• Title, Summary, Keyword: Composites

Search Result 8,409, Processing Time 0.062 seconds

Effect of Multi-walled Carbon Nanotube Dispersion on the Electrical, Morphological and Rheological Properties of Polycarbonate/Multi-walled Carbon Nanotube Composites

  • Han, Mi-Sun;Lee, Yun-Kyun;Kim, Woo-Nyon;Lee, Heon-Sang;Joo, Jin-Soo;Park, Min;Lee, Hyun-Jung;Park, Chong-Rae
    • Macromolecular research
    • /
    • v.17 no.11
    • /
    • pp.863-869
    • /
    • 2009
  • The effect of a multiwalled carbon nanotube (MWCNT) dispersion on the electrical, morphological and rheological properties of polycarbonate (PC)/MWCNT composites was investigated, with and without pretreating the MWCNTs with hydrogen peroxide oxidation and lyophilization. The resulting PC/treated MWCNT composites showed higher electrical conductivity than the PC/untreated MWCNT composites. The morphological behavior indicated the treated composites to have greater dispersion of MWCNTs in the PC matrix. In addition, the electromagnetic interference shielding efficiency (EMI SE) of the treated composites was higher than that of the untreated ones. Rheological studies of the composites showed that the complex viscosity of the treated composites was higher than the untreated ones due to increased dispersion of the MWCNTs in the PC matrix, which is consistent with the electrical conductivity, EMI SE and morphological studies of the treated composites. The latter results suggested that the increased electrical conductivity and EMI SE of the treated composites were mainly due to the increased dispersion of MWCNTs in the PC matrix.

Effects of Hexamethylene Diisocyanate as Coupling Agent on Mechanical Properties of Bamboo/PBS Composites (HDI가 대나무/PBS 복합소재의 역학특성에 미치는 영향)

  • Lee, Geum Mi;Oh, Ae Gyeong;An, Seung Kook
    • Textile Science and Engineering
    • /
    • v.53 no.1
    • /
    • pp.36-44
    • /
    • 2016
  • The purpose of this study is to improve the interfacial adhesion strength of bamboo/PBS composites by adding HDI (hexamethylene diisocyanate) as a coupling agent. Bamboo/PBS composites with HDI were fabricated by an internal mixer and a hot press machine. In addition, the effects of HDI as a coupling agent and various HDI contents on the mechanical properties of bamboo/PBS composites were investigated. Furthermore, the tensile properties, flexural properties, and Rockwell hardness of bamboo/PBS composites with HDI were evaluated. The obtained results showed that the mechanical properties of bamboo/PBS composites were improved with the addition of HDI. The morphology of fractured surfaces of bamboo/PBS composites was observed with SEM (scanning electron microscope), and the obtained SEM images showed evidence of improved interfacial adhesion between the bamboo fiber and PBS matrix. To analyze the composition change of bamboo/PBS composites, FT-IR (Fourier transform-infra red) spectroscopy was used. The FT-IR spectra of bamboo/PBS composites also showed positive effects of using HDI as a coupling agent. Finally, a comparison of various HDI contents, when all obtained results were combined, showed that bamboo/PBS composites with a HDI content of 1.5% had the most improved mechanical properties.

Mechanical Characteristics Evaluation of Metal Matrix Composites Cylinder Linear Fabricated by Thixoforging Process (Thixoforging Process에 의하여 제조한 금속복합재료 실린더라이너 부품의 기계적 특성 평가)

  • 허재찬;이승후;강충길
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.20 no.2
    • /
    • pp.58-65
    • /
    • 2003
  • The conventional forming process such as squeeze casting or die casting for fabricating metal matrix composites products have a disadvantage such as non homogenous distribution of reinforcement, weak bonding between matrix and reinforcement and cost increase in parts fabrication. Thixoforming process has been accepted as a new method for fabricating the net shaped metal matrix composites with lightweight and wear resistance. In this paper, the effect of volume fraction and reinforcement sizes on mechanical properties in cylinder liner part of metal matrix composites has been investigated with processes parameters such as pressure and velocity. Moreover, the methods to obtain the thixoforged composites cylinder liner with high quality has been proposed. To evaluate the composites cylinder linear fabricated at the conditions proposed in this study, mechanical properties of fabricated composites cylinder linear were compared with those of commercial composites cylinder linear.

