Ablation Behavior Research Articles

One-step preparation and ablation behavior of ZrC-SiC-Si coating for nose-shaped ZrC/C composites with gradient pore structure by vapor silicon infiltration

To improve the ablation resistance of the nose-shaped ZrC/C composites with gradient pore structure (ZrC/CGS), a ZrC-SiC-Si coating was prepared by one-step vapor silicon infiltration. The bonding strength between the ZrC-SiC-Si coating and the ZrC/CGS composite was 21.2 MPa. The hardness and elastic modulus of the ZrC-SiC-Si coating were 1650.5 ± 30.5 HV and 176.7 ± 3.2 GPa. As the temperature increased from 200 to 1500 ℃, the CTE of the ZrC-SiC-Si coated ZrC/CGS composites increased from 4.9 × 10−6 K−1 to 6.18 × 10−6 K−1. After ablation for 40 s using oxyacetylene torch with a heat flux 2.4 MW/m2, the linear ablation rate of the ZrC-SiC-Si coated ZrC/CGS composites decreased by 54.8% compared with that of the ZrC/CGS composites, and it could be maintained at 97.4% of the original heat resistance capacity. The finite element simulation results showed that the residual thermal stresses at the coating/matrix interface were in the range of 10.7–20.2 MPa. After ablation for 40 × 3 s, the ZrC-SiC-Si coating failed.

Comparative research on cyclic ablation behavior of C/C-ZrC-SiC and C/C-ZrC composites at temperatures above 2000 °C

The cyclic and single ablation behavior of C/C-ZrC-SiC and C/C-ZrC composites prepared by reactive melt infiltration were studied. The ablation resistance properties of cyclic ablation of 30 s × 4 and single ablation of 120 s was similar to that of 60 s × 4 and 240 s. The oxidation of the matrix and the peeling content of oxides are aggravated with the increased cyclic ablation numbers. Under the cyclic ablation mode, C/C-ZrC-SiC composites showed lower mass loss than C/C-ZrC composites. At the single ablation of 240 s, C/C-ZrC-SiC composites showed desirable ablation resistance owing to the formation of an effective heat/oxygen protection layer on the ablated surface.

Atomistic investigation of cavitation and ablation in tantalum foils under irradiation with x-rays approaching 5 keV

The rapid irradiation and heating of matter can lead to material removal via a process known as ablation. While previous investigations have focused on ablation with optical and soft x-ray pulses, the process is not well understood for the high-energy x-rays delivered at current x-ray free electron laser facilities. In this paper, we use hybrid two-temperature model molecular dynamics simulations to determine the damage threshold and dynamics for tantalum foils under irradiation with x-rays in the range 1--5 keV. We report that damage occurs for foils with thickness $\ensuremath{\ge}300$ nm when heated to around 1.25 eV/atom. This damage results from the combined processes of melting and cavitation, finally resulting in the removal of material layers. The predictions of this study, in terms of the cavitation threshold and underlying dynamics, could guide interpretation of experiments as well as applications including development of beamline optics for free-electron lasers. We report consistency between cavitation and ablation behavior in isochoric heating experiments and spall processes in hydrodynamic compression and release experiments, confirming the primary modes of damage are mechanical in nature for the x-ray energies investigated.

Method Development for the Quantitative Analysis of Multivitamin Supplements by Laser Ablation–Inductively Coupled Plasma–Mass Spectrometry (LA-ICP-MS)

We present the development and optimization of an analytical method based on Laser Ablation–Inductively Coupled Plasma–Mass Spectrometry (LA-ICP-MS) for the analysis of multivitamin dietary supplements. Samples were ground and mixed with a cellulose powder containing internal standard elements; the resulting powder was pressed into pellets. Two calibration strategies were compared: (1) using increasing mass fractions of cellulose powder fortified with multiple elements of interest and (2) matrix matching using a multivitamin reference material in addition to the multi-element cellulose powder. Laser and ICP-MS parameters were closely monitored to achieve optimal conditions for monitoring multiple elements in cellulose and multivitamins while reducing the variability between replicate measurements. An energy output of 0.5 J/cm2, a repetition rate of 30 Hz, and a He carrier gas flow rate of 800 mL/min provided the best compromise between sensitivity and reproducibility. These parameters produced the most similar ablation behavior between cellulose and a matrix-matched calibration strategy. The dissimilarities in ablation yield due to differences in focus on the surface of the samples were successfully corrected after normalizing to an internal standard, resulting in relative differences of less than 10%. The results from the two different calibration approaches were compared to those obtained from solution-based ICP-MS and Inductively Coupled Plasma–Optical Emission Spectroscopy (ICP-OES) analyses. For most multivitamins, both calibration methods (i.e., cellulose and matrix-matched calibrations) performed adequately for As, B, Co, Cr, Cu, Mg, Ni, Na, Pb, and Zn. Matrix-matched calibration additionally resulted in better recoveries for S and Fe. Overall, matrix-matched calibration resulted in better recoveries for more multivitamins in comparison with cellulose calibration.

