Slurry Impregnation Research Articles

Polymer impregnation and pyrolysis process for the preparation of Al2O3f/Al2O3 composites: A preliminary study

Currently, the primary method for preparing alumina fiber-reinforced alumina ceramic (Al2O3f/Al2O3) composites is the slurry impregnation (SI) process. However, this technique is plagued by the challenge of necessitating a high sintering temperature. Hence, an attempt was initiated to prepare Al2O3f/Al2O3 composites through the polymer impregnation and pyrolysis (PIP) method, with the objective of reduce thermal damage to the fibers during the preparation process. The high-temperature inorganic processing of the Al2O3 precursor was studied, ultimately leading to the selection of 900 °C as the optimal pyrolysis temperature for the PIP process. The microstructure and high-temperature mechanical properties of the obtained composites were studied. The results indicated that the composites maintained microstructure stability up to 1000 °C. The flexural strength almost unchanged (from 37.20 ± 4.09 MPa to 37.03 ± 2.01 MPa). At 1200 °C, the formation of mullite greatly increased the defect density in the matrix, leading to a decrease in the flexural strength (28.42 ± 5.50 MPa). After heat treatment at 1400 °C, some of the blocky matrix dissolved and filled partial pores, improving the flexural strength (42.60 ± 1.95) of the composites. The continuous increases in flexural modulus meant that the brittleness of the composites became stronger with increasing temperature.

Si-Y-C-B-Yb as a protective matrix for SiCf/SiC composites: Effects of infiltration temperature on microstructures and mechanical properties

To solve rapid failure of SiC Fiber-reinforced SiC Ceramic Composites (SiCf/SiC) under water-oxygen corrosion environment, novel SiCf/Si-Y-C-B-Yb composites was prepared in this study by Slurry Impregnation (SI) combined with Reactive Melt Infiltration (RMI) methods. Effects under different infiltration temperature on microstructures and mechanical properties of SiCf/Si-Y-C-B-Yb composites were systematically studied. Results showed that as the melting temperature rose, no significant differences were recorded in apparent density of SiCf/Si-Y-C-B-Yb composites while the porosity gradually increased. However, the Y diffusion layer gradually became thicker and changed from one layer to two layers due to the high temperature promoting the migration rate of Y element. Moreover, it revealed good corrosion resistance of SiCf/Si-Y-C-B-Yb composites in 50 vol% H2O+50 vol% O2 water-oxygen environment. At corrosion temperatures below 1250 °C, strength retention rate of SiCf/Si-Y-C-B-Yb composites significantly increased by 21.12 %, a value higher than that of SiCf/SiC composites. One hand, the formation of silicate phase on SiCf/Si-Y-C-B-Yb composites surface rose corrosion resistance, hindering further erosion from water-oxygen atmosphere. On the other hand, Oxidation activation energy of SiCf/SiC composites was estimated to be 131 kJ/mol while that of SiCf/Si-Y-C-B-Yb composites was 269 kJ/mol. Thus, SiCf/Si-Y-C-B-Yb possessed excellent performance in resisting water-oxygen corrosion.

Effect of SiC addition on the high-frequent cyclic ablation of C/C-AlSi composites

Components such as pistons in high-power diesel engines and barrels of rapid-fire weapons are often exposed to cyclic impacted high-temperature combustion. C/C-AlSi composites exhibit exceptional mechanical property, good particle erosion resistance and remarkable short-term anti-ablation ability. However, the cyclic ablation of the composite was primarily dominated by thermal stress damage between the alloy matrix and the carbon skeleton. In this study, SiC was utilized to mitigate such failures. C/C-SiC-AlSi composites were prepared by slurry impregnation method, and C/C-AlSi composites were also carried out for parallel comparison. The results indicate that the SiC and resin-carbon hybrids in the prepared composites are evenly distributed between the carbon fibers and the aluminium alloy matrix. Furthermore, the C/C-SiC-AlSi composites exhibit a greater density, a higher coefficient of thermal expansion and a better resistance to high frequent cyclic ablation. The mass ablation rate and linear ablation rate of the C/C-AlSi composites and the C/C-SiC-AlSi composites gradually decrease with increasing ablation time. When the ablation time is 200 s, the mass ablation rates of C/C-AlSi composite and C/C-SiC-AlSi composite are 0.20 mg/s and 0.12 mg/s, respectively. Compared to the two composites, the mass ablation rate of C/C-SiC-AlSi composite is reduced by approximately 40 %. The ablated morphologies indicated that the addition of SiC particles alleviated the thermal stress on the carbon skeleton and the alloy matrix, resulting in reduced mechanical damage.

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.

