医学超声成像的图像质量很大程度取决于超声换能器的特性。在换能器研制过程中，一项重要的任务是确定合适的匹配层材料及参数。为了满足高频超声换能器研制的需要，该文从理论及实验两方面研究了RTV615硅橡胶掺杂不同比例的氧化铝粉末后，所形成的复合材料的高频(20 MHz)声学特性参数，包括声速、声阻抗、声衰减系数等。结果表明，RTV615硅橡胶中掺杂氧化铝的体积分数为7.93%时，所形成的复合材料在20 MHz频率条件下声阻抗值提高52.94%，达到1.56×106 Pa·s/m，具有最佳的声阻抗匹配特性。因此，通过优化掺杂比例可有效改进硅橡胶材料的高频声学性能。

The quality of medical ultrasound imaging significantly depends on the performance of ultrasound transducer. During transducer fabricating, a key task is to determine appropriate materials and parameters of acoustic matching layers. To meet the requirements of the high frequency ultrasound transducer, in this paper the acoustic parameters of the composite of RTV615 silicone rubber mixed by alumina powder with different densities were investigated by theoretical models and experiments. The acoustic parameters include the sound speed, acoustic impendence and attenuation. The results show that the acoustic impendence of the 7.93% volume fraction of alumina doped composite is increased by 52.94%, up to 1.56×106 Pa·s/m at 20 MHz, which makes it more efficiently match with human tissue. It is a potential passive material for high frequency acoustic matching layer and transducer lens.

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国家科技支撑计划基金资助项目(2012BAI13B02)；苏州市技术专项基金资助项目（ZXY2012005）；中科院百人计划基金资助项目（Y223011302）；苏州市基础研究计划基金资助项目（SYG201433）