The three-body abrasive wear behaviour of carbon fabric reinforced epoxy (C-E) composites has been evaluated by the addition of graphite (G) particles as a secondary reinforcement. Three-body abrasive wear test were c...The three-body abrasive wear behaviour of carbon fabric reinforced epoxy (C-E) composites has been evaluated by the addition of graphite (G) particles as a secondary reinforcement. Three-body abrasive wear test were conducted using dry sand rubber wheel abrasion tester as per ASTM G-65 with three process parameters load, abrading distance and filler content. To assess the abrasive wear behaviour of particulate filled C-E composites satisfying multiple performance measure, grey-based Taguchi approach has been adopted. The experiments were designed according to Taguchi’s orthogonal array (L?27). The grey relational analysis was applied to convert a multi response process optimization to a single response. Using analysis of variance, significant contributions of process parameters have been determined. The results indicate that the addition of graphite particles into C-E composite increased the wear resistance considerably. It was observed that highest wear resistance of C-E composite was achieved with incorporation of 10 wt. % of graphite filler. Results indicate that the filler content and grit size of abrasive paper were found to be the most significant factor which has influence on the abrasive wear of C-E composite. The worn surface features were examined through scanning electron microscope to probe the wear mechanism.展开更多
Polyvinyl chloride (PVC) of different grades is the second most commonly used polymer for fabrication of electric cables and wires after polyethylene. Cables of domestic and industrial use of various capacities are fa...Polyvinyl chloride (PVC) of different grades is the second most commonly used polymer for fabrication of electric cables and wires after polyethylene. Cables of domestic and industrial use of various capacities are fabricated using different compounds of PVC. Mica is useful particulate filler extensively used to enhance the performance of many polymeric materials. It surface resistance and arc resistance improving its mechanical properties. In the present research work mica filled PVC composites of different concentrations were prepared using untreated and surface treated water ground mica of different particle size. Mica filled PVC composites were compounded for various compositions and test samples were prepared using compression moulding process. These samples were tested for electrical insulation and mechanical properties. The results shows enhancement in dielectric properties with improvement in Young’s modulus, stiffness, reduction in elongation at break and slight increase in shore D hardness of composites. Scanning electron microscopy was used to test the morphology of the samples which has shown proper distributions and adhesion of the filler mica in PVC matrix. There was some effect of surface treatment of mica on its mechanical and dielectric properties of the composite.展开更多
The present study focuses on the development of polymeric friction composites with short carbon fiber, micron and nano-sized fillers, additives with varying weight% in phenol formaldehyde (PF) matrix using hot compres...The present study focuses on the development of polymeric friction composites with short carbon fiber, micron and nano-sized fillers, additives with varying weight% in phenol formaldehyde (PF) matrix using hot compression moulding process. The composites prepared with fillers viz. Molybdenum disulfide or Molykote (MK) and multi walled carbon nanotubes (MWCNTs) in carbon fiber reinforced PF matrix is designated as Set-I composites. Inclusion of graphite and nano-clay in carbon fiber reinforced PF matrix is designated as Set-II composites. The prepared composites are tested in Dry sand rubber wheel abrasion wear test rig, following ASTM standards for evaluating the abrasive wear behaviour. From the routine experiments, it was observed that the presence of combined micro and nanofillers i.e. 11.5 wt% MK + 0.5 wt% MWCNTs of Set-I, has shown superior abrasion resistance among the study group. The test results of the Set-I and Set-II composites are analyzed using Taguchi experimental design followed by analysis of variance (ANOVA) to understand the contributions of wear control factors affecting the abrasive wear characteristics. Further, worn surface of selected samples is analyzed using scanning electron micrographs.展开更多
As thermal protection substrates for wearable electronics,functional soft composites made of polymer materials embedded with phase change materials and metal layers demonstrate unique capabilities for the thermal prot...As thermal protection substrates for wearable electronics,functional soft composites made of polymer materials embedded with phase change materials and metal layers demonstrate unique capabilities for the thermal protection of human skin.Here,we develop an analytical transient phase change heat transfer model to investigate the thermal performance of a wearable electronic device with a thermal protection substrate.The model is validated by experiments and the finite element analysis(FEA).The effects of the substrate structure size and heat source power input on the temperature management efficiency are investigated systematically and comprehensively.The results show that the objective of thermal management for wearable electronics is achieved by the following thermal protection mechanism.The metal thin film helps to dissipate heat along the in-plane direction by reconfiguring the direction of heat flow,while the phase change material assimilates excessive heat.These results will not only promote the fundamental understanding of the thermal properties of wearable electronics incorporating thermal protection substrates,but also facilitate the rational design of thermal protection substrates for wearable electronics.展开更多
