Investigation of Mechanical and Wear Behaviour of Al7075/SiC Composites Using Response Surface Methodology

Silicon - This work studies the effect of reinforcement weight percentage (Wt.%SiC) on wear and mechanical behaviour of the aluminium 7075 composites produced by the powder metallurgy technique....     

Fabrication,Mechanical and Wear Characterization of Silicon Carbide Reinforced Aluminium 7075 Metal Matrix Composite

Silicon - Al7075-SiC composites containing three different weight percentages, 5 %, 10 %, and 15 % of SiC, have been fabricated by powder metallurgy. Mechanical and tribological...     

Thermo-Mechanical Properties and Abrasive Wear Behavior of Silicon Carbide Filled Woven Glass Fiber Composites

A study was done to determine the effect of physical, mechanical, thermal and three body abrasive wear response of Silicon Carbide (SiC) filled Glass Fiber Reinforced Epoxy (GFRE) composites. The main purpose was to study the influence of different weight percentages (wt.%) of SiC filler in addition to that of glass fiber. A three body abrasive wear analysis was conducted by varying different factors such as fiber/filler reinforcement, abrasive particle size, normal load, sliding distance and sliding velocity. An attempt was made to find out the dominant factor and the effect of each factor on specific wear rate analysis. Physical and mechanical properties, i.e. density, hardness, tensile strength, flexural strength, inter laminar shear strength and impact strength, were determined for each weight percent of filler reinforcement to determine the behavior of mechanical properties with varying SiC filler loading. Thermo – mechanical properties of the material, i.e. storage modulus, loss modulus and tan delta with temperature were measured using a Dynamic Mechanical Analyzer (DMA). The result shows the increasing / decreasing trend and critical points of each analysis. The trend and major factors responsible for reducing the specific wear rate were determined. Mechanical properties, i.e. hardness and impact strength, increase with the increase in SiC content, whereas tensile strength, flexural strength and inter laminar shear strength decrease. Worn surfaces were studied using scanning electron microscopy (SEM) to give an insight into the wear mechanisms.     

Mechanical Properties of Alumina/Silicon Carbide Whisker Composites

The improvement of mechanical properties of Al₂O₃/SiC whisker composites has been studied with emphasis on the effects of the whisker content and of the hot-pressing temperature. Mechanical properties such as fracture toughness and fracture strength increased with increasing whisker content up to 40 wt%. In the case of the high SiC whisker content of 40 wt%, fracture toughness of the sample hot-pressed at 1900° decreased significantly, in spite of densification, compared with one hot-pressed at 1850°. Fracture toughness strongly depended on the microstructure, especially the distribution of SiC whiskers rather than the grain size of the Al₂O₃ matrix.     

Interfacial Characterization of Silicon Carbide Fiber/Lithia-Alumina-Silica Glass Matrix Composites

The development of the carbon-rich interphase in Nicalon SiC fiber/Li₂O-Al₂O₃–SiO₂ glass matrix composites was examined as a function of processing parameters with the use of high-resolution scanning electron microscopy and Auger electron spetroscopy. Specifically, hot-pressing temperatures (1000°, 1100°, and 1200°C) and times (15, 30, 60, and 240 min) were systematically varied in such a manner so as to fabricate dense composites suitable for evaluation of reaction kinetics. Carbon-rich interphase thickness, which ranged from 1400 to 5400 Å (140 to 540 nm), was observed to increase with either increasing times at constant temperature or increasing temperatures at constant time. The kinetics of formation of the carbon-rich interphase followed a diffusion-controlled model, with an activation energy of 25.4 kcal/mol.     

Reaction Bonding and Mechanical Properties of Mullite/Silicon Carbide Composites

Based on the RBAO technology, low-shrinkage mullite/SiC/ Al₂O₃/ZrO₂ composites were fabricated. A powder mixture of 40 vol% Al, 30 vol% A1₂O₃ and 30 vol% SiC was attrition milled in acetone with TZP balls which introduced a substantial ZrO₂ wear debris into the mixture. The precursor powder was isopressed at 300–900 MPa and heattreated in air by two different cycles resulting in various phase ratios in the final products. During heating, Al oxidizes to Al₂O₃ completely, while SiC oxidizes to SiO₂ only on its surface. Fast densification (at >1300°C) and mullite formation (at 1400°C) prevent further oxidation of the SiC particles. Because of the volume expansion associated with the oxidation of Al (28%), SiC (108%), and the mullitization (4.2%), sintering shrinkage is effectively compensated. The reaction-bonded composites exhibit low linear shrinkages and high strengths: shrinkages of 7.2%, 4.8%, and 3%, and strengths of 610, 580, and 490 MPa, corresponding to compaction pressure of 300, 600, and 900 MPa, respectively, were achieved in samples containing 49–55 vol% mullite. HIPing improved significantly the mechanical properties: a fracture strength of 490 MPa and a toughness of 4.1 MPa^.m^1/2 increased to 890 MPa and 6 MPa^.m^1/2, respectively.     