C/C–SiC composites derived from single‐source poly(silylene–acetylene) precursors

AbstractCarbon‐fiber‐reinforced carbon–silicon carbide (C/C–SiC) composites were prepared by impregnating carbon fibers with ethynylphenyl‐terminated poly(silylene–acetylene) (EPTSA) as a single‐source precursor with subsequent hot pressing and pyrolysis. The structural evolution, crystallization behavior, and graphitization of bulk C–SiC ceramics, as well as their mechanical properties and ablation behavior, were investigated. The EPTSA precursor starts to transform into inorganic SiC ceramic materials at 800°C, which is characterized by an amorphous structure with weight loss, shrinkage, and densification between 800 and 1000°C. The formation of SiC crystals inhibited the growth of the graphitic structure between 1000 and 1200°C. As the temperature was raised, both graphite and SiC crystals continued to grow, and the crystalline forms became more complete. The carbon‐fiber cloth (T300CF)‐reinforced C–SiC composite (T300CF/C–SiC) prepared using polymer infiltration and pyrolysis (PIP) exhibited excellent mechanical properties. After five PIP cycles, the flexural strength, flexural modulus, and interlaminar shear strength of the T300CF/C–SiC composite reached 169 MPa, 32.5 GPa, and 9.38 MPa, respectively. In addition, the chopped‐carbon‐fiber‐reinforced C–SiC composite fabricated using the PIP process demonstrated good oxyacetylene‐torch ablation properties.

Ablation behavior of (ZrC/SiC)3 alternate coating prepared on sharp leading edge C/C composites by CVD

A (ZrC/SiC)3 alternate coating was deposited on sharp leading edge (SLE) C/C composites by chemical vapor deposition (CVD). The ablation behavior was examined via oxyacetylene torch with heat flux of 2.38 MW/m2. The results indicated that the alternate coating exhibited great ablation resistance, providing an effective protection for C/C composites. In initial rapid heating stage, the (ZrC/SiC)3 alternate coating can relieve thermal stress, avoiding the peeling of coating and keeping an intact coating structure. In subsequent ablation, the SiC layers in central region were consumed rapidly, leaving layered interspaces. Three stacked ZrO2 layers were reserved with the assistance of the release of thermal stress by interspaces, offering a great anti-scouring effect. In transition and border regions, the alternate SiC layers can delay oxygen erosion of inner coating and C/C substrate by the formation of SiO2. It is believed that the results would be helpful for the design and application of anti-ablation coatings on SLE C/C composites.

Ablation behavior of a network interlacing ZrC-VC ceramic coating prepared by a pioneering spillover permeation

A novel network interlacing ZrC-VC ceramic coating was prepared by a pioneering spillover permeation. With the increase of Zr content in the blind vias, the content of ZrC in the coating and the density of the coating all decrease. The density of the coating on C/C–ZrC–SiC substrate is obviously higher than that on C/C substrate. The linear ablation rate of the novel ceramic coated C/C–ZrC–SiC composites was −0.06 μm/s with about 20 and 1.56 times reduction than C/C composites and C/C–ZrC–SiC composites respectively. The improved ablation resistance was attributed to a dense honeycomb ZrO2 layer filled with liquid vanadium oxide in the ablation center and the improved thermal radiation.

Effects of ZrC particle size on ablation behavior of C/C-SiC-ZrC composites prepared by chemical liquid vapor deposition

The particle size of ultra-high temperature ceramics (UHTCs) possesses a critical effect on ablation behavior of C/C-UHTCs composites. The role of ZrC particle size on ablation resistance of C/C-SiC-ZrC composites was studied in this work. Results displayed ZrC particles with ~1 µm produced a broken oxide coating on ablation surface, showing an unsatisfactory ablation resistance. It was difficult for ~3.8 µm ZrC particles to form a dense oxide coating, thus the coating could not hinder oxygen corrosion. ZrC particles with ~2.7 µm promoted the formation of a continuous and viscous oxide coating, delaying oxygen diffusion and resisting airflow scouring.

