Ablation and mechanical properties of ZrC-reinforced PBI resin matrix composites

With the rapid development of laser technology, there is an increasing demand for laser protective materials. Thus, the mechanical and ablation properties of composite materials need to be further enhanced. Herein, solution impregnation and hot-press molding were used to develop composites containing various mass ratios of ZrC to polybenzimidazole (PBI) resin (thickness = 3 mm) for laser ablation applications. The results showed that adding short carbon fiber (SCF) to ZrC/PBI composites improves the ablation and mechanical properties. The ZrC/PBI/SCF composites were ablated using a high-energy continuous laser (7 kW cm⁻²), and the composites did not burn through. The composites did not peel off or split as the ablation process progressed. With the increase in the ZrC content in the composites, dense oxide layers are formed, enhancing the ablation properties of the composites. The ZrC/PBI/SCF composite (the ZrC/PBI mass ratio = 2:1) exhibited the lowest mass loss (2.24%), mass ablation rate (0.119 mg s⁻¹) and linear ablation rate (0.032 mm s⁻¹). This indicates that ZrC/PBI/SCF composites can be used as protective materials in high-energy continuous laser applications.     

Fabrication of C/SiC composites by siliconizing carbon fiber reinforced nanoporous carbon matrix preforms and their properties

Reactive melt infiltration (RMI) has been proved to be one of the most promising technologies for fabrication of C/SiC composites because of its low cost and short processing cycle. However, the poor mechanical and anti-ablation properties of the RMI-C/SiC composites severely limit their practical use due to an imperfect siliconization of carbon matrixes with thick walls and micron-sized pores. Here, we report a high-performance RMI-C/SiC composite fabricated using a carbon fiber reinforced nanoporous carbon (NC) matrix preform composed of overlapping nanoparticles and abundant nanopores. For comparison, the C/C performs with conventional pyrocarbon (PyC) or resin carbon (ReC) matrixes were also used to explore the effect of carbon matrix on the composition and property of the obtained C/SiC composites. The C/SiC derived from C/NC with a high density of 2.50 g cm^?3 has dense and pure SiC matrix and intact carbon fibers due to the complete ceramization of original carbon matrix and the almost full consumption of inspersed silicon. In contrast, the counterparts based on C/PyC or C/ReC with a low density have a little SiC, much residual silicon and carbon, and many corroded fibers. As a result, the C/SiC from C/NC shows the highest flexural strength of 218.1 MPa and the lowest ablation rate of 0.168 µm s^?1 in an oxyacetylene flame of ～ 2200 °C with a duration time of 500 s. This work opens up a new way for the development of high-performance ceramic matrix composites by siliconizing the C/C preforms with nanoporous carbon matrix.     

Thermal expansion and mechanical properties of phenolic resin/ZrW2O8 composites

Phenolic resin/ZrW₂O₈ composites were successfully fabricated and their coefficient of thermal expansion (CTE) as well as mechanical properties was investigated. The CTE of the composites decreases from 46 × 10^–6 to 14 × 10^–6 K^?1 when the ZrW₂O₈ volume fraction increases from 0 to 52 vol %. The CTE of the composites is analyzed by some theoretical models; Schapery's upper bound provides the best estimate of the reduction in CTE. The Barcol hardness of the composites increases with an increase in the ZrW₂O₈ volume fraction. The bending strength of the composites with 19–25 vol % of ZrW₂O₈ fillers shows a maximum value of 130 MPa, which is 45% larger than that of phenolic resin without fillers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Electromagnetic wave absorption and mechanical properties of silicon carbide fibers reinforced silicon nitride matrix composites

