Thermal Protection Properties Research Articles

BaTiO3-B2O3-MgO-Na2O-CaO glass series: Radiation shielding, thermal, and mechanical properties

The effect of BaTiO3 on the mechanical, thermal and radiation shielding properties of the borate glass with the composition of (60-x)B2O3 + 10MgO + 15Na2O + 15CaO+(x)BaTiO3 (x: 0,2.5,5,7.5 and 10 mol%) were synthesized by the melt quenching method. The physical, thermal, mechanical and radiation protection properties of the glasses produced with this designed composition were carefully investigated. As the BaTiO3 amount increased from 0 % to 10 %, the density of the glass increased from 2.571 to 2.870 g/cm3 and the glass thermal stability (ΔT) also enhanced from 51 to 63. The LAC value at 276 keV, 0.2831 cm−1 for 0 % BaTiO3 and enhanced linearly with increasing BaTiO3 concentration and reach to 0.3475 cm−1 at 10 % BaTiO3. The experimentally obtained MAC values are in agreement with the theoretically calculated MAC values with XCOM and MCNP6.2. It was concluded that the increase in the BaTiO3 value of the glass positively affects the radiation shielding properties of the glasses.

Influence of Three-Dimensional Skeletal Support by Different Fiber Felts on Thermal Protection Properties of Aerogel Composites

Influence of Three-Dimensional Skeletal Support by Different Fiber Felts on Thermal Protection Properties of Aerogel Composites

Physiological and hygienic assessment of a multilayer set of personal protective equipment against low temperatures made using membrane materials

Introduction. Advanced personal protective equipment (PPE) against low temperatures is a high–tech product created using the latest achievements of science, design designs, ergonomic, aesthetic solutions that determine its thermal protection properties. The use of membrane materials in PPE from low temperatures allows them to combine low weight and high thermal protection properties, low air permeability and sufficient vapor permeability necessary to ensure heat and moisture exchange between humans and the environment. The study aims to determine the thermal protection properties of various sets of multilayer workwear and indicators of heat and moisture exchange of volunteers when modeling professional activity at low air temperature. Materials and methods. The authors have conducted a study in a microclimatic chamber with the participation of six practically healthy male volunteers. The researchers have determined the thermal protection properties of multilayer workwear of various configurations in accordance with GOST R 12.4.185-99 and MUK 4.3.1894-04. As test samples, they have used pipes of three different configurations to protect against low temperatures, wind, water, general industrial pollution and mechanical influences, as well as short-term exposure to open fire. The assessment of heat and moisture exchange indicators of various PPE configurations was carried out by specialists when modeling work activities with measurements of the relative humidity level in the layers of the kits and the level of accumulated moisture in each element of the PPE. Results. The authors have determined the values of thermal insulation of the studied materials and the scope of their application. To assess heat and moisture exchange, two samples of PPE were selected, made using membrane and cotton fabrics with similar thermal insulation values. The analysis of the results of studies of moisture exchange indicators showed a slightly lower efficiency of moisture evaporation of the control sample. The indicator of the relative humidity of the air under the shelter space and between the layers of the package of materials and clothing has shown its informative significance for assessing the effectiveness of moisture transfer from the surface of the human body to the environment. Conclusion. The results of a physiological and hygienic assessment of a set of multilayer clothing made of membrane materials have shown that various combinations of its constituent elements make it possible to create kits that provide adequate protection for an employee in a wide range of air temperatures and wind speeds. The use of membrane materials in combination with structural elements (ventilation openings) provides a more efficient transfer of moisture from the skin surface to the external environment, as evidenced by the values of the relative humidity index of the air under the clothing space and between the layers of clothing. Ethics. The study was approved by the local Ethical committee of the Izmerov Research Institute of Occupational Health (Minutes of the meeting No. 6 dated 07/20/12)

The role of PEG/glycerol ratio on the structure and corrosion protection properties of PU-silica coating

