Titanium carbonitride production

Combustion of undiluted Ti or Ti + 0.5 C compacts in gaseous nitrogen at pressures up to 1.4 MPa resulted in incomplete conversion to the nitride or carbonitride. The product included TiN and solid solutions of nitrogen in titanium for the Ti samples and a single non-stoichiometric titanium carbonitride phase for the Ti + 0.5 C samples. 

The most important metallic hard materials, as regards quantity, are tungsten carbide, WC, and titanium carbide, TiC with a production worldwide in 1995 of 20 10- t/a and 3.5 10 t/a respectively. Also worthy of mention is the 1.5 10 t/a of titanium carbonitride, Ti(C,N), produced in 1995, which is used as the hardening component in the cermet sector. Other metallic hard materials are produced in quantities below that of titanium carbide. In individual cases they can be very important as components of alloys in the realization of particular material properties. 

Nitrides such as TiN, AIN, ZrN, HfN, TaN, and Si3N4 and carbonitrides, such as TiCN, NbCN and ZrCN are among the important industrial products formed by the SHS process. Due to the high thermodynamic stability of titanium nitride and titanium carbide, their formation using the SHS method is highly favored even at relatively low pressures of nitrogen. 

An unusual new synthesis method involves carrying out reactions in a molten salt medium, and has been used on an industrial scale for the production of metallic nitride, carbide or carbonitride powders.25 An illustration of this CEREX process is the preparation of oxygen-free titanium nitride in molten calcium chloride. The method involves the reaction between titanium tetrachloride and calcium nitride ... 

Ternary phases with structures different from those of the phases of the binary boundary systems are more the exception than the rule. Such phases have been reported in the systems Nb-Mo-N, Ta-Mo-N, Nb-Ta-N, Zr-V-N, Nb-Cr-N, and Ta-Cr-N. Information about ternary transition metal-nitrogen systems is often available for specific temperatmes only. This is even more the case for quaternary nitride systems, which play a role in the production of carbonitride cermets where quaternary compounds of the types (Ti,Mo)(C,N) and (Ti,W)(C,N) are of interest (see Carbides Transition Metal Solid-state Chemistry), as well as in layer technology where titanium nitride-based coatings of the type Ti(C,B,N) are prepared by magnetron sputtering. Layers consisting of ternary compounds of the type (Ti,Al)N and (Ti,V)N also have favorable properties with respect to abrasion resistance. 

Analogously to silicon nitride, titanium nitride precursors can also be prepared by the reaction of titanium tetrachloride with fluid ammonia [89,90]. This leads to the precipitation of highly polymeric products, which can be transferred to metal nitrides or carbonitrides by calcining in ammonia or an inert gas atmosphere. 

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