Effect Of SiC Content Research Articles

Effects of Micro and Nano Sized SiC Powder on the Rheological Properties of Al Based Feedstocks for Low Pressure Injection Molding

This study investigates the effects of micro- and nano-sized SiC powder on the rheological behavior of Al based feedstocks for powder injection molding (PIM). Different compositions of Al feedstocks with additions of micro and nano-SiC powder were prepared and their rheological properties were measured with a rotational rheometer. The effects of SiC content and shear rate were investigated and activation energies were compared amongst the feedstocks. The results showed that nano-SiC powder has a prominent effect on the viscosity and yield stress whereas micro-SiC does not have an effective role and the base micro-Al powder determines the overall rheological behavior of the feedstock. It was found that the feedstocks reveal pseudoplastic behavior at low shear rates and dilatancy at high shear rates. The critical shear rate (γcrit) was 100 s-1 for changing the rheological behavior. The activation energy of a given feedstock was found to increase with micro-SiC content while the reverse trend was observed for nano-SiC.

Mechanical and electromagnetic shielding properties of carbon fiber reinforced silicon carbide matrix composites

Carbon fiber reinforced SiC matrix composites (Cf/SiC) were fabricated through chemical vapor infiltration. Effects of SiC content on the mechanical and electromagnetic properties of the as-prepared materials were studied systematically. The high volume fraction of SiC matrix is beneficial to the transfer of load to carbon fiber. With the increase of SiC content from 21.5 to 42.2 vol.%, the total porosity decreases from 38.5 to 17.8 vol.%, the flexural strength and fracture toughness of Cf/SiC increase from 38 ± 4 to 375 ± 10 MPa and from 6.2 ± 0.7 to 21 ± 0.3 MPa m1/2. The electromagnetic interference shielding effectiveness of as-prepared Cf/SiC decreases from 43 ± 1.4 to 31 ± 1.1 dB over the frequency range of 8.2–12.4 GHz with the increase of SiC content. The decease of electromagnetic interference shielding effectiveness is mainly attributed to the decline of absorption loss. With the increase of SiC content, the electrical conductivity of Cf/SiC diminishes, leading to the conspicuous drop of the conductive loss, which plays the key role in lowering the absorption loss of electromagnetic waves.

Corrosion and wear behavior of functionally graded Al2024/SiC composites produced by hot pressing and consolidation

Functionally graded Al2024/SiC composites (FGMs) with varying percentage of SiC (30–60%) were produced by hot pressing and consolidation method. The effects of SiC content and number of layers of Al2024/SiC FGMs on the corrosion and wear behaviors were investigated. The microstructures of these composites were characterized by a scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS). The corrosion performances of composites were evaluated by potentiodynamic polarization scans in 3.5% NaCl solution. Corrosion experiments shows that corrosion rate (1109mpy) of two layered FGMs which containing 50wt.% SiC were much higher than Al2024 matrix (2569mpy) and Al2024/50wt.% SiC composite (2201mpy). Mechanical properties of these composites were evaluated by microhardness measurements and ball-on-disk wear tests. As the applied load change from 15 to 20N, the wear rates of the Al2024 increased significantly and wear mechanism transformed from mild to severe wear regime. It has been shown that Al2024/40wt.% SiC composite has lower wear rate where adhesive and abrasive wear mechanisms play a major role.

On the Effect of SiC Content and Processing Temperature on Relative Density and Hardness of Hot Compacted Aluminum AA6061 Composite – Mathematical Empirical and Response Surface Approach

The AA6061 is reinforced by adding SiC at various volume fractions and, the mixture is hot compacted at different processing temperatures. The influences of such parameters are investigated on the product relative density along with its relevant Vickers hardness using quantitative and qualitative formulation approach. Empirical relationships are established to relate each of the controlling (independent) parameters (SiC% and hot compaction (HC) temperature), to the composites relative density and the hardness, as dependent variables. The developed models are examined for its adequacy and significance using several statistical criteria. Response surface and contour graphs are established to reflect the relevant function interrelations and, to provide a data base source for the prior design stage. Within the specified experimental domain, first order and nonlinear models are found independently adequate and significant to grasp the functional dependence between the relative density and both SiC and HC temperature. However, second order multiple model with quadratic components of SiC percent is found to best suit the hardness-SiC%-temperature functional relationship. Increasing SiC content is found to reduce the relative density of the composites regardless the hot compaction temperature while, up to about 18 vol.% SiCp relative ratio, it enormously and nonlinearly increases the composite hardness. Further increase in SiC% addition seems not to affect the composite hardness. Relative density of the resulting composite is decreased by increasing HC temperature.

