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Search Results: 1 - 10 of 8589 matches for " Composite materials "
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Processing of 5083 Aluminum Alloy Reinforced with Alumina through Microwave Sintering  [PDF]
Jagesvar Verma, Anil Kumar, Rituraj Chandrakar, Rajesh Kumar
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2012, DOI: 10.4236/jmmce.2012.1111121
Abstract: Today, there is an increasing demand worldwide for the advanced materials in order to obtain the desired properties. This is because a single material generally cannot meet the requirement of harsh engineering environment that is why the need for composites arises. Metal matrix composite is an important class of materials with high potential for structural applications requiring high specific modulus, strength and toughness. Metal matrix composites with unique properties are growing every day and widely used in different industries because of their high mechanical properties and wear resistance.
Preparation and Characterization of Mullite-Silica Aerogel Composite Material  [PDF]
Zhaofeng Song, Haiquan Zhao
Open Journal of Organic Polymer Materials (OJOPM) , 2018, DOI: 10.4236/ojopm.2018.84004
Abstract: Silica aerogel due to the high specific surface area, nanometer level pores and low density of the micro structure, had excellent heat-insulating properties. But the characteristics of silica aerogel with low density and high voidage resulted in poor mechanical properties. In order to improve the strength of materials and meet the actual needs, in this paper the heat-insulating composite material was made from the silica aerogel and mullite fiber. This kind of composite material mainly contented of mullite fiber, formed macro block structure, that gas gel is coated and filled with mullite fiber. Furthermore, the composite material had good strength and kept excellent thermal stability at 600°C. In addition the density of composite decreased with the increasing of the gas gel content.
Effects of Solution Atoms and Precipitates on Isochronal Annealing Behavior of Cold-Rolled Squeeze-Cast SiCw/Al Composites  [PDF]
Wenglong Zhang, Mingyuan Gu
Materials Sciences and Applications (MSA) , 2011, DOI: 10.4236/msa.2011.25062
Abstract: SiCw/Al and SiCw/6061Al composites, which contained 15 vol pct of whiskers, were fabricated through a squeeze cast route followed by cold rolling and isochronal annealing. Effects of whicker, solution atoms and precipitates on isochronal annealing behavior of cold rolled composites were investigated by comparing the isochronal annealing behavior between pure Al, SiCw/Al, solution-treated SiCw/6061Al and aged SiCw/6061Al. It was found that the recrystallization of SiCw/Al composite occurs earlier than that of pure Al, indicating SiCw has a role of particle stimulated nucleation. Solution atoms have no significant influence on the isochronal annealing behavior of SiCw/6061Al composite, while precipitates have such a strong retarding effect on the recrystallization of SiCw/6061Al composite that the isochronal annealing curve of aged SiCw/6061 composite loses the definable recrystallization step.
Predictions of Storage Modulus of Glass Bead-Filled Low-Density-Polyethylene Composites  [PDF]
Ji-Zhao Liang
Materials Sciences and Applications (MSA) , 2010, DOI: 10.4236/msa.2010.16050
Abstract: The factors affecting storage modulus (Ec') and quantitative characterization of polymer composites filled with inorganic particles were discussed in this paper. On the basis of Eshelby’s method and Mori’s work, an equation describing the relationship between the Ec' and the filler volume fraction, particle geometry as well as interfacial morphology was proposed. The Ec' of the glass bead filled low-density-polyethylene (LDPE/GB) composites was estimated by means of this equation under experimental conditions with temperature range of –150-100?C, frequency of 1 Hz and the amplitude of 0.6 mm, and compared with other equations proposed in literature. The results showed that the predictions for this equation were close to the measured data from the LDPE/GB composites.
Comparative Mechanical Properties of Bulk-Fill Resins  [PDF]
Atabek Didem, Yal??n G?zde, ?zta? Nurhan
Open Journal of Composite Materials (OJCM) , 2014, DOI: 10.4236/ojcm.2014.42013

Aim: The aim of this study was to compare the flexural and compressive strengths of a new sonicactivated bulk-fill system (Sonicfill) with other bulk-fill resins and a universal posterior composite resin. Materials and Methods: A low-stress flowable base resin material (SDR), a bulk-fill composite resin (Tetric Evo Ceram), a universal posterior composite (GC G-aenial), and the Sonicfill system were compared. The specimens were prepared for each group following ISO Standard 4049 (flexural strength) and ADA 27 specifications (compressive strength). One-way variance analysis and Kruskal-Wallis tests were used to determine the statistical differences among groups (p < 0.05). Results: The Sonicfill system presented significantly higher compressive strength than other groups (p < 0.001). For flexural strength results, although the Sonicfill system showed the highest values, no statistically significant differences were determined among all groups (p > 0.001). Conclusion: Due to the ability to place restorations with single increment and ease of use, the Sonicfill system can be an alternative for posterior restorations.

