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Dispersed SBA-15 rods have been synthesized with varying lengths, widths, and pore sizes in a low-temperature synthesis in the presence of heptane and NH(4)F. The pore size of the material can systematically be varied between 11 and 17 nm using different hydrothermal treatment times and/or temperatures. The particle length (400-600 nm) and width (100-400 nm) were tuned by varying the HCl concentration. All the synthesized materials possess a large surface area of 400-600 m(2)/g and a pore volume of 1.05-1.30 cm(3). A mechanism for the effect of the HCl concentration on the particle morphology is suggested. Furthermore, it is shown that the reaction time can be decreased to 1 h, with well-retained pore size and morphology. This work has resulted in SBA-15 rods with the largest pore size reported for this morphology.

Titanium carbonitride (TiC x N 1Àx ) powders were obtained by high-energy ball milling of elemental titanium and carbon (activated carbon or graphite) in a nitrogen atmosphere. The formation of the carbonitride phase was controlled by adequately choosing the experimental conditions of the milling process. The stoichiometry of TiC x N 1Àx powders was modified by adjusting the titanium-to-carbon molar ratio. The composition and cell parameters of the carbonitride phases were determined. Microstructural characterization of these phases showed a nanocrystalline nature.

Niobium, tantalum, and hafnium carbonitride nanopowders were obtained by high-energy ball milling of elemental metal and graphite in a nitrogen atmosphere. By adjusting milling parameters, a mechanically induced self-propagating reaction was observed during the formation of carbonitride phases. The stoichiometry of transition metal carbonitrides was controlled by fixing the starting metal-to-carbon molar ratio. Ignition of the reactant mixture was determined by the combined effect of nitrogen and carbon, gas, and solid reagents, respectively. The composition and lattice parameters were determined by X-ray diffraction measurements. Microstructural characterization showed a nanophase structure with a homogeneous chemical composition.

Cermets with a nominal composition (Ti 0.8 Ta 0.2 C 0.5 N 0.5 -20 wt% Co) were synthesised by a mechanically induced self-sustaining reaction (MSR) process from stoichiometric elemental powder blends. The MSR allowed the production of a complex (Ti,Ta)(C,N) solid solution, which was the raw material used for the sintering process. The pressureless sintering process was performed at temperatures between 1400 ºC and 1600 ºC in an inert atmosphere. The microstructural characterisation showed a complex microstructure composed of a ceramic phase with an unusual inverse core-rim structure and a Ti-Ta-Co intermetallic phase that acted as the binder.

Titanium silicon carbide (Ti3SiC2) and Ti3SiC2‐based composite powders were synthesized by isothermal treatment in an inert atmosphere as a function of initial compositions (mixtures). A high content of TiC was obtained in the final product when the initial mixtures contained free carbon. The use of TiC as a reagent was unsuccessful in obtaining Ti3SiC2. High Ti3SiC2 conversion was found for the initial mixtures containing SiC as the main source for silicon and carbon. An initial mixture with a large excess of silicon, 3Ti/1.5SiC/0.5C, was needed to obtain high‐purity Ti3SiC2. A reaction mechanism, where Ti3SiC2 nucleates on Ti5Si3C crystals and grows by long‐range diffusion of Ti and C, is proposed. The reaction mechanism was proposed to be based on silicon loss during the formation of Ti3SiC2.

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