Ablation Behavior Research Articles

The interface interaction within multi-phase oxides on the ablation behavior of the (Hf0.25Zr0.25Ti0.5)C-coated C/C composites

To investigate the effect of the multi-phase Ti-containing oxides on the ablation behavior of (Hf-Zr-Ti)C coating, the (Hf0.25Zr0.25Ti0.5)C coating was prepared on the SiC-coated C/C composites, and their ablation resistance was investigated. After ablation, Ti-poor and Ti-rich areas appeared on the coating surface, corresponding to the Ti-doped m-(Hf, Zr)O2 and o-(Hf, Zr)TiO4, respectively. Their interface interaction on the ablation resistance, microstructural evolution and defect initiation of the coating during ablation was discussed. The combination of the experimental results (SEM/TEM), first-principle calculation (VASP) and finite element simulation (ABAQUS) indicated the latter had poor plastic deformation to resist crack initiation and propagation compared to the former. The mechanical denudation produced the stress concentration, which resulted in some damaged areas appearing at the phase interface between Ti-doped m-(Hf, Zr)O2 and o-(Hf, Zr)TiO4, as well as the grain boundaries of different o-(Hf, Zr)TiO4 grains, in the forms of phase interface cracks and intergranular pores/cracks, respectively. Although these ablative defects accelerated the damage to the coating, without exposed carbon fibers and broken SiC coating after ablation for 120 s, the intact interface between SiC and C/C composites indicated that (Hf0.25Zr0.25Ti0.5)C coating had good ablation protection for C/C composites.

Ablation behavior and mechanisms of Cf/(CrZrHfNbTa)C‒SiC high‐entropy composite at temperatures up to 2450°C

AbstractThe oxide layer formed by ultra‐high melt point oxides (ZrO2, HfO2) and SiO2 glassy melt is the key to the application of traditional thermal structural materials in extremely high‐temperature environment. However, the negative effect of ZrO2 and HfO2 phase transitions on the stability of oxide layer and rapid volatilization of low viscosity SiO2 melt limit its application in aerospace. In this study, the ablation behavior of Cf/(CrZrHfNbTa)C‒SiC high‐entropy composite was explored systematically via an air plasma ablation test, under a heat flux of 5 MW/m2 at temperatures up to 2450°C. The composite presents an outstanding ablation resistance, with linear and mass ablation rates of 0.9 µm/s and 1.82 mg/s, respectively. This impressive ablation resistance is attributed to the highly stable oxide protective layer formed in situ on the ablation surface, which comprises a solid skeleton of (Zr, Hf)6(Nb, Ta)2O17 combined with spherical particles and SiO2 glassy melt. The irregular particles provide a solid skeleton in the oxides protective layer, which increased stability of the oxide layer. Moreover, the spherical particles have a crystal structure similar to that of Ta2O5 and are uniformly distributed in SiO2 glassy melt, which hinder the flow of SiO2 glassy melt and enhance its viscosity to a certain degree. And it reduces the volatilization of SiO2. In summary, the stable oxide layer was formed by irregular particles oxide and the SiO2 glassy melt with certain viscosity, thereby resulting in the impressive ablation resistance of the composite. This study fills a gap in ablation research on the (CrZrHfNbTa)C system.

Investigations of the Laser Ablation Mechanism of PMMA Microchannels Using Single-Pass and Multi-Pass Laser Scans.

