Performance evaluation of rubberised asphalt mixes containing WMA additives

The aim of this research is to investigate moisture susceptibility, rutting resistance and structural response of rubberised asphalt mixtures containing Warm Mix Asphalt (WMA) additives using Tensile Strength Ratio, dynamic creep test, wheel tracking and indirect resilient modulus. Furthermore, impact of WMA additives on compaction was evaluated by air void content of Marshall specimens. Two types of waxes, namely Sasobit and Rheofalt, and an anti-stripping additive, namely Zycotherm, were used to reduce mixing temperature of rubberised mixtures at concentrations of 0, 5, 10 and 15%. It was proved that not only does small amount of the anti-stripper (0.1%) decrease the production temperature effectively, but it also results in the most moisture damages resistance improvement compared to the waxes. Rheofalt, on the other hand, has the most effectiveness in improvement of rutting resistance and resilient modulus. Finally, Sasobit was found the most effective WMA additive regarding compaction effort efficiency.     

Microstructure and thermal conductivity of AIN ceramics containing additives

The effect on AIN ceramic of the addition of Y₂O₃, Yb₂O₃, Er₂O₃ and CaO were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermal conductivity measurements. The effect of grain boundary segregation and second phase distribution on the thermal conductivity are discussed. The Er₂O₃-CaO-and the Yb₂O₃-CaO-AIN ceramics have a higher thermal conductivity than the CaO-and the Y₂O₃-CaO-AIN ceramics. This is explained on the basis of the free energy of formation (G°), the vaporization of the sintering additives and the microstructural development. Oxidation of freshly cleaned surfaces of those AIN ceramics was studied.     

Laser ignition in internal-combustion engines: Sparkless initiation

Laser ignition has been implemented in a single-cylinder internal combustion engine fueled by gasoline. Indicator diagrams (cylinder pressure versus crank angle) were obtained for laser ignition with nano- and microsecond pulses of an Nd:YAG laser. The maximum power of microsecond pulses was below critical for spark initiation, while the radiation wavelength was outside the spectral range of optical absorption by hydrocarbon fuels. Apparently, the ignition starts due to radiation absorption by the oil residues or carbon deposit in the combustion chamber, so that the ability of engine to operate is retained. This initiation of spark-free ignition shows the possibility of using compact semiconductor quantum-cascade lasers operating at wavelengths of about 3.4 μm (for which the optical absorption by fuel mixtures is high) in ignition systems of internal combustion engines.     

Fracture phenomenology of a sintered silicon nitride containing oxide additives

Crack propagation mechanisms in a sintered silicon nitride containing various oxide additives (ceria, magnesia, zirconia and strontium oxide) were studied as a function of initial flaw size, temperature, applied stress and time. Surface cracks of controlled size were introduced using the microhardness indentation-induced-flaw technique. At 20° C, the fracture stress was found to depend on initial crack size according to the Griffith relationship and extrapolation of the data indicated that processing flaws of 20 to 35 were strength-controlling. The flexural strength was found to be independent of temperature from 20 to 800° C and the mode of crack propagation was primarily transgranular. At temperatures above 800° C the flexural strength decreased significantly, due to viscous flow of the glassy phase present in the material and resulting in sub-critical crack growth (SCG). The mode of crack propagation during SCG was essentially intergranular. Flexural stress-rupture evaluation in the temperature range 800 to 1000° C has identified the stress levels for time-dependent and time-independent failures.     

Structural investigation of the phase transition in perovskite titanate containing additives

The phase transformation from tetragonal to cubic for perovskite BaTiO₃ containing Dy₂O₃ and Ho₂O₃ has been studied by X-ray diffraction and infrared absorption spectra. The high-angle reflections (4.11) and (422) from the cubic phase give a set of doublets of the two wavelengthsK ₁ andK ₂. In the tetragonal structure each doublet is split into a set of partly overlapping doublets. The high broadening of absorption bands in the infrared spectra of heavily doped samples is attributed to symmetry changes from tetragonal to cubic.     

Electron beam induced explosive luminescence of PETN

We have studied the spectrum and kinetics of optical emission in the wavelength range from 550 to 1000 nm accompanying explosive decomposition of pentaerythritol tetranitrate (PETN) single crystals initiated by a nanosecond electron beam. The explosive luminescence kinetics reveals two components with a continuous spectrum, identified as luminescence accompanying the explosive decomposition, and a component with a linear spectrum due to molecular nitrogen formed as a result of explosion.     

Study of the kinetics in crystallization of neodymium-iron-boron alloy containing zirconium additives

The possibility of applying the Kolmogorov-Avrami equation to describe the kinetics of crystallization of Nd₂Fe₁₄B-based alloys is discussed; for the estimation of the fraction of the transformed volume, the results of magnetic measurements are used. A significant influence of zirconium additives on the kinetics of crystallization is revealed.     