Pressureless sintering behavior and mechanical properties of ZrB2–SiC composites: effect of SiC content and particle size

In the present paper, ZrB2–SiC composites were prepared by pressureless sintering at temperatures of 2000–2200°C for 1h under argon atmosphere. In order to prepare composite samples, ZrB2 powder was milled for 2h, then the reinforcing particles including of micron and nano-sized SiC powder were added. The mixtures were formed and, after the pyrolysis, they were sintered. Densification, microstructural and mechanical properties of ZrB2–SiC composites were investigated. The shrinkage of samples was measured both before and after the sintering, and the microstructure of samples was examined using scanning electron microscopy (SEM), equipped with EDS spectroscopy. Both mass fraction and size of SiC powder have a great effect on relative density, porosity, shrinkage, hardness and microstructure of these composites. The highest relative density and hardness were 98.12% and 15.02GPa, respectively, in ZrB2–10wt% SiCnano composite sintered at 2200°C.

High-frequency welding of glass-fiber-reinforced polypropylene with a thermoplastic adhesive layer including SiC

In this study, high-frequency (HF) welding of glass-fiber-reinforced polypropylene (GF/PP) was investigated with thermoplastic adhesive layers including SiC, which is able to heat by HF irradiation. The influences of SiC particle size and content on the dielectric properties of an adhesive layer were investigated experimentally. The influence of temperature on the tanδ/ε′ value was also investigated.In the HF welding process of GF/PP bonded with the thermoplastic adhesive layer, the effects of SiC content and particle size on the welding properties were examined. The GF/PP was completely welded in a short time when SiC with small particle size and high content was included in the adhesive and a good bond strength was also achieved. Thus, short time and high bond strength for the welding were achieved with the method using a thermoplastic adhesive layer with high tanδ/ε′ value.

Microstructure, mechanical property and wear performance of cold sprayed Al5056/SiCp composite coatings: Effect of reinforcement content

SiC particle reinforced Al5056 composite coatings were prepared by cold spraying using initial powders containing 15, 30, 45 and 60vol.% SiC. Effects of SiC content in the coating on microstructure, mechanical property and wear behavior of the coatings were studied. Experimental results show that the SiC particles in the coating improve the deformation of Al5056 particles and also increase the hardness of the coating. The cohesion strength of the composite coatings firstly increases and then decreases with the increase of SiC content in the coatings as a result of comprehensive effects of the SiC particles on improving the deformation of Al5056 particles and on reducing the effective contact area between the Al5056 particles. Finally, tribological tests show that the SiC particle and its content in the coatings would greatly influence the tribological behavior of the coatings. The worn tracks suggest that the delaminating wear is the wear mechanism of the Al5056 and Al5056/SiCp coatings at the present tribological condition.

Investigation on Slag Resistance of Magnesia Based Castable Containing SiC

Corrosion of four magnesia based castables with different SiC contents by ladle slag was conducted using the static crucible test. Effect of SiC content on the slag resistance of castables was investigated by XRD, SEM, EDAX. The reactions between refractories and slag were simulated through FactSage® thermochemical software. It has been found that SiC can increase the penetration resistance of magnesia based castables, not decreasing their corrosion resistance. With increasing the content of SiC, the SiO2 content and the viscosity of penetrated slag increase. The lower wettability of slag to SiC and the higher viscosity of penetrated slag affect the penetration resistance of magnesia based castables, whereas the reactions between slag and castables affect the corrosion resistance of magnesia based castables. The thermochemical simulation helps to understand the reaction mechanism.

