Papers by Keyword: TiC-TiB2 Composites

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Authors: F. Capel, L. Contreras, M.A. Rodríguez
1025
Authors: Dario Vallauri, Y. López, Bruno DeBenedetti, Ignazio Amato
Abstract: The aim of this work is the achievement of nanostructured TiC–TiB2 powders through a metastability approach based on the Self–propagating High–temperature Synthesis (SHS) process followed by quench to obtain highly metastable powder agglomerates. An optimisation of the reaction stoichiometry was carried out in order to obtain products with approximately eutectic composition (i.e. 67%mol TiC – 33%mol TiB2). An optimized amount of sodium borate was used as gasifying additive to produce dispersed nanostructured powder agglomerates. The metastability of the nanocomposite powders obtained through the (SHS+quench) route was evaluated by annealing. The morphological evolution of the powders after thermal treatment yielded a recrystallisation with limited grain growth of the nanostructured TiC–TiB2 phases and demonstrated the metastability of the products obtained by the (SHS+quench) route.
1005
Authors: Vladimir A. Shcherbakov, Anton V. Phitev, N.V. Sachkova, Fabio A. Deorsola, Dario Vallauri, Bruno DeBenedetti
Abstract: The aim of this work is the preparation and study of the mechanisms of structure formation of dense ceramics based on the TiC–TiB2–MeO system obtained by pressure–assisted Self-propagating High-temperature Synthesis. SHS systems were selected on the basis of thermodynamic analysis as suitable to realise regimes of synthesis with formation of liquid phase allowing a full densification. It was observed that at the adiabatic temperature the liquid phase formed in the SHS products consists of either melted oxides or eutectic TiC–TiB2. The results of microstructural observations and mechanical characterization confirm that the metal oxides effectively promote the densification of the final products and the grain refinement of the SHSproduced ceramic materials.
1018
Authors: Zhen Sheng Qu, Quan Yang, Zhong Min Zhao, Long Zhang, Chuan Zeng Pan, Min Quan Wang
Abstract: The large-bulk solidified TiC-TiB2 composites were prepared by combustion synthesis in high-gravity field. XRD, FESEM, SEM and EDS results showed that TiC-TiB2 composites were mainly composed of TiC matrix in which a number of fine TiB2 platelets were embedded, surrounded by the boundary regions consisting of (Cr, Ti) C0.63 carbides. The hardness, flexural strength and fracture toughness of TiC-TiB2 composites measured 28.5GPa, 750±25MPa and 6.2±0.5MPa•m1/2. High hardness of the composites benefits from the absence of the intermediate borides and the achievement of stoichiometric TiC phases due to rapid solidification, whereas the achievement of high strength benefits the refinement and homogeneity of the microstructures due to rapid separation of liquid oxides in high-gravity field and rapid coupled growth of TiC and TiB2 phases.
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