CO2 laser machining is a cost effective and time saving solution for fabricating microchannels on polymethylmethacrylate (PMMA). Due to the lack of research on the incubation effect and ablation behavior of PMMA under high-power laser irradiation, predictions of the microchannel profile are limited. In this study, the ablation process and mechanism of a continuous CO2 laser machining process on microchannel production in PMMA in single-pass and multi-pass laser scan modes are investigated. It is found that a higher laser energy density of a single pass causes a lower ablation threshold. The ablated surface can be divided into three regions: the ablation zone, the incubation zone, and the virgin zone. The PMMA ablation process is mainly attributed to the thermal decomposition reactions and the splashing of molten polymer. The depth, width, aspect ratio, volume ablation rate, and mass ablation rate of the channel increase as the laser scanning speed decreases and the number of laser scans increases. The differences in ablation results obtained under the same total laser energy density using different scan modes are attributed to the incubation effect, which is caused by the thermal deposition of laser energy in the polymer. Finally, an optimized simulation model that is used to solve the problem of a channel width greater than spot diameter is proposed. The error percentage between the experimental and simulation results varies from 0.44% to 5.9%.

Ablation and mechanical behavior of reusable Cf/SiC-ZrC with a gradient-structured matrix produced by reactive melt infiltration

Cf/SiC-ZrC renowned for its outstanding performance as a thermal protectant, has gaining widespread recognition. Recent research on this system has emphasized the development of a cost-effective and reusable version with increased thickness for extended use in thick-walled thermal structural components. Ablation resistance, high strength retention, and high thermal conductivity are crucial for successful aircraft reentry. In this study, a low-cost reactive melt infiltration (RMI) method is developed for preparing dense and high-performance large-thickness Cf/SiC-ZrC (L-Cf/SiC-ZrC) with a gradient-structured matrix. The use of a fine weave-pierced fabric preform structure enhances both the structural integrity and thermal conductivity of Cf/SiC-ZrC in the thickness direction. Simultaneously, the gradient-structured matrix, with appropriate contents of surficial ZrC and SiC exhibits erosion resistance, where the internal core with a high SiC content ensures remarkable strength retention. This unique matrix-structure design is achieved by integrating porous C with a single-stage pore structure and a high degree of graphitization degree, and a Si-Zr alloy with a unique composition. The 20 mm thick Cf/SiC-ZrC obtained via RMI has a density of 2.79 g/cm3 with an open porosity of 5.65 % and flexural strength of 224.3 ± 5.4 MPa. Under a heat flux of 4.186 MW/m2, Cf/SiC-ZrC exhibits an ablation rate of −0.004 mm/s after 60 s, demonstrating its resilience against ablation damage. Moreover, the post-ablation strength (166.0 ± 4.4 MPa) exceeds that of reported Cf/SiC-ZrC congeners, highlighting the robust load-bearing capability.

Ablation behaviour and mechanical performance of ZrB2-ZrC-SiC modified carbon/carbon composites prepared by vacuum infiltration combined with reactive melt infiltration

The development of advanced aircraft relies on high performance thermal-structural materials, and carbon/carbon composites (C/C) composited with ultrahigh-temperature ceramics are ideal candidates. However, the traditional routes of compositing are either inefficient and expensive or lead to a non-uniform distribution of ceramics in the matrix. Compared with the traditional C/C-ZrC-SiC composites prepared by the reactive melt infiltration of ZrSi2, C/C-ZrB2-ZrC-SiC composites prepared by the vacuum infiltration of ZrB2 combined with reactive melt infiltration have the higher content and more uniform distribution of the introduced ceramic phases. The mass and linear ablation rates of the C/C-ZrB2-ZrC-SiC composites were respectively 68.9% and 29.7% lower than those of C/C-ZrC-SiC composites prepared by reactive melt infiltration. The ablation performance was improved because the volatilization of B2O3, removes some of the heat, and the more uniformly distributed ZrO2, that helps produce a ZrO2-SiO2 continuous protective layer, hinders oxygen infiltration and decreases ablation.

