Ablation Behavior Research Articles

Ablation behavior of a SiC/ZrC–SiC coating on C/CA composite for high-temperature thermal protection

To enhance the ablation resistance of carbon-reinforced carbon aerogel (C/CA) composites, a SiC/ZrC–SiC coating was applied using slurry brushing and gaseous silicon infiltration techniques. The samples were exposed to an oxyacetylene flame at temperatures exceeding 2000 °C for 60 s, after which the peak front-side temperature of the coated C/CA was 288 °C lower than that of pure C/CA. The linear ablation rate of the coated C/CA (1.72 ± 0.08 μm/s) decreased by 89.7% compared to that of pure C/CA (16.4 ± 0.08 μm/s). The reduction in the front-side temperature was attributed to the high emissivity of the SiC coating and the evaporation of SiO2 during ablation. Moreover, due to its low oxygen permeability, the dense SiO2–ZrO2 layer prevented the inner coating and matrix from further oxidation. In addition, the introduction of phenolic resin nanoparticles within the C/CA matrix limited heat conduction, resulting in a peak back-side temperature of only 91 °C for the 10-mm-thick sample.

Enhanced high temperature ablation resistance of dense ZrB2–Al2TiO5 composite coating by very low-pressure plasma spraying

ZrB2-based composite coatings with addition of Al2TiO5 were prepared via very low-pressure plasma spraying using mechanically mixed powder of ZrB2 and Al2O3-40 wt%TiO2 (AT40). The ablation behavior of the composite coating was investigated using a high temperature plasma jet at a temperature of ∼2500oC. Results demonstrate the addition of AT40 improved the ablation resistance of the ZrB2 coatings at high temperatures. The coating with 17 vol%AT40 addition exhibited the lowest ablation rate, approximately 1.33 μm/s, which is only one-third of that of the pure ZrB2 coating. The added AT40 filled the pores between ZrO2 crystals during ablation, reducing oxygen penetration and lowering the ablation rate. However, excessive addition of AT40 hindered gaseous B2O3 release and thus led to large pore formation, impairing the protective effect. The ZrB2-AT40 coating is a promising candidate for high-temperature applications.

Laser ablation behavior and mechanism of Cf/C–SiC composites under different laser energy densities

Ceramic matrix composite (CMC) is typical difficult-to-machine material, laser assisted machining (LAM) is an effective method to solve the problem of poor machinability, and a deep understanding of the interaction between laser and material can lay a foundation for LAM. Aiming at the unclear mechanism of microstructure formation, crack propagation and material hardness evolution of laser-irradiated CMC, laser ablation behavior and mechanism of Cf/C–SiC composites under different laser energy densities were studied in this paper. The results show that Cf/C–SiC presents two different states of modification and ablation under irradiating. In modified state, fiber interface in central area is oxidized, and crystal transformation occurs. Amorphous Si–O–C, Si and spherical SiO2 exist in edge deposition area, and continuous phase disappears in heat affected zone. In ablative state, carbon nanosheets and clusters are formed in ablation groove. Surface of convex and deposition area are composed of sedimentary basement and clusters, and there are recast layer and heat affected zone in cross section. When thermal stress exceeds interfacial bond strength and critical matrix stress, the fiber interface debonding and matrix cracking occur, and both transgranular and intergranular fracture exist in the matrix. When laser scanning direction is perpendicular to fiber extension, crack propagation can be inhibited. The propagation and intersection of cracks and coarsening of SiC crystal phase in heat affected zone lead to the decrease of matrix microhardness. The results of this study can be used to provide references for parameters selection and theoretical support for LAM of CMC.

Ablation behavior of gradient ceramic-polymer composites in wind tunnel environment

Ceramic matrix composites are desirable for applications in extreme environments due to the excellent ablation resistance, but few ceramic materials can exhibit a matched load bearing capacity currently. The technological potential of functionally graded materials, such as improved ablation resistance and enhanced load-bearing capacity, has opened up the feasibility for designing highly efficient thermal protection materials. In this study, composite insulation tiles, with three-dimensional braided carbon fibers in a ceramic-polymer continuous gradient matrix, are designed and fabricated by using a temperature-controlled polymer-derived ceramic method. The ablation behavior of the specimens exposed to high-temperature high-speed wind tunnel environments has been investigated at a total enthalpy of 15.8 MJ/kg. Temperature response, morphology and composition characteristics are obtained, which allows detecting oxidation resistance and thermal stability of the gradient composites. The results showed that the formation the silicon oxide layer covering the ablated surface and the inner gradient layer composed of amorphous SiCN ceramics display a key role in resisting ablation and reducing heat conduction. Meanwhile, the underlying resin layer can display superior load-bearing capacity at environment temperatures lower than pyrolysis. The present study highlights high ablation behavior of continuous gradient ceramic-polymer composites, offering a possibility in developing thermal protection composites with good trade-off between thermal and mechanical properties.

