Porous sound-absorbing materials prepared from fly ash.

The use of modified fly ash for preparing porous sound-absorbing materials and the optimum conditions of fly ash modification were studied. The effects of sintering temperature, sintering time, forming pressure, and other experimental conditions on porous sound-absorbing materials were also investigated. Results showed that the average volume density of the finished product was 0.93 g/cm3, the compressive strength was approximately 1.2 MPa, and the average porosity was nearly 60%. The average sound absorption coefficient of the sample in a low-frequency band was approximately 0.353, and the overall average sound absorption coefficient was nearly 0.458. The optimal preparation conditions were as follows: sintering temperature was 1100 °C, sintering time was 5 h, and molding pressure was 2 MPa.