Microstructure of Silicon Carbide/Carbon Composites and Relationships with Mechanical Properties

Three different 2-D SiC/C composites, analyzed by TEM, have mechanical performances directly controlled by the interfacial structure resulting from processing. Localized attachment of the fibers to a brittle matrix constituent is shown to be responsible for composite weakening by impeding interface debonding and sliding. Moreover, the particulate phase used in the matrix is found to have a strong influence. There is a consequent sensitivity of composite strength to the particulate properties. Finally, it is demonstrated that the hindrance of debonding and sliding caused by the brittle matrix phase can be suppressed by using a C fiber coating.     

Tensile and Flexural Behaviour of Basalt Composites with Silicon Carbide Fillers

Silicon - The requisite in need of biopolymer materials in the automotive, aerospace, biomedical, sports and construction domains driven the present research attempt. The research aims to fabricate...     

Microstructure and Mechanical Properties of Mullite–Silicon Carbide Composites

Mullite-SiC-whisker composites were prepared by powder processing using two commercial SiC whiskers. These composites were prepared by sintering rather than hot-pressing. A mulliteSlC-powder composite and a base line mallite material were also prepared for comparison with the two whisker composite materials. Fracture toughness measurements showed significant enhancement in only one of the whisker composite materials. The microstructure of the four materials was examined by scanning electron microscopy and transmission electron microscopy to assist in the explanation of the mechanical behavior of these composites. The examinations suggested that most of the toughening results from second-phase particles, with only limited toughening from effects associated with whiskers per se. In one case, higher toughness was partially associated with the formation of sialon phase by reaction with the whiskers and the furnace environment.     

Effect of Carbon and Silicon Carbide/Carbon Interlayers on the Mechanical Behavior of Tyranno-SA-Fiber-Reinforced Silicon Carbide-Matrix Composites

Several CVI-SiC/SiC composites were fabricated and the mechanical properties were investigated using unloading–reloading tensile tests. The composites were reinforced with a new Tyranno-SA fiber (2-D, plain-woven). Various carbon and SiC/C layers were deposited as fiber/matrix interlayers by the isothermal CVI process. The Tyranno-SA/SiC composites exhibited high proportional limit stress (∼120 MPa) and relatively small strain-to-failure. The tensile stress/strain curves exhibited features corresponding to strong interfacial shear and sliding resistance, and indicated failures of all the composites before matrix-cracking saturation was achieved. Fiber/matrix debonding and relatively short fiber pullouts were observed on the fracture surfaces. The ultimate tensile strength displayed an increasing trend with increasing carbon layer thickness up to 100 nm. Further improvement of the mechanical properties of Tyranno-SA/SiC composites is expected with more suitable interlayer structures.     

碳化硅晶须/碳化硅颗粒/聚丙烯复合材料的结构优化设计和模型拟合

以聚丙烯(PP)为基体,以单一碳化硅晶须( SiCw)、碳化硅颗粒(SiCp)和混杂SiCw/SiCp为导热填料,共混/模压制备PP基导热复合材料.结果表明:同等用量下,混杂SiCw/SiCp填充PP具有比单一SiCw或SiCp填充PP更佳的导热性能,且随SiCw/SiCp用量的增加而增加;当SiCw/SiCp质量分数为50％时,导热性能最佳,其导热系数为0.856 W/(m· K),为纯PP的5倍多.PP的拉伸强度与冲击强度随SiCw/SiCp用量的增加先增加后降低,当混杂SiCw/SiCp质量分数为10％时,力学性能最佳.相比SiCp而言,SiCw更易在PP中形成导热网链.     

Influence of Ferrotitanium and Silicon Carbide Addition on Structural Modification,Nanohardness and Corrosion Behaviour of Stir-Cast Aluminium Matrix Composites

Silicon - The use of aluminium based composite is becoming widespread in the industries where enhanced mechanical and improved corrosion resistance properties are required. Microstructural...     

Synthesis,Characterization and Wire Electric Erosion Behaviour of AA7178-10 wt.% ZrB2 Composite

Silicon - In this work, AA7178-10 wt.% ZrB2 Metal Matrix Composite was produced using stir casting route and the mechanical properties of the composites were studied. The microstructure and...     

碳化硅/氟橡胶复合材料的制备与性能研究

采用机械共混法制备碳化硅（SiC）/氟橡胶（FKM）复合材料,SiC添加前用偶联剂KH-560进行表面改性,研究改性SiC用量对SiC/FKM复合材料性能的影响。结果表明：随着改性SiC用量的增大,SiC/FKM复合材料的硬度增大,拉伸强度在一定范围内得到有效提升,阻尼性能和耐液体介质性能略有降低;当改性SiC用量为15份时,SiC/FKM复合材料具有良好的加工性能、物理性能、阻尼性能、热稳定性和耐液体介质性能,综合性能较优异。     

Dry Sliding Friction and Wear Behaviour of AA6082-TiB2 in Situ Composites

Silicon - In this study a composite with AA6082 as the matrix and TiB2 as the reinforcement has been fabricated by in situ method. The effect of TiB2 addition on the mechanical and tribological...     