Effect of Plasma Treatment of Aluminum on the Fracture Toughness of Aluminum/CFRP Composites (알루미늄의 플라즈마 표면처리가 알루미늄/CFRP 복합재의 파괴인성에 미치는 영향)

  • 신명근;이경엽
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.20 no.8
    • /
    • pp.153-157
    • /
    • 2003
  • In the present work, the effect of plasma treatment of aluminum on the fracture toughness of CFRP/aluminum composites was investigated. The surface of the aluminum was treated by a DC plasma. The plasma treatment was carried out at volume ratio of acetylene gas to nitrogen gas of 5:5 and the treatment time used was 30 sec. Cracked lap shear specimens of aluminum/CFRP composites were made using secondary bonding procedure. Fracture toughness of aluminum/CFRP composites was determined using the work factor approach. Then, the fracture toughness of plasma-treated aluminum/CFRP composites was compared with that of untreated aluminum/CFRP composites. The results showed that the fracture toughness of plasma-treated aluminum/CFRP composites was about 50 % higher than that of untreated aluminum/CFRP composites.

Erosion Behavior of SiC Coated C/C Composites with Condition of Combustion Test

  • Joo, Hyeok-Jong;Min, Kyung-Dae;Lee, Jae-Won
    • Carbon letters
    • /
    • v.4 no.3
    • /
    • pp.133-139
    • /
    • 2003
  • Carbon/carbon composites are ideal candidates for a number of aerospace applications including structural materials for advanced vehicles, leading edges, structures of re-entry and hypersonic vehicles and propulsion systems. One serious defect for such application of the carbon/carbon composites is their poor oxidation resistance in high temperature oxidizing environments. SiC coating was employed to protect the composites from oxidation. It is mechanically and chemically stable under extreme thermal and oxidative environments, provides good adhesion to the substrate, and offers good thermal shock resistance. The SiC layer on the nozzle machined from the carbon/carbon composites was formed by pack-cementation method. Then, erosion characteristic of SiC coated carbon/carbon nozzle was examined by combustion test using a liquid rocket motor. The erosion rates were measured as function of combustion pressure, ratio of oxygen to fuel, combustion time, density of the composites and geometry of reinforced carbon fibre in the composites. The morphology change of the composites after combustion test was investigated using SEM and erosion mechanism also was discussed.

  • PDF

Development of Carbon-Ceramic Composites using Fly Ash and Carbon Fibers as Reinforcement

  • Manocha, S.;Patel, Rakesh
    • Carbon letters
    • /
    • v.7 no.1
    • /
    • pp.27-33
    • /
    • 2006
  • Carbon-ceramic composites were fabricated by using fly ash and PANOX fibers as reinforcement. Fly ash, because of its small size particles e.g. submicron to micron level can be effectively dispersed along with fibrous reinforcements. Phenolic resin was used as carbon precursor. Both dry as well as wet methods were used for forming composites. The resulting composites were characterized for their microstructure, thermal and mechanical properties. The microstructure and mechanical properties of composites are found to be dependent on type of the fly ash, fibrous reinforcements as well as processing parameters. The addition of fly ash improves hardness and the fibers, which get co-carbonized on heat treatment, increase the flexural strength of the carbon-ceramic composites. Composites with dual reinforcement exhibit about 30-40% higher strength as compared to the composites made with single reinforcement, either with fly ash as filler or with chopped fibers.

  • PDF

Effect of MML on the Wear Behavior of Al/SiCp Composites (Al/SiCp 복합재료의 마모거동에 미치는 MML의 영향)

  • Kim, Yeong-Sik;Kim, Kyun-Tak
    • Tribology and Lubricants
    • /
    • v.25 no.1
    • /
    • pp.66-72
    • /
    • 2009
  • Al-based composites reinforced with SiC particulate were fabricated using a thermal spray process, and dry sliding wear behavior of the composites was investigated. Pre-mixed Al and SiC powders were sprayed on an A16061 substrate by flame spraying, and dry sliding wear test were performed under various sliding speed and applied load conditions against ${Al_2}{O_3}$ ball. Wear behavior of the composites was studied by using scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). And build-up mechanism of MML on the worn surface of the composites was examined. It was revealed that these MML was formed of debris from the contact surface of the composites and effected to wear behavior of the composites protecting the contact surface of the composites.

Thermal behavior of Flame Retardant Filled PLA-WF Bio-Composites

  • Choi, Seung-Woo;Lee, Byoung-Ho;Kim, Hyun-Joong;Kim, Hee-Soo
    • Journal of the Korean Wood Science and Technology
    • /
    • v.37 no.2
    • /
    • pp.155-163
    • /
    • 2009
  • This study examined the thermal stability of PLA-WF bio-composites. Wood flour (WF)-filled PLA bio-composites were reinforced with the flame retardants, Melamine pyrophosphate (MPP), resorcinol bis (diphenyl phosphate) (RDP) and zinc borate (ZB). The flame retardant was compounded with PLA and natural biodegradable filler. The thermal properties of the biodegradable polymer and bio-composites reinforced with the flame retardant were measured and analyzed by DSC, DMA and TGA. The results showed that the flame retardant-reinforced biodegradable bio-composite exhibited improved thermal properties.