Applied Mechanics and Materials Vol. 307

Abstract: In order to study the precipitaion of Ni3Si particle in undercooled Ni-Si alloy, calorimetric analyses were carried out using non-isothermal measurements by DSC. The scanning electron microscopy (SEM) and the transmission electron microscopy (TEM) measurements were used to describe qualitatively and quantitatively the precipitate microstructures. The non-isothermal DSC thermograms exhibited one reaction peaks and it indicated that the precipitation process is an exothermic reaction. The evolution for the precipitate was obtained in the as-solidified Ni-Si alloy subjected to DT=195K, meanwhile, the precipitate size was found increased with decreased heating rate in the TEM images. The largest precipitate size was about 120nm, and the precipitates still kept spherical shape. Model prediction for the precipitation of Ni3Si particle has been performed. Good agreement with experimental data has been achieved

Abstract: To established an strength factor model of PCM (Phosphogypsum Consolidation Materials) innovatively based on tests and mathematical methods of factor analysis whose influences to strength performance were quantitative analyzed. To build a mechanism schematic diagram about the mineral formation of PCM which visually analyzed its internal mineral formation mechanism. Making use of ESEM (Environmental Scanning Electron Microscope), the micro mineral structures about three typical kinds of PCM in different gray sand ratios were compared and analyzed, and focused on the micro quantitative analysis on the C-S-H gel in order to elaborate the relevance between microscopic mechanism and strength mathematical factor model.

Abstract: This paper presents analytical solutions of the thermal stresses in a functionally graded solid cylinder with fixed ends in elastic region. These thermal stresses are due to the uniform heat generation inside the cylinder. Material properties of the functionally graded (FG) cylinder vary radially according to a parabolic form. The material properties are assumed to be independent of the temperature which are yield strength, elasticity modulus, thermal conduction coefficient, thermal expansion coefficient and Poisson’s ratio. The solutions for the thermal stresses are valid for both homogeneous and functionally graded materials.

Abstract: In this paper, the multi-hydroxyl polyamines researched by ourselves are used in the slurry of the copper wiring CMP of GLSI, which makes the slurry alkalization. It also has the using as a pH adjusting agent, complexion agent of copper ion, multi- metal chelating agents, aminating agent of acidic oxides, pH buffer, stainless steel corrosion inhibitor, the active agent and pro-oxidant. It improves the property of slurry and solves many different of acidity slurry. The alkalinity slurry contained the multi-hydroxyl polyamines is environmental, inexpensive and composition- simplified. Without the toxic BTA which is must be used in the international and has side effect, the slurry can achieve the high speed and high flat. In the same time the low pressure and the little abrasive can be realized, which provide the new material for the removal of TSV copper film.

Abstract: Polyetheretherketone (PEEK), a tough semi-crystalline thermoplastic polymer with excellent mechanical properties and polytetrafluoroethylene (PTFE), valued for its low friction coefficient are popular materials used for the production of bearings. In this work, rolling contact fatigue (RCF) tests were performed in order to investigate wear on bearing surfaces by using the Fourier Transform Infrared Spectroscopy (FT-IR). It is reported that PEEK’s specific peak at 1243cm^-1 was shifted and PEEK’s polymer bearing crystalline content level on wear surface remained unchanged by contact stress or wear debris adhesion.

Abstract: Multi-walled carbon nanotubes (MWCNT) were dispersed in a mixture of sulfuric and nitric acid with volume ratio of 3:1. Carboxylic acid-functionalized MWCNTS (MWCNT-COOH) were obtained by oxidation pristine MWCNTs via sonication in sulfuric-nitric acid. Epoxy-based nanocomposites reinforced with MWCNTs with and without functionalization were prepared. Chemical functionalization of MWCNTs by oxidation (MWCNT-COOH) was confirmed by FTIR. The properties of nanocomposites were characterized using scanning emission microscopy (SEM). Experimental results showed that functionalization of MWCNTs improved the dispersion of MWCNTs in epoxy matrix compared to those containing MWCNTs without functionalization.

Abstract: Understanding the frictional behavior between glass and metals at elevated temperatures is necessary for accurate modeling and simulation of the precision glass molding (PGM) process, and can help in determining the required geometry of molds, inserts, and dies to produce various optical components. In this research, the frictional behavior of N-BK7, an oxide glass, at elevated temperatures in contact with plain steel has been studied. The results show two important phenomena related to temperature. First, the stick-slip phenomenon is more pronounced at higher temperatures close to the glass transition temperature. This is expected since relaxation and creep of glass occur by molecular diffusion, which becomes more rapid as temperature increases. Second, when the temperature is above the glass transition temperature and the glass begins to behave viscoelastically, the stick-slip friction behavior shows an exponential increase in friction force prior to the onset of sliding that is characterized by a jump in the position data on the order of several micrometers, and is consistent with the response of a viscoelastic material to applied load.

Abstract: NiTi shape memory alloy is considered to be the most important shape memory alloys for its salient superelasticity and shape memory effect,which are displayed in martensitic transformations.In this paper, first-principles plane-wave method is utilized to systemically investigate the geometrical and electronic structures of NiTi (100) surface.Calculated the adsorption of oxygen atoms on the Ti/ NITI different location .The formation energy, Millikan population analysis results show that the Oxygen atoms easy to be adsorbed on the surface of Ti end surface,formation of TiO2.

Abstract: Acoustic wave propagation in solids can carry valuable information on mechanical properties and is therefore used to determine Young, E, bulk, K and shear, G moduli which depend on longitudinal and transverse velocity VL and VT respectively. In this context acoustic microscopy can successfully be used in the investigations of porous materials. In micro-analysis, it directly determines the mechanical properties of materials via acoustic signature, V (z); this signature is obtained by recording the change in the reflected acoustic signal with the defocusing distance, z, as the sample is moved towards the acoustic lens. In this work, we simulate the porous alumina (PAl2O3) acoustic signature, V (z), as a function of porosity to evaluate the output signal attenuation at different operating frequencies. We continue our simulation by the determining of the propagating velocities as a function of porosity by the use of the fast Fourier transform (FFT). In a large part of this work, our interest concerns the study of the porous alumina microstructure by calculating the elastic constants. We compare then the obtained values of Young and bulk moduli to the published data given by various ultrasound methods.

Abstract: The compressive strength development process of recycled coarse aggregate concrete (RCAC) directly affects the safety of the engineering structures, which is an important research topic in the concrete mechanics. According to the statistics of the experimental results, the development mechanism principle of the compressive strength of RCAC gradually increasing with curing time was analyzed. The mathematical property was introduced to reveal the defects of the traditional hyperbolic model of the time-relative compressive strength (TRCS), and to point out that the mathematical nature of the ideal TRCS model should have. A new CES model was presented for TRCS. The mathematical analysis shows that the hyperbolic model is a special case of the CES model, and in another hand the CES model overcomes the defects of the hyperbolic model.