Ablation Properties Research Articles

Research status and prospect on nanotube/nanowire multi-scale-reinforced C/C composites

Carbon/carbon (C/C) composite has become a good candidate as an ultra-high temperature structural material for thermal structure in aerospace and other fields due to its low density and high temperature mechanical properties. However, conventional C/C composites cannot meet the application requirements of sharp thin-wall structure, because the pyrolytic carbon matrix is brittle and the single micron carbon fiber cannot effectively enhance the sharp thin-walled area. This paper reviews the preparation methods of nanotube/nanowire reinforced C/C composites and their effects on the structure and properties of the composites. The development status of introducing carbon nanotubes (CNTs), silicon carbide nanowires (SiCNWs) and hafnium carbide nanowires (HfCNWs) on the mechanical and ablative properties of C/C composites, as well as the toughening mechanism and ablation resistance mechanism of the composites are summarized. In view of the shortcomings of the composition, method and single test performance of the nano-reinforced material introduced at present, it is proposed to further improve and innovate the process technology on the base of these studies, and conduct reasonable component and structure design, so as to deeply study the high temperature mechanical properties and toughening mechanism of multi-scale toughened C/C composites.

Effects of Carbon Source on Ablation Property of C/C–ZrC–SiC Composites and SiC Coating under Plasma Flame

Effects of Carbon Source on Ablation Property of C/C–ZrC–SiC Composites and SiC Coating under Plasma Flame

Influence of copper contamination on ablation damage of C/SiC composites under simulated thermal environment of arc heater

Carbon fiber (CF) reinforced silicon carbide composites (C/SiC) are high-performance lightweight and high-strength materials, rendering promise as hot-structure materials for high-speed aircraft. However, it is critical to evaluate the performance of C/SiC composites in simulated aerodynamic thermal environment due to the impure air of wind tunnel. Herein, we analyze the influence of copper contamination on ablation properties of C/SiC composites in arc heater. Failure mechanism of C/SiC composite is revealed by combining experimental results of static oxidation and theoretical evaluation of ablation process under arc heating. Overall, the presence of copper accelerates oxidation and glassification processes of SiC matrix by forming low-temperature compounds. In addition, the influence of fiber orientation on ablation damage of C/SiC composites is evaluated by combining the distribution of copper-containing phases, airflow distribution, and discrepancies in direction-based thermal conductivity. Results reveal that continuous CF-reinforced micro-zone ceramics resist airflow shear denudation. Furthermore, ablation behavior of needle-punched C/SiC composites under arc heating is discussed in detail.

Ablation properties of C/C-UHTCs and their preparation by reactive infiltration of K2MeF6 (Me = Zr, Ti) molten salt

Ultra-high temperature ceramic-modified C/C composites (C/C-UHTCs) were prepared by the reactive infiltration of K2MeF6 (Me = Zr, Ti) mixed with Si and Zr-Si powders. Molten salt infiltration can be divided into two stages: salt ion melt and Me-Si alloy melt. In the temperature range below 1400 °C, Zr and Si dissolve in the molten salt, are carried by the ion melt, and precipitate at the PyC interface to form carbides. Above 1400 °C, a large amount of molten salt volatilises and thermally decomposes. The Me-Si alloy forms a melt and infiltrates the C/C matrix, and finally forms C/C-ZrC-SiC, C/C-Ti3SiC2-SiC, and C/C-ZrC-TiC-SiC composites. The C/C-ZrC-SiC composite with the highest ZrC content exhibited the lowest mass rate (2.6 ± 0.02 mg/s) and linear ablation rate (0.82 ± 0.04 μm/s), which were reduced by 43.5 and 50.8 %, respectively, compared to the unmodified C/C-ZrC-SiC composite.

