Applied Mechanics and Materials Vols. 599-601

Abstract: With high requirement setting for hard disk substrate surface quality, abrasive-free polishing (AFP) has attracted more researchers’ attention. In this paper, the influence of Mn (Ⅱ) ion on AFP of hard disk substrate in the H₂O₂ based slurry was investigated. The experiments results show that Mn (Ⅱ) ion can effectively increase the material remove rate (MRR) and improve the planarization of hard disk substrate. Furthermore, the acting mechanism of Mn (Ⅱ) ion in AFP of hard disk substrate was analyzed. The electron spin-resonance spectroscopy (EPR) analysis shows that Mn (Ⅱ) ion in the H₂O₂ based slurry not only can increase the concentration of ·OH free radical, but also can make H₂O₂ decompose to ·O₂^– free radical. These free radicals can accelerate the chemical etching and increase the MRR of hard disk substrate.

Abstract: Al₂O₃ ceramics are widely used in aerospace, defense industry, microelectronics industry and many other fields, but the precision machining methods of this material are restricted because of the high hardness. Therefore, this paper makes an orthogonal experiment of high-speed micro-milling Al₂O₃ ceramics by machining full-diameter micro-grooves. The feasibility of micro-milling Al₂O₃ ceramics with diamond coated tools is verified. In the experiment, surface roughness values obtained are treated as evaluation indexes. And the influences of many process parameters on the workpiece surface roughness are analyzed by range analysis method. These parameters are spindle speed, feed rate and axial depth of cut. Then optimized the process parameters and obtained a set of suitable parameters to micro-mill Al₂O₃ ceramics.

Abstract: Experimental study on the burning behavior of four kinds of common automotive internal decorating materials including fur cushion, flannel cushion, dacron seat cover and felt carpet by means of cone calorimeter are introduced in this paper. Compared with the four kinds of materials from the perspective of ignition time, HRR, peak HRR and carbon monoxide release rate under different heating flux, burning behaviors of these materials are analyzed. According to analysis results, the risk of automotive fire disasters can be objectively evaluated. In a word,it’s helpful to study their burning behaviors and point out proper methods of application.

Abstract: As the raw materials of Na₂WO₄•2H₂O and ZnSO₄•7H₂O, ZnWO₄ micron spheres and nanorods were synthesized with CH₃COOH as the complexing agent by a hydrothermal method at 180 °C for 24h. We analyzed the effect of different pH values in reaction solutions on phase compositions, morphologies and luminescent properties of the ZnWO₄ powders. The as-synthesized products were characterized by XRD and SEM. The down-conversion spectrum was measured with spectrophotometer under the excitation wavelength of 291nm. The results indicated that there was a wide emission peaks at 400~550nm. The luminescent intensities of ZnWO₄ nanorods synthesized at pH value of 9, 10 and 11 were much stronger than that of ZnWO₄ micron spheres synthesized between the pH values of 4 to 8.

Abstract: Through discussing the characteristics of metal matrix composites, the mechanical properties of metal matrix composites is analyzed, the mechanical parameters of metal matrix composites is tested by experiment, the specific application is instructed in the field of aviation, the development direction of metal matrix composites is pointed out combining with the characteristics of material itself.

Abstract: Medical use quartz components for electromagnetic shielding materials research topics very rarely, therefore, intend to systematic development of coated quartz glass materials. The considerations for against electromagnetic waves (Electromagnetic Interference Shielding, EMI), one conductive coating film is required. The anti-high-frequency electromagnetic waves also need magnetic coating film. The thin film is translucent with a poor crystallinity, must be heat-treated to have good crystallization and conductivity, and therefore finds the feasible of Ni-based coating and interface effects also have the academic importance. This program is to deposit Ni-based thin film on different quartz planes (Ni/SiO2), and explores the effect of heat treatment on the structure. That contains crystalline characteristics (doping concentration: the Ni-base matrix doping Fe, 10at%~ 50at.%), optical properties and electrical conductivity. Finally, the electromagnetic shielding effect (EMI) of the coating structure is assessed. So, the application data for the characteristics of interface layer and anti-electromagnetic (EMI) properties are obtained. building materials extended to the health care system materials systems. The results show that Sn-40Al-xNi film increased the electromagnetic interference (EMI) shielding after annealed. For the Sn-40Al-10Ni films with higher Ni atomic concentration, the low frequency EMI shielding could be improved. For the sputtering films the annealed treatment not only had higher electric conductivity but also increased the high frequency EMI shielding.

Abstract: ZSM-5/MCM-41 composite zeolites were synthesized by a two-step hydrothermal crystallization procedure using binary templates of cetyltrimethylammonium bromide (CTAB) and tetrapropylammonium hydroxide (TPAOH). The effects of aluminum content on zeolite particle morphology and structure were studied. Powder X-ray diffraction (XRD) results showed that the composite zeolites are of both MCM-41 structure and zeolitic MFI structure. SEM results showed that the morphology of composite zeolites is significantly influenced by the aluminum content.

Abstract: Ti6Al4V component has been formed by hot isostatic pressing (HIPping) using internal graphite mould with Ni isolation layer. The shape of the graphite had no deformation after HIPping. The Ni isolation layer with a thickness of approximately 5μm on graphite before HIPping was diffused into the dense Ti6Al4V component surface and formed a uniform, compact and crack free layer with a thickness of approximately 100μm after HIPping. The Ni diffusion layer is not damaged after removing the graphite mould by unpolluted sandblasting. The interface topography and the elements diffusion have been assessed and it is found that the non-machined surface of Ti6Al4V component was improved by using graphite mould than those used mild steel. The roughness of non-machined surface after removing the graphite mould by sandblasting is Ra=1.6μm, and the roughness of non-machined surface after removing the mild steel by acid pickling is Ra=10.8μm. It is concluded that graphite mould could be used for the HIPping process to produce complex-shaped components.

Abstract: Taking Fe/NaY zeolite as catalysts, a range of nitrogen doped carbon nanotubes (N-CNTs) were synthesized by chemical vapor deposition method (CVD) at 1073K using ethanediamine, dimithylethanediamine and tetramethyl ethanediamine as nitrogen source and carbon source, respectively. The structural and compositional properties of N-CNTs were characterized by XRD, SEM and TEM. The results illustrate the microstructure of N-CNTs is strongly dependent on the N/C ratio of precursors. With the increase of N content in precursors, N-CNTs became shorter, more disorder, coarser surface and the average bamboo segment distance increased from 40 nm to 60 nm. A mechanism for the formation of the N-CNTs grown from three precursors with different N/C ratio has been proposed based on experimental observations.

Abstract: The feasibility and applicability of delamination damages localization methods with various defined damage indexes for the damaged composite laminated beam were studied. The results indicate that, for the modal strain energy method, damage indexes defined by strain energy difference are more effective to locate the delamination damage than that of strain energy ratio. For energy response method, damage index defined by the second difference can effectively locate the delamination damage in the composite laminated beams.