Investigation of Heat Transfer to HfB2-SiC-Based Ceramics in Underexpanded Dissociated-Nitrogen Flows and Analysis of the Surface

Колесников, А. Ф.; Кузнецов, Н. Т.; Muravyеva, T. I.; Нагорнов, И. А.; Сахаров, В. И.; Sevastyanov, V. G.; Симоненко, Е. П.; Симоненко, Н. П.; Чаплыгин, А. В.; Shcherbakova, O. O.

doi:10.1134/s0015462822040061

Cited by 10 publications

(10 citation statements)

References 35 publications

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“…Thus, it was found that the previously observed surface chemical processes for samples of HfB 2 –SiC and HfB 2 –SiC–C G composition under the influence of high-enthalpy nitrogen flows at ~2000 °C [ 54 ] take place at a much lower temperature of ~1550–1600 °C.…”

Section: Resultsmentioning

confidence: 94%

“…Earlier, the authors studied the behaviour of the ceramic material HfB 2 -30 vol.%SiC and the sample modified with 2 vol.% graphene (HfB 2 -SiC-C G ), when heated in underexpanded jets of a dissociated nitrogen high-frequency plasmatron VGU-4 [ 54 ]. It was found that at the heat flux density in the range of 244–290 W·cm –2 , both samples acquired a surface temperature of ~2000 °C and significantly changed their chemical composition: a hafnium carbonitride phase appeared and significantly decreased the content of silicon carbide.…”

Section: Resultsmentioning

confidence: 99%

“…The sample in the form of a cylinder, with a diameter of 15 mm and a thickness of ~3.2 mm, was injected into the high enthalpy jet at the plasmatron anode power (N) of 64 kW, and then the sample was incubated at these conditions for 10 min (600 s). The geometry of the model, in which the samples were fixed, is described in detail in [ 53 , 54 , 59 ]: the samples were mounted on friction in the seat of a water-cooled calorimeter, the gap was filled with flexible SiC-based thermal insulation and carbon fibres in order to minimize heat losses.…”

Section: Methodsmentioning

confidence: 99%

“…A correction made to the real values of average temperatures in the central region, determined with an infrared pyrometer, made it possible to estimate the spectral coefficient of radiation and its change during the course of exposure. The method of determining the heat flux to the face of the sample is described in detail in [ 54 ].…”

Section: Methodsmentioning

confidence: 99%

“…The authors have not found a study of the interaction of ultra-high-temperature ZrB 2 +HfB 2 +SiC+C CNT ceramic with high-enthalpy flows of other gas compositions, such as nitrogen, which is the main component of the Saturn satellite Titan atmosphere (98.4%) [ 47 , 48 ], or carbon dioxide, prevailing in the Mars atmosphere [ 49 , 50 , 51 , 52 ], despite the extreme practical relevance. The authors previously studied the behaviour in supersonic jets of dissociated nitrogen of graphite samples [ 53 ] and HfB 2 –SiC and HfB 2 –SiC–C (graphene) ceramics [ 54 ], which showed that there occurred a significant change in the surface chemical nature due to ongoing reactions with atomic nitrogen and silicon removal at elevated temperatures, which causes a change in the emissivity and catalyticity.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of the Effect of Supersonic Flow of Dissociated Nitrogen on ZrB2–HfB2–SiC Ceramics Doped with 10 vol.% Carbon Nanotubes

et al. 2022

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The method of fabricating dense ultra-high temperature ceramic materials ZrB2–HfB2–SiC–CCNT was developed using a combination of sol-gel synthesis and reaction hot pressing approaches at 1800 °C. It was found that the introduction of multilayer nanotubes (10 vol.%) led to an increase in the consolidation efficiency of ceramics (at temperatures > 1600 °C). The obtained ZrB2–HfB2–SiC and ZrB2–HfB2–SiC–CCNT materials were characterized by a complex of physical and chemical analysis methods. A study of the effects on the modified sample ZrB2–HfB2–SiC–CCNT composition speed flow of partially dissociated nitrogen, using a high-frequency plasmatron, showed that, despite the relatively low temperature established on the surface (≤1585 °C), there was a significant change in the chemical composition and surface microstructure: in the near-surface layer, zirconium–hafnium carbonitride, amorphous boron nitride, and carbon were present. The latter caused changes in crucial characteristics such as the emission coefficient and surface catalyticity.

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Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%