Silicon Carbide Composites Research Articles

Investigation of Influence of Silicon Carbide Phase and Chemical Composition on its Recovery

When employing the cast iron manufacturing technology involving the use of silicon carbide, it was discovered that recovery of silicon carbide and that of its individual elements, viz., carbon and silicon varied. Based on the results obtained from a diffraction analysis and electron microscope investigation with electron microprobe analysis, the genuine structural and chemical features of industrial-grade silicon carbide were described. The phase composition of silicon carbide is inhomogeneous and consists of particles of the a-SiC crystalline silicon carbide and oxidized non-crystalline silicon carbide whose basis is a solid solution “carbon-silicon”. Recovery of silicon carbide by molten cast iron determined by the increase in the contents of carbon and silicon during the melting process is inversely on the content of the a-SiC phase.

Development of a porous catalytic converter for the dehydrogenation of cumene to α-methylstyrene

A porous catalytically active membrane based on α-Al2O3 has been synthesized. Powdered additives of the eutectic composition of magnesium oxide and silicon carbide were introduced with the initial corundum filler to synthesize the membrane frame with high open porosity and physical and mechanical characteristics. Then, pressing was carried out at a pressure of 40 to 70 MPa, followed by sintering in the process combustion mode. Additives Re2O7 and WO3 up to 4 wt. % was introduced into the initial mixture by a simple technological method to impart catalytic properties to the synthesized membrane. The scientific foundations have been developed for creating a technology for one-stage production of catalytically active ultraporous membrane converters effective for the processes of cumene dehydrogenation to α-methylstyrene.

Enhancing the tensile properties of SiC composites by a two-dimensional CNT film

Tensile properties of silicon carbide (SiC) ceramics were improved by introducing a two-dimensional carbon nanotube film (CNTf) with excellent mechanical properties. CNTf was first assembled by floating catalyst chemical vapor deposition (CCVD); then CNTf with the pyrolytic carbon interfacial layer (CNTf/PyC) was prepared by chemical vapor infiltration (CVI). Afterwards, SiC was infiltrated into the CNTf and CNTf/PyC preforms by the CVI process, to prevent the uneven dispersion and agglomeration of CNT and damage caused by high temperature sintering. Two composites (CNTf/SiC, CNTf/PyC/SiC) were ultimately prepared, and their microstructures and tensile properties were studied. The results show that the tensile strengths of CNTf/PyC, CNTf/SiC and CNTf/PyC/SiC are 716 ± 60, 153 ± 11, and 155 ± 12 MPa, respectively, which illustrates that SiC ceramic reinforced by CNTf exhibits excellent tensile properties. Besides, the porosities of CNTf/SiC and CNTf/PyC/SiC are 17.4% and 22.6%, respectively. CNTf/PyC/SiC shows higher porosity but better tensile properties, indicating that the PyC interfacial layer enhances the tensile properties of CNTf/SiC composite. In addition, the strengthening and toughening mechanisms are also discussed.

Hafnium silicate formation during oxidation of a permeable silicon + HfO2 powder composite system

Silicon bond coats, applied to silicon carbide composites used in gas turbine engines as a part of an environmental barrier coating (EBC) system, arrest the transport of oxidizing species to the SiC composite by forming a SiO2 thermally grown oxide. Above 1200°C, a crystalline ß-cristobalite SiO2 phase is formed that subsequently undergoes a large thermal contraction during its ß→α-cristobalite transformation upon cooling, leading to oxide layer cracking and eventual EBC delamination. A model system of silicon particles in a highly porous HfO2 particle matrix is used to investigate the rate and mechanism by which ß-cristobalite SiO2 is dynamically converted to hafnium orthosilicate (HfSiO4; Hafnon) when oxidizing silicon is in contact with m-HfO2. The study compares the net rate of SiO2 formation in the model silicon + HfO2 system with that on only silicon particles, and finds that the thickness of the SiO2 layer that forms during high temperature (1250–1316°C) oxidation can be greatly reduced by the hafnon formation reaction. The study also investigates the mechanism by which hafnon forms, and reports a SiO2 rumpling process when its outward (radial) growth is locally constrained by HfO2 particles. Since hafnon is phase stable over the temperature range of EBC interest, and has a thermal expansion coefficient similar to silicon, the dynamic conversion of SiO2 to hafnon provides a promising approach for controlling the delamination of EBC systems that use silicon bond coats.