In this work, investigation was made of the effect of incorporation of polyethylene glycol (PEG) in glycerol-based PU-silica coatings, with the aim of enhance thermal, mechanical, and corrosion protection properties, and establish a comprehensive knowledge regarding the synthesis of novel hybrid PU coatings with variable PEG/glycerol molar ratio. Nuclear magnetic resonance (13C NMR) and Fourier transform infrared (FTIR) spectroscopy analyses showed the conjugation of the PEG to the PU structure by urethane bonds, with the samples prepared using a higher amount of PEG presenting a less rigid structural conformation. Small-angle X-ray scattering (SAXS) measurements demonstrated a correlation between the inorganic fractal dimensionality and the PEG amount. The increasing PEG content contributes to improve thermal stability, coating roughness, and scratch hardness, that achieves typical values of 230 °C, 115 nm and 6H, respectively. As an anticorrosive barrier for steel, the 1.5 μm thickness coating prepared with 75 % glycerol and 25 % PEG exhibits an impedance modulus exceeding 10 GΩ.cm2 over 28 days in contact with saline solution. This new PEG/glycerol-based PU-silica coating proves highly suitable functional features for anticorrosive applications, offering commendable thermal stability, low thickness, high scratch resistance, and impressive impedance.

Structure-property relationship of polyhedral oligomeric silsesquioxanes/polydimethylsiloxane superhydrophobic coatings for cotton fabrics

Cotton fabrics are extensively utilized in daily life due to striking advantages such as softness, breathability, skin-friendliness, and cheapness. However, they are susceptible to being contaminated owing to inherent amphiphilicity, severely affecting service lifespan and aesthetic perception. To address this issue, three distinct types of the POSS/PDMS composite coatings are explored, and applied to cotton fabrics, respectively. Subsequently, the correlations between structures of POSS and properties of the composite coatings on the modified cotton fabrics are discussed. The results show that the three types of the POSS/PDMS composite coatings impart the modified fabrics with robust superhydrophobicity even in harsh environments including mechanical damage, chemical corrosion and UV-irradiation. Notably, the damaged POSS/PDMS composite coatings on cotton fabrics can exhibit excellent superhydrophobic self-healing capability by simple heating. Meanwhile, the modified fabrics also show excellent performances in self-cleaning, anti-fouling, anti-icing and oil-water separation applications. Additionally, due to multifunctional groups of MTPOSS, the cotton fabric treated by the MTPOSS/PDMS composite coating exhibits more excellent thermal, mechanical, and UV protection properties without significantly compromising its air permeability as compared to those of the other coated cotton fabrics. This work will pave the way to exploitation and applications of novel multifunctional textiles.

Shaping of thermal protective properties of basalt fabric-based composites by direct surface modification using magnetron sputtering technique

Abstract A direct modification of the surface of the basalt fabric was carried out by using magnetron sputtering to obtain composites intended for effective protection against contact and radiant heat. One-layer composite with a coating of aluminum (Al) and zirconium dioxide (ZrO2), two-layer composite with a coating of Al/ZrO2, and two-layer composite with a coating of Al/(ZrO2 + titanium dioxide [TiO2]) were deposited on the fabric surface. Scanning electron microscopy with energy-dispersive X-ray spectroscopy analysis was used to assess the coating on basalt fabrics and determine their chemical composition. Parameters such as thermal conductivity coefficient, resistance to radiant heat, and resistance to contact heat for a contact temperature of 250°C were determined for assessment of the composites from the point of view of protective properties. The similarity analysis of composites was performed to state the impact of coating components’ content and coating thickness on chosen parameters. It was found that a two-layer composite in which the outer layer is Al and the inner layer is a mixture of ZrO2 and TiO2 provides good thermal insulation properties. The composites capable of protecting against contact heat at the first efficiency level and against radiant heat at the second efficiency level were obtained.

Thermal protection properties of profiled timber with peat-vermiculite insulation

Today, the use of environmentally friendly materials is becoming increasingly important. The construction of energy-saving buildings with enclosing structures made of insulated profiled timber, is one of the most promising areas in low-rise construction.Materials having minimum negative impact on the environment during their operation, include new construction insulation materials based on peat-vermiculite granules. The paper studies the main physical properties of wooden exterior walls made of profiled timber, in which peat vermiculite is used as insulation, thermal conductivity of which ranges from 0.05 to 0.06 W/(m·K). For this purpose, numerical simulation is performed for the heat-mass transfer in wooden enclosing structures made of insulated timber with three different connector options.The temperature and heat flow distributions are obtained as a result of modeling stationary thermal conductivity processes in timber structures. It is shown that plywood connectors do not affect the thickness temperature distribution in wooden walls with peat-vermiculite insulation. An increase in thermal conductivity of insulation has no significant effect on the temperature difference along the connector axis or outside the region of its temperature influence.It is found that the thickness of the peat-vermiculite insulation layer should be at least 0.176 m to ensure the compliance with the main requirements for thermal protection properties of enclosing structures in the climatic conditions of Tomsk. The greatest heat loss with a minimum insulation thickness is observed for the wall made of profiled insulated timber with T-shaped connectors. A high-strength timber with the additional central lamella has the best thermal protection with the lowest insulation thickness.

