Applied Mechanics and Materials Vols. 130-134

Abstract: The nonlinear ionization process was discussed in detail induced by femtosecond pulse in Lithum Niobate (LN) crystal. The MPI provides “seed” electrons for avalanche ionization process, and avalanche becomes significant when the density of electron created by MPI over 10²⁰ cm^-3. Recombination process leads to an obvious drop of electron density and then a dynamic equilibrium is achieved between the generation of electron and the recombination process, and the density is dependent on the incoming field.

Abstract: A MoS₂/TiO₂ nanocomposite was synthesized and characterized. Its lubricating properties and photocatalytic activity were also investigated, respectively. The as-prepared MoS₂/TiO₂ nanocomposite presented anti-friction properties better than those of the pure nanoMoS₂. However, the difference in the anti-wear properties was not very notable between the pure nanoMoS₂ and the MoS₂/TiO₂ nanocomposite. Moreover, the MoS₂/TiO₂ nanocomposite was also an excellent photocatalyst for the degradation of organic chemicals.

Abstract: The friction and wear behaviors of PTFE composites filled with irregular or spherical copper powders were experimentally investigated. The effects of shape, content and size of the copper powders on the tribological properties of the PTFE composites were discussed. The results showed that the friction coefficients of the PTFE composites filled with irregular copper powders are higher than that of pure PTFE. While the friction coefficients of the PTFE composites filled with spherical copper powders were almost always lower than that of pure PTFE. Both irregular and spherical copper powders can effectively decrease the wear of the composites. The wear of the composites filled with spherical copper powders will gradually decrease with the increase of the content of copper. But the effect of the content of irregular copper powder on the wear of the composites was not so obvious. The friction coefficients and wear depths of the composites increase with the decrease of the Cu size. The increase amplitudes in friction coefficients and wear depths of the spherical Cu filled composites are smaller than those of the irregular Cu filled composites.

Abstract: Pulverizing the waste thermosetting phenol-formaldehyde resins by the self-developed machine which is used to recycle thermosetting plastics, studying the variable laws of fractions of different particle changing with the pulverization time, and establishing a pulverizing dynamic model by regression analysis. The results show that the particle distribution parameters b and m are not constants but the functions of pulverization time; the established equation of regression dynamic is high accurate which clearly describes the pulverization process.

Abstract: Czochralski lifting device is the key equipment for crystal growth. Due to laser crystal growth mechanism could decide its slow growth speed, so Lifting device is required to operate under the ultra-low speed situation chronically. According to shock, shake, fraction and crawl of movement system affected speed stability, the paper carries out a nobel design to laser Czochralski lifting system through alternated servo technology and its precision is analyzed comprenshensively. The long-term experimental data showed by using changed plus PID control method that the system has high precision and better reliability and it is suitable to grow large-size laser crystal. Meanwhile, the design system makes use of common spare parts and can meet the requirements for large scale industrialization.

Abstract: This paper using low-pressure pre-mixed abrasive water jet to cutting composite material,testing and verifying feasibility of the low pressure abrasive water jet cutting , analyzes the abrasive waterjet working parameters on cutting of influence which performance level and interaction effect.

Abstract: A three-dimensional model was developed to simulate the laminar flow and convective heat transfer in rectangular silicon microchannels，which have hydraulic diameter of 95.3，92.3 ,85.8 , 80 and 75μm respectively．The rationality of the simulation methods and results were validated by comparing with experimental data. The simulation results indicate that the aspect ratio has a significant impact on the Poiseuille number. Conventional fluid flow theory is fit for researching the fluid flow in microchannels, Po is a constant that is not dependent on the Reynolds number.

Abstract: NiZnO thin films had been fabricated on c-plane sapphire substrates using photo-assisted metal organic chemical vapour deposition system. The crystal quality of the films had been improved greatly comparing to the results in earlier reports. The crystal structure analysis indicated the NiZnO kept the basic wurtzite structure until the content of Ni attained 0.18. The crystal and electrical properties of the films showed the content of Ni had an important effect on the properties of NiZnO films.

Abstract: The aim of this paper is to investigate the effect of supports on the actual stress distribution of the single-lap adhesive joints under tension using the three-dimensional finite element methods. Five layers of elements were used across the adhesive thickness in order to obtain an accurate indication of the variation of stresses. All the numerical results obtained from the finite element analysis show that the spatial distribution of all components of stress are similar for different interfaces though the stress values are obviously different. The results also show that most of the maximum stresses occur at the interface 1. It can be seen from the results that the stresses are concentrated near the left free ends of the adhesive layer while the centre region of the adhesive layer is mostly stress-free.

Abstract: C₄F₈/N₂ gas mixtures are possible substitutes for SF₆, because of its good insulation characteristics and low influence to environment. The thrust of this paper is to verify the dew point of C₄F₈ and C₄F₈/N₂ gas mixtures, the dew points of C₄F₈/N₂ mixtures are achieved using experimentally measuring and theory calculating method. The experimental data obtained is compared to that predicted from the Clausius-Clapeyron equation, Trouton’s rule and vapor pressure equation. The results show that the experimental data verify well with the predictions. So the prediction method can be used to predict the dew point of C₄F₈/N₂ gas mixtures for different charging pressures.