Curing mechanism, thermal and ablative properties of hexa-(4-amino-phenoxy) cyclotriphosphazene/benzoxazine blends

The demand for ablative material with high performance is eager in the aerospace industry. In this paper, hexa-(4-amino-phenoxy)-cyclotriphosphazene (CPA) was synthesized and then blended with bisphenol-A aniline benzoxazine (BA-a) firstly. The curing mechanism, thermal and ablative properties of cured blends were studied. The addition of CPA not only can decrease the curing temperature but can also increase the crosslink density of polybenzoxazine which is further beneficial for the improvement of thermal properties of cured blends. When the content of CPA is 5%, the Tg of the cured blend increases by 20 °C, and the char yield at 800 °C increases from 25.2% for pure polybenzoxazine to 49.2%. The oxyacetylene ablation tests showed that the ablation rate of cured blends could reach 0.047 mm s−1 while that of polybenzoxazine is 0.128 mm s−1. Further discussion based on SEM, XRD, Raman spectra showed that the CPA can effectively improve the graphitization degree of ablated samples and improve the integrity of graphite layer crystals. Moreover, the density functional theory (DFT) calculations and bond order analysis predict the bonding breakage sequence which is the C–N bonds between BA-a and CPA (N3–C55) > P–O bonds (P2–O12) > phosphazene ring, which means the phosphazene ring shows an effect after benzoxazine partly decomposed. The preparation method by adding CPA to benzoxazine to improve the ablative performance is facial and easy, which provides a new way of making novel ablative materials.

Ablation properties of zinc borate and aluminum hypophosphite filled silicone rubber composites

AbstractThe ablative properties of epoxy modified silicone rubber composites filled with zinc borate (ZB) and aluminum hypophosphite (AHP) were studied. The decomposition of the added fillers and covering connection of residual on the substrate contribute to the improvement of heat insulation. The ablation test shows that the formation of a dense char layer with certain strength is key to improving the ablative properties. The optimal ablative performance is achieved when the concentration of ZB and AHP is 10 and 5 phr, respectively. Under such circumstances, the linear ablation rate is as low as 0.032 mm/s, which is about 61% lower than the pure silicone rubber. Furthermore, the structure and composition of the formed char layer were analyzed using X‐ray diffraction analysis, scanning electron microscopy, and Fourier transform infrared spectroscopy.

Ablation and thermal insulation properties of silicone rubber-polyarylacetylene-carbonwoven laminates for solid rocket motor

ABSTRACT Silicone rubber-polyarylacetylene-carbon woven laminates (SRWL) with two-dimensional structure were prepared using needled technique. The ablation and insulation mechanism of SRWL were investigated by oxyacetylene flame system, equilibrium swelling technique, thermogravimetry (TG), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results showed that the molecular weight between the crosslinks of the interlaminar complex is reduced with the increasing of the content of polyarylacetylene (PA). SRWL with PA has superior anti-ablation properties and high residue compared with that of without PA. With the increasing of PA content, the linear ablation rate of SRWL first decreases and then increases. When the content of PA is 10 phr, the linear ablation rate is 0.0276 mm s−1 and the back-face temperature peak is 71 °C. SRWL filled with 10 phr concentration of PA show comparably improved ablation properties and PA hinders the thermal transmission because of forming of compactly integrated self-protection refractory layer, ceramic compounds such as SiC, Si and some endothermic behaviour.

A Numerical Approach to Study Ablation of Large Bolides: Application to Chelyabinsk

In this study, we investigate the ablation properties of bolides capable of producing meteorites. The casual dashcam recordings from many locations of the Chelyabinsk superbolide associated with the atmospheric entry of an 18 m in diameter near-Earth object (NEO) have provided an excellent opportunity to reconstruct its atmospheric trajectory, deceleration, and heliocentric orbit. In this study, we focus on the study of the ablation properties of the Chelyabinsk bolide on the basis of its deceleration and fragmentation. We explore whether meteoroids exhibiting abrupt fragmentation can be studied by analyzing segments of the trajectory that do not include a disruption episode. We apply that approach to the lower part of the trajectory of the Chelyabinsk bolide to demonstrate that the obtained parameters are consistent. To do that, we implemented a numerical (Runge–Kutta) method appropriate for deriving the ablation properties of bolides based on observations. The method was successfully tested with the cases previously published in the literature. Our model yields fits that agree with observations reasonably well. It also produces a good fit to the main observed characteristics of Chelyabinsk superbolide and provides its averaged ablation coefficient σ = 0.034 s2 km−2. Our study also explores the main implications for impact hazard, concluding that tens of meters in diameter NEOs encountering the Earth in grazing trajectories and exhibiting low geocentric velocities are penetrating deeper into the atmosphere than previously thought and, as such, are capable of producing meteorites and even damage on the ground.