A Multifunctional Approach to Optimizing Woven Fabrics for Thermal Protective Clothing

This paper presents a detailed exploration of the development and characterization of multifunctional dual-purpose woven fabrics for thermal protective clothing. Through this research, 69 woven fabric prototypes have been carefully designed and produced, integrating various raw materials, yarn, and woven fabric construction parameters, with the aim of optimizing thermal protection properties while ensuring comfort and durability. The analysis led to the identification of two optimal woven fabric samples, which, upon further testing, exhibited exceptional dimensional stability, crease recovery, tear resistance, as well as abrasion and water resistance. Furthermore, the thermal properties were evaluated, demonstrating exceptional flame resistance, limited heat transmission, and high thermal insulation. Additionally, the study evaluated dynamic thermal properties, contact conductive heat transfer, air permeability, water vapour resistance, and thermal resistance of two clothing systems constructed from selected woven fabrics. Statistical analysis confirms significant differences between clothing systems, highlighting the influence of yarn composition and fabric structure on thermal performance and comfort, where one system exhibits better thermal insulation characteristics suitable for colder environments while the other excels in breathability for warmer climates. The developed woven fabrics meet high standards for protective clothing against heat and flame, surpassing currently available comparable woven fabrics on the market in terms of efficacy and performance. This research provides insights into the intricate balance between protection, comfort, and durability of woven fabrics, contributing to advancements in protective textile technology.

Carbon/ZrO2 aerogel composite microtube superfoam.

High-performance thermal insulation materials with broad application prospects have attracted great attention. The introduction of new microstructures into thermal protection materials can significantly improve the thermal insulation performance. The tubular microstructure has obvious advantages such as thermal insulation, lightweight, mechanical, and other properties. Therefore, the microtubular structure has become an important reference microstructure for the development of high-performance thermal insulation materials. In this paper, the carbon/ZrO2 aerogel composite microtube superfoams with excellent thermal protection properties were prepared by a vacuum filtration and high-temperature carbonization method. The ZrO2 aerogel precursor solution can be quickly and uniformly adsorbed on the inner and outer walls of cellulose microtubules. These adsorbed ZrO2 aerogel precursor solution films can be converted into ZrO2 alcohol gel shells under the acceleration and promotion effect of citric acid at 65 °C. The micromorphology of the ZrO2 aerogel shell on the inner and outer walls of the composite microtubes can be efficiently controlled by the concentration of the ZrO2 aerogel precursor solution and the carbonization temperature. The carbon/ZrO2 aerogel composite microtube superfoam exhibits a lower thermal conductivity, lower density, good mechanical properties, and high ablation resistance. The thermal conductivity of the carbon/ZrO2 aerogel composite microtube superfoam is as low as 0.040 ± 0.001 W m-1 K-1. The residual rate of the carbon/ZrO2 aerogel composite microtube superfoam is still as high as 84.33% after butane flame ablation for up to 3600 seconds.

Improving thermal insulation and fire resistance of ceramifiable EVA/ceramic hybrid composites via low temperature sintering and foaming strategy

Energy efficient buildings, propulsion components and thermal protection systems require materials with high thermal protective properties. Traditional polymer composites or ceramic materials have limited comprehensive applications because of their poor thermal protective properties or poor processability. Herein, a novel fire resistant and thermally insulating polymer/ceramic hybrid ceramifiable composite was developed based on low temperature sintering principle and foaming on fire strategy. Specifically, the influences of raw materials of low temperature ceramics, such as glass frit, phosphate, etc, on the properties of ceramifiable ethylene-vinyl acetate (EVA) composites were investigated. Its fire resistance and thermal insulation properties were evaluated by simulating different sintering environments. The results show that the ceramifiable composite exhibits the highest improvement in fire resistance because a crystalline phase was formed at high temperatures. Gas evolution from the thermal decomposition of ammonium polyphosphate (APP) and EVA contributes to the formation of the porous structure in ceramic residues. The optimal system can resist above 1000 °C flame for 30 min without disintegration, and the temperature of the unfired side was maintained around 200 °C. The reliability of the strategy was verified by the effective medium theory model.

