Document Type : Research Article
Authors
Abstract
The composite material is an emerging opportunity for improving the loss factor. In the present context, AA7075 was fabricated in induction furnace using elemental addition such as Zn, Mg and Cu and ex-situ reinforcement of 10wt. % graphite particulates with three types of composites viz 3 to 10 μm (C1), 53 to 66 μm (C2) and 106 to 150 μm (C3). The melt was poured at 780 o C and cast into the steel mold then hot forged at a strain rate of 3- 5x10-3 s-1 in three stages with net cross-section reduction in the range of 30-33%. Solutionizing at 470 o C was followed by artificial aging at 120 o C. Characterization was carried out by SEM and DMA at two selected frequencies 0.1Hz and 1Hz over the temperature range of 30 to 250 o C. Significant improvement in storage modulus (E’) and loss modulus (E”) noticed in C2 as compared to the C1, C2 and monolithic alloy. A threshold value of the volume to the surface of graphite reinforcement has arrived for an improved loss factor. A generalized experimental model formulated to account for 12 influencing parameters and the significance of damping capacity with the response to graphite content has been established.
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