Investigation of drilling 2D C<sub>f</sub>∕C–SiC composites with brazed diamond core drills

Abstract. Drilling carbon fiber reinforced silicon carbide composites still forms a big challenge for machining because of their special braided structure and anisotropy. In this study, through the drilling of 2D Cf∕C–SiC composites, two kinds of brazed diamond core drills with different abrasive distributions were compared. The results showed that the drilling force and torque of the two drills decreased with the increase in the spindle speed and increased with the increase in the feed speed. Under the same drilling conditions, the drilling force and torque of the brazed diamond drill with the ordered abrasive distribution were far lower than those of the brazed diamond drill with the random abrasive distribution. Also, the quality of the holes drilled by the drill with the ordered abrasive distribution was better than that of the holes drilled by the drill with the random abrasive distribution, which is attributed to the uniform abrasive spacing provided by the drill with the ordered abrasive distribution.

Towards structural design and thermal management of advanced 2D CMCs

Advanced 2D carbon fiber reinforced silicon carbide (C/SiC) composites are highly advantageous, owing to the excellent temperature tolerance of carbon and the good oxidation resistance of SiC. Therefore, they have been regarded as the most promising thermal structural materials that operate in thermal shock environments. However, studies pertaining to their thermomechanical properties at elevated temperatures are sparse. The understanding of the structural design and thermal management of ceramic matrix composites remains rooted in the idea of traditional bulk materials. In this study, for the first time, the thermal-mechanical-oxidation coupled behaviors of a 2D plain-weave C/SiC material are investigated on an in-house built testing machine that is heated via induction from room temperature to 1400 °C in air. The high-temperature thermal properties are evaluated based on the proposed models and available experimental data. The thermal shock resistance in the simulated environments is subsequently studied. Safe and hazardous thermal shock conditions are identified. Improved methods for structural design and thermal management are proposed.

Parametric Optimization of ZrB2–SiC Composites Sintered Through Microwave Sintering Using Grey Relational Taguchi

Zirconium Diboride (ZrB2) is known as an ultra-high temperature ceramic with applications in various industries like refractory and foundry industries. In conjunction with Silicon Carbide (SiC), ZrB2ceramic finds extensive applications in the nose caps and leading edges of atmospheric re-entry vehicles and rocket propulsion. The primary objective is to optimize the output responses viz., Vickers micro hardness, relative density, compressive strength of ZrB2-30 vol.% SiC composites developed through microwave sintering. The three control factors viz., sintering temperature, heating rate and holding time are chosen as input process parameters for microwave sintering. Taguchi’s L9orthogonal array is used to obtain experimental runs. The Grey Relational Taguchi provides the optimal process parameters by binding the multiple responses (relative density, vickers micro-hardness, and compressive strength) into single comprehensive response [i.e., Grey Relational Grade (GRG)]. The results confirm that the optimal parameters attained using Grey Relational Taguchi maximize the performance characteristics of the microwave sintering process.

The effect of heat treatment on tensile properties of 2D C/SiC composites

AbstractTwo‐dimensional (2D) carbon fiber reinforced silicon carbide (C/SiC) composites with different initial strength were prepared by chemical vapor infiltration (CVI). After tensile property testing, results exhibited that as the heat‐treatment temperature (HTT) increases to 1900°C, the tensile strength and toughness of the low strength specimen (LSS) increased by 110% and 530%, while the high strength specimen (HSS) increased by 5.4% and 550%, respectively. As observed from morphologies, the heat treatment increases the graphitization of the amorphous PyC interphase, which leads to the weakening of interfacial bonding strength (IBS). Meanwhile, the defects arising from heat treatment cause thermal residual stress relaxation. Therefore, the tensile strength and toughness of LSS with relatively high initial IBS increase significantly as HTT increases. For HSS with moderate initial IBS, the heat treatment slightly improves the tensile strength, but significantly improves the toughness. Consequently, the post‐heat‐treatment tensile properties of 2D C/SiC composites can be regulated by varying HTTs and different initial strength.

