FABRICATION AND DAMPING BEHAVIOR OF BARIUM TITANATE REINFORCED COPPER MATRIX COMPOSITES

摘要

The damping behavior of paniculate reinforced copper-barium titanate composites (CBT composites) fabricated using powder metallurgy techniques was evaluated between 25℃ and 165℃ at a frequency of 1 Hz using dynamic mechanical analysis (DMA). Retention of the ferroelectric tetragonal phase of the barium titanate particulates after composite fabrication was determined by differential scanning calorimety (DSC). DMA results indicate that the damping capacity, tanδ, of copper is enhanced by incorporation of barium titanate particulates in the metallic matrix. The magnitude of the enhanced damping was greater for large barium titanate particulate sizes. The damping capacity of this CBT composite was high from room temperature up to the Curie temperature of barium titanate, after which there was a slight drop in damping values. This drop results from a loss of ferroelectric damping mechanisms above the Curie temperature. At the Curie temperature, ferroelectric tetragonal barium titanate transforms into a paraelectric cubic form. In composites fabricated using small barium titanate particulates (～2μm), ferroelectricity did not have a significant effect on damping capacity, due to the destabilization of the ferroelectric properties in fine grained and small barium titanate particulates.