It is difficult for ceramic matrix composites to combine good electromagnetic wave (EMW) absorption properties (reflection coefficient, RC less than -7 dB in X band) and good mechanical properties (flexural strength more than 300 MPa and fracture toughness more than 10 M P·m^1/2). To solve this problem, two kinds of wave-absorbing SiC fibers reinforced Si₃N₄ matrix composites (SiC_f/Si₃N₄) were designed and fabricated via chemical vapor infiltration technique. Effects of conductivity on EM wave absorbing properties and fiber/matrix bonding strength on mechanical properties were studied. The SiC_f/Si₃N₄ composite, having a relatively low conductivity (its conduction loss is about 33% of the total dielectric loss) has good EMW absorption properties, i.e. a relative complex permittivity of about 9.2-j6.4 at 10 GHz and an RC lower than ?7.2 dB in the whole X band. Its low relative complex permittivity matches impedances between composites and air better, and its strong polarization relaxation loss ability help it to absorb more EM wave energy. Moreover, with a suitably strong fiber/matrix bonding strength, the composite can transfer load more effectively from matrix to fibers, resulting in a higher flexural strength (380 MPa) and fracture toughness (12.9 MPa?m^1/2).     

Mechanical properties of graphene oxide reinforced alumina matrix composites

Graphene oxide (GO) reinforced alumina matrix composites have been fabricated by using graphene oxide synthesized by a modified Hummer's method. Samples were prepared by powder metallurgy and consolidated by Spark Plasma Sintering (SPS). The influence of GO addition on the microstructure and mechanical properties of the composites was investigated. Results show a significant increase (almost 35%) of the fracture toughness for composites containing 0.5 wt% graphene oxide compared to sintered pure alumina. In order to find reasons for this improvement Scanning/Transmission Electron Microscopy (SEM/TEM) observations were carried out. They reveal a good interface between the reinforcement and the matrix as well as such mechanisms like branching, deflection and bridging of crack propagation.     

Preparation and properties of 2D C/SiC-ZrB2-TaC composites

Two-dimensional (2D) C/SiC-ZrB₂-TaC composites were fabricated by chemical vapor infiltration (CVI) combined with slurry paste (SP) method. 2D laminate was prepared by stacking carbon cloth that was pasted with a mixture of polycarbosilane-ZrB₂-TaC slurry. A small amount of carbon fiber tows were introduced into the preform in the vertical direction. After heat-treated at 1800 °C, the 2D laminate was densified with SiC by CVI to obtain 2D C/SiC-ZrB₂-TaC composites. Properties including flexural strength, interlaminar shear strength, and thermal expansion of the composites were investigated. The ablation test was carried out under an oxyacetylene torch flame. The morphologies of the ablated specimens were analyzed. The results indicate that the adding vertical fiber tows and heat-treatment at 1800 °C can greatly improve the mechanical properties of the composites. The co-addition of TaC and ZrB₂ powders into C/SiC composite effectively enhance its ablation resistance.     

Plasticized/graphite reinforced phenolic resin composites and their application potential

Plasticized graphite (PG)/phenolic resin composites are candidates for positive temperature coefficient resistivity (PTCρ) thermistors, which are used for self‐recoverable elements that provide protection from overcurrents, gasoline sensors, and electrostatic charge and electromagnetic wave shielding in many kinds of electrical devices. The morphology and network structure of PG/phenolic resin composites have been characterized with scanning electron microscopy and with measurements of the crosslinking density, bound resin content, degree of crystallinity, viscosity, surface energy, thermal conductivity, enthalpy, and glass‐transition temperature. In addition, mechanical properties such as the tensile strength, Young's modulus, Shore A hardness, and elongation at break for resins filled with PG have been studied. The electrical properties of the composites have been measured to relate the PG volume fraction to the electrical conductivity. A large PTCρ value has been observed for all samples. The mechanism of the PTCρ effect in the materials is related to the thermal expansion and highest barrier energy of the composites. Switching behaviors of the current and voltage for all samples have been observed. The applicability of PG/phenolic resin composites for temperature controllers and gasoline gas sensors has been examined. The antistatic charge dissipation and dielectric constant as functions of the PG content have been studied. Finally, the experimental electromagnetic interference of the PG/phenolic composites has been investigated in the frequency range of 1–15 GHz and compared with a theoretical model. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 697–709, 2007     