Finite Element Investigation of the Influence of SiC Particle Distribution on Diamond Cutting of SiCp/Al Composites

Characteristics of internal microstructures have a strong impact on the properties of particulate reinforced metal composites. In the present work, we perform finite element simulations to elucidate fundamental mechanisms involved in the ultra-precision orthogonal cutting of aluminum-based silicon carbide composites (SiCp/Al), with an emphasis on the influence of particle distribution characteristic. The SiCp/Al composite with a particle volume fraction of 25 vol% and a mean particle size of 10 μm consists of randomly distributed polygon-shaped SiC particles, the elastic deformation and brittle failure of which are described by the brittle cracking model. Simulation results reveal that in addition to metal matrix tearing, cutting-induced particle deformation in terms of dislodging, debonding, and cracking plays an important role in the microscopic deformation and correlated machining force variation and machined surface integrity. It is found that the standard deviation of particle size to the mean value has a strong influence on the machinability of microscopic particle–tool edge interactions and macroscopically observed machining results. The present work provides a guideline for the rational synthesis of particulate-reinforced metal composites with high machinability.

Investigations on morphology and material removal rate of various MMCs using CO2 laser technique

The efficient machining of metal matrix composite becomes important factor with respect to the high strength and hardness properties. The presented research work observes the influence of CO2 laser processing parameters on various metal matrix composite materials in terms of material removal rate (MRR). A comparison has been explored between various composite materials such as silicon carbide (SiC), aluminum oxide (Al2O3), and zirconium oxide (ZrO2) metal matrix composites for MRR. This results in novel research in context of MRR that examines the microstructure of machined work material. In the present study, to determine MRR various weighing evaluations and topography of machined surface were studied. The results indicated that the focal position, cutting speed and reinforced particles are the significant parameters for MRR. The morphological and metallurgical changes such as formation of recast layer have been analyzed using scanning electron microscope. The chemical composition of machined work materials and formation of new compound have been identified using EDS/XRD technique.

Nitride bonded silicon carbide composites based on artificial ceramic binders

The mass compositions for the production of silicon carbide materials on a nitride bond, in which artificial ceramic binders based on silicon and silicon carbide were used as initial binders, were studied. The influence of the firing regime and the composition of the binder on the main physicomechanical characteristics and microstructure of the samples after nitriding firing is studied.

2D exhaust nozzle with multiple composite layers for IR signature suppression

The IR (Infrared) signature generated from hot sections of the aircraft increases potential to be traced by IR detection system and severely reduces aircraft survivability during the mission. Main sources of IR signature are high temperature parts of the aircraft and the engine such as exhaust nozzle, jet pipe, rear-fuselage, and exhaust gas plume above 400 °C, and they generate detectable 3 to 5 um wavelength IR signature. The novel 2D engine exhaust nozzle with multiple composite layers is proposed to suppress high temperature IR signature from behind, in this study. The 2D exhaust nozzle with ellipse-shaped cross-sections with high aspect ratios can disperse high temperature core gas flow, and can enhance mixing performance with bypass air flow. Thus, this reduces the exhaust gas plume temperature and masks the engine hot sections from behind. In order to suppress high temperature IR signature from the nozzle surface, this study constructs a ceramic insulator between the outermost surface layer and the innermost surface layer. The innermost surface layer is constituted by C-SiC (carbon fiber reinforced silicon carbide composite) with excellent erosion performance for high speed and high temperature gas above 1400 °C, and the outermost layer is formed of CFRP (Carbon Fiber Reinforced Plastic) that can maintain structural strength even with the axial thrust and inner pressure. In this study, the 2D-shape C-SiC nozzle was fabricated through melting Si infiltration process, and the nozzle was completed by stacking ceramic insulator and CFRP above it. The engine application test confirmed that the outermost temperature of the proposed exhaust nozzle was kept below 100 °C, and the IR signature was also reduced by 20% compared to the coaxial exhaust nozzle. The 2D exhaust nozzle proposed in this study can be applied to aircraft that requires stealth capability through structural optimization in the future works.