Surface Optimization of ZrC–SiC Inner Layer to Enhance Ablation Property of SiC/ZrC–SiC Multi-Layer Coating for C/C Composites

A ZrC–SiC inner layer was fabricated on carbon/carbon composites by pack cementation at different temperatures, aiming to prepare a transition layer for subsequent deposition of SiC and ZrC–SiC layer by chemical vapor deposition and plasma spray. Results show that the structure and phase composition of the inner layer significantly affected the interface bonding strength and thermal shock resistance of the multilayer, which played a vital role in resisting ablation. The jagged and porous surface of the inner layer led to forming a root-like pinning interface, generating a sawtooth combination between the layers. Moreover, the inner layer with high SiC content decreased the coefficient of thermal expansion mismatch between the inner and outer layers. Therefore, the enhanced ablation resistance of the optimum coating was attributed to the improved interface bonding strength and thermal shock resistance caused by the ZrC–SiC inner layer with rough and porous surface structure.

In situ construction of fiber‐supported micro‐porous char structure to enhance anti‐ablative performance of silicone rubber composites

AbstractAblation‐resistant polymeric composites play a crucial role in the thermal protection system for the entire aerospace industry. Constructing a stable char layer especially with low thermal conductivity is essential to enhance the ablation resistant properties of polymer‐based ablatives. In this article, basic magnesium carbonate (MgCO3) and carbon fibers (CFs) were introduced to silicone rubber with an aim of building fiber‐supported micro‐porous char structure in situ, thereby improving ablation resistance properties. Thermogravimetric analyses revealed that the addition of MgCO3significantly increased the char residue of the composites. Oxyacetylene torch tests indicated that the addition of MgCO3/CFs greatly improved the thermal insulation of the composites, and the linear ablation rates of the composites were reduced by 30.76% compared to the virgin silicone rubber. Shore A hardness and thermal conductivity tests revealed that composites with 10 phr MgCO3exhibited a char structure with proper strength and low thermal conductivity. SiC, Mg2SiO4, and MgSiO3were produced in the MgCO3/CFs‐modified composites, as characterized by X‐ray diffraction. Combined with macro lens and scanning electron misroscopy, it was proven that a fiber‐supported micro‐porous and thermally insulated char structure was conducive to the improvement of the ablation properties, which can be applied to aerospace systems for thermal shielding applications.

Lagrangian particle model for 3D simulation of pellets and SPI fragments in tokamaks

A 3D numerical model for the ablation of pellets and shattered pellet injection fragments in tokamaks in the plasma disruption mitigation and fueling parameter space has been developed based on the Lagrangian particle (LP) method Samulyak et al (2018 J. Comput. Phys. 362 1–19). The pellet code implements the low magnetic Reynolds number MHD equations, kinetic models for the electronic heating, a pellet surface ablation model, an equation of state that supports multiple ionization states, radiation, and a model for grad-B drift of the ablated material across the magnetic field. The LP algorithm is highly adaptive, capable of simulating a large number of fragments in 3D while eliminating numerical difficulties of dealing with the tokamak background plasma. The code has achieved good agreement with theory for spherically symmetric ablation flows. Axisymmetric simulations of neon and deuterium pellets in magnetic fields ranging from 1 to 6 Tesla have been compared with previous simulations using the FronTier code, and very good agreement has also been obtained. The main physics contribution of the paper is a detailed study of the influence of 3D effects, in particular grad-B drift, on pellet ablation rates and properties of ablation clouds. Smaller reductions of ablation rates in magnetic fields compared to axially symmetric simulations have been demonstrated because the ablated material is not confined to narrowing channels in the presence of grad-B drift. Contribution of various factors in the grad-B drift model has also been quantified.

Effects of LaB6 on composition, microstructure and ablation property of the HfC-TaC-SiC doped C/C composites prepared by precursor infiltration and pyrolysis

HfC, TaC and SiC with different proportions were introduced into Cf/LaB6 preform to fabricate four kinds of UHTC doped C/C composites. Results show that LaB6 could react with HfC or TaC to establish a compact ceramic structure. After ablation for 120 s, the composites doped with LaB6-HfC-TaC-SiC possessed the best ablation property, and the ablation rates were 1.129 mg/s and 3.133 μm/s. A layer with La2Si2O7, La2Hf2O7 and LaTaO4 is observed due to the reactions between La2O3 and other binary oxides. Further ablation was suppressed and stability of the multi-phase layer is therefore confirmed, indicating good coordination among the oxides.

