Titanium nitrides are widely used in manufacturing cermets,
cutting tools, decorative, refractory and cover layer for metals
and alloys [1–5] because of its desirable properties such as
high hardness, high thermal conductivity, high temperature stability
and good corrosion resistance. Titanium nitride powders
are usually synthesized by direct nitridation of titanium hydride
or dioxide, carbon-reduced nitridation of titanium dioxide and
self-propagating combustion synthesis [6–8]. All these techniques
involve high temperature, and they are not easy to be used to synthesize
nano-sized materials.
Fine grain titanium nitride powders can be synthesized by ball
milling of titanium with boron nitride, nitrogenous organic solution,
nitrogen gas or ammonia gas at room temperature [9–12].
Such obtained titanium nitride powders usually have some impurities,
which are hard to remove. It was reported that the nitridation
of elements like Si, Fe and Ti is more easily to occur in ammonia
rather than in nitrogen [13,14]. However, milling titanium in
flowing gas involves a special design that has some technical difficulties.
In this letter, a novelty simple method for nano-sized titanium
nitride synthesis is reported. It is found that nano-crystalline titanium
nitride can be prepared by reactive ball milling of titanium
powders and urea at room temperature. This milling process avoids