MECHANICAL CHARACTERIZATIONS AND ELECTROMAGNETIC WAVE SHIELDING PROPERTIES OF METALLIC NI PARTICULATED Al2O3 CERAMIC MATRIX COMPOSITES

Abstract

The present paper describes producing alumina ceramic matrix composites reinforced with nickel at ratios of 1 % to 7 % by weight and their resultant mechanical and electromagnetic properties. In this study powder metallurgy method was used and samples obtained at 1440 degrees C for 1 h in graphite powder. Argon atmosphere has widely used to produce metallic particulate reinforced ceramic based composites to prevent oxidation risk of metallic particulate. However, in this study using a graphite powder it can be easily sintered bulk materials in a ceramic pot. The firing shrinkage of sintered test materials ranged from 20.14 to 21.19 %. Uniform distribution of ductile nickel particles in the matrix was characterized by SEM microscopy and the presence of nickel and alumina phases were confirmed by EDS and XRD analysis. It was found that the fracture toughness of test materials increased with the nickel content from 3.0 to 7.05 MPa.M-1/2. A slightly decreasing for hardness values was also detected. Hardness and fracture toughness was determined using Vickers indentation technique with applying, 0.98 and 98 N load respectively. Electromagnetic shielding effectiveness of nickel particle reinforced alumina composites were investigated in the in the wide range high frequencies of 12.4-18 GHz (Ku band). The experimental results indicate that in addition to increasing the mechanical properties electromagnetic characteristics of the composite has been preserved.