Effect of shaping methods on the mechanical properties of Al-SiC composite

Al-SiC composites were successfully produced with improved mechanical properties. Effect of SiC content, its particles size and shaping method were investigated. Three shaping methods of conventional powder metallurgy (PM), hot press (HP) and hot extrusion (EX) were used. The hardness of the samples was measured by Vickers method. Tensile and compression tests were performed for the characterization of mechanical properties. Microstructure was monitored by optical microscopy. Maximum relative density (RD) was obtained for hot pressed samples. Higher SiC content with smaller particles size had the best effect on the mechanical properties such as yielding point (YP), ultimate tensile strength (UTS) and hardness. Maximum hardness (6.57 GPa) and UTS (212 MPa) were obtained for Al-20%SiC with SiC mesh size of 1000. Maximum YP was obtained for Al-20%SiC in compression test (143.64 MPa) that is larger than it in tensile test (117.96 MPa). Remarkable difference exists between HP and extrusion methods at higher SiC contents. The YP of EX samples are larger than HP samples. Strains at known stress (562 MPa) of EX samples are smaller than HP samples.

Effect of SiC Content on the Ablation and Oxidation Behavior of ZrB₂-Based Ultra High Temperature Ceramic Composites.

The ablation and oxidation of ZrB2-based ultra high temperature ceramic (UHTC) composites containing 10%, 15% and 30% v/v SiC were tested under different heat fluxes in a high frequency plasma wind tunnel. Performance was significantly affected by the surface temperature, which was strongly dependent on the composition. Composites containing 10% SiC showed the highest surface temperature (>2300 °C) and underwent a marked degradation under both conditions. In contrast, composites with 30% SiC exhibited the lowest surface temperature (<2000 °C) and demonstrated excellent ablation resistance. The surface temperature of UHTCs in aerothermal testing was closely associated with the dynamic evolution of the surface and bulk oxide properties, especially for the change in chemical composition on the exposed surface, which was strongly dependent on the material composition and testing parameters (i.e., heat flux, enthalpy, pressure and test time), and in turn affected its oxidation performance.

Effects of SiC contents on the dielectric properties of SiO2f/SiO2 composites fabricated through a sol-gel process

Abstract SiC powders have been synthesized through a combustion process using Si powders and carbon black as starting materials. As a C-enriched α-SiC solid solution, the prepared SiC powders contain antisite defects of CSi and graphite state of sp2C, revealing good real part e′ and imaginary part e″ of permittivity. Subsequently, SiO2f/SiO2 composites are fabricated via a sol-gel process employing three-dimensional braided quartz fiber fabrics as a skeleton and a mixture of high-purity silica sol and the synthesized SiC powders as slurry. The effects of the SiC contents on the dielectric properties of the composites are investigated. The real and imaginary parts of the complex permittivity (e′ and e″) of the composites increase first before they decrease with an increasing SiC content from 0 to 40 wt.%. The maximum e′ and e″ are obtained at the SiC content of 20 wt.% in the range of 8–18 GHz, and the bandwidth with the reflectivity below − 10 dB of the SiO2f/SiO2 composite with 20 wt.% SiC powders is 5 GHz, which can well meet the requirements as good microwave absorbing materials.

Effect of SiC content, additives and process parameters on densification and structure–property relations of pressureless sintered ZrB2–SiC composites

The effect of SiC content, additives, and process parameters on densification and structure–property relations of pressureless sintered ZrB2–(10–40vol%) SiC particulate composites have been studied. The ZrB2–SiC composite powders mixed by ball-milling with 1.2wt% C (added as phenolic resin) and 3wt% B4C have been uniaxially cold-compacted and sintered in argon environment at 1950–2050°C for 2h, or at 2000°C for durations between 1/2 and 3h. The amount of densification is found to increase with sintering duration, and by prior holding at 1250 and 1600°C for reduction of oxide impurities (ZrO2, B2O3 and SiO2) on powder particle surfaces by the aforementioned additives. Presence of SiC with average size smaller than that of ZrB2 appears to aid in densification by enhancing green density, increasing WC content by erosion of milling media, and inhibiting matrix grain growth. Both SiC and WC appear to aid in reduction of oxide impurities. Furthermore, the impurities enriched in W, Fe and Co obtained from milling media are found to be segregated at ZrB2 grain boundaries, and appear to assist in densification by forming liquid phase, which completely wets the ZrB2 grains. Hardness increases with SiC content or with sintering duration till 1h, but decreases for periods ≥2h due to grain growth. The experimentally measured elastic moduli approaches corresponding theoretically predicted values with increasing SiC content due to reduction in porosity.