High-temperature oxidation and ablation behavior of (Zr1/3Hf1/3Ti1/3)C ceramic

With the increasing requirements on thermal protection systems of aerospace aircraft, multi-component ultra-high temperature ceramics (MC-UHTCs) are emerging and considered to be candidate materials. In this work, (Zr1/3Hf1/3Ti1/3)C ceramics were prepared by hot pressed sintering, and the behaviors from oxidation to ablation of the ceramics over a wide temperature range was systematically investigated for the first time. The oxidation rate is controlled by oxygen diffusion at initial stage with high activation energy and is slower at lower oxygen partial pressure. The intermediate layer (Zr,Hf,Ti)CxOy, along with the dense oxide layer formed through preferential oxidation, plays a crucial role in hindering oxygen diffusion. Diffusion of Zr, Hf, and Ti elements during oxidation results in Ti enrichment on the ablation surface, enhancing ablation protection. However, high temperatures and prolonged ablation times cause Ti-rich oxides dissipation and significant evaporation of TiO, resulting a porous surface, compromising ablation protection efficacy.

Effects of Zr/Ti ratios on the structure and ablation characteristics of (Zr,Ti)C–SiC composites

Dense (Zr,Ti)C–SiC composites containing a dual-phase solid solution were fabricated by spark plasma sintering using homemade Mg-modified multiphase ceramic powders as raw materials. The ablation behaviour suggested that the composite with a molar ratio of Zr/Ti = 3:1 exhibited the best ablation resistance, with low mass and linear ablation rates of −2.56 ± 0.89 mg/s and 1.26 ± 0.40 μm/s, respectively, after ablation for 90 s under a plasma flame test at around 2300 °C. It is asserted that the formation of an oxide film consisting of a self-sintered ZrO2 skeleton and a high-viscosity Ti–Mg–Si–O liquid phase was responsible for the excellent ablation resistance, which has remarkable efficacy in resisting the scouring effect of ablative flames and the erosion induced by oxidizing gases on the composite matrix.

Laser ablation behavior and mechanisms of 3D carbon fiber reinforced ZrB2-SiC composite

The high-performance 3D Cf-PyC/ZrB2-SiC composite was fabricated by vibration-assisted slurry impregnation and low-temperature hot pressing. The composite exhibited superior laser ablation resistance, leading to a low linear loss rate of 1.56×10−2 mm/s at laser power density of 4878 W/cm2 (Power 300 W, Laser beam diameter 2.8 mm) for 90 s. The coupling effect of a dense SiO2 layer in fringe region followed by dense ZrO2 layer in transitional region and next porous ZrO2 layer in center region achieved superior laser ablation resistance.

Ablation behavior of Y2O3 modified HfC-based coatings for carbon/carbon composites above 2200°C

To improve the ablation resistance of C/C composites, Y2O3 with different contents modified HfC-MoSi2 multi-phase coating was prepared by supersonic atmospheric plasma spraying. The microstructural and phase compositional evolution of as-prepared coating was studied both before and after ablation. The effect of Y2O3 content on the ablation resistance and behavior of the coating was investigated in detail. The results showed that the incorporation of Y2O3 enhances the high-temperature stability of SiO2 oxide films and suppresses their volatilization at elevated temperatures. Furthermore, the formation of Y2Hf2O7 and Y2Si2O7 through the reaction between Y2O3, HfO2 and SiO2 promotes the development of a compact oxide scale, effectively inhibiting gas diffusion into the interior of the coating. Consequently, these improvements contribute to enhanced ablation resistance of the coating.

Ablation mechanism of Cf/(Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C-SiC composite during plasma ablation above 2000 °C

Air plasma ablation behavior of Cf/(Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C-SiC composite was studied systematically with the surface temperature above 2000 °C at the ablation center. It presents a linear recession rate of 0.15 μm/s and a mass recession rate of 2.05 mg/s after ablation at 4 MW/m2 (2000 °C) for 300 s. Associated with the temperature gradient of the ablation surface, the oxidation products at different locations mainly consist of (TiZrHfNbTa)Ox, (ZrxHf1–x)6(NbyTa1–y)2O17, Ti(NbxTa1–x)2O7, (HfxZr1–x)SiO4, and SiO2. Due to the synergistic effect of the multi-component oxides, oxidation products form a protective structure composed of high melting point oxide skeleton filled with relatively low melting point phases. It retards oxygen inward diffusion and prevents the composite fragmentation caused by plasma mechanical scouring. It is believed that the results would be helpful for further improving the ablation resistance by component design of high entropy ceramics and their composites.

