Advanced Materials Research Vols. 750-752

Abstract: CNTs/Al composites were fabricated by high energy ball milling. The phase structure and consti- tuent of the preparation process were analyzed. The interface reaction and the formation process of the interface reaction product Al₄C₃ were discussed by thermodynamics and kinetics. The result shows that no Al₄C₃ can be found in Al-CNTs composite powders fabricated by high energy ball milling. Al₄C₃ exists in the inter- face after pressureless sintering. And no appreciable amount of Al₄C₃ was observed in CNTs/Al composites directly by powder metallurgy. It shows that high energy ball milling can benifit the interface reaction. And the purified CNTs, never milled, is stable in the preparation process of CNTs/Al composites by powder metallurgy.

Abstract: The dispersive characteristic of in-plane elastic waves propagating through laminated piezoelectric phononic crystal with imperfect interface is studied in this paper. First, the transfer matrix method (TMM) and the Bloch theorem are used to derive the dispersion equation. Next, the dispersion equation is solved numerically and the dispersive curves are shown in Brillouin zone. The pass band and the stop band of in-plane wave propagating normal to the laminated periodic structure with spring imperfect interface are investigated. The effects of the spring or mass parameter are discussed.

Abstract: Use VDBF-250 vacuum hot pressing sintering furnace TiC10/Cu-Al₂O₃ composite was prepared by vacuum-pressed sintering. In the cold isotatic pressing machine for sintering state sample was cold isostatic pressing and detection performance. Using the Gleeble-1500D simulator, the high-temperature plastic deformation behavior of TiC10/Cu-Al₂O₃ composite was investigated at 450850°C with the strain rate of 0.0011s¹ and total strain of 0.7 the dynamic recrystallization behavior of the composite was studied. The results show that the density, microhardness and electrical conductivity of the composite are 98.53%, 161HV and 48.7%IACS. After the isostatic cool pressing, The comprehensive performance of the material were improved. The softening mechanism of the dynamic recrystallization is a feature of high-temperature flow stressstrain curves of the composites, and the peak stress increases with the decrease of deformation temperature or the increase of strain rate, and Belong to temperature and strain rate sensitive material.

Abstract: In this study, three kinds of single-layered spunbonded nonwovens with different specifications were prepared as materials. The relation between layer number and pore structure (morphology characteristics, pore size and pore distribution, and Solid Volume Fraction) was studied. The results show that mean pore size decreases as layer number increases and the degree tends to be gentle. But the change law of maximum pore size is not obvious. Furthermore, pore size distribution of single-layered or two-layered nonwovens is concentrated and further increase in layer number doesnt have obvious effects on it . Air permeability reduces when the layer number increases and the variation trend accords with that of mean pore size.

Abstract: The influence of long glass fiber (LGF) content on properties of PVC/PP composites were investigated by means of scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), and mechanical properties. The experimental results demonstrate that long glass fiber could effectively improve the mechanical properties and storage modulus of PVC/PP. The DMA reveals good miscibility between PVC and PP. Based on SEM, good interfacial adhesion between matrix and long glass fiber in PVC/PP/LGF composites was observed. All results in this paper were consistent, and showed long glass fiber could effective influence the properties of PVC/PP, which were proved by the mechanical properties of the composites.

Abstract: The ordinary loom was used to weave different sections of 3D honeycomb fabrics based on the reasonable design of maps and parameters. It could save production cost to ordinary loom used to weave 3D fabrics and controllability of fabrics was good. The fabric was used as enhance phase, 307-3 polyester resin was used as matrix, and VARTM process was used in making 3D honeycomb basalt fibers woven composites. The composites can overcome the shortcomings such as poor integrity, easy to be cracked, low interlaminar strength and easy to be damaged. This study provides theoretical guidance for 3D textile composites.

Abstract: In two steps casting processing, distribution of SiC particles gradually tends to be uniform with the increase of stirring time. The performance of composite improves gradually with the increase of ultrasonic processing time. Compared with the 7050 alloy, the composite after ultrasonic processing has the higher mechanical properties.

Abstract: This study was carried out to discuss the influence of curing temperature on the performance of conductive composites filled with nickel-coated graphite (NCG). The electrical conductivity, crosslink density, mechanical properties and tensile fracture morphology have been investigated. The results indicated that curing temperature had great impact on the electrical conductivity and mechanical properties. Voluem resistivity decreased from 43.1 to 0.08 ohm-cm at 125°C-205°C, and the reason was discussed in light of formation and break of the conductive network in the composites. The stability of SR-NCG cured at 165°C-205°C were also better than those cured at other curing temperature. Besides, tensile strength increased from 2.41 to 7.19Mpa at 125°C-225°C, elongation at break have a 56% increase, and Shore A hardness also incresed from 74 to 82.

Abstract: Effect of functionalized multi-walled carbon nanotubes (MWCNT) on the interfacial properties of ramie fiber/polylactic acid (PLA) matrix was studied. Ramie fibers were respectively covered by the pristine MWCNT, carboxyl functionalized MWCNT and hydroxide functionalized MWCNT through the simple dip coating method. Scanning electron microscopy (SEM) results showed that all kinds of MWCNT were distributed on the fiber surface at random with some aggregations. Compared to the pristine MWCNT coated fibers with a water contact angle of 84.5 degree, the functionalized MWCNT coating made the fiber surface more hydrophobic. Polarization microscopy indicated that the functional MWCNT could provide the nucleation to form the intact crystalline structure of PLA on the fiber surface. Micro-bond tests showed that the coating of MWCNT on the fiber surface had no significant effect on the interfacial shear strength (IFSS).

Abstract: Chemically coupling functionalization multi-walled carbon nanotube (MWCNTs)/nylon-6 (PA6) composites were prepared. The nanotubes were first treated by a volume ratio of 3:1 mixture of concentrated H₂SO₄/HNO₃, and then the γ-aminopropyl-triethoxysilane (KH-550) was carried onto the surface of MWCNTs. Effect of MWCNTs coupling treatment on the mechanical and electrical properties of the MWCNTs/PA6 composites were investigated. The impact strength, tensile strength and modulus of p-MWCNTs (coupling process)/PA6 composites increase by 115.9%, 27.2% and 167.7%, respectively, compared with those of the pure nylon-6 resin. A significant increase of the electrical conductivity of the p-MWCNTs/PA6 composites with respect to the original-MWCNTs and a-MWCNTs/PA6 composites due to the increased compatibility with the matrix due to the formation of an inter face with stronger interconnections.