Influence of the material properties and the process parameters on the ablation behavior for the laser structuring of the diffusion media for fuel cells

Hydrogen-powered polymer electrolyte membrane fuel cells (PEMFCs) show promising potential to power a wide range of mobile and stationary applications and to reduce greenhouse gas emissions significantly. In PEMFCs, the oxygen transport and the water transport are essential for a long lifetime and high-performance characteristics. The diffusion media (DM), located between the bipolar plate and the catalyst-coated membrane, is a crucial component of the fuel cell that significantly affects the cell-internal processes. Usually, the DM is a two-layer material system consisting of a microporous layer based on carbon black particles coated onto a porous gas diffusion layer (e.g., carbon paper). The properties of the microporous layer regarding the water transport at high current densities and, consequently, the fuel cell’s performance and lifetime can be improved by laser structuring. Within this work, different microporous layers with varying binder content and porosities were structured by locally ablating the material using ultrashort-pulsed laser radiation in the infrared wavelength range. The effect of varying process parameters was additionally investigated. Furthermore, the ablation efficiencies were calculated for increasing pulse repetition rates to qualify a process window for an industrial structuring process. The size of the micro-drillings and the heat-affected zone surrounding the hole were evaluated through topographic and microstructure analyses using a laser scanning microscope and a scanning electron microscope with energy-dispersive x-ray spectroscopy. The results showed a rather small influence of the porosity and composition of the microporous layer on the ablation behavior. In contrast, the laser structuring parameters influenced the micro-drilling geometry significantly.

Machine Learning Approaches for Predicting the Ablation Performance of Ceramic Matrix Composites

Materials used in aircraft engines, gas turbines, nuclear reactors, re-entry vehicles, and hypersonic structures are subject to severe environmental conditions that present significant challenges. With their remarkable properties, such as high melting temperatures, strong resistance to oxidation, corrosion, and ablation, minimal creep, and advantageous thermal cycling behavior, ceramic matrix composites (CMCs) show great promise as a material to meet the strict requirements in these kinds of environments. Furthermore, the addition of boron nitride nanoparticles with continuous fibers to the CMCs can offer thermal resistivity in harsh conditions, which will improve the composites’ strength and fracture toughness. Therefore, in extreme situations, it is crucial to understand the thermal resistivity period of composite materials. To forecast the ablation performance of composites, we developed six machine learning regression methods in this study: decision tree, random forest, support vector machine, gradient boosting, extreme gradient boosting, and adaptive boosting. When evaluating model performance using metrics including R2 score, root mean square error, mean absolute error, and mean absolute percentage error, the gradient boosting and extreme gradient boosting machine learning regression models performed better than the others. The effectiveness of machine learning models as a useful tool for forecasting the ablation behavior of ceramic matrix composites was effectively explained by this study.

Multiphysics modeling for local structural heat source and high-speed airflow coupled ablation behavior of the lightweight quartz fiber-reinforced phenolic (LQFRP) composite

Multiphysics modeling for local structural heat source and high-speed airflow coupled ablation behavior of the lightweight quartz fiber-reinforced phenolic (LQFRP) composite

Carbonization mechanism and ablation behavior of Zr/Hf-ZrC1−x/HfC1−x rods prepared by in-situ reaction method

Carbonization mechanism and ablation behavior of Zr/Hf-ZrC1−x/HfC1−x rods prepared by in-situ reaction method

Ablation behavior of ZrC-SiHfOC-MoSi2 coating for carbon/carbon composites under Ar-O2 plasma flame

To improve ablation resistance of ZrC-SiMOC-based (M = transition metal) coatings, a ZrC-SiHfOC-MoSi2 coating was investigated. The results showed that the MoSi2 shell limits the decomposition of SiC under SAPS and decreases pores of the coating. ZrC-SiHfOC coating showed large-area peeling after an Ar-O2 plasma flame ablation for 90 s. In contrast, ZrC-SiHfOC-MoSi2 coating revealed low ablation rates after ablation for 360 s, with the mass and linear ablation rates of −0.05 mg/s and 0.14 μm/s, respectively. MoSi2 provides rich SiO2 to form ZrSiO4 to reduce the damage by plasma flame, thereby improving the ablation resistance of ZrC-based coatings.