Long-term ablation behavior of Al4SiC4-YB4 modified Cf/ZrB2-SiC composites at 2600 °C

Long-term ablation behavior of Al4SiC4-YB4 modified Cf/ZrB2-SiC composites was characterized by air plasma torch at 2600 °C for 300 s. The phase composition and the microstructure evolution of the composites were investigated. The addition of YB4 promotes the formation of nano t-Zr0.92Y0.08O1.96 crystals, decreasing the phase transition stress in the oxide layer and reducing the volatilization of the glassy phase. However, the addition of Al4SiC4 reduces the melting point of Zr-based oxides and the viscosity of the oxide layer. Therefore, the air plasma torch blows the oxide layer away, leading to the increase of linear recession rate.

Mechanical properties, thermophysical properties, and long-term ablation behaviours of C/C–ZrC– ZrB2– W–Cu composites

Spacecraft thermal protection materials need to survive long-term exposure to oxygen-containing environments at 2400 °C. In this study, a high-density and low-porosity metal-ceramic-modified composite was prepared at a low temperature (1500 °C) in the presence of W and Cu using combined slurry brushing and reactive melt infiltration methods. An investigation of the composite formation mechanism and the effects of W and Cu indicated that W and ZrB2 were formed via dissolution-precipitation and the external diffusion of C and B, respectively. The low reaction temperature and the metallic phases significantly improved the mechanical properties, thermophysical properties, and long-term ablation behaviours of C/C–ZrC–ZrB2–W–Cu. Compared to traditional C/C–ZrC, the flexural strength and fracture toughness of the composite increased by 71.56 % and 90.05 % to 345.95 MPa and 14.52 MPa m1/2, respectively, and the thermal conductivity increased by 174.93 % to 59.11 W/m·K. In addition, W and Cu effectively lowered the surface temperature by nearly 250 °C during 300 s ablation, and the mass and line ablation rates decreased to −0.272 mg/s and −0.247 μm/s, respectively.

Ablation behavior at full-temperature ranges of C/SiC in combustion gases containing water vapor

In order to clarify the ablation behavior of C/SiC ceramics in the combustion gases containing water vapor, we proposed a novel ablation model of C/SiC at full-temperature ranges and simulated the ablation behavior of C/SiC ceramics under combustion gases environments by using our program developed in MATLAB. The numerical results indicate that the comparison between the calculation and the experimental data is in good agreement. The surface temperature of C/SiC ceramics is positively correlated with heat flux, enthalpy and pressure, while negatively correlated with the mass fraction of H2O in the combustion gases. Furthermore, the surface recession of C/SiC increases with the increase of heat flux or water vapor content but decreases with the increase of pressure. This study can predict the ablation behavior of C/SiC ceramics in combustion gases environments, and then guide for optimization of C/SiC components in scramjet engines.

A theoretical model considering the photochemical and photothermal behavior of arc radiation-induced gassing materials ablation

In this study, we introduce a theoretical model designed to explore both the photochemical and photothermal behavior of arc plasma radiation-induced ablation in gassing materials. We employ time-dependent density functional theory to analyze the photochemical behavior, while reactive force field molecular dynamics are used to explore the photothermal behavior. The phenomena, behavior and consequences of valence shell electronic excitation are analyzed in terms of ultraviolet (UV) absorption, electron-hole distribution, and Mayer bond order. Based on the photochemical findings, we apply a periodic electric field that corresponds to the vibration frequency of the permanent dipole moment to simulate infrared radiation, and convert UV photon energy into atomic kinetic energy to analyze UV radiation. This atomic-scale insight into photothermal behavior enables us to identify the final composition of ablation gases, including H2, CO, H2O, NH3, as well as specific cyanides, amines, and hydrocarbons. The results of the theoretical model and physical properties indicate that the concentration of hydrogen-containing gases in the ablation gas significantly affects the arc extinguishing capabilities of different polymers. Finally, we propose modification schemes suitable for polymers in power circuit breakers, considering UV absorption and smoke black production. Additionally, we present the potential application of theoretical models for calculating the ablation rate, necessitating further in-depth re-search.

