosity is positively related with heating rate,while pore diameter is negatively correlated.With the increase of heating rate,range of pore diameter is narrowed and the sound absorption performance in the low-frequency is improved significantly.Apparent porosity decreases slightly when the heating rate is higher than 20℃/min.The sound absorption performance of porous ceramsite is positively correlated with apparent porosity.The pore structure of ceramsite has an optimal pore size range(≤2.5μm),and the optimal average pore diameter is 0.3μm,too large or too small pore size is not conducive to the optimization of the overall sound absorption performance.