金屬基複合材料次表面性質的超音波研究

Abstract

本文量測表面波的波速及衰減係數，用以評估顆粒補強金屬基複合材料的 次表面性質。本研究根據Rose發展之接觸式表面波量測方法，設計製作一 低頻之接觸式表面波量測機構，在等向性金屬材料上驗證，表面波速的實 驗結果與理論值比較，誤差小於0.7%。氧化鋯顆粒補強鋅鋁銅合金及碳化 矽顆粒補強之鋁基複合材料的實驗結果顯示，表面波波速隨補強顆粒的重 量比值增加而增快，並與材料表面耐磨耗性的對數成正比例。由實驗量測 也建立了不同顆粒重量比值之金屬基複材的表面波衰減與頻率之關係。 The subsurface properties of metal matrix composites are investigated by measurement of surface acoustic waves in this thesis. A correlation of the wear resis- tibility and weight fraction of particle-reinforced Zircon/ZAS and SiC/Al with the wavespeeds and attenua- tion factors of low-frequency surface acoustic waves is established. A contact-type fixture, followed Rose' literature, has been developed to transmit and receive surface acoustic waves on the specimens. The accuracy and validity of this fixture have been verified in vari- ous isotropic metal blocks. The measurement errors are below 0.7%. Experimental results of those metal matrix composite specimens show that surface wave velocity in- creases with the weight fraction and is proportional to the logarithm of wear resistibility. The frequency- dependence of attenuation factors with respect to vari- ous weight fractions is also established quantitatively.