Microstructure, wear behaviour and laser ablation behaviour of double glow plasma alloyed Ta[sbnd]W coating

TaW alloy is considered a crucial candidate for barrel protective coatings due to its high melting point, excellent high-temperature performance, and ablative resistance. In this study, TaW coating was deposited on the surface of PCrNi3MoVA gun steel by double glow plasma alloying (DGPA) technique. The morphology, phase structure, wear property, and laser ablation behaviour of the TaW deposited coating was studied and analyzed by means of scanning electron microscope (SEM), energy dispersive spectroscopy detector (EDS), X-ray diffractometer (XRD), ball-on-disk friction test, and laser pulse heating experiment. The results showed that the coating was dense and metallurgically bonded to the substrate. The coating was primarily composed of the α-Ta phase, and W was solidly dissolved in the Ta to form a mutual solution with solid-solution strengthening effect. The wear mechanisms of TaW coating were adhesive wear and oxidative wear. During the laser pulse heating (LPH) process, the transition region, center region, and splash region appeared successively in the ablation area of the coating. After 10 s of ablation, only a region with a diameter of 0.1 mm was penetrated, highlighting the effective protective role of the TaW infiltrated layer on the substrate.

Preparation of Y2Si2O7 fibrous porous ceramics and its ablation behavior with different heat fluxes

Fibrous porous ceramics have been receiving more and more applications in the thermal protection field of vehicles. In this study, we prepared Y2Si2O7 fibrous porous ceramics (YFPCs) from Y2Si2O7 fibrous membranes via the molding method. The influence of sintering time and binder concentration on the properties of YFPCs was studied, and the oxyacetylene ablation behavior with different heat fluxes was also investigated. The results showed that YFPCs obtained at 2 h sintering time had a stable component composition and constant mechanical strength. YFPCs prepared at 40 wt% binder concentration had the maximum density and compressive strength, 0.47 g/cm3 and 0.68 MPa, respectively. The as-prepared ceramics exhibited favorable ablation resistance after oxyacetylene ablation for 120 s. The minimum linear ablation rate was 2.02 μm/s when the ablated surface temperature reached 1390 °C. When the surface temperature increased to 1872 °C and 2200 °C, the fibers on the ablated surface began to melt, and the linear ablation rate increased to 9.63 μm/s and 77.63 μm/s, respectively.

Microstructure and excellent arc ablation resistance of Ni–8Al coating on copper substrate by high-speed laser cladding

In the case of electrical contact, copper alloys are often unable to withstand arc ablation and premature failure. To solve this issue, Ni-8wt.%Al (Ni–8Al) coatings were successfully prepared on copper substrates utilizing the high-speed laser cladding. In addition, the microstructure evolution, microhardness, electric conductivity and arc ablation resistance of the prepared coatings were investigated in detail. As a result, the achieved Ni–8Al coatings were structurally dense with good metallurgical bonding to the substrate, of which the microstructure showed a bottom-up evolution of fine sub-grain structure. Notably, the microhardness of the coating was 191.7 HV0.2, representing an increase of 82.57% compared to the substrate, and the electrical conductivity was 18.03 %IACS, approaching that of pure nickel. Additionally, the increase in ablation currents led to changes in the ablation behaviors and failure mechanisms of both the substrate and coating. At high currents, a huge arc ablation crater appeared in the center of the substrate due to the reaction force of the anode flame and the difference in surface tension between the liquid metal at the center and the edge of the molten pool. Nevertheless, the coatings showed better arc ablation resistance due to the improvement of molten pool stability during arc ablation by the in situ formed Al2O3 layer on the coating surface.