Revealing damage evolution and ablation behavior of SiC/SiC ceramic matrix composites by picosecond laser high-efficiency ablation

The picosecond laser was utilized to fabricate the slanting microholes efficiently on SiC/SiC ceramic matrix composites. The machining damage, material oxidation, and temperature field were mainly analyzed through static and in-situ detections. The damage evolution and ablation behavior of SiC/SiC composites were qualitatively and quantitatively revealed. The results showed that the lowest peak temperature of the slanting microhole was 282.6 °C. The heat accumulation effect and thermal stress that was tensile stress in nature present caused recasts, microcracks, fiber fracture, fiber debonding, and fiber stripping. Fibers and matrix underwent slight oxidation, forming SiO2 recasts through the phase transition. The pulse energy, frequency, and inclination angle regularly affected the quantity, size, and distribution of microcracks, material removal rate (MRR), and hole wall roughness. The maximum MRR was about 2.5 mm3/s, corresponding to the minimum time was 0.9 s. The circularly polarized picosecond laser could process parallel striped laser-induced periodic surface structures (LIPSS) on the hole wall.

Microstructure and ablation behaviour of C/C-SiC-ZrC-Cu composites prepared by reactive melt infiltration

To satisfy the requirements for the new generation solid rocket motors on high ablation-resistant throat materials, an idea that merges passive and active thermal protection together was applied to modify carbon/carbon composites. In this study, SiC and ZrC were used as passive thermal protection materials along with the active thermal protection material Cu to modify C/C composites. C/C-SiC-ZrC-Cu composites were prepared by two-step reactive melt infiltration, which involved the infiltration of Si/Zr followed by Cu/Ti. The Cu content of the C/C-SiC-ZrC composites was controlled by controlling the open porosity of the porous C/C-SiC-ZrC composites. Microstructure, composition and ablation resistance of the C/C-SiC-ZrC-Cu composites were investigated. The results showed that the composites with high Cu content and density exhibited excellent short-term ablation resistance under the 42 kW plasma flame, with a negative linear ablation rate after 20 s of ablation. The active heat dissipation of Cu during the ablation process results in a significant reduction of the thermal response temperature on the composite surface. Moreover, the generated Si-Ti-Zr-O layer could form an effective barrier to protect the matrix.

Study on multi-scale ablation behavior of C/SiC composites under high-energy CW laser irradiation

This work conducts ablation experiments and multi-scale numerical simulations of C/SiC composite materials under CW laser action. The highest surface temperature, macroscopic and microscopic ablation morphology, and approximate ablation threshold for C/SiC composites at different power densities were obtained. A multi-scale ablation calculation method for C/SiC composite materials under CW laser action was established using the level-set method. At the meso-scale, a macro-mesoscopic cross-scale surface ablation model was established, taking into account factors such as solid heat transfer, heat exchange of chemical reactions, differential temperature rise process between internal fibers and matrix, and differences in ablation behavior of two-dimensional plain weave fabrics. The experimental and microscale simulation results indicate that different ablation behaviors (oxidation and sublimation) occur in different regions, resulting in “shoot tip” fibers and residual matrix pore morphology. This work can provide theoretical and experimental basis for the design and precision machining of C/SiC materials.

Effect of different rare earth fluoride doping on microstructure and ablation properties of C/C–ZrC–SiC composites prepared by molten salt assisted reactive melt infiltration

The effect of doping with rare earth elements of different ionic radii on the ablation resistance of C/C–ZrC–SiC composites was investigated and the ablative behavior and ablation resistance of C/C–ZrC–SiC composites with the addition of different rare earth elements was tested. Although rare-earth doped stabilized zirconia has been used for a long time in the field of thermal barrier coatings, the existing techniques are usually coating modifications with rare-earth oxide or boride additions, it is difficult to prepare coatings that can be used on the surface of carbon matrix materials due to the large difference in the coefficients of thermal expansion. Therefore, this study attempts to introduce rare earth components into the interior of C/C–ZrC–SiC composites for matrix modification. The results show that the addition of rare earth elements enhances the ablation performance of the composites, but the mechanism of enhancement is different: rare earth ions with a smaller radius difference from Zr4+ ions stabilize the crystal structure of ZrO2 by forming replacement solid solutions and stabilize the surface oxide film structure by preventing the homogeneous multiphase transformation of the oxide to achieve higher ablation performance; whereas rare earth ions with a larger radius difference from Zr4+ ions cannot stabilize ZrO2 by replacement solid solutions, but instead form high viscosity, low volatility liquid phase oxides to heal the surface defects of the oxide film and reduce liquid phase dissipation to enhance ablation performance.

