Improving the damping properties of composites using ferroelectric inclusions

Abstract

This paper presents a recently developed composite constructed in an attempt to improve damping properties by using ferroelectric inclusions in a constrained medium. Several samples of this new composite have been made and tests of their damping properties are presented here. Damping properties of materials are of great interest in many applications. The focus here is on the development of composites with ferroelastic components to develop a new class of materials having improved temperature-dependent damping properties. Typical damping materials, such as viscoelastic materials, have damping values that decrease with increasing temperature. The work presented here considers a material system consisting of fine particles of vanadium dioxide (VO2) and zinc oxide (ZnO) incorporated into matrix materials (tin and polymer adhesives) to produce composite materials with improved damping properties. A number of mechanical damping tests have been conducted on the prepared composites at a frequency range of 0-2000 Hz and over a broad temperature range using piezoceramic exciters and miniature accelerometers. The mechanical vibration test results show that VO2 and ZnO give significantly higher damping values at approximate to 68 degrees C (155 degrees F) and 29 degrees C (85 degrees F). For example, approximate to 15 and 12% damping is achieved at the first and second resonance frequencies, respectively. This significant improvement on the damping of the composite materials may be because of the ferroelasticity and/or viscoelasticity at those particular temperatures. It has also been observed that etching of substrate surfaces improves the adhesion between composite materials and surfaces for better damping results. These composites offer high damping at elevated temperatures and hence may provide useful solutions to applications requiring increased damping.