Atomistic insight on temperature-dependent laser induced ultrafast thermomechanical response in aluminum film

Laser-induced ultrafast thermomechanical responses significantly impact ablation behaviors. Previous studies have focused on experimental observations, offering limited insights into the atomic phase transition process. This study explores the thermomechanical response of aluminum film to temperature changes using Molecular Dynamics coupled Two-Temperature Model (MD-TTM) and pump-probe imaging. The experimental results align closely with the simulations. In the simulations, the higher initial temperature tends to confine the heat to surface layer, creating regions of high potential energy. This confinement effect leads to accelerated surface melting, as evidenced by the more rapid decrease in reflectivity captured through ultrafast imaging. As the initial temperature increases from 300 K to 500 K, the stress distribution calculations show more pronounced surface spallation and reduced interior fractures. This alteration may impede thermal conduction from the surface to the interior. Consequently, the surface's enhanced thermomechanical response lowers the ablation threshold of the aluminum film by approximately 10 % and results in a significantly flatter ablation crater. In our opinion, integrating full-size MD-TTM simulations with ultrafast imaging provides deeper atomistic insights into the dynamics of ultrafast heat and mass transfer, which is crucial for improving processing quality and expanding technological capabilities.

Fracture mechanical and ablation behaviors of C/SiC–Cu3Si–Cu interpenetrating composites and their dependence on metal addition and interface thickness

The C/SiC–Cu3Si–Cu interpenetrating composites were prepared by the ceramization and metallization of carbon fiber reinforced carbon aerogel (C/CA) preforms. Fracture mechanical and ablation behaviors as well as their dependence on metal addition and PyC interface thickness were investigated. With the presence of metallic components, the C/SiC–Cu3Si–Cu composites show pseudo-plastic fracture, typical brittle-plastic mixed fracture, and then ladder-like fracture with the PyC interface thickness increasing due to the co-existence of ductile and brittle components, obviously different from the fracture of conventional ceramic matrix composites. The composite with 3.0 μm-thick interface has the highest flexural strength of 292.8 MPa due to the proper interfacial bond strength and residual compressive stress. The composite with 1.9 μm-thick interface has the highest work of fracture but relatively low fracture toughness due to the abundant modes of crack propagation. The anti-ablation property is deteriorated with increased PyC thickness due to the weakened transpiration cooling effect and reduced oxide scale quality. The composite with 0.9 μm-thick interface exhibits lower mass and linear ablation rates of 0.054 mg cm−2 s−1 and 0.018 μm s−1 after ablation at 2200 °C for 600 s, respectively. This work provides vital insights into the control of the overall performance of carbon fiber reinforced ceramic-metal matrix composites.

Effect of stress on the steady state ablation morphology of C/C composites

During the ablation process in the thermal protection system, carbon/carbon (C/C) composites exhibit a characteristic steady state ablation morphology that includes needle-like fibers and sheath-like matrix, with deep depressions between the fibers and matrix. A theoretical explanation describing the formation of inherent steady state ablation morphology of C/C composites is proposed and we suggest that the radial thermal stress at the interface between the fibers and matrix affects the ablation thermochemical reaction of the interphase. Then, a quantitative relationship between stress and the ablation velocity of the interphase is proposed based on the mechanical coupling theory and a mesoscopic theoretical analysis model including mechanochemical coupling relationship of the steady state ablation morphology of C/C composites is established. In the mesoscopic model of steady state ablation morphology, the effect of stress on the steady state ablation morphology of C/C composites is analyzed. The results reveal that stress plays a significant role in determining the steady state ablation morphology of C/C composites, with its influence being comparable to that of material properties. Moreover, this work can be extended to further explore the ablation behavior of other ablation thermal protection composites. These findings provide valuable insights into understanding the interactions between different phenomena occurring during the ablation process of C/C composites.