The Effect of SiC Content on Pressureless Sintered Si&lt;sub&gt;2&lt;/sub&gt;ON&lt;sub&gt;2&lt;/sub&gt;-SiC Ceramic

The Si¬2ON2-SiC ceramic was fabricated by pressureless sintering method. In this paper we researched the effect of SiC content (50%, 70% and 90%) on the performance of silicon oxynitride bonded silicon carbide ceramics. Through testing and analyzing the SEM, XRD, density and porosity of the final silicon oxynitride bonded silicon carbide ceramic samples, the results show that: changes in SiC content not only affect the bulk density of the composites but also affect the phase composition and the microstructure of fracture surface. The most compactness experimental product is sintered at1500°C containing 50wt% SiC.

The effect of SiC particle size on the properties of Cu–SiC composites

SiC particulate-reinforced copper composites were prepared by powder metallurgy (PM) method and conventional atmospheric sintering. Scanning electron microscope (SEM), X-ray diffraction (XRD) techniques were used to characterize the sintered composites. The effect of SiC content and particle size on the relative density, hardness and electrical conductivity of composites were investigated. The relative densities of Cu–SiC composites sintered at 700°C for 2h are ranged from 97.3% to 91.8% for SiC with 1μm particle size and from 97.5% to 95.2% for SiC with 5μm particle size. Microhardness of composites ranged from 143 to 167HV for SiC having 1μm particle size and from 156 to 182HV for SiC having 5μm particle size. The electrical conductivity of composites changed between 85.9% IACS and 55.7% IACS for SiC with 1μm particle size, between 87.9% IACS and 65.2% IACS for SiC with 5μm particle size.

Effect of the SiC Content on the Tribological Properties of Hybrid Al/Gr/SiC Composites Processed by &lt;i&gt;In Situ&lt;/i&gt; Powder Metallurgy (IPM) Method

The Al/Gr/SiC hybrid composites have attracted a considerable attention owing to their high wear resistance combined with a low friction coefficient. In these composites graphite acts as a solid lubricating agent and lowers the friction coefficient. However, it reduces the mechanical properties of the composite. The presence of hard SiC particles in these hybrid composites increases the hardness and strength and compensates for the weakening effects of graphite. Powder metallurgy (P/M) is an important processing technique for processing of these MMCs but requires a relatively long mixing time for obtaining a uniform distribution of graphite and SiC particles in the matrix alloy. In the present study for the first time a new method, namely "in situ powder metallurgy (IPM)" is applied for preparation of Al/SiC/Gr hybrid composites. In this work, the effects of different contents (0-40 vol.%) of SiC particles on the morphology and size distribution of the IPM produced Al/Gr/SiC powder mixtures containing 9 vol.% of graphite particles was investigated. Then Al/Gr/SiC compacts were prepared by cold pressing of different powder mixtures and after sintering, the effects of SiC content on the density, microstructure, hardness and wear properties of the resultant hybrid composites was investigated.

Effect of SiC content on the processing, compaction behavior, and properties of Al6061/SiC/Gr hybrid composites

Aluminum matrix composites reinforced with SiC and graphite (Gr) particles are a unique class of advanced engineered materials that have been developed to use in tribological applications. The conventional techniques for producing these composites have some drawbacks. In this study, a new method, namely In situ Powder Metallurgy (IPM), is applied for the preparation of Al6061/SiC/Gr hybrid composites. In this method, the stir casting and the powder metallurgy synthesizing processes are combined into an integrated net shape forming process. 0–40 vol.% of SiC particles with an average size of 19 μm, along with 9 vol.% of uncoated Gr particles, were introduced to the molten 6061 aluminum alloy. Then, the slurries were stirred in a specified time–temperature regime resulting in mixtures of the SiC, Gr, and aluminum powder particles. The powder mixtures were cold pressed in six different pressures (between 250 and 750 MPa) and sintered. Finally, the produced composites were heat treated and their hardness and wear properties were investigated. Homogenous distribution of the SiC and Gr particles within the powder mixtures and the hybrid composites is clear from the SEM images. The results also show that the SiC particles decrease the compressibility of the hybrid powders and improve the hardness of composites. The best wear resistance is achieved in the hybrid composite containing 20 vol.% SiC particles.

