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Carbon/carbon composites have been typically used to protect a rocket nozzle
from high temperature oxidizing gas. Based on the Fourier’s law of heat
conduction and the oxidizing ablation mechanism, the ablation model with
non-linear thermal conductivity for a rocket nozzle is established in order
to simulate the one-dimensional thermochemical ablat...
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Citations
... As shown in Ref. [3], the structural nature of the formation of non-equilibrium versus time temperature distributions of the working surfaces of carbon-carbon products results in different surface oxidation rates during short-term (~8 sec) and longer-term (60 to 120 sec) exposure to the same temperatures. The authors of Ref. [3] have established the effect of thermal conductivity of the fragments of working surfaces on their degradation rate. ...
... As shown in Ref. [3], the structural nature of the formation of non-equilibrium versus time temperature distributions of the working surfaces of carbon-carbon products results in different surface oxidation rates during short-term (~8 sec) and longer-term (60 to 120 sec) exposure to the same temperatures. The authors of Ref. [3] have established the effect of thermal conductivity of the fragments of working surfaces on their degradation rate. ...
... As opposed to structural graphite, the absolute value of TCLE for CCCM is 3 to 4 times less, and assumes negative values in the range of temperatures below 1,000 K; -the modulus of elasticity values for dense graphite in the temperature range from 300 to 2,800 K are provided in Ref. [21] and constitute 9 to 12 GPa. Based on the experimental results, the following non-linear approximation equations can be used to describe these values: 3 -0.0071T 2 + 5.0759T + 3129.7, R 2 = 0.85, ...
A heating of a carbon-made product and thermophysical properties of a carbon material in the temperature range from 300 to 2,500 K were studied. A discrete-heterogeneous mechanism of heating the surface of a multi-dimensionally reinforced carbon-carbon composite material (CCCM) subject to accelerated heating was revealed. Based on the results of testing carbon materials in the temperature range from 300 to 3,000 K, a numerical stress analysis of the product was performed, in which the arising stress condition was considered to be resultant from constraining the deformation of the heated parts of the product by relatively cold fragments. The safety factor levels were found for different parts of the product. It was shown that an additional increase in thermal strength as part of the combined definition of thermal resistance of CCCM products is associated with high thermal conductivity of 1D-reinforced rods of material structure.
... Thermal protection systems are essential for the safety of vehicles subjected to severe aerodynamic heating [1]. A lot of researches have been performed on this subject [2][3][4]. Thermal contact resistance (TCR) is the most common quantity characterizing interfacial heat transfer and is also an open issue in the thermal protection system of multi-layer structures. The process of heat transfer across an interface is a complex thermal problem which depends on not only the thermal physical properties of the contact materials, but also the interfacial conditions. ...
To explore whether pressure and temperature can affect thermal contact resistance, we have proposed a new experimental approach for measurement of the thermal contact resistance. Taking the thermal contact resistance between phenolic resinand carbon-carbon composites, cuprum, and aluminum as the examples, the influence of the thermal contact resistance between specimens under pressure is tested by experiment. Two groups of experiments are performed and then an analysis on influencing factors of the thermal contact resistance is presented in this paper. The experimental results reveal that the thermal contact resistance depends not only on the thermal conductivity coefficient of materials, but on the interfacial temperature and pressure. Furthermore, the thermal contact resistance between cuprum and aluminum is more sensitive to pressure and temperature than that between phenolic resin and carbon-carbon composites.
In order to improve mechanical property and ablation resistance of carbon/carbon (C/C) composites, nano-diamond particles were introduced into carbon fiber preforms by vacuum ultrasonic treatment. These particles could enhance the fiber/matrix interfacial bonding owing to the pinning effect and could contribute to the crack deflection. The flexural strength could be increased by 111.5% for composites modified with the optimal concentration of ethanol/diamond dispersion, compared with those without diamond. Such enhanced interfacial bonding is also beneficial to resist the mechanical denudation under the oxyacetylene torch; meanwhile, the oxidative erosion of C/C composites could be reduced since diamond particles increase their thermal conductivity, causing the mass and linear ablation rates decreased by 61.5% and 54.6% respectively. With excessive particles added, the fiber pull-out would be blocked due to over-strengthened bonding and cracks could not propagate along the interfaces, decreasing flexural strength of the composites; the structural defects including pores and micro-cracks are produced excessively, which would be exposed to the flame and play a negative role on the anti-ablation performance.
