Initial stages of oxidation of near-stoichiometric titanium carbide at low oxygen pressures

Shabalin, Igor L.; Vishnyakov, Vladimir; Bull, D. J.; Keens, S.G.; Yamshchikov, L. F.; Shabalin, Leonid I.

doi:10.1016/j.jallcom.2008.04.067

Cited by 22 publications

(14 citation statements)

References 19 publications

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“…it is easy to understand the submicrone grains, whiskers and nano-particles containing nitrogens have diff erent values of Young's modulus comparing with the alumina matrix and themselves. Th ese kinds of materialstructures have a composition of several Young's modulus, multiple mechanical properties and named hetero-modulus materials [15,16,17,18,19]. Th e dynamic strengths of these developed new heteromodulus ceramics were examined under collisions with high density metallic bodies fl ying with speeds higher than 800 m/ sec.…”

Section: Fig 2 Typical Destruction Of Ceramic Items During High Spementioning

confidence: 99%

Alumina-based hetero-modulus ceramic composites with extreme dynamic strength – phase transformation of Si3N4 during high speed collisions with metallic bodies

Gömze¹,

Gömze²

2009

Epitoanyag - JSBCM

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Till today several kinds of ceramics and ceramic matrix composites are developed for extreme environmental conditions. Most of these ceramics have microstructures with relatively "big" crystals, having high rigidness and strong inclination to nick, pitting and rigid fractures, so they are not usable for collision with metallic or other bodies under high speeds like 800 m/sec or more. On the basis of several years experiments in development and testing of ceramic materials and corundum matrix composites the authors successfully developed new alumina-matrix composite materials reinforced with Si 2 ON 2 , SiAlON, AlN and Si 3 N 4 . These new alumina based ceramic matrix composites were tested under collisions with different metallic bodies having high densities and speeds higher than 800 m/sec. During the collisions the kinetic energy of flying metallic objects distributing to fracture energies, heatings and recrystallizations both of ceramic and metallic bodies. In the centres of collisions, where oxygen was absent, the authors have found new, high density "diamond-like Si 3 N 4 " materials with cubic crystals, where nitrogen atoms distributed in the centres of the cubes. These new crystal structures of Si 3 N 4 in the alumina matrix have extreme dynamic strength and hardness, like diamond. Having surplus of oxygene in the centres of collisions this new "diamond-like Si 3 N 4 " was not observed, when a very strong oxydation of metallic bodies was taken place. Using the energy conception of collision, the authors mathematically described the energy engorgements of destruction of ceramic materials and heating of participating bodies as well as energy engorgement used for the phase transformations of ceramic and metallic particles during their collision.

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Section: Fig 2 Typical Destruction Of Ceramic Items During High Spementioning

confidence: 99%

Alumina-based hetero-modulus ceramic composites with extreme dynamic strength – phase transformation of Si3N4 during high speed collisions with metallic bodies

Gömze¹,

Gömze²

2009

Epitoanyag - JSBCM

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“…However, the application field of zirconium carbide is limited under air due to its low oxidation resistance [9]. As a consequence, they are progressively transformed into oxycarbides during their use through carbon-oxygen substitution [10][11][12]. Therefore, the accurate quantification of light elements (C and O) in heavier matrices is a topic of significant interest in order to define the actual stoichiometry of the studied oxycarbides and to connect these compositions to their expected properties.…”

Section: Introductionmentioning

confidence: 99%

Novel insight into the chemical analysis of light elements in oxycarbides

et al. 2018

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Pure powders of TiCxO(1-x) solid solution were synthesized through the carbothermal route. The chemical analysis of the light elements in the as-obtained TiCxO(1-x) oxycarbides powders were performed by Instrumented Gas Analysis (IGA). The cell parameters of the samples were determined with an accuracy of about 2% by means of X-ray powder diffraction and the internal standard method. As a result, a model correlating the cell parameters to the chemical composition was established. These reference TiCxO(1-x) oxycarbides powders were then sintered in order to obtain pellets of dense ceramics. After having determined that the sintering process does not change the chemical composition of the starting powder, chemical analysis of the different samples of the solid solution were successfully undertaken by Ion Beam Analysis techniques (IBA). The Nuclear Reaction Analysis (NRA) method -that was used to analyse light elements with very high sensitivity -was coupled with Rutherford Back Scattering (RBS) analysis in order to accurately determine the metallic over light elements ratio and to determine the stoichiometry of the phase on massive samples. Exhaustive simulations of the NRA spectra were performed and demonstrated that discrete compositions of the TiCxO(1-x) can be efficiently measured locally for bulk samples. Compared to IGA results, the relative amounts of carbon and oxygen of bulk materials were determined with a bias lower than 5%. This protocol being implemented for the TiCxO(1-x) system was then tested on HfCxO(1-x)with the same success.3

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“…Instead, TiC is probably transformed into TimXn species which are intermediate phases such as oxycarbide(TiCxO1-x) and unstable oxide (TimOn). The formation of intermediate phases during the initial stages of oxidation remains to be elucidated [13]…”

Section: Crystal Structurementioning

confidence: 99%

Synthesis of Mesoporous TiO2 with a Template Free One Step Reaction of Acid-Catalyzed TiC

Buapan¹,

Chaichana²,

Chitpong³

et al. 2018

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Mesoporoustitania (TiO2) having high specific surface areas of 163 to 306 m 2 /g was prepared by a template-free one step reaction between TiC precursor and aqueous nitric acid (HNO3) solution. The effects of reaction parameters including acid concentration, reaction time and temperature were investigated. The properties of the prepared TiO2 induced by those parameters were characterized by various techniques such as thermal gravimetric/differential thermal analysis (TG/DTA) and X-ray diffraction (XRD). It was found that the TiC was completely oxidized to TiO2 at reaction time of 8 h, 70 C with 5 M HNO3. At this condition, the obtained TiO2 composed a mixed phase of 45% anatase and 55% rutile and showed the highest pore volume of 0.239 cm 3 /g with specific surface area of 306 m 2 /g. Moreover, all the anatase was transformed into the rutile when the reaction time reached 48 h. The rates of the rutile transformation increased with increasing the acid concentrations but decreased with increasing the reaction temperatures. The pore volumes and the specific surface areas were reduced by increasing the acid concentrations or the reaction temperatures. It is possibly because at the conditions of the high acid concentrations or the high temperatures, the mesoporous framework of TiO2 was collapsed. Based on the acid conditions, a peptization process was adopted to describe the effects of all investigated parameters.

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Initial stages of oxidation of near-stoichiometric titanium carbide at low oxygen pressures

Cited by 22 publications

References 19 publications

Alumina-based hetero-modulus ceramic composites with extreme dynamic strength – phase transformation of Si3N4 during high speed collisions with metallic bodies

Alumina-based hetero-modulus ceramic composites with extreme dynamic strength – phase transformation of Si3N4 during high speed collisions with metallic bodies

Novel insight into the chemical analysis of light elements in oxycarbides

Synthesis of Mesoporous TiO2 with a Template Free One Step Reaction of Acid-Catalyzed TiC

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