Synthesis of Porous Ceramic Materials for Catalytically Active Membranes by Technological Combustion and Sintering

A porous, catalytically active membrane based on coarse-fraction silicon carbide was synthesized. Ultrafine additives with an eutectic composition of magnesium oxide and silicon carbide, which during sintering at temperatures from 1100 to 1450°C form a liquid phase in the form of clinoenstatite MgSiO3 that wets the coarse-size SiC particles and forms a strong porous framework of the membrane, were introduced into the initial SiC powder to synthesize the membranes. The pore size of the ceramic material was studied as a function of the pressing pressure, which made it possible to obtain a highly porous ceramic membrane with pore size optimized for dehydrogenation of ethylbenzene into styrene. Modification of the pore surfaces to 10% Re – W by means of active components using the alkoxy method is performed in order to give the synthesized membrane the catalytic properties required for realizing the dehydrogenation process.

High-temperature flexural strength of I-CVI processed Cf/SiC composites with variable interphases

The effect of single-layer pyrocarbon (PyC) and multilayered (PyC/SiC)n=4 interphases on the flexural strength of un-coated and SiC seal-coated stitched 2D carbon fiber reinforced silicon carbide (Cf/SiC) composites was investigated. The composites were prepared by I-CVI process. Flexural strength of the composites was measured at 1200 °C in air atmosphere. It was observed that irrespective of the type of interphase, the seal coated samples showed a higher value of flexural strength as compared to the uncoated samples. The flexural strength of 470 ± 12 MPa was observed for the seal coated Cf/SiC composite samples with multilayered interphase. The seal coated samples with single layer PyC interphase showed flexural strength of 370 ± 20 MPa. The fractured surfaces of tested samples were analyzed in detail to study the fracture phenomena. Based on microstructure-property relations, a mechanism has been proposed for the increase of flexural properties of Cf/SiC composites having multilayered interphase.

Optimization of tool wear parameters in machining AA7075/SiC composite

Thirty experiments were planned as per face centred central composite design. Turning of AA7075–10 wt.% silicon carbide (SiC) (particle size 20–40 µm) composites was carried out using tungsten carbide inserts. Flank wear and crater wear were measured by scanning electron microscope (SEM). Experimental data was used to develop regression model. Desirability approach was utilized to get optimum values of process parameters so that values of flank wear and crater wear are minimum. GA technique had given the very close values of minimum flank wear as compared to value obtained by experimental, regression modelling and desirability analysis by 20%, 4.25% and 3.7% respectively. Minimum crater wear value obtained by GA technique are about 47%, 29.44% and 46% less than the value obtained by experiment, regression modelling and desirability analysis. Hence, it can be said that if turning of AA7075–10 wt.% SiC (20–40 µm) composites is done at optimum values of parameters obtained by GA, it will result in minimum flank and crater wear. Novelty of this research work is that 03 different techniques were used to obtain optimum process parameters, so that tool wear during turning of AA7075/SiC will be minimum. Turning at optimum parameters obtained by GA, resulted in minimum flank and crater wear. AA7075/SiC, composite has applications in automobiles, marines, aeroplanes and space vehicles.

A Review on Mechanical and Tribological Properties of Graphite, Silicon Carbide and Pineapple Leaf Fibre Reinforced Polymer Composites

This paper presents a review of the mechanical and tribological properties of a reinforced polymer matrix composite of graphite, Silicon Carbide (SiC), and Pineapple Leaf Fibre (PALF). Also investigated are the factors influencing the properties such as type and variety of natural fibres, type of matrix materials, fibre length and their orientation, surface treatment to improve the interfacial property of fibre, type of graphite, and its particle size. Also discussed is the tribological property of SiC and its application for improving the wear property of the composite. It is hoped that this review article would be useful to those working in the domain of polymer matrix composites with SiC, graphite and natural fibre leaves such as pineapple leaf. How to cite this article: Mahadevareddy, Adveesh B, Hiremath VK. A Review on Mechanical and Tribological Properties of Graphite, Silicon Carbide and Pineapple Leaf Fibre Reinforced Polymer Composites. J Adv Res Mfg Mater Sci Met Engr 2020; 7(3): 11-22. DOI: https://doi.org/10.24321/2393.8315.202004

Development of AA 5083 based hybrid surface composites via friction stir processing

The demand for advanced materials with low density and high strength is always present in areas like aerospace, automotive, and military applications. Aluminum based hybrid composites are the new generation group of materials that have the prospective to satisfy the above need. In the present work, an attempt was made to develop AA 5083 reinforced with silicon carbide and titanium oxide surface composites. Number of passes, revolving speed, and welding speed were the process parameters considered and varied in three levels. Ultimate tensile strength was measured and modeling equation was developed by response surface methodology and suitability of the equation was checked by ANOVA. The model was best to predict the ultimate tensile strength of the processed workpiece and it was observed that number of passes was the dominating parameter followed by revolving speed. The ultimate tensile strength of the processed workpiece was 237Mpa with an increase of nearly 50%.