High toughness Al2O3/LaPO4/Al2O3 composites fabricated by slurry impregnation sintering process

Continuous Al2O3 fiber-reinforced Al2O3 matrix (Al2O3/Al2O3) composites, aimed at aerospace applications, are recognized for their low density, high strength, and resistance to oxidation but suffer from limited toughness. To address this problem, a study was undertaken that utilized a slurry infiltration and sintering (SIS) process for the fabrication of Al2O3/Al2O3 composites with enhanced toughness. Composites have a microstructure that fine Al2O3 matrix filled the voids of coarse Al2O3 matrix, enhancing the tortuosity of crack propagation paths and thereby increasing the toughness of the composites. Additionally, the incorporation of LaPO4 coatings was explored as a means to further augment toughness. Findings indicate that the optimal Al2O3/Al2O3 composites, exhibiting superior performance, were fabricated at 1200 °C, achieving a density of 2.97 g/cm3, flexural strength of 209 ± 20 MPa, and fracture toughness of 13 ± 3 MPa m1/2. A 320 nm LaPO4 coating was found to enhance the fracture toughness of the composites by approximately 20.70 %. Consequently, the SIS technique, complemented by the application of LaPO4 coatings, represents a highly effective approach for the production of Al2O3/Al2O3 composites with significantly improved toughness.

Al2O3f/Al2O3 composites with high bending strength prepared via a MnO2 modified slurry impregnation method

The limitations of oxide/oxide ceramic matrix composites lie in the need to improve their mechanical properties. It is challenging to reconcile the conflict between matrix densification at high temperature and the potential thermal damage to fibers. The concept of using element doping to control the sintering behavior of matrix was initially applied to prepare alumina-based ceramic matrix composites (CMCs). To lower the sintering temperature of the Al2O3 matrix, MnO2 dopant was used as a sintering aid. As a result, the thermal damage to alumina fibers was decreased, and the mechanical properties of the composite were significantly enhanced. The effect of MnO2 content on the bending strength and micro-morphology of the composite was investigated. The composite exhibits optimal mechanical properties with a 0.01 wt% MnO2 doping, and its bending strength is approximately 405 MPa. The investigation aimed to determine the mechanism by which the fluctuation in micro-mechanical properties of the composites with different MnO2 contents. After the thermal aging at 1000℃ for 500 h, the bending strength of the N610/Al2O3-0.01 composite decreases to 297 MPa. The evolution and mechanism of thermal aging damage have been studied.

Influence of Slurry Impregnation Technique of Recycled Concrete Aggregates on the Roller Compacted Concrete Pavement

Influence of Slurry Impregnation Technique of Recycled Concrete Aggregates on the Roller Compacted Concrete Pavement

Microstructure and Properties of C/HfC-SiC Composites Prepared by Slurry Impregnation Assisted Precursor Infiltration Pyrolysis

Microstructure and Properties of C/HfC-SiC Composites Prepared by Slurry Impregnation Assisted Precursor Infiltration Pyrolysis

Outstanding mechanical and ablation resistance of C/C–ZrC–W composites prepared via slurry impregnation and reactive melt infiltration at 1500 ℃

To improve the mechanical properties and ablation resistance of Cf-reinforced ceramic-based materials, ZrC–W cermet composites (C/C–ZrC–W) were prepared in C/C preforms using slurries and low-temperature reactive melt infiltration, and their microstructure, formation mechanism, and mechanical and ablation properties were investigated. The obtained results revealed that the formation of C/C–ZrC–W composites involved the dissolution–precipitation and C diffusion processes. Owing to the precipitation of W nanoparticles in the ZrC phase and interdiffusion of W/ZrC, the fabricated C/C–ZrC–W composites exhibited superior mechanical properties with a flexural strength of 280.65 ± 12.84 MPa and fracture toughness of 13.87 ± 0.56 Mpa.m1/2. The formation of a Zr–W–O dense oxide layer resulted in the excellent ablation performance of the C/C–ZrC–W composites in oxyacetylene flame with a temperature of 2200 °C, and their mass ablation rate and linear ablation rate were 1.14 mg/s and 2.42 µm/s, respectively. The described method can be potentially used for preparing high-strength, high-toughness, and ablation-resistant materials at low temperatures.

An Ultrathin CNFs/CF Composite and the Performance of Electromagnetic Interference Shielding

The catalyst layer was introduced by a novel slurry impregnation process. In this process, phenolic resin, Ni particles and SiO2 particles are acted as adhesives, catalysts and dispersants, respectively. CNFs which have a high length-diameter ratio were in situ grown on the surface of carbon fabrics via the CVD method. The microstructure, electrical conductivity, skin depth and electromagnetic interference shielding effectiveness (EMI SE) of CNFs/CF under different reaction times were investigated. The optimal process of CNFs/CF was obtained at 800[Formula: see text]C for reacting 15[Formula: see text]min. In this condition, CNFs have a good graphitization degree and the diameter is around 25[Formula: see text]nm. Since the CNFs/CF composite possesses numerous channels, the electrical conductivity increases and the skin depth decreases. The electromagnetic (EM) waves could be trapped and attenuated, yielding outstanding EM shielding effectiveness. The total shielding effectiveness (SE[Formula: see text] values were significantly under the ultrathin thickness. Consequently, the specific SE[Formula: see text] values of CNFs/CF reached 172.9 dB/cm, which means that the EM shielding effectiveness is excellent.