The effect of fibre sizing and compatibilizer of polypropylene/poly(butylene terephthalate) blends on the mechanical and interphase properties of basalt fibre reinforced composites

The effect of basalt fibre sizing on the mechanical and interphase properties of fibre‐reinforced composites was studied. Two different chemical preparations of the fibre surface (PBT‐compliant and PP‐compliant) were used. The polymer matrix was prepared from polypropylene/poly(butylene terephthalate) (PP/PBT) immiscible polymer blend and the effect of different compatibilizers on the composite properties was evaluated. SEM hints at improved fibre adhesion to the polymer matrix when a PP‐compliant sizing is applied. SEM also reveals improved compatibilization effects when block copolymer instead of multiblock copolymer is used for the PP/PBT blend preparation. The pull‐out test was applied to quantitatively evaluate the interface adhesion between the fibres and matrices. It showed a high value of the interfacial shear strength between basalt fibres modified with PP‐compliant sizing and polymer blend compatibilized by block copolymer, thus confirming good adhesion. One possible explanation of such good mechanical properties can be related to the chemical interactions between functional groups, mainly maleic anhydride on basalt fibres and the polyolefin component (PP) of the polymer matrix. © 2017 Society of Chemical Industry     

Technological properties of celsian reinforced glass matrix composites

Monoclinic celsian derived from an innovative route, i.e. cation exchanged zeolites heat-treated at low temperature, was added at different contents (10, 20, 30 wt%) to a glass matrix, in order to improve its mechanical and electrical performances. The effect of the celsian reinforcement was evaluated by testing several properties of the composite materials, such as the elastic modulus, abrasion resistance, flexural strength and electrical insulation. The results so far obtained suggest that the addition of the monoclinic celsian to the glass matrix may produce low-cost particulate composites with interesting technological properties.     

碳纤维增强树脂基复合材料的应用研究

碳纤维增强树脂基复合材料以其优异的综合性能成为当今世界材料学科研究的重点。本文介绍了的碳纤维增强复合材料的性能，简述了增强机理、成型工艺及其应用领域和发展趋势。     

Fabrication and properties of Cf/(Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C-SiC high-entropy ceramic matrix composites via precursor infiltration and pyrolysis

In this work, C_f/(Ti_0.2Zr_0.2Hf_0.2Nb_0.2Ta_0.2)C-SiC high-entropy ceramic matrix composites were reported for the first time. Based on the systematic study of the pyrolysis and solid-solution mechanisms of (Ti_0.2Zr_0.2Hf_0.2Nb_0.2Ta_0.2)C precursor by Fourier transform infrared spectroscopy, TG-MS and XRD, C_f/(Ti_0.2Zr_0.2Hf_0.2Nb_0.2Ta_0.2)C-SiC with uniform phase and element distribution were successfully fabricated by precursor infiltration and pyrolysis. The as-fabricated composites have a density and open porosity of 2.40 g/cm³ and 13.32 vol% respectively, with outstanding bending strength (322 MPa) and fracture toughness (8.24 MPa m^1/2). The C_f/(Ti_0.2Zr_0.2Hf_0.2Nb_0.2Ta_0.2)C-SiC composites also present excellent ablation resistant property at a heat flux density of 5 MW/m², with linear and mass recession rates of 2.89 μm/s and 2.60 mg/s respectively. The excellent combinations of mechanical and ablation resistant properties make the C_f/(Ti_0.2Zr_0.2Hf_0.2Nb_0.2Ta_0.2)C-SiC composites a new generation of reliable ultra-high temperature materials.     