Ablation properties and mechanisms of BN-coated Cf-reinforced SiBCNZr ceramic composites under an oxyacetylene combustion torch

The ablation properties andmechanisms of BN-coated Cf-reinforced SiBCNZr composites under an oxyacetylene combustion torch were investigated. The mass and linear ablation rates of the Cf/SiBCNZr ceramic matrix composites were lower than those of Cf/SiBCN and SiCf/SiBCN composites, reaching 0.0022 mg/s and 0.0136 mm/s, respectively. The ablation resistance of the SiBCN ceramics was enhanced by the addition of Zr, whereas the BN-coated Cf increased the thermal shock resistance of the SiBCNZr ceramics. No macrocracks were found on the ablation surface of the Cf/SiBCNZr specimen. The ablation mechanisms based on different ablation temperatures, phase evolution during ablation, and ablation morphologies in the different ablation regions consisted of oxidation of the carbon fibre and ceramic matrix, emission of various gases, the flow of high-viscosity SiO2, and denudation of Cf under the erosion of the ablation flame.

Lightweight multiscale hybrid carbon-quartz fiber fabric reinforced phenolic-silica aerogel nanocomposite for high temperature thermal protection

Multiscale hybrid method is reported to enhance thermal ablative and insulative properties of lightweight ablative materials in high temperature oxidation extreme environment. A novel lightweight hybrid carbon-quartz fiber fabric reinforced phenolic-silica (C-QF/PSi) aerogel nanocomposite was fabricated through impregnation using C-QF hybrid needled felt as three-dimensional reinforcement and PSi hybrid aerogel as matrix. The prepared aerogel nanocomposite perfectly inherits their nanoporous microstructure and fascinating properties, resulting in remarkable high compressive strength (5.96–17.01 MPa), low thermal conductivity (~0.112 W/(mK)). In particular, good thermal ablative and insulative properties in oxy-acetylene oxidizing flame (linear ablation rate as low as 0.017 mm/s and internal temperature peaks below 100 °C at 80 mm in-depth position when the surface temperature exceeds 2000 °C). From mentioned above, this lightweight composite presents huge application prospects in thermal protection and heat insulation field, especially in aerospace industry.

Influence of composite structure design on the ablation performance of ethylene propylene diene monomer composites

Abstract By introducing functional fillers into the ethylene propylene diene monomer matrix, the anti-ablation, thermal insulation, and adhesive layer were prepared, respectively. We have studied the mechanical properties, ablation properties, thermal insulation properties, and bonding properties of different composite structures after design and analyzed the ceramic mechanism. The results showed that the content of ceramic fillers improved the thermal stability and ablation properties of anti-ablation layer composites. The formation of liquid structure can fill the hole defects and ablation pit. The foaming agent improved thermal insulation properties of the thermal insulation layer, and the strength of the bonding layer has been greatly improved. The design of the composite structure can not only reduce the density but also have an excellent thermal insulation effect. And as the thickness of the heat insulation layer increases, the heat blocking effect becomes more excellent.

Effect of Antimony Trioxide and Carbon Black on the Mechanical Properties and Ablation Properties of Liner Insulation in Rocket Motors

This study focused on the mechanical properties and ablation properties of liner insulation in rocket motors for improving rocket performance by means of tensile strength, elongation, ablation rate and density. The following parameters were varied: amount of zinc oxide, antimony trioxide and carbon black (N550). It was found that the insulation of the rocket motors with antimony trioxide and carbon black provided higher the elongation and ablation rate. Thus, it was able to endure more heat from hot gas in combustion chamber. The result suggests that use of antimony trioxide and carbon black as filler in liner insulation can improve the thermal insulators and case-bonded in rocket motor between the solid propellant and the rocket motor tube.

