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Mechanochemical Formation of Metal–Ceramic Composites
Author(s) -
Welham Nicholas J.,
Willis Paul E.,
Kerr Tony
Publication year - 2000
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.2000.tb01144.x
Subject(s) - materials science , rutile , titanium , ilmenite , microstructure , titanium carbide , crystallite , titanium diboride , aluminium , ball mill , metallurgy , hot pressing , nitride , titanium nitride , tin , composite material , indentation hardness , mineralogy , ceramic , chemical engineering , chemistry , layer (electronics) , engineering
A mechanical activation technique has been used to form composites of alumina with titanium carbide, nitride, or carbonitride, both with and without elemental iron. The composites were formed by reacting elemental aluminum with either ilmenite (FeTiO 3 ) or rutile (TiO 2 ) concentrates in the presence of carbon and/or nitrogen in a ball‐mill at ambient temperature. The reaction was complete for the ilmenite samples after milling but was completed only for rutile under hot pressing conditions. Microhardness measurements indicated that the composites had hardnesses in the range 19–30 GPa (1740–2750 VHN), with only a small variation within each sample. Elemental mapping of the pressed pellets indicated that titanium and aluminum were evenly distributed on a submicrometer level whereas iron tended to coalesce into <20 μm particles in the presence of TiC. The coalescence decreased with the carbon content of the hard material until iron was evenly distributed with TiN. A superstoichiometric amount of aluminum led to the formation of iron–aluminum phases which decreased the iron coalescence. The XRD crystallite size of the alumina was 30–50 nm and was 25–50 nm for the titanium phases, confirming the extremely fine microstructure.