Optimization and Effect of Reinforcements on the Sliding Wear Behavior of Self-Lubricating AZ91D-SiC-Gr Hybrid Composites

Silicon - This article statistically investigates the effect of various parameters such as material factors: silicon carbide (SiC) fraction, graphite (Gr) fraction and mechanical factors: normal...     

Polypropylene Hybrid Composites: A Preliminary Study on the use of Glass and Coconut Fiber as Reinforcements in Polypropylene Composites

Polypropylene hybrid composites were made using coconut and glass fibers as reinforcing agents in the polypropylene matrix. The incorporation of both fibers into the PP matrix has resulted in the reduction of flex-ural, tensile, and impact strengths and elongation at break. The reduction has been attributed to the increased incompatibility between the fibers and the PP matrix, and the irregularity in fiber size, especially for biofibers as shown by scanning electron micrographs. Both the flexural and tensile moduli have been improved with the increasing level of fiber loading. Most of the properties tested for Composites with high glass fibers/low biofiber loading are comparable with the ones with low glass fiber/high biofiber loading. The results show that more biofibers could be incorporated in hybrid composites which would give the same range of properties as the composites with higher loading of glass fibers.     

Alumina/Silicon Carbide Nanocomposites by Hybrid Polymer/Powder Processing: Microstructures and Mechanical Properties

Nanocomposites with fine, coarse, and bimodal silicon carbide (SiC) particle-size distributions were hot pressed and examined by transmission electron microscopy, scanning electron microscopy, and optical microscopy, as well as by four-point-bend and indentation tests. The finer SiC nanophase was introduced homogeneously by coating a silicon-containing polymer onto the alumina (Al₂O₃) powder, followed by a pyrolysis procedure; for the coarser SiC, nanophase conventional powder processing was used. Powder- and polymer-processed nanocomposites both had their maximum strengths at 5 vol% of SiC. High-strength nanocomposites that contained a higher volume fraction of SiC could be fabricated when the two methods were combined in a hybrid processing route. The SiC phase in the resulting hybrid materials originated from both the polymer and the SiC powder. The mechanical properties of these materials could be correlated with the fabrication route. Processing-flaw populations and calculated Griffith-flaw sizes were not only smaller, but they were also significantly different in the nanocomposites, in comparison to those in Al₂O₃ ceramics; this may explain the strength increase in Al₂O₃/SiC nanocomposite materials.     

Fabrication of Ceramic Hip Implant Composites: Influence of Silicon Nitride on Physical,Mechanical and Wear Properties

This study examined the effects of silicon nitride reinforcement on physical, mechanical and wear properties of different ceramic (zirconium oxide, magnesium oxide, chromium oxide and aluminum oxide) containing hip implant composites. The hip implant composites were produced using conventional mixing and spark plasma sintering methods by substituting aluminum oxide (68, 70.5, 73 and 75.5 wt.%) with silicon nitride (0, 2.5, 5 and 7.5 wt.%). Experimental results showed that silicon nitride content had significant effect on the evaluated physical, mechanical and wear properties. The density of the composites found to decrease whereas void content, Young’s modulus, hardness, wear resistance and fracture toughness first decreased (for 2.5 wt.%) and then increased with the increasing amount of silicon nitride content. The maximum hardness, Young’s modulus, wear resistance and fracture toughness values of 28.64 GPa, 280.18 GPa, 0.0076 mm³/million cycles and 11.84 MPa.m^1/2, respectively were registered for 2.5 wt.% silicon nitride additions that also had the lowest void content (0.38%).

     

Process and Mechanical Properties of in Situ Silicon Carbide-Nanowire-Reinforced Chemical Vapor Infiltrated Silicon Carbide/Silicon Carbide Composite

A SiC nanowire/Tyranno-SA fiber-reinforced SiC/SiC composite was fabricated via simple in situ growth of SiC nanowires directly in the fibrous preform before CVI matrix densification; the purpose of the SiC nanowires was to markedly improve strength and toughness. The nanowires consisted of single-crystal β-phase SiC with a uniform ∼5 nm carbon shell; the nanowires had diameters of several tens to one hundred nanometers. The volume fraction of the nanowires in the fabricated composite was ∼5%. However, the composite did not show significant increase in strength and toughness, likely because of strong bonding between the nanowires and the matrix caused by the very thin carbon coating on the nanowires. Little debonding and pullout of SiC nanowires from the matrix were observed at the fracture surfaces of the composite.