Ablation behavior of (Hf–Ta–Zr–Nb–Ti)C high‐entropy carbide and (Hf–Ta–Zr–Nb–Ti)C–xSiC composites

AbstractThe ablation behavior of (Hf–Ta–Zr–Nb–Ti)C high‐entropy carbide (HEC‐0) was investigated using a plasma flame in air for different times (60, 90, and 120 s) at about 2100°C. The effect of SiC content on the ablation resistance of HEC–xSiC composites (x = 10 and 20 vol%) was also studied. The linear ablation rate of HEC‐0 decreases with increasing ablation time, showing the positive role of the oxide layer with a complex composition. The linear ablation rate of HEC–10 vol% SiC (0.3 µm s−1) is only a 10th of that of HEC‐0, showing a significant improvement in ablation resistance, probably due to the formation of a protective oxide layer containing melted SiO2 and refractory Hf–Zr–Si–O oxides.

Ablation behavior under oxyacetylene torch of ZrC coating modified by SiC/TaC nanocomposites

Plasma-sprayed ZrC coating modified by polymer-derived SiC/TaC nanocomposite was prepared on SiC-coated carbon/carbon composites to improve the long-life ablation resistance ability. In terms of the modifiers in coatings, the SiC/TaC nanocomposites were more stable without being oxidized or molted obviously owing to the “TaC embedded in SiC” nanostructure. The thickness increase rate of SiC/TaC modified coating decreased by 41% compared with ZrC-SiC-TaC coating after ablation for 180 s. The improved ablation resistance was attributed to the thermally grown Zr6Ta2O17 and Ta2O5, which inhibited crack propagation and promoted ZrO2 sintering, forming a dense and protective layer.

Effect of different SiC/TaSi2 contents on ablation behavior of ZrB2 coating

In the present work, the ablation behavior of four kinds of ZrB2-based composite coatings with different SiC/TaSi2 contents was evaluated by a plasma flame at 1750–2000 ℃. The types of oxidation products, as well as their formation processes and influence were analyzed based on microstructure characterizations and thermodynamic calculations. The results show that obvious ablation/oxidation-resistance differences of ZrB2-SiC-TaSi2 coatings were detected. The coating of low TaSi2 content was characterized with the disappearance of SiC-depleted region and the formation of a dense intermediate oxide layer, exhibiting better ablation resistance, while the increase of TaSi2 deteriorated the ablation resistance, which conduced to the formation of oxidation layers with loose structure.

Effect of surface air cooling on the high frequent cyclic ablation of C/C–SiC–ZrB2–ZrC composite under ms-scale single loading

Influence of surface air cooling on the high frequent cyclic ablation of layer-structural C/C–SiC–ZrB2–ZrC composite was mainly studied. Tests were performed by alternant plasma and surface cooling airflow for 200 cycles under ms-scale single loading. The C/C–SiC–ZrB2–ZrC composite displayed good ablation resistance. And the ablation rates decreased firstly and then rose up with increasing of the airflow rate from 0 to 4 m3/h, whereas the highest surface temperature presented an inverse relationship. The lowest ablation rates were 0.12 μm/s and 0.038 mg/s under surface airflow of 2 m3/h. Morphologies and phases of the ablated surface indicated that the low-speed airflow was helpful to the spread out and accumulation of the ablation products whereas the stronger airflow caused surface cracks and fragments of the composite. The intensities of the mechanical erosion under different surface air cooling dominated the high frequent cyclic ablation behavior.

