Advanced Materials Research Vols. 311-313

Abstract: The continuous progress of the electronic industries put forward a new requirement to the electronic components that must have an excellent heat conduction performance. Thus diamond-Cu composite is developed as a high thermal conductivity and low coefficient of thermal expansion material. A vacuum hot pressing method is chosen to prepare diamond-Cu composites and the thermal conductivity of the diamond-Cu composite is researched. The effects of different contents of chromium, the size of diamond particles and the content of diamond particles on the thermal conductivity of the diamond-Cu composite are discussed. The results demonstrate that the chromium element can improve the thermal conductivity of the composites and the thermal conductivity is largest when the content of chromium is 3 percent.

Abstract: Based on the investigation and analysis on the pavement structure, material and traffic accidents of highway tunnel, security and function of transition section at highway tunnel’s entrance and exit are analyzed, and some useful suggestions for tunnel’s transition pavement structure are given in this article.

Abstract: Cutting heat and the resulting temperature change material properties, thus it produces tremendous influence to cutting force, tool condition and surface roughness. The cutting heat generated by the power ultrasonic vibration cutting process were is calculated in this paper, the power ultrasonic vibration cutting is studied by using the finite element software, the conclusions are that during power ultrasonic vibration cutting, the cutting heat generated depends on the net cutting time of a vibration cycle, the rapid cooling is the main reason for lower cutting temperature in the separation stage of the workpiece and tool, and the maximum temperature of the tool is greater than conventional turning, but the average temperature of the tool is low than traditional turning.

Abstract: In order to investigate the multi-axial mechanical properties of a kind of PU (polyurethane) foam, some experiments in different loading conditions including uni-axial tension, uni-axial compression, hydrostatic compression and three-point bending were conducted. It is shown that the hydrostatic component influences yield behavior of PU foam, the yield strength and degree of strain hardening in hydrostatic compression exceed those for uni-axial compression. In terms of the differential hardening constitutive model, the evolution of PU foam yield surface and plastic hardening laws were fitted from experimental data. A finite element method was applied to analyze the quasi-static responses of the PU foam sandwich beam subjected to three-point bending, and good agreement was observed between experimental load-displacement responses and computational predictions, which validated the multi-axial loading methods and stress-strain constitutive model parameters. Moreover, effects of two foam models applied to uni-axial loading and multi-axial loading conditions were analyzed and compared with three-point bending tests and simulations. It is found that the multi-axial constitutive model can bring more accurate prediction whose parameters are obtained from the tests above mentioned.

Abstract: Impact analysis of an advanced laminated composite comprising aerospace 2024-T3 aluminum alloy and resin impregnated E-glass fiber layers with different stacking sequences is presented in the paper. The panel under study is subjected to load-time history equivalent to the low velocity crash using FEM software ANSYS 12. Stress values in the laminate are found to be discontinuous at the interfaces whereas the displacements are continuous across the interfaces. The maximum stress and displacement values in the laminate are comparable with those in monolithic aluminum alloy panel of same thickness.

Abstract: Minerals particles such as diatomite and perlite can be reinforced by coating their surfaces with aluminum silicate or zirconium silicate. Scanning electron microscopy shows that the surface of the coated particles is covered by a layer of a glassy/ceramic type coating. Test results indicate that the compaction strength of perlite particles can be increased significantly, approximately 9–fold in the case of the aluminum silicate coating. The aluminum silicate and zirconium silicate coated diatomite fillers also increase paint film scrub resistance either due to the harder glassy/ceramic coatings on diatom surface or due to the stronger bonding between the coated diatomite particles and the resin.

Abstract: The Ni-P-TiO₂ coatings were successfully obtained on foamed nickel by electroless plating technique. Materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive analysis (EDS) studies. The degradation effect of the prepared coating for the dyes was studied at the same time. Results showed that the appearances of coatings were fine and the amount of TiO2 in the coatings reached at 9.85wt%. The specimens exhibited excellent photocatalytic activity, the decolorization ratio of reactive black GR and methylene blue reached to 92.40% and 95.27% after 4 hours and 6 hours respectively irradiated by the same ultraviolet lamp.

Abstract: The FeAl/Al₂O₃ composites were fabricated by hot-pressing process in this research. The Fe-Al intermetallics compounds powders were fabricated by mechanical alloying and heat treatment. The FeAl powders and Al₂O₃ powders were mixed and the FeAl/Al₂O₃ composite powders were prepared. The FeAl/Al₂O₃ composites bulks were fabricated by hot-pressing process at 1300°C for 2h under the pressure of 35MPa. The phase composition and microstructure of the FeAl intermetallics compounds powders produced by mechanical alloying and heat treatment were investigated. The phase composition and microstructure of the FeAl/Al₂O₃ composites produced by hot-pressing process were investigated. The XRD patterns results showed that the Fe-Al intermetallics compounds powders were fabricated by mechanical alloying for 60h. The FeAl intermetallics compounds powders were fabricated by heat treatment at 800°C, 900°C and 1000°C. The microstructure showed that the mean particles size of the FeAl intermetallics compounds powders produced by mechanical alloying and heat treatment was rather fine and about 4-5μm. The XRD patterns results showed that there existed FeAl phase and Al₂O₃ phase in sintered composites. The FeAl/Al₂O₃ composites bulks exhibited the homogenous and compact microstructure. The mean particles size of FeAl was about 4-5μm and the mean particles size of Al₂O₃ was about 4-5μm. The microstructure of the FeAl/Al₂O₃ composites became more homogenous and compact with the increase of FeAl content.

Abstract: CPM9V high speed steel(HSS) ring billet was prepared by spray forming(SF), the yield is 83.5%, porosity is 0.8%, spray forming preparation method and technological parameter were illustrated. The microstructure and carbide morphology on the different position of billet were observed. The results show that carbide particles have small size, regular shape and uniform distribution, alloy element without segregation. There are some pores and defects in the position of ring billet closed to deposition substrate, come from spray forming instability beginning stage.

Abstract: Three-ply Kevlar fiber/epoxy composites used as static ring of ship propeller were manufactured by winding molding. The density of the composites was measured with a GP-300EW type density tester. Barcol hardness of the composites was measured with HBa-1 type Barcol hardness tester. The morphology of cross section of the composites was observed with a VNT-100 type metallography microscope. It was concluded that three-ply Kevlar fiber had low density and reinforcement effect.