Microwave-assisted method to degrade phenol using persulfate or hydrogen peroxide catalyzed by Cu-bearing silicon carbide.

The radical generation properties of hydrogen peroxide and persulfate for phenol degradation were investigated under microwave irradiation using copper-doped silicon carbide (Cu/SiC) composites as catalyst. The results showed that 90% and 70% of phenol and total organic carbon (TOC), respectively, were removed within 7 min. Microwave activation of hydrogen peroxide and sodium persulfate in terms of thermal effects and accelerated electron transfer was analyzed by degradation kinetics and X-ray photoelectron spectroscopy (XPS). The microwave activation of Na2S2O8 demonstrated that the hot spots promote decomposition of persulfate more rapidly and the rate of persulfate decomposition was more than three times the activation rate of a normal heating method. There is a synergistic effect between Cu and microwave radiation, which is highlighted by the H2O2 activation; ·OH was generated due to the redox cycle between Cu(I)/Cu(II) and was responsible for phenol degradation using H2O2. High performance liquid chromatography (HPLC) analysis indicated that hydroxylation and sulfate radicals addition of phenol were the initial oxidation reaction steps of hydrogen peroxide and persulfate, respectively, followed by further oxidation to form short-chain carboxylic acids.

A Micromechanical Fatigue Limit Stress Model of Fiber-Reinforced Ceramic-Matrix Composites under Stochastic Overloading Stress.

Fatigue limit stress is a key design parameter for the structure fatigue design of composite materials. In this paper, a micromechanical fatigue limit stress model of fiber-reinforced ceramic-matrix composites (CMCs) subjected to stochastic overloading stress is developed. The fatigue limit stress of different carbon fiber-reinforced silicon carbide (C/SiC) composites (i.e., unidirectional (UD), cross-ply (CP), 2D, 2.5D, and 3D C/SiC) is predicted based on the micromechanical fatigue damage models and fatigue failure criterion. Under cyclic fatigue loading, the fatigue damage and fracture under stochastic overloading stress at different applied cycle numbers are characterized using two parameters of fatigue life decreasing rate and broken fiber fraction. The relationships between the fatigue life decreasing rate, stochastic overloading stress level and corresponding occurrence applied cycle number, and broken fiber fraction are analyzed. Under the same stochastic overloading stress level, the fatigue life decreasing rate increases with the occurrence applied cycle of stochastic overloading, and thus, is the highest for the cross-ply C/SiC composite and lowest for the 2.5D C/SiC composite. Among the UD, 2D, and 3D C/SiC composites, at the initial stage of cyclic fatigue loading, under the same stochastic overloading stress, the fatigue life decreasing rate of the 3D C/SiC is the highest; however, with the increasing applied cycle number, the fatigue life decreasing rate of the UD C/SiC composite is the highest. The broken fiber fraction increases when stochastic overloading stress occurs, and the difference of the broken fiber fraction between the fatigue limit stress and stochastic overloading stress level increases with the occurrence applied cycle.

Design and strategy for next-generation silicon carbide composites for nuclear energy

Silicon carbide (SiC) ceramic-based composites continue to be attractive material options for fusion in-vessel components and fission reactor core structures because of their exceptional high-temperature capability and favorable neutronic properties. As performance data accumulates, the limitations of the current generation of nuclear-grade SiC composites are becoming more apparent. These limitations mainly involve strength degradation during high-dose neutron irradiation. This paper discusses several options for improving the performance of the next generation of SiC composites to enhance the radiation resistance, along with new experimental results on neutron irradiation resistance. The main emphasis is on the selection of the fibers and the design and development of alternative interphase layers for advanced composites.