Ablative properties of laminated ZrB2-SiC ceramic modified by SiC whisker in oxyacetylene environment

To improve the long-term service of existing laminated ceramics at ultra-high temperature, laminated ZrB2-SiC/SiCw (ZSS) ceramic was prepared by hot-pressing with SiCw (SiC-whisker) as interface layer. After ablated in oxyacetylene at 3000 °C for 100 s, the structure of ZSS remained intact and the linear and mass ablation rates were 0.12 ± 0.03 μm s−1 and 0.43 ± 0.09 mg s−1, respectively. Such excellent ablation resistance of ZSS was attributed to the reduction of the surface temperature and the formation of SiO2 layer by SiC whisker, which resulted in prominent oxidation protection and strong bonding strength at interface.

Effect of nanopowders (TiO2 and MMT) and aramid honeycomb core on ablative, thermal and dynamic mechanical properties of epoxy composites

The present work investigates the ablative, thermal and dynamic mechanical properties of epoxy resin modified with nano-titanium dioxide and organomodified monmorillonite. The composites properties with aramid honeycomb core as stiffness reinforcement were compared with those without honeycomb. Samples have been subjected to combustions gases at a temperature above 1900 °C during 120 s. The best thermal protective properties, i.e. the lowest: temperature of the rear surface area and ablative weight loss were exhibited by the composites containing 3.75% of oMMT and 1.25% of TiO2 with aramid honeycomb core. Dynamic mechanical thermal analyser measurements were carried out on an Instrument DMA SDTA861. The tests were performed by using a compression deformation mode in the temperature range from 20 °C to 140 °C. The glass transition temperature (Tg) was determined from the position of the maximum value of tan δ. This temperature reached values from about 74 °C (with tan δ = 0.59) to 79 °C (for tan δ = 0.66). The highest values of the complex modulus M* were in the range from 70 MPa to 465 MPa, for all phase compositions, but at temperature of 140 °C the complex modulus M* had much lower values in the range of 20–25 MPa.

Ablation and thermal properties of ethylene propylene diene rubber/carbon fiber composites cured by ionizing radiation for heat shielding applications

In this study, new composites were prepared from ethylene propylene diene rubber (EPDM) that loaded with various concentrations of short carbon fibers (SCFs) ranged from 5 up to 20 part per hundred part of rubber (phr). Aluminum trihydroxide (ATH) was added by two concentrations, namely 10 and 30 phr to EPDM/SCFs composites to enhance its heat shielding. Foaming agent, azodicarbonamide (ADC) was added to increase ablation resistance. Composites were prepared on open rubber roll mills, and then the rubber composites were gamma ray irradiated at different doses of 25, 50, 75, 100 and 150 kGy. Fiber incorporation into rubber matrix has been proven as a key factor in enhancing tensile strength and flame retardant properties of fabricated composites. The prepared composites were characterized by using various analytical methods counting physico-mechanical properties, thermal gravimetric analysis (TGA), Ablation test (oxy acetylene test) and propagation flame test. The utmost mechanical performance was reported for the incorporated 5 phr of carbon fiber into EPDM at 100 kGy. Also, the flame retardancy and ablation properties for composites were enhanced by increasing addition of carbon fibers and ATH in presence of ADC.

A comparison of ablative resistance properties of liquid silicone rubber composites filled with different fibers

AbstractFlexible ablative materials play a key role in thermal protection systems to protect space vehicles during hypersonic flight missions. In this work, epoxy resin modified liquid silicone rubber was adopted as elastomeric matrix. Two inorganic fibers (carbon fibers (CF) and quartz fibers (QF)) and two organic fibers (aramid fibers (AF) and poly (p‐phenylene benzobisoxazole) fibers (PBO)) were chosen as functional fillers. The ablation resistance and thermal insulation properties were evaluated using oxyacetylene torch test. Microstructure and phase composition of the char layer was fully characterized to investigate the ablation mechanism. SEM observations revealed that the fibers are well dispersed and integrated in the matrix. TGA analysis indicated that the inorganic fibers possess significantly higher thermal stability than organic fibers. In addition, a molten silica film can be formed on the material surface, which can exert a better thermal protection effect on the matrix. Furthermore, the ablation test shows that the linear ablation rate decreases first and then increases with an increase of fiber content. This work provides basic data to guide optimal selection of fibrous ablatives to enhance ablation performance.