Preparation, mechanical and ablation properties of a C/C-TaB2-SiC composite

A C/C-TaB2-SiC composite was successfully prepared by high-solid-loading slurry impregnation combined with polymer infiltration and pyrolysis. The composite had a density of 3.46 g/cm3 and consisted of pyrolyzed carbon, carbon fibers, TaB2 particles, and precursor-derived SiC with their mass fractions of 7.8%, 13.0%, 58.6%, and 20.6%, respectively. The C/C-TaB2-SiC composite possessed a flexural strength of 248.2 ± 16.8 MPa and a fracture toughness of 13.7 ± 1.6 MPa·m1/2, and demonstrated a non-brittle fracture behavior. After exposure to oxyacetylene flame with a heat flux of 4.18 MW/m2 for 120 s, the ablation temperature of the sample surface reached a maximum of 2263°C, and the mass and line ablation rates were 2.24 mg/s and 12.92 μm/s, respectively. The ablation resistance mainly comes from the hindrance of oxygen diffusion by the oxide layer composed of tantalum oxide and a small amount of SiO2. The raw/processed data required to reproduce these findings cannot be shared at this time due to the fact that the authors do not have permission to share data.

From outer space to inside the body: Ultra-high temperature ceramic matrix composites for biomedical applications

Ultra-high temperature ceramic matrix composites (UHTCMCs) are a new class of carbon fiber-reinforced non-brittle ceramics possessing a unique combination of properties (e.g. high fracture toughness, damage tolerance and corrosion resistance), originally developed for use in extreme hot and harsh environments, such as those found in aerospace and industrial applications. Interconnections between very remote fields more and more frequently come across to discover new solutions. In this study, we investigated the compression strength and cytotoxicity of UHTCMCs designed as biomaterials for future applications inside the body. Indeed, despite the advancements in the designing, manufacturing and surface modification, current prostheses are made of metals or alloys with well-known disadvantages. Near-fully dense Cf/ZrB2-SiC composites were manufactured through slurry impregnation followed by spark plasma sintering. A preliminary biological in vitro study demonstrated materials’ lack of cytotoxicity, making them promising candidates for further investigation for biomedical purposes.

Production of artificial humic acid from corn straw acid hydrolysis residue with biogas slurry impregnation for fertilizer application

This study investigated hydrothermal humification of corn straw acid hydrolysis residue with biogas slurry impregnation, aiming at producing water-soluble artificial humic acid fertilizer for fertilizer application and soil remediation. Hydrothermal humification parameters, including potassium hydroxide concentration (1–3 mol/L), retention time (2–6 h), and temperature (140–180 °C), were investigated using water as the liquid phase. The selected hydrothermal humification condition was 1.5 mol/L potassium hydroxide at 180 °C for 4 h. Moreover, biogas slurry impregnation (0–30 days) was evaluated to improve humic acid yield without introducing additional chemicals or energy input. Biogas slurry as the liquid phase increased the humic acid production by 73.24% with 5 days of impregnation compared to the control due to the alkalinity. The humic acid concentration was sufficient for China's national standard of water-soluble humic acid fertilizers in such conditions. The organic components in biogas slurry were involved in artificial humification as a precursor, forming C–N bonds with humic acid. The product with fortified nitrogen-containing functional groups enhanced the nutrient slow-release characteristics and water retention capabilities. The pot experiment further confirmed that artificial humic acid prepared in this study not only promoted the growth of plants but also achieved soil remediation.

Mechanical and ablation properties of 3D orthogonal woven C/C-SiC composite based on high-solid-loading slurry impregnation

Mechanical and ablation properties of 3D orthogonal woven C/C-SiC composite based on high-solid-loading slurry impregnation

Optimization of Slurry Impregnation Technique for Upcycling Carbonated Recycled Concrete Aggregates for Paving Concrete Applications

Optimization of Slurry Impregnation Technique for Upcycling Carbonated Recycled Concrete Aggregates for Paving Concrete Applications

Long-term oxidation of MoSi2-modified HfB2–SiC–Si/SiC–Si coating at 1700°C

ABSTRACT Slurry impregnation and gaseous Si infiltration were effectively used to produce compact MoSi2-doped Si–HfB2–SiC/Si–SiC (HMSS/SS) coatings with a thickness of 250 μm to protect carbon fibre reinforced carbon (Cf/C) composites from oxygen corrosion at 1700°C. The HMSS/SS coating obtained with a mosaic structure makes it possible to protect Cf/C composites at 1700°C for 276 h and the mass reduction is only 0.99%. The pinning effect of the embedded hafnia, the generated MoB together with the Hf, Mo co-doped Si-based glass layer, which successfully prevented the migration of oxygen, was attributed to the superior oxidation protection ability of the HMSS/SS coatings. This work provides a practical method for successfully extending the service life of Cf/C composites in the aerospace industry.

