Magnetic Properties of Carbon Composite Material Prepared by Ball-Milling

Abstract

Carbon-metal composite materials are expected for application to the catalyst and the electromagnetic wave absorbers. In this study, carbon-metal composite materials synthesized by the ball-milling (BM) process. Elemental powder of the Carbon (purity 99.9 %) was used. In this study the SUS304 γ-austenite stainless steel was used for the container and the balls. The weight ratio of ball to powder was 120:1. BM was carried out for maximum 216 ks at a speed of 11.4 Hz and the BM system was water-cooled by high-power BM apparatus (NEV-MA8, Nissin-Giken, Japan). The samples prepared by BM were removed from the pot in a glove box under argon. Obtained samples were somewhat contaminated from ball or container of stainless steel due to heavy scraping action between ball and container. BM for 216 ks yielded metallic phase (SUS304) to transform to α'-martensite due to heavy strain given to the γ-austenite during ball milling as mentioned above. As the result, fine metallic grains with equivalent composition to SUS304, C₇₀Fe₂₀Cr₆Ni₃ were distributed in carbon. This composite material was fully magnetized to 10 Am² kg^-1 at the magnetic field of 2.0 MA m^-1.