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Carbon fabric reinforced phenolic composites were widely used as TPSs (thermal protection system) material in the aerospace industry. However, their limited oxidative ablation resistance restricted their further utility in more serious service conditions. In this study, the surface-decorated ZrB2/SiC and its modified carbon fabric reinforced phenol...
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My articale about synthesis and study of some properties of phenolic resin and their thermal stability study
Citations
... Furthermore, PR is limited in thermal protection systems due to its insufficient thermal stability under high temperature [11]. Various efforts had been made to develop a novel PR with improved thermal-oxidative stability and higher weight residual at high temperature, by introducing high-melting and thermal-stable compounds containing inorganic elements via covalentcoalaent chemical bonding or physical blending, such as boron [12], silicon [9], phosphorous [13,14], zirconium [15], and titanium [16]. Among these, silicon-modified phenolic resin (SiPR) has attracted significant attention due to its good thermal-oxidative stability, and flame-retardant properties [11,17]. ...
ReaxFF molecular dynamics (ReaxFF-MD) simulations and X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman, Fourier transform infrared spectroscopy (FT-IR), ²⁹Si NMR were used to investigate the temperature-dependent pyrolysis gas release behavior, dynamic evolution of microstructure, and fundamental carbonization mechanism of silicon-modified phenolic resin (SiPR). An improved and effective algorithm for model building was used to construct the cross-linked SiPR simulation model by considering three reactions in the actual experimental cross-linking process with adjustable occurrence rates. Tracking and analysis of the structures showed that with the continuous release of pyrolysis gas, the residual Si and C-containing components decomposed, rearranged, and aggregated into different phase structures. The Si-units agglomerated and underwent phase separation stages. The carbonization process was divided into three periods: initial aromatization, merging and flattening, and residual healing. These findings may shed light on the polysilicon phase distribution and carbonization mechanism of SiPR.
... Other nanoscaled fillers, such as carbon nanotubes, silica, ZrB 2 , ZrSi 2 ,TiB 2 ( Figure 8D) have been also studied (Ding et al., 2019): as a representative result, TiB 2 particles included in carbon-phenolic (T/C-Ph) composites prepared by compression moulding reacted, at high temperature, with oxygen-containing molecules, by coating the residue of phenolic after pyrolysis with glassy B 2 O 3 , assuring in this way improved mechanical performance at high temperature. Nano-modified carbon fabric represents another opportunity to enhance the ablation behavior of these materials (Xu et al., 2020a;Xu et al., 2020b). ...
During last decades a plethora of high temperature materials have been developed to work as a Thermal Protection System (TPS). Carbon based materials such as graphite, which possesses low density, high heat capacity and high energy of vaporization, have been used as TPS material. However, graphite has relatively poor mechanical properties, but exhibits low resistance to the thermal shocks. Accordingly, to bypass the limitation of graphite, carbon fibers are typically introduced in a carbon matrix to produce Carbon/Carbon Composites (CCCs). Among the different families of TPS solutions, Polymeric Ablative Materials (PAMs), produced combining high char yield matrices - mainly phenolic resins - and Carbon Fibers (CFs) are used to manufacture Carbon/Phenolic Composites (CPCs) i.e. the most important class of fiber reinforced PAM. Carbon fibers are traditionally produced from Polyacrylonitrile (PAN), Rayon and Pitch. Some limited researches also aimed to use cyanate-esters, bismaleimides, benzoxazines matrices in combination with ex-PAN-CFs, ex-Rayon-CFs, and ex-Pitch-CFs. In our paper, after covering the science and technology of these state-of-the-art fiber reinforced TPS materials, a review of current challenges behind the manufacturing of new, high char yield matrices and carbon fibers derived from alternative precursors will be provided to the reader. In particular, the possibility to produce CFs from precursors different from PAN, Rayon and Pitch will be reported and similarly, the technology of non-oil based phenolics, bismaleimides, cyanate-esters and benzoxazines will be discussed. The effect of the use of nanosized fillers on these matrices will also be reported. More in detail, after a preliminary section in which the state of the art of technologies behind carbon/phenolic composites will be covered, a second part of this review paper will be focused on the most recent development related to non-oil based phenolics and biomass derived carbon fibers. Finally, an outlook focused on the maturity of the lab-scale protocols behind the researches at the base of these non-traditional raw materials from an industrial point of view will conclude this review paper.
The evolution of hypersonic vehicles has raised higher requirements for thermal protection materials, which have become the focus of research on how to meet the lightweight and less ablative. Herein, a yttrium silicate‐coated carbon fiber felts (YS‐CFs) reinforced phenolic aerogel‐like (PR) composites were prepared. The YS‐CFs/PR with the addition of 12 % hexamethylenetetramine exhibited low density (0.540 g/cm³), low thermal conductivity (0.145 W/(m⋅K)), and good thermal stability. Specifically, under an oxyacetylene flame examination with 2.44 MW/m² heated for 120 s, its mass ablation rates (9.833 mg/s) and line ablation rates (5 μm/s) were decreased by 40.8 % and 32.6 %, respectively, compared to others. The results show that the composites with these combined properties can meet the requirements for thermal protection materials in the field of hypersonic vehicles.