High‐Temperature Oxidation at 1900°C of ZrB2–xSiC Ultrahigh‐Temperature Ceramic Composites

Oxidation of ZrB2‐based ultrahigh‐temperature ceramic composites containing 10, 20, and 30 vol% SiC was performed at 1900°C for 1 h in air. ZrB2–20 vol% SiC exhibited the highest oxidation resistance at this temperature and formed a dense coherent oxide scale after oxidation, whereas a strong degradation was observed for both ZrB2–10 vol% SiC and ZrB2–30 vol% SiC. In addition, cracks and spallation in the oxide scale were also detected for the latter materials. The oxidation behaviors of ZrB2–SiC composites were investigated. The effect of SiC content was analyzed and oxidation models were proposed to describe the observed microstructures.

The effect of SiC particles added in electroless Ni–P plating solution on the properties of composite coatings

To verify the relationship between the properties of composite coatings prepared on Q235 steel and the SiC content of electroless Ni–P–SiC composite coatings, systematic experiments with varied SiC contents and surfactants have been conducted. The experimental results indicated the approximate linear relation between the SiC content and the hardness of composite coatings. With the increasing of SiC content, wear resistance increases correspondingly. In particular, the effect of SiC content on the corrosion resistance of Ni–P–SiC composite coatings immersed in different corrosive solutions (i.e. 5% H 2SO 4, 20% NaOH and 3.5% NaCl) is explored, followed by a comparative analysis of the corrosion resistance between Ni–P and Ni–P–SiC coatings. Corrosion test indicates that NaOH solution makes no differences in the corrosion resistance between Ni–P coatings and electroless Ni–P–SiC composite coatings, both being uncorroded. Exposed to NaCl solution, the corrosion resistance of electroless Ni–P–SiC composite coatings decreases gradually with the increasing of SiC content in coatings. In H 2SO 4 solution, the corrosion resistance of coatings increases initially and decreases afterwards with the sustained increasing of SiC content in coatings, and the optimized corrosion resistance is obtained at a SiC content of 9.41 wt.%. Finally, a competent electroless Ni–P–SiC composite plating process producing a high wear resistance and sound corrosion resistance of the coatings is obtained.

In Situ Processing and High‐Temperature Properties of Ti3Si(Al)C2/SiC Composites

Ti3SiC2 has many salient properties including low density, high strength and modulus, damage tolerance at room temperature, good machinablity, and being resistant to thermal shock and oxidation below 1100°C. However, the low hardness and poor oxidation resistance above 1100°C limit the application of this material. The poor oxidation resistance at temperatures above 1100°C was because of the absence of protective layer in the scale and the presence of TiC impurity phase. TiC impurity could be eliminated by adding a small amount of Al to form Ti3Si(Al)C2 solid solutions. Although the high‐temperature oxidation resistance was significantly improved for the Ti3Si(Al)C2 solid solutions, the strength at high temperatures was lost. One important way to enhance the high‐temperature strength is to incorporate hard ceramic particles like SiC. In this article, we describe the in situ synthesis and simultaneous densification of Ti3Si(Al)C2/SiC composites using Ti, Si, Al, and graphite powders as the initial materials. The effect of SiC content on high‐temperature mechanical properties and oxidation resistance were investigated. The mechanisms for the improved high‐temperature properties are discussed.

Influence of inoculant and/or SiC addition on characteristics of grey cast iron

The influence of inoculant additions on the cooling curve characteristics, microstructure and chill depth of hypoeutectic grey cast iron melts treated with FeSi or SiC as silicon carriers has been investigated. The effect of SiC content, when used simultaneously with FeSi as a silicon carrier, on the solidification behaviour of melts with an identical carbon equivalent has also been studied. It has been found that the addition of SiC instead of FeSi as a silicon carrier resulted in variations in the thermal analysis characteristics and microstructure together with decreasing chill depth. These effects were more pronounced for inoculated melts. It was also observed that the maximum amount of A-type graphite, the finest microstructure and the minimum chill depth were obtained with 1.6–2.0 wt-%SiC additions, for grey cast iron melts (treated with SiC and FeSi) having carbon equivalents of 4.2%.