Polyimide aerogels with low thermal conductivity and high-temperature stable properties prepared by lyophilization for flexible thermal protection

Polyimide aerogel, presenting an outstanding new material for lightweight protective thermal insulation, has garnered significant attention in the aerospace field. Despite its potential, due to the high production cost of the supercritical drying method used for its preparation, its widespread application is limited. In this research, a series of lightweight polyimide aerogels (F-PIAs, 3,3',4,4'-biphenyl tetracarboxylic dianhydride (s-BPDA) and 4,4'-diaminodiphenyl ether (ODA)) with excellent thermal protection properties were prepared by lyophilization. The findings indicated that F-PIAs (Freeze-dried polyimide aerogels) exhibited comparable physical characteristics to S-PIAs (Supercritical-dried polyimide aerogels), while their preparation cost was even more economical. F-PIAs exhibits excellent flexible and compression behavior (compression strength up to 1.16 MPa, modulus up to 12.8 MPa), which provide a great structural basis for the production of molded thermal insulation protective materials. The average pore diameter of F-PIAs is in the range of 7∼11 nm. The nanoporous structure leads to the gas within the pores of the aerogel producing the Knudsen effect, thereby significantly enhancing the thermal insulation performance of the aerogel. The thermal conductivity of F-PIA-4 (Freeze-dried polyimide aerogels with a solid content of 4%) at room temperature is as low as 0.023 W·m−1·K−1, which is superior to the PIAs (0.043 W·m−1·K−1) prepared by lyophilization in literature. Its thermal diffusion coefficient changes from 0.108 mm2·s−1 to 0.18 mm2·s−1 in the temperature range of 27°C to 200°C, demonstrating good thermal insulation performance at high temperatures. Meanwhile, after heating on a 150°C flat plate for 11 min and 41 s, the surface temperature of F-PIA-4 was only 36.2°C, further verifying its excellent thermal insulation performance. The results of the TGA experiment on F-PIA-4 demonstrated the high-temperature stability of aerogel (Td5% is higher than 523°C, Td10% is higher than 566°C). The exceptional properties of F-PIAs hold significant practical reference value in helping to reduce the manufacturing cost of high-performance aerogel thermal insulation materials, thereby enabling their widespread application in aerospace, military, and civil field.

Synthesis of carbon aerogels with controlled morphology and pore structure to modulate their bulk density and thermal conductivity via a quick one-pot preparation strategy

How to improve the preparation efficiency and reduced production costs in synthesizing high-performance polymer-derived carbon aerogel materials with ultra-low density and excellent thermal protection properties is currently a crucial research topic that has been plaguing scientists for decades. In this study, we innovatively propose a “one-pot” preparation strategy to synthetize carbon aerogel, which can simplify the complex processes of conventional fabrication methods, greatly shorten the preparation time of phenolic resin-based organic aerogel, and obtain the corresponding carbon aerogels after carbonization. Here, a series of carbon aerogel samples are obtained by regulating the solvent species, and their physicochemical properties such as morphology, pore structure shrinkage, density, and thermal conductivity of these samples are discussed in detail. CA@isoamylol is screened out exhibiting the lowest bulk density (0.15 g/cm3) and thermal conductivity (0.0499 ± 0.0029 W/m·K at 25 °C and 0.1069 ± 0.0090 W/m·K at 1200 °C), which is comparable to the reported values of best-in-class carbon aerogel values, and much lower than the conventional carbon foams. The synthesized CA@isoamylol is promising as a condidate for thermal insulation material. It is expected that the “one-pot” method could alleviate the above-mentioned bottlenecks of the carbon aerogel discipline to produce high-performance carbon aerogel materials with a low-cost and efficient routes.