The Effect of γ-Radiations on Dielectric Properties of Composite Materials PE + x vol% TlGaSe2  [PDF]
E. M. Gojayev, A. G. Hasanova
Open Journal of Inorganic Non-metallic Materials (OJINM) , 2015, DOI: 10.4236/ojinm.2015.54006
Abstract: The purpose of the paper is to study the effect of gamma irradiation on the temperature dependence of the dielectric constant \"\"and dielectric loss (tanδ) of composite materials PE + x vol% (0≤ x ≤ 10). Measurements are carried out with an alternating current at a frequency of 1 kHz using the measuring bridge E-20. Measurements are carried out at temperature range 300 - 450 K, irradiated at doses of 50, 100 and 150 kGy. It is revealed that in all irradiated samples with increasing volumetric filler content increase the dielectric characteristics of composites PE + x vol%. TlGaSe2. Temperature variation of the dielectric parameters, after gamma irradiation are the result of occurring in the electron-ion and polarization at the interface of the matrix polymer with filler of TlGaSe2.
Sintered composite gradient tool materials
J. Miku?a,G. Matula,K. Go?ombek,L.A. Dobrzański
Archives of Materials Science and Engineering , 2008,
Abstract: Purpose: Development of a new generation of the composite gradient tool materials with the core sintered withthe matrix obtained using the powder metallurgy of the chemical composition corresponding to the HS6-5-2 highspeedsteel reinforced with the WC and TiC type hard carbide phases with the growing portions of these phases inthe outward direction from the core to the surface.Design/methodology/approach: Powder Metallurgy, SEM, X-Ray Microanalysis.Findings: Powder metallurgy processes were used to fabricate the proposed gradient materials, i.e., compacting inthe closed die and sintering. The method of sequential pouring of the successive portions of the powder mixes intothe die was used to ensure a high ductility of the fabricated material core with the HS6-5-2 steel matrix reinforcedwith the hard WC and TiC carbides phases, so that portions of powder with the high percentage of the hard carbidesphases would form the outer layers of the prepreg.Practical implications: Employment of powder metallurgy for fabricating the steel based tool materials givesthe possibility to preserve properties characteristic of the traditional cemented carbides and with the high ductilitycharacteristic of steel, yet better than the traditional sintered high-speed steels obtained with the ASP method.Originality/value: Providing of high properties characteristic of cemented carbides with the high ductilitycharacteristic of steel can be mostly because of the possibility of ensuring the gradients of the chemicalcomposition and properties, cutting simultaneously fabrication costs thanks to savings made on the hard carbidephase, used in the tool surface layer only.
Structure of sintered gradient tool materials
G. Matula,K. Go?ombek,J. Miku?a,L.A. Dobrzański
Journal of Achievements in Materials and Manufacturing Engineering , 2009,
Abstract: Purpose: Investigation of influence of sintering conditions onto the structure of composite gradient tool materials. The chemical composition of the investigated materials’ core was corresponding to the M2 high-speed steel and was reinforced with the WC and TiC type hard carbide phases with the growing portions of these phases in the outward direction from the core to the surface.Design/methodology/approach: Powder Metallurgy, SEM, X-Ray Microanalysis.Findings: Changing of technological properties and structure of composite gradient tool materials (depending on the compositions of used mixtures and sintering temperature) was analyzed and described.Practical implications: Tool materials used especially for cutting tools and plastic forming tools.Originality/value: Providing of high properties characteristic of cemented carbides keeping high ductility characteristic of steel was achieved.
Dureza knoop de resinas compostas em fun??o do número relativo de radicais livres
MENEZES, Marco Aurélio de;MUENCH, Antonio;
Revista de Odontologia da Universidade de S?o Paulo , 1998, DOI: 10.1590/S0103-06631998000300015
Abstract: the present study had the purpose of determining the relative number of free radicals of three composites with clear and dark colors. intensities of irradiation were: 110, 180, 300, and 580 mw/cm2, for 10, 20, 30, 40, 50, 60, 80 and 90 seconds. hardness was determined for the clear colors of the composites, using 110 and 300 mw/cm2 irradiation intensities, for 20, 40, 60, and 80 seconds, on front and deep surfaces, at the ages of 5 minutes, 1 hour, 1 day, 1 week, and 1 month. the conclusions were that: depending on the resin, clear colors present more free radicals; the number of free radicals increases with higher intensity and longer irradiation time; composite z100 is much richer in free radicals than silux plus and heliomolar ro; higher intensity of irradiation leads to increasing hardness; longer irradiation time increases hardness of silux plus and heliomolar ro, but not that of z100; hardness increases with age; in depth hardness is very low; z100 is much harder than the other two resins; z100 is less sensitive to irradiation intensity.
Research on the Thermal Insulation Potential of Some Composites Made of Biodegradable Materials
Pro Ligno , 2011,
Abstract: The paper is structured on three parts: the first one presents 18 types of composite panels made of biodegradable materials, as follows: wood chips and natural textile fibers as reinforcing materials and various binders: mineral ones, wheat flour, acrylics, in various combinations. The second part presents the experimental determination of the thermal conductivity coefficient for the proposed panels. The third part of the paper presents the conclusions.
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