含纳米铜添加剂的汽油机油行车试验研究

用电子扫描透镜(SEM)、粒径分析仪对实验室制得的油溶性纳米铜颗粒进行了分析。通过摩擦实验确定了作为SF15W/40汽油机油添加剂纳米铜颗粒的最佳添加量。通过行车试验对添加纳米铜颗粒的机油与参比机油的理化参数、金属含量及油耗进行了比较。结果表明:纳米铜颗粒在基础机油中具有良好的分散性,平均粒径约16.8nm。机油中纳米铜颗粒的最佳添加量为0.8%。行车过程中,纳米铜颗粒机油的黏度、酸值、闪点的变化很小,因而有更好的抗氧化性和抗磨性;行车4000km后,油中Fe元素含量为26.78mg/kg,而参比油此时达到66.93mg/kg。添加了纳米铜颗粒机油的车辆具有较低的百公里油耗,最大节油率15.1%。     

Cure shrinkage characterization and modeling of a polyester resin containing low profile additives

Resin Transfer Moulding (RTM) has great potential as an efficient and economical process for fabricating large and complicated composite structural components. The low capital investment cost required and process versatility in component integration and assembly make RTM very attractive for high volume automotive applications. One of the challenges facing the automotive field is the resulting surface finish of manufactured components. The shrinkage associated with the curing of thermoset resins contributes to the poor surface quality. Low profile additives (LPA) are added to the resin to compensate for the cure shrinkage; however their effects on the thermal, rheological and morphological properties of polyester resins are not well understood. In this paper, the effect of LPA on cure kinetics, cure shrinkage and viscosity of a polyester resin is studied through differential scanning calorimetry (DSC) and special rheological techniques. Models are developed to predict cure shrinkage, LPA expansion, cure kinetics and viscosity variations of the resin as a function of processing temperature. Finally, morphological changes in the resin with and without LPA, during isothermal cure, are studied with hot stage optical microscopy. The results show that the LPA content in the range tested had no significant effect on the cure kinetics. However, higher LPA content reduced cure rate and cure shrinkage. A minimum of 10% LPA was required to compensate for cure shrinkage. Shrinkage behavior of all formulations was similar until a degree-of-cure of 0.5. However, resin formulations with higher LPA content showed expansion at later stages during curing.     

2,4-MDNI/PETN低共熔物的制备与性能表征

为降低高能炸药季戊四醇四硝酸酯（PETN）的感度,使用钝感高能炸药1-甲基-2,4-二硝基咪唑（2,4-MDNI）与PETN制备了2,4-MDNI/PETN二元混合体系。通过差示扫描量热法（DSC）研究了不同组分比例的2,4-MDNI/PETN的熔融液化过程,建立了2,4-MDNI/PETN二元混合体系的T-x相图,并得到低共熔物组成。研究了不同升温速率下2,4-MDNI/PETN低共熔物的分解过程,并计算了其热分解反应动力学参数。通过体积收缩率、凝固表面微观形貌等研究了2,4-MDNI/PETN低共熔物的凝固性能。测试了2,4-MDNI、PETN及2,4-MDNI/PETN低共熔物的机械感度,并计算了2,4-MDNI/PETN低共熔物的爆轰参数。结果表明:2,4-MDNI/PETN低共熔物中2,4-MDNI与PETN的摩尔比为71∶29,平均熔融温度116.9 ℃,平均热分解反应温度207.5 ℃,热分解反应活化能167.05 kJ/mol,体积收缩率14.4%,撞击感度32%,摩擦感度0,生成焓－37.1 kJ/mol,理论密度1.732 g/cm³,计算爆速8 031 m/s,爆压27.89 GPa。表明2,4-MDNI的加入可以显著降低PETN的感度,同时保持其较高的能量水平。     

Fracture surface energies of high explosives PETN and RDX

Journal of Materials Science -     

Experimental study of heat transfer to liquids containing additives of high polymers and surfactants

Results of investigation are presented on a change in the mean coefficient of heat transfer to water containing small additives of polyacrylic amide and surfactants with variation in the rate and in the thermal head.Translated from Inzhenerno-fizicheskii Zhurnal, Vol. 64, No. 1, pp. 34–38, January, 1993.     

Laser action in polymeric gain media containing scattering particles

Optical pumping of polymer sheets containing laser dyes and TiO(2) nanoparticle scatterers results in emissions that exhibit laser behavior with linewidths as low as 4 nm. The input-output characteristics, effects of index matching on the emission, damage thresholds, wavelength stability, and possible applications of these new materials are discussed.     

Laser Surface Melting on cast iron containing undercooled graphite

Laser surface melting experiments were carried out on an alloy cast iron with 3% C, 2% Si and 0.25% Ti containing undercooled graphite. Different heating times and energy densities were used to achieve different penetration depths and cooling rates. The microstructures obtained after surface melting and after various heat treatments are presented and discussed. It is shown how the cooling rate and concentration influence the solidification behaviour of high carbon cast irons. The composition chosen for the experiments can be considered as representative of many cast irons.     

Real time low temperature decomposition of explosives - PETN

Chemiluminescence NO/NO_x analyzers have been used to make real-time measurements of PETN decomposition products near storage temperatures. Over the