Investigation of Thermal and Solar Properties of Aerogel Powder Coated Textiles

Aerogels, the lowest-density solids in the world, have very effective thermal insulation properties with their extremely high surface area and porous structure. Recently, there has been an increasing interest in using aerogels in the textile industry, especially to obtain functional and technical textiles. In this study, thermal and solar properties of polyester fabrics coated at different concentrations (1 %, 2 %, and 4 %) of aerogels with different particle sizes (~ 8 µm, 0 – 80 µm, 0 – 0.5 mm) were investigated. It was observed that the aerogel particle size and concentration had a significant effect on the thermal and solar properties, and the lowest thermal conductivity coefficient and thermal resistance values (0.036 W/mK and 14.33 m2 K/W, respectively) appeared at the largest particle size and maximum concentration. In contrast, the solar reflectance values of the coated samples decrease up to 62 % with increasing aerogel particle size. In a conclusion, the coating method with aerogel powders could be applied to improve the thermal insulation and solar protection properties of mainly curtains, tents, tarpaulins, and sportswear fabrics.

Incorporating Variable Porosity into the Determination of Effective Permeability in Interchanging Double Cloth Woven Fabrics Using Darcy's Law.

Woven fabrics are widely used for thermal protection due to their porosity, which provides thermal insulation and breathability. This research focuses on investigating the influential parameters in the thermal protective properties of layer interchanging double cloth, including the woven structure and varying yarn fineness. The properties affecting the protective properties and comfort of multilayered woven fabrics include the fabric thickness, fabric porosity, and air permeability. Darcy's law is applicable for determining the effective air permeability of woven fabrics. By understanding and controlling fabric porosity, it becomes possible to develop thermal protective clothing that combines improved comfort, cost-efficiency, and effectiveness. This study represents a novel approach for the clarification of airflow permeability behavior in complex structures of elastic multilayer woven fabrics using Darcy's law. This innovative approach expands the understanding of permeability in fabrics beyond single-layer fabrics with vertical pores or 3D fabrics used in resin injection processes.

Influence of DETA on Thermal and Corrosion Protection Properties of GPTMS-TEOS Hybrid Coatings on Q215 Steel

High-performance coating could be used to protect steels in engineering. The GPTMS-TEOS hybrid coatings were successfully prepared using (3-glycidoxypropyl) trimethoxysilane (GPTMS) and tetraethylorthosilicate (TEOS) as reaction raw materials and diethylenetriamine (DETA) as both a curing agent and catalyst at room temperature. The hybrid coating contained amorphous SiO2 and was characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The DETA content of the hybrid coating has a significant impact on the performance of the coating. As the DETA content increases, the thermal stability of the hybrid coating increases at 400–600 °C due to the production of more SiO2 in the amine-rich state. However, the gelation time decreases dramatically, preventing the hybrid coating from better infiltrating the surface of the steel substrate. In addition, there are not enough silicon hydroxyl groups to bond with the hydroxyl groups on the surface of carbon steel and adhesion is significantly reduced. Therefore, hybrid coatings with a moderate DETA content (NH:epoxy ratio equivalent to 1:1) show the best corrosion resistance, with a third-order magnitude increase in corrosion resistance compared to that of carbon steel.

Studies on the growth mechanism of aluminide coating on K444 alloy surface by chemical vapor deposition

The studies of the growth mechanism of aluminide coatings by chemical vapor deposition (CVD) is an important prerequisite for optimizing the thermal protection properties of aluminide coatings and improving the CVD process parameters; however, the current research on the growth mechanism of CVD aluminide coatings on nickel-based alloys is relatively limited, and there is a lack of systematic studies in this area. In this work, aluminide coatings were prepared on the surface of nickel-based superalloys by the CVD method, and elemental diffusion and microstructure effects between coating and substrate at different deposition temperatures and times, as well as the growth kinetics and formation mechanism of CVD aluminide coatings were investigated. The results showed that the coating prepared on the surface of K444 nickel-based high-temperature alloy by CVD was an externally diffused aluminide coating with a bilayer structure: the outer layer of the coating was the β-NiAl phase. The interdiffusion layer was mainly composed of nickel-aluminum compounds, carbides, and topologically close-packed phase. The growth of the CVD aluminide coating was mainly controlled by the grain boundary diffusion mechanism.