Ablation behaviour of Csf/ZrB2-SiC composites fabricated by direct ink writing and reactive melt infiltration

Pitch-based short carbon fibres reinforced Csf/ZrB2-SiC composites were fabricated by direct ink writing of short carbon fibres, followed by slurry impregnation and reactive melt infiltration. Ablation behaviour of the Csf/ZrB2-SiC composite was studied by air plasma test. It is indicated that the skeleton of the oriented short carbon fibres provides heat diffusion channels. Consequently, temperatures at the ablation surface are as low as ∼1730 oC and ∼2000 oC respectively at 4 MW/m2 and 5 MW/m2. The composite presents outstanding ablation-resistant performance with a linear recession rate of ∼ − 0.04 µm/s and mass recession rate of ∼ − 3.40 mg/s at 4 MW/m2, ∼ − 0.17 µm/s and ∼ 3.58 mg/s at 5 MW/m2. It is revealed that the fibres area and matrix area of the composite present different ablation mechanisms. The fibres area is ablated severely, while the matrix area presents excellent ablation-resistance with continuous ZrO2-SiO2 protective layer.

Processing and characterization of ultra-high temperature ceramic matrix composites via water based slurry impregnation and polymer infiltration and pyrolysis

Uncoated PAN-based carbon fibre-reinforced ultra-high temperature ceramic matrix composites via aqueous ZrB 2 powder-based slurry impregnation coupled with mild polymer infiltration and pyrolysis, using allylhydrido polycarbosilane as source of amorphous SiC(O), were manufactured. To demonstrate the versatility of the process to realize tailored materials, unidirectional (UD), two dimensional (2D) and needle-punched (2.5D) cloths were impregnated. Microstructure and mechanical properties were investigated and correlated with fibre properties and architecture. The flexural strength was found over 250 MPa for unidirectional reinforced material, while the modulus exceeded 250 GPa for needle-punched one. The homogeneous distribution of UHTC phase around each single fibre and the weak fibre/matrix interface, due to the mild pyrolysis conditions, are the hallmark of this process and the key to improve durability and performance of materials for extreme environments without the application of expensive coating on fibres.

Colloidal methods for the fabrication of Mn3O4-graphene film and bulk supercapacitors

Composite Mn3O4-graphene electrodes are fabricated by different colloidal processing methods, such as screen printing (SP), electrophoretic deposition (EPD) and slurry impregnation (SI) for energy storage in thin film and bulk supercapacitors (SCs). Good capacitive behavior of electrodes is linked to beneficial effect of current collectors and advanced colloidal processing. The results presented stress the importance of poly[1-[4-(3-carboxy-4-hydroxyphenylazo) benzenesulfonamido]-1,2-ethanediyl, sodium salt] (PAZO), which is used as a versatile co-dispersing, charging, binding and film forming agent for Mn3O4 and graphene. The effect of PAZO is linked to aromatic structure of its chelating monomers, which facilitate the fabrication of advanced inks for SP, suspensions for EPD and concentrated slurries for SI. Good capacitive behavior of thin film and bulk electrodes is achieved at low impedance. The properties of the SC electrodes make them promising for energy storage.

Effect of annealing treatments on the mechanical behaviour of UHTCMCs prepared by mild polymer infiltration and pyrolysis

Cf/ZrB2–SiC composites were produced by water-based slurry impregnation followed by six cycles of polymer infiltration and pyrolysis at 1000 °C. Despite the mild temperature of pyrolysis, the flexural strength of this composite showed values in excess of 500 MPa even at elevated temperature, up to 1400 °C. The abrupt decay of strength at 1500 °C stimulated the need to investigate the effect of additional thermal treatments enabling the crystallization of the amorphous polymer derived SiC(O). Annealing treatments, carried out between 1400 °C and 1900 °C, led to evident microstructural changes that in turn affected the flexural strength measured both at room temperature and at 1500 °C. The microstructural evolution was carefully analysed and 1400 °C was identified as the best trade-off between temperature of the annealing treatment and mechanical performance. After annealing at 1400 °C, the strength of the composite at room temperature decreased from the initial 500 MPa for untreated samples to 300 MPa due to the creation of new porosity, but this strength value was then maintained up to 87% at 1500 °C. Annealing at higher temperatures were detrimental for microstructure and strength.