Control of multiphase evolution and Al-deficiency in reactive-sintered MoAlB ceramics with excessive Al

MoAlB is a ternary boride of MAB phases with strong resistance to oxidation and ablation at service temperature, thanks to preferential Al diffusion to form a protective oxide scale. However, excessive Al were often necessary in sintering of MoAlB ceramics, suggesting that a liquid-phase densification might occur thus leading to complex microstructures. By quantitative SEM analysis, ~17 mol.% Al2O3 phase was found common in MoAlB ceramics. The liquid-phase of Al-Mo-B-O facilitates the direct conversion from MoB to MoAlB before in situ formation of Al2O3. An intermediate Mo3Al8 phase competes with layered conversion, which limits the insertion rate of Al into B-B layers of MoB to form abundant Al-deficient stacking-faults. Intermetallic Mo3Al8 phase precipitates further in the intergranular regions parallel to the crystallization of Al2O3, leaving the reprecipitation of remaining Al. Both layered-conversion and intergranular oxides can improve ablation behavior for MoAlB ceramics, as well as fracture toughness and compressive strength.

High-entropy (Hf0.25Zr0.25Ti0.25Cr0.25)B2 ceramic incorporated SiC-Si composite coating to protect C/C composites against ablation above 2400 K

The ablation behavior and protection mechanism of high-entropy (Hf0.25Zr0.25Ti0.25Cr0.25)B2 ceramic incorporated SiC–Si (HETMB2-SiC-Si) composite coating on C/C composite were investigated under ultra-high temperature (up to 2404 K) dynamic ablation test using oxyacetylene torch (OAT). Thermodynamic computations, multicomponent oxide phase diagrams, schematic diagram of the oxidation protection effect of multi-component ceramics, as well as microstructure and composition evolution analyses were built and carried out. Compared with the monolithic or conventional solid-solution diborides incorporated SiC-based composite coatings, the HETMB2-SiC-Si composite coatings presented the minor mass and thickness changes after ablation for 60 s. The oxidation-dominated ablation procedure with good resistance to mechanical scouring mainly contains the selective oxidation of each elements in the coating materials, the phase separation of the Zr, Hf and Ti (group IVB) oxides, the selective melting of Si (group IVA) and Cr (group VIB) oxides, as well as the oxygen diffusion. This resulted in differentiated oxidation scale with enhanced high-temperature thermally-stable and defect-sealing ability under different ablation environments (regions). This work provides precious and insightful information for introducing high‐entropy materials to improve the heat resistance of high-temperature thermal protection systems applied in increasingly severe environments.

MoSi2 modified HfC coating for the ablation protection of SiC-coated C/C composites: Ablation resistance and behavior

To improve the ablation resistance of HfC coating, HfC-MoSi2 coatings with different MoSi2 content were prepared on SiC-coated carbon/carbon (C/C) composites by supersonic atmospheric plasma spraying (SAPS). The effects of MoSi2 content on the microstructure, phase composition and ablation behavior of HfC-MoSi2 coating were investigated. The ablation resistance of as-prepared coatings was tested under the oxyacetylene flame with a heat flux of 2.4 MW/m2. The results showed that the HfC-(25 vol%) MoSi2 coating exhibited better ablation resistance, and its mass and linear ablation rate are 0.23 mg/s and 0.48 µm/s, respectively. Such good performance was ascribed to the formation of Hf-Si-O compound phases, which effectively filled the diffusion channel of oxygen and improved the compactness of the coating.

Ablation behaviour of (Hf-Ta-Zr-Nb)C high entropy carbide ceramic at temperatures above 2100 °C

The ablation behaviour of (Hf-Ta-Zr-Nb)C high entropy carbide (HEC4) was studied at temperatures above 2100 °C using a plasma flame gun in air. The microstructures, phase and chemical compositions of the HEC4 samples were investigated after ablation. The mass ablation rate of the HEC4 samples increased with increasing ablation time from 0.21 mg cm−2 s−1 for 60 s to 0.45 mg cm−2 s−1 for 120 s. Compared to the mono- and binary carbides with commonly decreased mass and thickness after ablation, the HEC4 samples with the increased mass and thickness after ablation showed good resistance to mechanical scouring at such high temperatures and an oxidation controlled ablation mechanism. The ablation processes mainly include the oxidation of the carbide, the phase separation of the oxides, the melting of oxides, and the diffusion of oxygen. A composition gradient in the oxide layer was detected due to the different melting temperatures of the different oxides; Nb-Ta rich oxides formed at the front surface melted and became enriched at the edge of the samples, and the Zr-Hf rich oxides were enriched in the centre of the samples. The oxide layer with complex compositions and phase distributions acted as an effective ablation barrier.