Study on the ablation behavior of C/SiC composite materials under the action of local structural thermal sources

This study uses ablation testing on C/SiC composite materials under local structured thermal sources with a wide range of heat flux densities, simulating the harsh local conditions caused by discontinuous structural interference on spacecrafts. The thermal response, ablation laws, and ablative perforation time of C/SiC composite materials are obtained under different heat flux densities. The experimental findings demonstrate that there are notable differences in the morphology of the ablation pits under various heat flux conditions. As the heat flux density increases, the temperature of the local structure heat source action center on the target surface increases, the depth and outer diameter of the erosion pits increase, and the wall surface of the erosion pits gradually tends to be smooth. Under the influence of local structural heat sources, the creation of material ablation pits and the process of material perforation are predicted using the improved Umeshmotion+ALE+birth and death element method. For various conditions, the temperature field results and ablation morphology are well predicted by the numerical simulation results. Numerical calculations can be used to analyze the thermal stress and oxidation sublimation contribution rates of targets under the action of structural heat sources.

Microstructure evolution and ablation mechanisms of Csf/ZrB2-SiC composites at different heat fluxes under air plasma flame

In this study, short carbon fibre (Csf) reinforced ZrB2-SiC composites were fabricated via direct ink writing followed by precursor infiltration and pyrolysis. The ablation behaviour of the composites was investigated at heat fluxes of 4–6 MW/m2 under an air plasma flame, which revealed excellent ablation resistance with negative linear ablation rates of − 0.1 to − 0.5 µm/s. The results showed that ZrO2-SiO2 oxide layer was formed on the ablation surface after ablation, which provided effective protection to the internal materials. With an increase in heat flux, ZrO2 precipitated from the SiO2 melt first in the form of nano-tetragonal ZrO2 (t-ZrO2), owing to the vaporisation of SiO2. During cooling, the nano t-ZrO2 particles were retained, and some of them reacted with SiO2 to form ZrSiO4, thus improving the thermal stability of the SiO2-ZrO2 oxide layer. In contrast, t-ZrO2 agglomerated and grew owing to capillary force and finally transformed into monoclinic ZrO2 (m-ZrO2). Moreover, a higher heat flux led to the size of precipitation ZrO2 increases, meanwhile increasing the content of t-ZrO2 and ZrSiO4 in the oxide layer.

Ablation behavior and mechanisms of high-entropy rare earth titanates (Y0.2Gd0.2Ho0.2Er0.2Yb0.2)2Ti2O7 coating deposited by plasma spraying technology

High-entropy rare earth titanates (Y0.2Gd0.2Ho0.2Er0.2Yb0.2)2Ti2O7 (YHT) have great application potential in the thermal protection coating field. In this work, the YHT coating was successfully prepared by atmospheric plasma spraying. The influence of different spraying powers and coating ablation behavior by plasma flame on the phase composition and microstructure morphology of the coating surface, cross-section and fracture surface were investigated using X-ray diffraction, scanning electron microscopy and atomic force microscope. Results show that the YHT powder has a sufficiently melted state before impacting the metal substrate and the coating can be effectively deposited through optimizing the plasma spraying power. And the YHT coatings undergo slight sintering, leading to the formation and growth of a spherical structure at 1200 °C, while the grain preferential growth, mechanical failure and water-like structure occurred due to strong thermal shock at 1400 °C. In addition, when the coating surface temperatures are 1200 °C and 1400 °C, the corresponding heat insulation temperatures are 590 °C and 620 °C, respectively, indicating that YHT coating has good thermal insulation ability. This study provides a powerful theoretical basis and technical support for the application of high-entropy rare earth titanates YHT as a thermal protection material for high temperature devices.