A high-temperature structural and wave-absorbing SiC fiber reinforced Si3N4 matrix composites

The SiC_f/Si₃N₄ composite with low–high–low permittivity sandwich structure was designed for high-temperature electromagnetic (EM) wave absorption and mechanical stability. The SiC_f/Si₃N₄ possessed the remarkable mechanical properties at room temperature (the flexural strength is 357 ± 16 MPa and the fracture toughness is 10.8 ± 1.7 MPa m^1/2) for the strong fiber strength, moderate interface bonding strength and uniform matrix. Furthermore, the retention rate is as high as 80% at 800 °C. The A/B/C nanostructure and the sandwich meta-structure endowed the SiC_f/Si₃N₄ with an excellent EM absorbing property at room temperature. The SiC_f/Si₃N₄ still absorbed 75% of the incident EM waves energy in X and Ku bands when the temperature increases up to 600 °C, which is only 6% lower than that at room temperature, for the partial compensation of the decreased interfacial polarization loss for the increased conductivity loss and dipole polarization loss.     

Effects of phenolic resin contents on microstructures and properties of c/sic-diamond composites

In this paper, C/SiC-diamond composites were obtained by chemical vapor infiltration (CVI) and reactive melt infiltration (RMI), and the effects of phenolic resin contents on the microstructures and properties of as-obtained C/SiC-diamond composites were studied. The results suggested a significant influence of phenolic resin contents on the pore structure of the composites before reactive melt infiltration (RMI), as well as phase composition and density of the matrix after RMI. The mechanical properties of composites were shown to correlate with the threshold effect of phenolic resin. Sample R5 prepared with high phenolic resin contents displayed significantly declined mechanical properties. On the other hand, adjustment of the phenolic resin content yielded samples with maximum room temperature thermal conductivity reaching 14.75 W/(m·K). The theoretical thermal conductivity of the composites calculated by the Hasselman-Johnson (H-J) theoretical model was estimated to 24.52 W/(m·K). Overall, the increase in phenolic resin content led to unreacted diamond-C regions and the formation of substantial porosity. These features reduced the thermal conductivity of the resulting C/SiC-diamond composites.     

Sugarcane bagasse reinforced phenolic and lignophenolic composites

Lignin, extracted from sugarcane bagasse by the organosolv process, was used as a partial substitute of phenol (40 w/w) in resole phenolic matrices. Short sugarcane fibers were used as reinforcement in these polymeric matrices to obtain fiber‐reinforced composites. Thermoset polymers (phenolic and lignophenolic) and related composites were obtained by compression molding and characterized by mechanical tests such as impact, differential mechanical thermoanalysis (DMTA), and hardness tests. The impact test showed an improvement in the impact strength when sugarcane bagasse was used. The inner part of the fractured samples was analyzed by scanning electron microscopy (SEM), and the results indicated adhesion between fibers and matrix, because the fibers are not set free, suggesting they suffered a break during the impact test. The modification of fiber surface (mercerization and esterification) did not lead to an improvement in impact strength. The results as a whole showed that it is feasible to replace part of phenol by lignin in phenolic matrices without loss of properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 880–888, 2002     

Mechanical and ablation properties of 2D-carbon/carbon composites pre-infiltrated with a SiC filler

In order to improve the mechanical and ablation properties of 2D-carbon/carbon composites, a SiC filler was added to a 2D-preform before isothermal chemical vapor infiltration densification by using a powder infiltration technique. Backscattered electron images showed that the SiC filler was mainly concentrated between the fiber bundles and between the layers. The tensile and flexural strengths of the composites were improved by the addition of the SiC filler because of the increase of interfacial surface areas between the bundles and between the layers, the less residual open porosity, and also the strong bonding between the SiC particles and the pyrocarbon matrix. The composites with filler experienced a 15.2% lower thickness erosion rate and a 51.7% lower mass erosion rate, compared to those C/C without filler. This was attributed to the low oxygen permeability of the SiO₂ shielding the exterior inter-bundle pores as well as to a thermal barrier effect.     

