粉煤灰的超细粉磨及其对水泥性能的影响实验研究

本试验选用了内蒙古鄂尔多斯电力集团棋盘井电厂的粗粉煤灰,其活性指数为67.1%,达不到粉煤灰用于作水泥混合材料的国家标准(大于70%)。采用机械活化的措施——超细粉磨,将粉煤灰磨细到不同的细度和比表面积,这时粉煤灰的活性指数不仅合格,而且当将它掺入到P·II52.5等级的纯硅酸盐水泥中时,即使掺入量高达40%~50%,仍可得到P·F42.5等级或42.5R等级的粉煤灰硅酸盐水泥。这为扩大粉煤灰的利用提供了有效的措施。

Ultrafine grinding of fly ash and its influence on cement properties

With its high spatial resolution and excellent detection capability, high-frequency ultrasound is a valuable tool in clinical studies, biomedical research, and nondestructive testing (NDT) of high value manufacturing (HVM). However, a major bottleneck in further progress is the development of ultrasonic transducers for high-frequency applications. In the paper, we introduce basic principles of ultrasonic transducers and briefly review existing ultrasonic transducer techniques. Following this, we address current technical challenges of high-frequency ultrasonic transducer techniques and provide practical solutions, illustrating our recent efforts to develop state-of-the-art high-freq uency ultrasonic transducer arrays. Finally, we discuss the future prospects of high-frequency ultrasonic transducer techniques.