Dual Properties of Microwave Absorption and Thermal Protection in La0.5Sr0.5FeO3–Al2O3 Pseudobinary Composites

As multifunctional material for microwave absorption and thermal protection, the dielectric and thermophysical properties of equilibrium phases in LSF(La0.5Sr0.5FeO3)–Al2O3 pseudobinary phase diagram are investigated herein. Four pseudobinary composites are obtained by sintering at 1400 °C for 10 h with different raw components (x wt% LSF‐(100−x) wt% Al2O3, x = 20, 40, 60 and 80), labeled as LSFA20, LSFA40, LSFA60, and LSFA80, respectively. After sintering, the main equilibrium phase in LSFA20 and LSFA40 composites is SrAl12O19‐based solid solution. For LSFA60 and LSFA80, however, LSF‐based and SrAl12O19‐based solid solutions are the main equilibrium phases. The increase of conductive LSF content results in the highest dielectric loss tangent and the best microwave absorbing property in LSFA80, in which the bandwidths for reflection loss less than −10 and −5 dB are about 2.37 and 7.7 GHz, respectively, when the thickness is only 1.5 mm. The thermophysical properties reveal that the thermal conductivity in LSF‐Al2O3 pseudobinary composites shows weak temperature dependence because of the opposite contribution between phonons and electrons. It is lower than that of the traditional thermal barrier coating material of 8 wt% Y2O3‐stabilized zirconia (8YSZ).

Preparation and Thermal Protection Properties of Basalt/Polyimide Three-Dimensional Spacer Woven Fabrics

Preparation and Thermal Protection Properties of Basalt/Polyimide Three-Dimensional Spacer Woven Fabrics

Fiber-reinforced alumina-carbon core-shell aerogel composite with heat-induced gradient structure for thermal protection up to 1800 °C

High performance thermal insulation materials are urgently demanded for hypersonic spacecraft. Aerogels are considered as promising candidates owing to their low density and low thermal conductivity. However, some deficiencies, such as the unsatisfactory high-temperature thermal insulation properties and the non-exfoliation-resistant particle porous structure of ceramic aerogels, the ease of oxidation and large carbonization shrinkage of carbon aerogels, remain great challenges for their further applications in high-temperature aerobic ablation environments. Here, we report a multiscale fiber-reinforced Al2O3-carbon core–shell aerogel composites with low density (0.23–0.31 g·cm−3), excellent mechanical properties (4.89 MPa at 10% strain) and ultra-low carbonization shrinkage (as low as 1.33%). Benefiting from the synergistic effect of in situ nano-doped light-shading carbon layers, porous Al2O3 ceramic rod skeleton and oriented fibers, the composites demonstrate an extremely low high-temperature thermal conductivity (0.055 W·m−1·K−1 at 1200 °C) that is far superior to those of existing high-temperature insulating aerogel composites. In addition, the unique heat-induced gradient structure also confers outstanding thermal protection properties to the composite at 1800 °C with a liner ablation rate of 6.44 μm·s-1and a mass loss rate of 0.167 mg·s−1. This work not only opens a new path for the preparation of thermal superinsulating materials used for spacecraft, but also provides a simple solution to the difficulty of compatibility between low-density insulating porous skeleton and ablation-resistant tough structures, thereby enabling thermal insulation materials to possess desired ablation-resistant properties.

THE INFLUENCE OF FRACTAL DIMENSION OF OXIDE LAYER ON PASSIVE OXIDATION OF THE C/SiC COMPOSITE

The C/SiC composite is a promising material for ablation-resistant thermal protection in near-space hypersonic environments. The formation of an SiO2 oxide layer through passive oxidation on the surface of the composite is a significant factor influencing its performance. It is essential to accurately predict the thickness of the SiO2 oxide layer and the recession and mass loss of the C/SiC composite during passive oxidation. The SiO2 oxide layer is a typical porous media exhibiting self-similarity and thus fractal theory can be applied to establish the relation between the oxygen flow rate and microstructural parameters of the oxide layer. The Weierstrass–Mandelbrot (WM) function is employed to simulate the rough interfaces between the SiO2 oxide layer and the C/SiC composite to evaluate the influence of the fractal dimensions of the oxide layer on the performance of thermal protection of the C/SiC composite. The results show that the C/SiC composite exhibits improved thermal protection performance when accompanied by a lower tortuosity fractal dimension and a higher pore area fractal dimension of the oxide layer. Conversely, the composite demonstrates enhanced ablation resistance with a higher tortuosity fractal dimension and a lower pore area fractal dimension of the oxide layer. The predictions of the calculation model show good agreement with the experimental data and demonstrate the critical influence of microstructural parameters of the oxide layer on passive oxidation of the composite, providing practical implications for designing materials with desired thermal protection or ablation resistance properties.