Experimental Study on the Influence of Carbon Black Nano Particles on Ablative Properties of Carbon/Phenolic and Silica/Phenolic Composites

The study focus on fiber‐reinforced polymer composite materials, which are widely used in the mechanical industries for various applications. While using the composite materials, mechanical properties such as tensile, flexural, and interlaminar shear strength plays vital role in selection of composite materials. The current work aims to investigate the influence of adding nanosilica at varying weight percentages (0, 2, and 4) to the epoxy matrix on the tensile, flexural, and interlaminar shear strengths of the fiber‐reinforced polymer hybrid nanocomposite. The five carbon and four Kevlar layer hybrid polymer nanocomposites are made with woven fibers. The method used to improve the dispersion of nanosilica in the epoxy resin was high‐speed shearing. The hand lay‐up process was used to manufacture hybrid polymer nanocomposite laminates, which were then effectively postcured. The tests for tensile strength, flexural strength, and interlaminar shear strength were carried out in accordance with ASTM standards D3039, D790, and D2344, respectively. According to the tested specimens, a hybrid composite including 2 wt.% of nanosilica with epoxy provides better tensile strength of 6.83%, flexural strength of 10.13%, and interlaminar shear strength of 13.54% more than a hybrid composite without nanosilica. At 4 wt.% of nanosilica addition to epoxy matrix, the tensile, flexural, and interlaminar shear strength decreased when compared to 2 wt.% of nanosilica due to agglomeration. The addition of 2 wt.% nanosilica to the epoxy matrix in carbon/Kevlar fiber‐reinforced polymer hybrid composites yields superior tensile, flexural, and interlaminar shear strength compared to other weight percentages.

To shield re-entry spacecraft from the extreme heat experienced during hypersonic flight through a planet's or the earth's atmosphere, thermal protection systems (TPS) were developed. This work involved the fabrication of composites using a polyacrylonitrile (PAN) based carbon fabric (Cf)-phenolic resin matrix (PR) modified with different weight percentages (wt.%) of silicon carbide (SiC), namely 0 wt.% (Cf/PR), 1wt.%, 3wt.%, and 5wt.%. The composites were prepared using the hydraulic hot press method. The manufactured composites were analyzed for their thermal conductivity and resistance to ablation using an oxyacetylene torch test. Furthermore, the ablated composites underwent X-ray diffraction (XRD), revealing a SiO2 compound layer on the ablated composite surface. The experimental results demonstrated that the Cf/PR composites modified with 3wt.% of SiC exhibited superior characteristics. The composites consist of 3wt.% Cf/PR-SiC exhibited a thermal conductivity value of 0.57 W/m K. Additionally, these composites showed a noticeable decrease in the mass ablation rate (MAR) at 0.0052 mm/sec and linear ablation rates (LAR) at 0.025061 gm/sec. This study proposed an effective way to improve the thermal and ablation characteristics of TPS materials.

ZrB2–SiC coating to protect carbon/carbon composites against ablation

In order characterize the outstanding performance of the three dimensional (3D) hybrid composites, the charpy and flexural test has been carried out. 3D fiber structures have been achieved by using hand lay-up process and machine stitching method. Materials for hand lay-up and machine stitching process were glass fiber, jute fiber, and epoxy resin and nylon fiber respectively. Two dimensional (2D) glass fiber composite and 2D hybrid composite with the same stacking sequence as three dimensional (3D) counterparts have also been fabricated for the comparison of impact and flexural strength. The impact strength of 3D hybrid composite was increased (5-10%) compared with that 2D glass fiber and 2D hybrid composites. The flexural strength and modulus of 3D hybrid composite were increased (5-10%) compared with that of 2D hybrid composites.

We introduce a novel processing method, in which we utilize assisting nanomaterials, i.e. cellulose nanocrystals (CNCs), to incorporate pristine carbon nanotubes (CNTs) in CFRP composites. We show that hybrid CFRPs made with CFs coated with CNC-bonded CNTs exhibit higher flexural and interlaminar shear strength (ILSS) compared to those coated with functionalized CNTs. Coating the CF layers with 0.2 wt% functionalized CNTs (fCNTs) increases the flexural strength by 8%. However, when the CF layers are coated with 0.2CNC-0.2pCNT (pristine CNT), the flexural strength enhances by 31% compared to that of the uncoated composites. The ILSS follows a similar trend to that of flexural strength, where fCNT increases 12% the ILSS, however, 0.2CNC-0.2pCNT enhances the ILSS by 42% compared to that of neat CFRP composites. Therefore, CNC-pCNT coated CFRP exhibits 23% higher flexural strength and 30% higher ILSS compared to those coated with only fCNT.