This article studies the frost resistance of polyvinyl alcohol (PVA) fiber reinforced cementitious composites. The test samples contain different PVA fiber volume fractions such as 0, 0.5%, 1% and 2%. The freeze-thaw ...This article studies the frost resistance of polyvinyl alcohol (PVA) fiber reinforced cementitious composites. The test samples contain different PVA fiber volume fractions such as 0, 0.5%, 1% and 2%. The freeze-thaw test is carried on in TDR type apparatus. The outward appearance, the weight loss factor and the relative dynamic elastic modulus are analyzed, and conclusions are drawn that PVA fibers can significantly improve the frost resistance of cementitious composites and frost resistance of PVA fiber reinforced cementitious composites with fiber volumetric fraction of 1% is better.展开更多
Nickel tartrate precursor particles were synthesized by the liquid phase precipitation method in an ethanol-water-ammonia mixed solution,with tartaric acid and using nickel chlorate as raw materials,with the pH value ...Nickel tartrate precursor particles were synthesized by the liquid phase precipitation method in an ethanol-water-ammonia mixed solution,with tartaric acid and using nickel chlorate as raw materials,with the pH value controlled at 4.0,and the temperature controlled at 50 ℃.Nickel particles with complicated morphology were prepared by the decomposition of nickel taratrate precursor particles at temperatures of 360,380 and 400 ℃,respectively.The study of infrared spectroscopy(IR) indicated that the product was pure nickel tartrate.The studies of the atomic absorption spectrometry(AAS) and organic elemental analysis(OEA) indicated that the molar ratio of Ni2+to(C4H4O6)2-is close to 1:1.The studies of the differential scanning calorimeter and thermo-gravimetric analysis(DSC-TG) indicated that the chemical formula Ni2(C4H4O6)25H2O was confirmed.The studies of X-ray diffractions(XRD) indicated that the silvery white metal powders were pure Ni,with a face-centered cubic crystal structure.The images of scanning electron microscopy(SEM) showed that the morphology of metal Ni particles was obvious spherical and radiate.The diameter of nickel tartrate particles was about 60 μm,which consisted of many nanolathes;and the diameter of metal Ni particles was about 30 μm,which consisted of many lathes about 0.5 μm in thickness.展开更多
Effect of the laser treatment on electroless Ni-P-SiC composite coatings was investigated. The microscopic structure, surface morphology, ingredient, and performance of the Ni-P-SiC composite coatings were synthetical...Effect of the laser treatment on electroless Ni-P-SiC composite coatings was investigated. The microscopic structure, surface morphology, ingredient, and performance of the Ni-P-SiC composite coatings were synthetically analyzed by the use of X-ray diffraction apparatus, scanning electron microscope, energy distribution spectrometer, micro-hardness tester, wear tester and so on. It was found that the composite coatings did make crystalloblastic transformation after laser heating. Structural analysis confirmed that some new types of phase Ni2Si or Ni3Si compound would emerge in the Ni-P-SiC coatings after laser treatment. The micro-hardness measurement results showed that when the laser power was 450 W with scanning speed of 0.5 m/min, the hardness of the coating was superior to the coating obtained by the conventional furnace heating, and wear resistance of the composite coating after laser treating could also improve.展开更多
文摘The three-body abrasive wear behaviour of carbon fabric reinforced epoxy (C-E) composites has been evaluated by the addition of graphite (G) particles as a secondary reinforcement. Three-body abrasive wear test were conducted using dry sand rubber wheel abrasion tester as per ASTM G-65 with three process parameters load, abrading distance and filler content. To assess the abrasive wear behaviour of particulate filled C-E composites satisfying multiple performance measure, grey-based Taguchi approach has been adopted. The experiments were designed according to Taguchi’s orthogonal array (L?27). The grey relational analysis was applied to convert a multi response process optimization to a single response. Using analysis of variance, significant contributions of process parameters have been determined. The results indicate that the addition of graphite particles into C-E composite increased the wear resistance considerably. It was observed that highest wear resistance of C-E composite was achieved with incorporation of 10 wt. % of graphite filler. Results indicate that the filler content and grit size of abrasive paper were found to be the most significant factor which has influence on the abrasive wear of C-E composite. The worn surface features were examined through scanning electron microscope to probe the wear mechanism.
文摘Polyvinyl chloride (PVC) of different grades is the second most commonly used polymer for fabrication of electric cables and wires after polyethylene. Cables of domestic and industrial use of various capacities are fabricated using different compounds of PVC. Mica is useful particulate filler extensively used to enhance the performance of many polymeric materials. It surface resistance and arc resistance improving its mechanical properties. In the present research work mica filled PVC composites of different concentrations were prepared using untreated and surface treated water ground mica of different particle size. Mica filled PVC composites were compounded for various compositions and test samples were prepared using compression moulding process. These samples were tested for electrical insulation and mechanical properties. The results shows enhancement in dielectric properties with improvement in Young’s modulus, stiffness, reduction in elongation at break and slight increase in shore D hardness of composites. Scanning electron microscopy was used to test the morphology of the samples which has shown proper distributions and adhesion of the filler mica in PVC matrix. There was some effect of surface treatment of mica on its mechanical and dielectric properties of the composite.
