Microwave absorbing efficiency of Al matrix composite reinforced with nano-Ni/SiC particles

Abstract

An Al/Ni-SiC composite was prepared. Nickel at 10 wt% along with SiC particles was used as a reinforcement for the Al matrix. Two different techniques were used for the fabrication process: coating of SiC particles with nano-nickel particles via the electroless deposition technique and mechanical mixing of Ni and SiC powders. Ni –SiC powder at 5, 10 and 15 wt% was mixed with the Al matrix for 24 h and then compacted at 840 MPa. The sintering process was performed at 600 °C for 1 h in a vacuum furnace. The microstructure and phase composition were studied using both scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The density and coefficient of thermal expansion (CTE) were measured. The magnetic parameters were detected using a vibrating sample magnetometer (VSM). A vector network analyser was used to estimate the microwave absorption ability. For the two groups of samples, Ni-SiC was homogenously distributed throughout the Al matrix. XRD indicated the presence of Al, Ni, SiC, Ni3Al and AlNi5Si2 intermetallics. The CTE results indicated an enhancement with increasing Ni-SiC percentage. All samples exhibited good microwave absorption. The maximum microwave loss of the composites was −28 dB in the frequency range of 8.75–12.8 GHz. Keywords: Powder metallurgy, Microwave absorption, Al/Ni-SiC composite, Microstructure, Coefficient of thermal expansion