The mechanical behavior of carbon-fiber-reinforced polymer (CFRP) laminates manufactured using plasma-assisted solvolysis recycled fibers was evaluated experimentally through a comprehensive mechanical testing campaign. The plasma-assisted solvolysis parameters were selected based on an earlier sensitivity analysis. Prepregs made from both virgin and recycled carbon fibers were fabricated via a hand lay-up process and manually stacked to produce unidirectional laminates. Longitudinal tension tests, longitudinal compression tests, and interlaminar shear strength (ILSS) tests were performed to assess the fundamental mechanical response of the recycled laminates and quantify the retention of mechanical properties relative to the virgin-reference material. Prior to mechanical testing, all laminates underwent ultrasonic C-scan inspection to assess manufacturing quality. While both laminate types exhibited generally satisfactory quality, the recycled-fiber laminates showed a higher density of defects. The recycled laminates preserved around 80% of their original tensile strength and maintained an essentially unchanged elastic modulus. Compressive strength was more susceptible to imperfections introduced during remanufacturing, with the recycled laminates exhibiting roughly a 14% decrease compared with the virgin material. On the contrary, the compressive modulus was largely retained. The most substantial reduction occurred in ILSS, which dropped by 58%. Overall, the results demonstrate that plasma-assisted solvolysis enables the recovery of carbon fibers suitable for remanufacturing CFRP laminates, while the observed reduction in mechanical properties of recycled CFRPs is mainly attributed to defects in manufacturing quality rather than to intrinsic degradation of the recycled carbon fibers.

Growth of ZnO nanorods/flowers on the carbon fiber surfaces using sodium alginate as medium to enhance the mechanical properties of composites

Influence of polymerization mode on flexural properties of esthetic resin luting agents

The purpose of this study is to evaluate the impact of different infill patterns on the mechanical and ballistic behaviour of 3D-printed carbon-nylon composites. The carbon nylon material was used to print samples with different infill patterns such as (Tri-Hexagon, Cubic, and Gyroid) and with an infill density of 80%. The mechanical tests such as tensile, flexural, impact, and interlaminar shear strength (ILSS) were examined on the printed samples. The results have shown that the gyroid pattern had shown better performance in mechanical characteristics. The mechanical characteristics of 3D printed samples with gyroid pattern showed improvements of 16.63% in tensile strength, 5.64% in flexural strength, 6.52% in impact strength, and 16.72% in ILSS respectively in contrast with tri-hexagon infill pattern. Micrograph evaluation was done on the damaged surfaces of tensile and flexural tested specimens. The microscopy image of the gyroid pattern’s fractured surface has revealed improved bonding, minimal voids, and no delamination, which may be the cause of the increase in mechanical properties. Besides, the micrograph image revealed that more voids in the cube pattern, are considered to be responsible for its lower mechanical performance. The high-velocity impact test was done to examine the energy absorption behaviour and damage propagation of 3D printed samples with an infill density of 80%. The findings revealed that the gyroid pattern improved their impact resistance. The ballistic impact test results show that the gyroid pattern affords better energy absorption because of its continuous structure, and efficiently disperses impact energy throughout the sample’s entire volume. The printed samples with the gyroid pattern showed a 5.24% rise in energy absorption than the cube pattern. The optimal infill density and infill pattern could be used to make materials for impact applications due to their better mechanical and energy absorption abilities.

High-performance three-dimensional boron nitride fiber reinforced silicon nitride (BNf/Si3N4) composites were prepared by the infiltration and pyrolysis (PIP) process using BN fiber fabrics as the reinforcing body and excellent nitride organic precursor (Perhydropolysilazane, PHPS) as the Impregnated liquid. The ablation resistance of the composite was evaluated by plasma jet ablation test in air. The results show that a uniform and dense interface layer is formed on the fiber surface, with thickness is about 100 nm, and the XRD test shows that it is hexagonal BN (h-BN). The density of the composite reaches more than 1.72 g·cm-3 and the bending strength is more than 80 MPa. Under the condition of plasma jet ablation test at 2000 °C / 200 s, the mass ablation rate is 3.32 × 10-4 g/s, the linear ablation rate is 4.78 × 10-3 mm/s. The prepared materials have excellent resistance to high temperature ablation, and are expected to be used in the field of high temperature microwave transparent such as high mach missile radome, antenna window and so on.