文摘The present study focuses on the development of polymeric friction composites with short carbon fiber, micron and nano-sized fillers, additives with varying weight% in phenol formaldehyde (PF) matrix using hot compression moulding process. The composites prepared with fillers viz. Molybdenum disulfide or Molykote (MK) and multi walled carbon nanotubes (MWCNTs) in carbon fiber reinforced PF matrix is designated as Set-I composites. Inclusion of graphite and nano-clay in carbon fiber reinforced PF matrix is designated as Set-II composites. The prepared composites are tested in Dry sand rubber wheel abrasion wear test rig, following ASTM standards for evaluating the abrasive wear behaviour. From the routine experiments, it was observed that the presence of combined micro and nanofillers i.e. 11.5 wt% MK + 0.5 wt% MWCNTs of Set-I, has shown superior abrasion resistance among the study group. The test results of the Set-I and Set-II composites are analyzed using Taguchi experimental design followed by analysis of variance (ANOVA) to understand the contributions of wear control factors affecting the abrasive wear characteristics. Further, worn surface of selected samples is analyzed using scanning electron micrographs.
基金Project supported by the National Natural Science Foundation of China(No.11772030)the Aeronautical Science Foundation of China(No.2018ZC51030)the Opening fund of State Key Laboratory of Structural Analysis for Industrial Equipment of Dalian University of Technology(No.GZ19117)。
文摘As thermal protection substrates for wearable electronics,functional soft composites made of polymer materials embedded with phase change materials and metal layers demonstrate unique capabilities for the thermal protection of human skin.Here,we develop an analytical transient phase change heat transfer model to investigate the thermal performance of a wearable electronic device with a thermal protection substrate.The model is validated by experiments and the finite element analysis(FEA).The effects of the substrate structure size and heat source power input on the temperature management efficiency are investigated systematically and comprehensively.The results show that the objective of thermal management for wearable electronics is achieved by the following thermal protection mechanism.The metal thin film helps to dissipate heat along the in-plane direction by reconfiguring the direction of heat flow,while the phase change material assimilates excessive heat.These results will not only promote the fundamental understanding of the thermal properties of wearable electronics incorporating thermal protection substrates,but also facilitate the rational design of thermal protection substrates for wearable electronics.
基金supported by the National Natural Science Foundation of China (Nos. 50968011 and 51168033)the Natural Science Foundation of Inner Mongolia (No. 2009MS0716)the Springfield Plan in Ministry of Education (No. Z2004-2-15026)
文摘This article studies the frost resistance of polyvinyl alcohol (PVA) fiber reinforced cementitious composites. The test samples contain different PVA fiber volume fractions such as 0, 0.5%, 1% and 2%. The freeze-thaw test is carried on in TDR type apparatus. The outward appearance, the weight loss factor and the relative dynamic elastic modulus are analyzed, and conclusions are drawn that PVA fibers can significantly improve the frost resistance of cementitious composites and frost resistance of PVA fiber reinforced cementitious composites with fiber volumetric fraction of 1% is better.
基金Funded by National Natural Science Fundation of China(No.51002126)Open Project of State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials(No.10zxfk30)
文摘Nickel tartrate precursor particles were synthesized by the liquid phase precipitation method in an ethanol-water-ammonia mixed solution,with tartaric acid and using nickel chlorate as raw materials,with the pH value controlled at 4.0,and the temperature controlled at 50 ℃.Nickel particles with complicated morphology were prepared by the decomposition of nickel taratrate precursor particles at temperatures of 360,380 and 400 ℃,respectively.The study of infrared spectroscopy(IR) indicated that the product was pure nickel tartrate.The studies of the atomic absorption spectrometry(AAS) and organic elemental analysis(OEA) indicated that the molar ratio of Ni2+to(C4H4O6)2-is close to 1:1.The studies of the differential scanning calorimeter and thermo-gravimetric analysis(DSC-TG) indicated that the chemical formula Ni2(C4H4O6)25H2O was confirmed.The studies of X-ray diffractions(XRD) indicated that the silvery white metal powders were pure Ni,with a face-centered cubic crystal structure.The images of scanning electron microscopy(SEM) showed that the morphology of metal Ni particles was obvious spherical and radiate.The diameter of nickel tartrate particles was about 60 μm,which consisted of many nanolathes;and the diameter of metal Ni particles was about 30 μm,which consisted of many lathes about 0.5 μm in thickness.
文摘Effect of the laser treatment on electroless Ni-P-SiC composite coatings was investigated. The microscopic structure, surface morphology, ingredient, and performance of the Ni-P-SiC composite coatings were synthetically analyzed by the use of X-ray diffraction apparatus, scanning electron microscope, energy distribution spectrometer, micro-hardness tester, wear tester and so on. It was found that the composite coatings did make crystalloblastic transformation after laser heating. Structural analysis confirmed that some new types of phase Ni2Si or Ni3Si compound would emerge in the Ni-P-SiC coatings after laser treatment. The micro-hardness measurement results showed that when the laser power was 450 W with scanning speed of 0.5 m/min, the hardness of the coating was superior to the coating obtained by the conventional furnace heating, and wear resistance of the composite coating after laser treating could also improve.