Investigations of the tribological properties of carbon fabric reinforced phenolic polymer composites filled with several nanoparticles

The carbon fabric composites filled with several nanoparticles were prepared by dip‐coating and hot press molding technique. The friction and wear behavior of the resulting composites were studied systematically using a block‐on‐ring arrangement. Experimental results showed that the optimal content of nanoparticles as fillers contributed to improve the tribological properties of the carbon fabric composites. Moreover, the friction and wear properties of the fabric composites were closely dependent with the sliding conditions. The differences in the transfer film formed on the counterpart surface during the friction process also accounted for the friction and wear behavior of carbon fabric composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Fabrication of hybrid matrix/silane modified carbon fabric composites and study of their mechanical properties

Carbon fiber reinforced polymer composites are an extremely strong and light fiber-reinforced plastics that contains carbon fiber. In the present study, carbon fabrics were treated with various weight percentages of silane and were confirmed by spectral analysis (Fourier transform infrared). The treated carbon fibers were reinforced in hybrid resin (a combination of vinyl ester and epoxy at a ratio of 80:20) by using vacuum-assisted resin transfer mold technique. The composites were tested to know their tensile strength, modulus, flexural strength, modulus, and interlaminar shear strength. The hybrid matrix specimen was also prepared and tested for the mechanical properties and confirmed the miscibility by differential scanning calorimetry and X-ray diffraction. The mechanical properties of hybrid matrix composites (HMCs) were studied by fracture surface morphology with scanning electron microscope. The mechanical properties of the HMCs increased with silane treatment. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47695.     

Evaluation of fade‐recovery performance of hybrid friction composites based on ternary combination of ceramic‐fibers,ceramic‐whiskers,and aramid‐fibers

Hybrid composite friction material based on ternary combination of potassium titanate whiskers, alumino‐silicate ceramic fibers, and aramid fibers were fabricated and evaluated for their physical, mechanical, and tribo‐performance. The frictional response, friction‐fade, friction‐recovery, and wear properties have been characterized on a Krauss friction tester following ECE R‐90 regulation. Optimally, the composite with hybrid reinforcement incorporations in the form of ceramic‐whiskers, ceramic‐fiber, and aramid‐fiber in the ratio of 13.75 : 13.75 : 2.5 has potentially been explored as a functionally feasible friction‐material for braking applications. The interdependence of fade, recovery, disc temperature rise, and wear characteristics is established via thematic correlation diagram. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Mechanical properties and ablation resistance of HfC nanowire modified carbon/carbon composites

Hafnium carbide nanowires (HfCnws) were in-situ grown in carbon/carbon (C/C) composites, and subsquently the preforms were densified by isothermal chemical vapor infiltration to obtain HfCnws modified carbon/carbon (HfCnws-C/C) composites. Morphology and microstructure of HfCnws were examined, and the effect of HfCnws on the mechanical property and ablation resistance of C/C composites were also investigated. Results show that introducing HfCnws refined the grain size of pyrolytic carbon (PyC). The out-of-plane compression, interlaminar shear and flexual strength of HfCnws-C/C composites increased by 120.80%, 45.60% and 94.65%, respectively compared with pure C/C, and the HfCnws-C/C shows good ablation resistance under oxy-acetylene flame ablation.     

Mechanical properties and tribological performance of alumina matrix composites reinforced with graphene-family materials

This paper introduce the formation of alumina matrix composites reinforced with multilayered graphene, graphene oxide and nickel-phosphorus coated multilayered graphene. The powder metallurgy technique followed by the Spark Plasma Sintering (SPS) method were utilized to fabricate the specimens. The influence of graphene-family material additions on microstructure was investigated, and correlated with measurements of mechanical properties. The emphasis of the research has been placed on the tribological performance conducted with the use of the ball-on-disc method under loads of 10 N and 30 N. Both the wear tracks of composites and the corresponding counterparts were carefully analysed, to evaluate the combined influence of mechanical properties and tribofilm formation on the measured wear rates. All results were compared to pure alumina as a reference specimen.