This study advances the design of high-performance hybrid composites by integrating experimental characterization, multi-criteria decision-making, and statistical optimization. Epoxy-based composites reinforced with jute (J), glass (G), and carbon (C) fibers were fabricated in six distinct stacking sequences and evaluated for tensile strength, flexural strength, tensile modulus, flexural modulus, and break strain. The C5 configuration, featuring carbon fibers on the outer layers and glass fibers internally, demonstrated exceptional flexural strength (227 MPa) and tensile modulus (7.79 GPa), underscoring the critical role of fiber placement in optimizing mechanical performance. While C5 exhibited a marginal reduction in tensile strength (3.7% lower than C1), its balanced properties validated the efficacy of hybrid architectures. AHP-TOPSIS analysis ranked configurations using weighted mechanical criteria, identifying CG4C as optimal for balanced performance. To validate and refine this selection, Response Surface Methodology (RSM) was employed to model nonlinear relationships between stacking parameters and mechanical responses. High predictive accuracy (R² > 0.90 for modulus and break strain) and desirability-based optimization confirmed C5’s superiority, achieving a composite desirability score of 0.57. This work establishes a novel framework bridging decision-theoretic ranking (AHP-TOPSIS) and statistical modeling (RSM), demonstrating their synergistic utility in composite design. The methodology not only identifies optimal configurations but also quantifies trade-offs between strength, stiffness, and ductility, offering a scalable pathway for developing sustainable, application-specific hybrid composites. By validating rankings against RSM-predicted performance regions, this approach enhances confidence in material selection processes for structural and high-stiffness applications in aerospace, automotive, and construction industries.

This article presents a structured comparative review of carbon-phenolic and carbon-elastomeric ablative composites used in thermal protection systems for aerospace and hypersonic applications. The review critically examines the influence of various ceramic, metallic oxide, and polymeric fillers on ablation behaviour, char formation, mechanical integrity, and erosion resistance. Reported studies employing oxy-acetylene torches, plasma wind tunnels, flames, and laser ablation are systematically analyzed using metrics such as linear ablation rate (LAR), mass ablation rate (MAR), heat flux, and exposure duration. The role of hybrid filler systems in enhancing char stability and thermal resistance is discussed through mechanistic correlations between filler chemistry, char microstructure, and ablation performance. Key challenges in data normalization and cross-comparison are highlighted. Finally, the article outlines specific future research directions, including multi-physics ablation modelling, AI-assisted material design, graded thermal protection architectures, and in-situ diagnostics, to advance the development of next-generation ablative composites.

Influence of water immersion on mechanical properties of quasi-isotropic glass fibre reinforced epoxy vinylester resin composites

Fiber-reinforced polymer composites are used as emerging materials to repair oil and gas transmission pipelines without stopping the flow of fluids inside. These pipelines are subjected to harsh environment conditions such as being buried under soil and being exposed to high humidity, high temperatures, and different chemicals. It is important to predict the useful life of composite repairs in these harsh conditions in order to design better and to have robust repair solutions. This study evaluates mechanical properties, namely tensile strength tensile modulus, flexural strength, flexural modulus, and lap shear strength, of composite laminates when exposed to harsh environmental conditions such as hot-wet [70°C/85% relative humidity (RH)] for 0, 2, 4, and 6 weeks, steam autoclave [121°C and 1,05,000 Pa (1.05 bar)] for 0, 6, and 12 h, and ultraviolet (UV) ray exposure of type UVA-340 at 50°C for 0 and 2 weeks. The glass fiber–reinforced polymer (GFRP) composite laminates are prepared by hand layup process and are cut using a water-jet cutting process to avoid machining defects and to keep a good surface finish. The specimens are exposed to these corresponding environmental conditions for different periods of time, and the changes in their mechanical properties are studied. The tensile strength, flexural modulus, and lap shear strength values are compared with unexposed specimens. Decreases in strength and modulus values are observed for exposed specimens. A simple empirical expression is developed to predict the usable lifetime of a composite repair system exposed to such different harsh environmental conditions.

Comprehensive oxidation mechanisms of heterogeneous laminated HfB2–SiC/Ti ceramics under oxyacetylene conditions