Ablative behavior and mechanism of SiC f/SiBCZr composites prepared by PIP process

Ablative behavior and mechanism of SiC _f/SiBCZr composites prepared by PIP process

Microstructural evolution and ablation behaviors of NbSi2/SiO2–Nb2O5/X (X=MoSi2, MoSi2-Yb2O3, MoSi2-Yb2O3–ZrC) multilayer coatings on Nb alloy in different ablation environments

To improve the high-temperature ablation resistance of Nb alloys, multiphase-multilayer ceramic coatings were prepared using a novel strategy combining halide activated pack cementation (HAPC) and liquid plasma-assisted particle deposition and sintering (LPDS) methods. The MoSi2, Yb2O3, and ZrC particles were deposited individually or co-deposited on the NbSi2 bottom layer to obtain NbSi2/SiO2–Nb2O5/MoSi2 (Mo), NbSi2/SiO2–Nb2O5/MoSi2-Yb2O3–SiO2 (MoYb), NbSi2/SiO2–Nb2O5/MoSi2-Yb2O3–ZrO2–ZrC (MoYbZr) multilayer ceramic coatings, respectively. Results showed that all three coatings remained intact after propane ablation (1500 °C), exhibiting excellent ablation resistance. For the harsher oxyacetylene ablation environments with higher temperatures (1800 °C), Mo coating suffered from long cracks, bubbling, and localized spalling and MoYb coating sprouted massive cracks without spalling. The oxide scale integrity of the MoYbZr coating was well maintained without cracks, exhibiting excellent resistance to oxyacetylene ablation attributed to the incorporation of Yb2O3 and ZrC. The mass and linear ablation rates of MoYbZr coating were only 0.137 mg/s and 0.196 μm/s after oxyacetylene ablation, which were 25.14 % and 49.61 % lower than that of MoYb coating, and 88.01 % and 75.37 % lower than that of the Mo coating, respectively. The Yb2O3 strengthened the Si–O bonding in the SiO2 network and increased the viscosity of the SiO2 scale, thus enhancing the self-healing ability of the oxide scale and slowing down the evaporation of SiO2. The oxidation products (ZrO2 with SiO2) from MoSi2 and ZrC further reacted to produce ZrSiO4, which can inhibit microcrack creation and extension. Micropores in the Zr–Si–O oxide scale mitigated thermal stresses, inhibited crack initiation and extension. The Yb2O3, Yb2SiO5, and ZrSiO4 embedded in the SiO2–ZrO2 scale acted as pinning effects, enhancing the high-temperature structural stability, thereby improving the ablation resistance of the MoYbZr coatings.

Ir–Zr coating through a pack cementation method for ultra-high temperature applications

An Ir–Zr intermetallic coating was prepared onto Re/Ir coated graphite through a pack cementation method. The microstructure, nanoindentation and ablation behaviors of the coating system were investigated. The Ir–Zr coating was about 20 μm thick and consisted of 4 intermetallic phases which showed a quasi-gradient transition in composition. Nanoindentation measurements indicated that most of the intermetallic phases had higher hardness but lower Young's modulus compared to pure iridium. By ablation test in a high-frequency plasma wind tunnel, the heat flux limit of the Ir–Zr coating was measured to be about 6.1 MW/m2, and the endurance time was about 100 s under this condition. The coating failed at ∼2240 °C during the ablation test when the iridium melted, but the unfused parts remained complete and in good adhesion with the iridium beneath. The average normal emissivity between 2 and 5 μm of the sample was measured to be ∼0.82 at around 2092 °C before failure, which was higher than pure iridium and bulk ZrO2.

Nanosecond laser ablation behavior of C/SiC composites under water layer protection: Experiments and theoretical investigation

Due to their excellent properties, C/SiC composites have gradually become a high-quality choice for structural parts in aerospace and other fields. However, the manner by which to achieve high-quality and efficient surface micromachining is still the focus of current research. In this study, we explored a new method of underwater nanosecond laser processing of C/SiC composites to obtain a machined surface with high cleanliness, less redeposition, and small heat affected area. The ablation behavior and material removal mechanism in the air and water environments were analyzed and compared by using a variety of characterization methods in combination with thermodynamic theory. The changes of the groove depth, width, surface morphology in different fiber directions, and material composition in the two environments were analyzed. The results showed that the removal of materials is realized by thermochemical corrosion in both environments. The water environment benefits from the cooling function of water layer, which alleviates heat accumulation in the processing area, and the heat affected area is small. Furthermore, the mechanical action of the water layer captured the vast majority of SiO2 produced by oxidation reaction, effectively avoiding its redeposition on the machined surface and improving the surface cleanliness. For C/SiC composites, this work provides a feasible method for high-quality processing.