Given the increasing requirements for ablative thermal protection materials, there is an urgent need for boron phenolic resin (BPR) composites with excellent high‐temperature strength properties as well as ablation performance to address the structural failure during the ablation process of these devices. Herein, modified pickling asbestos (MPA) was successfully incorporated into BPR to prepare MPA‐modified BPR (MPABPR). In addition, one‐dimensional MPA with improved dispersion and compatibility was used to fabricate a fiber‐reinforced network inside of BPR for the first time, which effectively increased the high‐temperature strength and ablation resistance of BPR. The results demonstrated that the high‐temperature strength of MPABPR was optimally improved by 25% compared to pure BPR. Meanwhile, when the content of MPA was only 5 wt%, the linear and mass ablation rates of MPABPR could reduce to 0.046 mm/s and 0.043 g/s, which were 34.3% and 23.2% lower than that of pure BPR, respectively. This study has the enormous potential to provide a new strategy for preparing high‐performance BPR matrix materials.
Highlights
The dispersion and compatibility of PA are improved by modification.
MPA constructs a fiber‐reinforced network that can strengthen the carbon layer.
The ablative properties of MPABPR have great advantages over the BPR.
The compressive strength of carbonized MPABPR 5 is 25% higher than that of BPR.
Hypersonic vehicles encounter hostile service environments of thermal/mechanical/chemical coupling, so thermal protection materials are crucial and essential. Ceramizable composites have recently attracted intensive interest due to their ability to provide large-area thermal protection for hypersonic vehicles. In this work, a novel ceramizable composite of quartz fiber/benzoxazine resin modified with fused SiO2 and h-BN was fabricated using a prepreg compression molding technique. The effects of the fused SiO2 and h-BN contents on the thermal, mechanical, and ablative properties of the ceramizable composite were systematically investigated. The ceramizable composite with an optimized amount of fused SiO2 and h-BN exhibited superb thermal stability, with a peak degradation temperature and residue yield at 1400 °C of 533.2 °C and 71.5%, respectively. Moreover, the modified ceramizable composite exhibited excellent load-bearing capacity with a flexural strength of 402.2 MPa and superior ablation resistance with a linear ablation rate of 0.0147 mm/s at a heat flux of 4.2 MW/m², which was significantly better than the pristine quartz fiber/benzoxazine resin composite. In addition, possible ablation mechanisms were revealed based on the microstructure analysis, phase transformation, chemical bonding states, and the degree of graphitization of the ceramized products. The readily oxidized pyrolytic carbon (PyC) and the SiO2 with a relatively low melting point were converted in situ into refractory carbide. Thus, a robust thermal protective barrier with SiC as the skeleton and borosilicate glass as the matrix protected the composite from severe thermochemical erosion and thermomechanical denudation.
The addition of nano- and microfillers to carbon-fiber-reinforced polymers (CFRPs) to improve their static mechanical properties is attracting growing research interest because their introduction does not increase the weight of parts made from CFRPs. However, the current understanding of the high strain rate deformation behaviour of CFRPs containing nanofillers/microfillers is limited. The present study investigated the dynamic impact properties of carbon-fiber-reinforced phenolic composites (CFRPCs) modified with microfillers. The CFRPCs were fabricated using 2D woven carbon fibers, two phenolic resole resins (HRJ-15881 and SP-6877), and two microfillers (colloidal silica and silicon carbide (SiC)). The amount of microfillers incorporated into the CFRPCs varied from 0.0 wt.% to 2.0 wt.%. A split-Hopkinson pressure bar (SHPB), operated at momentums of 15 kg m/s and 28 kg m/s, was used to determine the impact properties of the composites. The evolution of damage in the impacted specimens was studied using optical stereomicroscope and scanning electron microscope. It was found that, at an impact momentum of 15 kg m/s, the impact properties of HRJ-15881-based CFRPCs increased with SiC addition up to 1.5 wt.%, while those of SP-6877-based composites increased only up to 0.5 wt.%. At 28 kg m/s, the impact properties of the composites increased up to 0.5 wt.% SiC addition for both SP-6877 and HRJ-15881 based composites. However, the addition of colloidal silica did not improve the dynamic impact properties of composites based on both phenolic resins at both impact momentums. The improvement in the impact properties of composites made with SiC microfiller can be attributed to improvement in crystallinity offered by the α-SiC type microfiller used in this study. No fracture was observed in specimens impacted at an impact momentum of 15 kg m/s. However, at 28 kg m/s, edge chip-off and cracks extending through the surface were observed at lower microfiller addition (≤1 wt.%), which became more pronounced at higher microfiller loading (≥1.5 wt.%).
TiSi2 reinforced boron phenolic composites (TP) and Vitreous silica fabric reinforced TiSi2/boron phenolic composites (VTP) were prepared by compression molding, and their thermal, mechanical, ablation properties were studied. TG results show that thermal stabilities and residual carbon rate of boron phenolic are improved after introducing TiSi2 particles. Compared with VTP-0 (containing 0 phr TiSi2), flexural strength of VTP-60 (containing 60 phr TiSi2) pyrolysis product increases by 29.5% at 1 200 °C. Raman spectrum shows that TiSi2 particles promote the ordering of the glass carbon structure of VTP pyrolysis product. Compared to VTP-0, the linear and mass ablation rates of VTP-60 reduce by 32.1% and 77.5%, respectively. XRD and SEM indicate the formation of an oxide coating layer, TiO2-SiO2, integrates the bulk and protects the underlying materials from damage under high temperature oxygen-containing airstream. All these results prove that mechanical properties of pyrolysis product, thermal, and ablation resistance are improved by addition of TiSi2 particles.
Advancements in nanotechnology have inspired the development of magnetic polymer composites (MPCs) exhibiting magneto-static, magnetic permeability, and electromagnetism (EM). These have influenced their usage in the suppression of EM interference, integrative sensoring, health mitigation, and so on, and further enlarged their scope of applications in electronics, aerospace, biomedicals, and automobiles. Thus, this paper elucidates recently emerging advancements in MPCs, novel usages, challenges, and future prospects.