High temperature oxidation and ablation behaviors of HfB2-SiC/SiC coatings for carbon/carbon composites fabricated by dipping-carbonization assisted pack cementation

To improve the uniformity and the content of HfB2 in HfB2-Si-based ceramic coating and alleviate the damage of substrate, and then enhance the high-temperature (1700 °C) oxidation and cyclic ablation resistances of carbon/carbon composites, a close-knit double layer HfB2-SiC/SiC coatings with a mosaic structure and high content of HfB2 were prepared by a novel dipping-carbonization assisted pack cementation methods (DPCHS/S). In contrast, a HfB2-SiC/SiC coatings were also fabricated by pack cementation (PCHS/S). Results revealed that the oxidation and ablation protective performances of the DPCHS/S coatings were superior to those of PCHS/S coatings. After 30 thermal cycles between 1500 °C and room temperature, the mass gain of the coated sample was 0.78%, and the mass loss was 1.65% after oxidation at 1700 °C for 156 h. Moreover, under an oxyacetylene torch ablation for 180 s (3 cycles), the linear ablation rate of the DPCHS/S coated specimen was 1.62 μm/s, which was much lower than that of PCHS/S coated specimen (3.08 μm/s).

Novel strategy and multi-scale modelling of integrated multifunctional composite for thermal protection under extreme environment

In order to overcome the shortcomings of the heritage thermal protection materials with only a single function as well as the macroscopic evaluation method lacking the consideration of manufacture parameters, in this study, a novel strategy of integrated multifunctional composite with an overall 3-Dimensional reinforcement weave fabric and multifunctional zones was prepared, and a new multi-scale computational modelling for evaluating its thermal protection performance was established. The properties of constitute materials were characterized, as well as the thermal and ablative behavior of the integrated multifunctional composite were tested by oxyacetylene test. The new modelling took the detail weaving parameters as well as the physical and chemical mechanisms of the composite into consideration. The model was solved by our FORTRAN codes. The experimental and simulation results showed that this new integrated composite had high structural efficiency, thermal insulation and recession resistance. The multi-scale computational modelling can be applied on the evaluation of the performance of the integrated woven composite in a bottom-up manner, which gives a refined design method for thermal protection materials.

Ablation behaviour of Cf–ZrC-SiC with and without rare earth metal oxide dopants

Continuous carbon fibre/carbon composites are candidates for ultra-high temperature applications due to their ability to retain their strength at elevated temperatures, however they easily oxidize and ablate in high temperature oxygen-based environments, a fact that seriously limits their applications in the aerospace industry. The introduction of ultra-high temperature ceramics (UHTCs) as a matrix in carbon fibre preforms effectively improves their oxyablation resistance at ultra-high temperatures in air atmospheres. In the present study, zirconium carbide-based ultra-high temperature ceramic matrix composites (UHTCMCs) simultaneously doped with silicon carbide and rare earth (RE) metal oxides were prepared by a slurry impregnation and pyrolysis method using phenolic resin as the bonding agent. The combination of injection and vacuum impregnation achieved a maximum density of up to 60% of theoretical. These composites were subsequently evaluated in terms of their ablation properties using an oxyacetylene (OAT) torch at temperatures of ∼2500 °C for 60 s. No significant surface damage was observed on any of the ablated samples. When ceria was used as the RE metal oxide dopant, the evidence suggests that cerium silicate was formed by the ceria dissolving in the molten silica; though this didn't appear to offer very much additional oxyablative protection. In contrast, when yttria was used, it improved the performance via stabilization of the cubic zirconia that formed on oxidation; this provided the greatest protection of all the samples tested. The combination of both ceria and yttria yielded the combined mechanism.

Mechanical and ablative properties improvement of HfC-SiC coatings upon introduction of TiC

A novel structural Hf-Ti-Si-C multiphase solid solution coating was designed and manufactured by chemical and solid solution reactions to improve the mechanical and ablation behavior of HfC-SiC coatings. Results show that, with TiC addition, the formed HfxTi1−xC and (Ti1−xHfx)3SiC2 solid solutions can significantly enhance the micro-mechanical and ablation properties of the coating. The improved hardness and modulus, as well as the reduced ablation rates are mainly attributed to the optimized structure and solid solution reinforcing effect of coating. Moreover, the Ti-additives are conducive to restrain the active oxidation of SiC. Furthermore, HfTiO2 can reduce the oxides cracking due to the inhibited crystal transformation of HfO2 and its good self-healing ability, forming a dense and stable oxide scale with superior thermal protection.