Mechanism of mass transfer with combustion of the SHS-system Mo + B

Babkin, Sergii; Bloshenko, V. N.; Borovinskaya, I. P.

doi:10.1007/bf00789667

Cited by 10 publications

(5 citation statements)

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“…The combustion of the MA mixture started at T ig = 490 °C, being lower than the melting point of aluminum by 130 °C, which may also indicate that gas-phase reactions were intensified in the mixture after HEBM due to an increase in the oxygen content. MoB boride can be formed via the mechanism of gas-phase mass transfer of volatile MoO 3 and B 2 O 2 oxides toward B and Mo particles, respectively [ 53 , 54 , 55 , 56 ].…”

Section: Resultsmentioning

confidence: 99%

Phase Formation during the Synthesis of the MAB Phase from Mo-Al-B Mixtures in the Thermal Explosion Mode

Potanin,

Bashkirov,

Kovalev

et al. 2024

Materials

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This work focused on the production of the MoAlB MAB phase through self-propagating, high-temperature synthesis in the thermal explosion mode. The influence of the method of a Mo-Al-B-powder reaction mixture preparation on the combustion temperature, mechanism, and stages of the MAB phase formation in the combustion process was investigated. The combustion temperatures of the mixtures obtained in the rotary ball mill and high-speed planetary ball mill were 1234 and 992 °C, respectively. The formation of intermediate compounds Mo3Al8 and α-MoB in the combustion front, along with MoAlB, was established using the time-resolved X-ray diffraction method. In the case of the mixture prepared in a ball mill, the primary interaction in the combustion front occurred through the Al melt, and in the case of using a planetary mill, solid-phase reactions played an important role. The mechanical activation of the mixture in a planetary mill also accelerated the processes of phase formation. The method of a reaction mixture preparation has virtually no effect on the MoAlB MAB phase content in combustion products (92–94%), but it does affect their structure. The synthesis products have a lamellar structure composed of MAB grains with a thickness of ~0.4 μm and a length of ~2–10 μm.

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Section: Resultsmentioning

confidence: 99%

Phase Formation during the Synthesis of the MAB Phase from Mo-Al-B Mixtures in the Thermal Explosion Mode

Potanin,

Bashkirov,

Kovalev

et al. 2024

Materials

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“…Химический анализ содержания кислорода показал, что в порошке молибдена его количество составляет 1,08 %. Возможность образования MoO 3 показана в работах [36][37][38] Полученные методом ДР данные свидетельствуют о том, что МАВ-фаза MoAlB кристаллизуется из расплава без формирования промежуточных соединений. Данная стадийность превращений отличается от фазообразования при синтезе МАХфаз.…”

Section: результаты и их обсуждениеunclassified

Self-propagating high-temperature synthesis of MoAlB boride ceramics based on MAB-phase

Potanin

Bashkirov

Pogozhev

et al. 2022

Izv. VUZ. Poroshk. Met.

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This study focuses on the combustion kinetics and mechanisms of reaction mixtures in the Mo–Al–B ternary system taken so that the MoAlB MAB phase was formed. The effect of the initial temperature on the key combustion parameters was demonstrated. Reaction mixture preheating was found to weakly affect the maximum combustion temperature. The effective activation energy of self-propagating high-temperature synthesis (SHS) was calculated. Phase diagrams in the Mo–Al–B system were built using the AFLOW and Materials Project databases. The phase composition and structure of the synthesized ceramics with MoAlB lamellar grains 0.4 μm thick and ~2–10 μm long as a main component were studied. The DXRD lines of MoB and Mo2B5 intermediate borides with their total content of ≤3 % were also identified. Scanning electron microscopy and energy dispersive spectroscopy studies revealed that the Al2O3 phase was present in the intergranular pores. A sequence of chemical transformations in the combustion wave was studied, and a hypothesis about the structure formation mechanism was put forward. MoO2 and Al2O3 can be the primary phases during SHS, and the MoAlB phase is formed from the boron-containing aluminum–molybdenum melt. Submicron-sized MoB precipitates are formed in the post-combustion zone due to the partial oxidation of aluminum by the dispersion strengthening mechanism.

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“…Thorough studies were conducted regarding the SHS in the binary systems Mo–Si and Mo–B, including the mathematical modelling of the combustion mechanisms, investigations of the impact of the mechanical activation (MA) on the reactivity of the mixtures, as well as studies of the influence of the different raw materials, samples size, and stoichiometry of the reaction mixture on the combustion kinetics (combustion regime, combustion temperature and velocity) and phase composition of combustion products. However, only a limited amount of data concerning the SHS of ceramics in the ternary Mo–Si–B system was published.…”

Section: Shs In Mo–si–b Systemmentioning

confidence: 99%

SHS of Silicon‐Based Ceramics for the High‐Temperature Applications

et al. 2018

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High-temperature materials attract a growing interest from both the scientists and engineers, since the increase of the operating temperatures is crucial for the enhancement of many energy conversion processes. Another area of application of high-temperature materials is high-velocity air flight, where the ultra-high temperature ceramics (UHTCs) are pivotal for the creation of robust nose tips and leading edges of the skins of high-velocity jets. Compounds of refractory metals with silicon, such as TaSi 2 , MoSi 2 , ZrSi 2 , are characterized by unrivaled resistance in aggressive environments. However, most of them are not suitable for application as high-temperature structural materials due to the low mechanical properties. Therefore, they are frequently used as a constituent for the high-temperature composite materials such as TaSi 2 -SiC, ZrC-MoSi 2 , ZrB 2 -MoSi 2 , ZrB 2 -ZrSi 2 . One of the most convenient ways of producing these composite materials is self-propagating hightemperature synthesis (SHS), known for its high productivity, energyefficiency, and ecological safety. This review summarizes the latest developments of the SHS of the silicon-based high-temperature ceramics.

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Mechanism of mass transfer with combustion of the SHS-system Mo + B

Cited by 10 publications

References 0 publications

Phase Formation during the Synthesis of the MAB Phase from Mo-Al-B Mixtures in the Thermal Explosion Mode

Phase Formation during the Synthesis of the MAB Phase from Mo-Al-B Mixtures in the Thermal Explosion Mode

Self-propagating high-temperature synthesis of MoAlB boride ceramics based on MAB-phase

SHS of Silicon‐Based Ceramics for the High‐Temperature Applications

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