Papers by Keyword: Interface Properties

Abstract: We investigated the impact of high-temperature H₂/Ar mixture gas treatment of 4H-SiC(0001) surfaces before SiO₂ deposition on the electrical properties of SiO₂/SiC interfaces. Physical characterizations revealed that the SiC surface treated by the H₂/Ar mixture gas exhibited a (√3×√3)R30° structure composed of Si-O bonds, indicating that a well-ordered and stable silicate adlayer was formed by the treatment to passivate SiC(0001) surface. Electrical defects at the CVD-grown SiO₂/SiC interface was significantly reduced by the treatment. Consequently, a peak electron mobility in SiC-MOSFETs with the deposited gate oxides was enhanced to 24.9 cm²/Vs.

Abstract: In modern manufacture, like in automotive industry, high quality products and high output rates as well as low costs are achieved by highly efficient processes. Optimized tool design represents a key factor for such processes, leading to long tool life and hence to low tooling costs. Early in the industrial manufacturing chain of roller bearings for example, hot bars are sheared into billets, which are subsequently transported automatically to the first forming stage of a press. The shear blades should have a high wear resistance at high temperatures. In this study the first bi-metal composite shear blade made by spray-forming has been developed and tested in industrial environment. The composite tool has been deposited in a co-spray forming process to directly combine a hard-facing alloy layer with a hot working steel body in order to take advantage of the high microstructural homogeneity and the low segregation generated in spray forming. After machining, heat treating and quality inspection of the new material composite, the hot working tool was used in manufacture to prove its wear resistance and durability. The results show that the interface properties of the composite are of high quality and the material has a lower vulnerability to cracks after use in production than the conventional tool, respectively material. Only the porous zone near the interface leads to fissures which are partially going deep into the tool. Hence the parameters of the co-spray forming process need to be improved.

Abstract: For the situation that digital switching device interface testing is relied on manual and automatic testing system development cost is high, the paper has adopted the reconfigurable technology. And by using the reusable character of general testing system, a special testing system is built, which can solve the contradiction between testing benefit and testing efficiency. The new system consists of hardware reconfigurable matching front-end and software reconfigurable virtual instrument. It has improved the switching device interface testing efficiency and accuracy, and shorten the construction cycle. Its component parts are reconfigurable, and flexible to assemble. It has good generality and expansibility, and certain practical utility. The idea has also provided instructions for designing similar testing system.

Abstract: Nonionic surface active agent AO-1, n-butanol, kerosene and water were mixed in varying proportions to compound micro-emulsion. According to different phase states of each micro-emulsion, some systems with representative were picked up, and then tested the interface properties of oil phase of the systems above. The experimental results show that there is a system with low interfacial tension and steady surface tension.

Abstract: Effects of pulsed electric fields (PEF) treatment on interface properties of phospholipids dispersion were studied. Results showed that the conductivity of solutions with different concentration after PEF treatment increased while surface tension value decreased with increasing electric field strength. The absolute value of zeta potential firstly increased when the field intensity was within 0~20 kV/cm, and then decreased if the field intensity increased further. It can be inferred that the torque of phospholipids molecule may have changed and phospholipids molecule have rearranged after PEF treatment. Moreover, as a resemblance to biological membrane structure, the phospholipid molecules of cell membrane may generate micropores after rearrangement, which result in the cell electroporation.

Abstract: The deposition process and interface properties of electro-thermal explosion sprayed WC/Co coating were studied by numerical simulation and experimental observation in this paper. The variety rule of the deposition particles / metal substrates interface temperature, the critical remelting condition of the substrates surface, and the interface removment speed of deposition particles were numerical simulated by finite element method. Results show that the remelting depth of the substrate increased with increasing spraying particle temperature and particle size. Structures and interface properties of the electro-thermal explosion sprayed WC/Co coating was analysed based on the numerical results. The morphologies, AES patterns, element distributions, TEM micrographs were experimentally observed and compared with the simulatin results. Which show that the finite element analysis is in good agreement with the experimental results, suggesting that the analysis in the present work is reliable.

Abstract: Geotechnical prestressed anchorage structures are widely used in high slope, deep foundation pit, dam and other geotechnical reinforcement engineerings. Under the influence of the outside environment, its pretensioned force is not fixed, but presents a kind of approximate closed cyclic loading mode, under which the development and evolution regularity of the interface shear stress for the inner bond section of geotechnical prestressed anchorage structure is directly related to the ultimate bearing capacity and its long-term durability. In the experiment, the means of indoor model test was adopted, in which the different loading scheme and loading amplitude were taken into account and the interfaces mechanical properties of inner bond section for geotechnical prestressed anchorage structures under cyclic loading were studied. According to the test results, the development and evolution regularity of the interface shear strain for the inner bond section is revealed, and the long-term durability of the geotechnical anchorage bolt under cycle loading is put forward.

Abstract: There are several models on the relationship structures and properties of the composite fiber / matrix interface [1]. Including literature proposes the development of micromechanical tests suitable for assessing the shear strength of the interface fiber / polymer matrix. The first test which allowed to characterize the fiber / matrix interface is the pull-out test developed by Broutman [2]. It consists in extracting the fiber from the matrix that can be in block form, gout or disk of resin. To reduce the variation in results due to the geometries used, it was agreed to use a drop of resin with small dimensions. The test is to characterize the fiber / matrix interface of natural thermosetting or thermoplastic by determining the shear stress.

Abstract: In this paper, current-voltage (i-Vg) results from different kinds of n-type InP Schottky diodes are reported. The diodes were fabricated on an unintentionally doped n-type (100) indium phosphide substrate, and the i-Vg characteristics were measured in the temperature range 100 300 K. For the ideality factor, n always exhibited a small (1) but continuous increase with the voltage. At higher forward voltage, slightly higher values of n were due to series resistance effect; in other words, the interface state density always remained small. However, it was possible to obtain some information in the case of discrete interface traps. It was shown that i-Vg measurements can be used as a fast method to determine the densities of the interface states when they equilibrate with the semiconductor.

Abstract: The present investigation attempts to understand the friction welding characteristics of Aluminum alloy AlCu and steel AISI 4140. In spite, many trials were applied to achieve the sound weld zone of direct bonding between Aluminum and steel. The formation of intermetallic phase and crack in the near weld zone resulted in a lower tensile strength of joints relative to those of other welding technique. Therefore, to prevent intermetallic phase and crack formation at the interface, pure copper was used as insert powders for stress relief buffer layer. This study also envisages the influence of process parameters which include resident preform densities, friction pressure, upset pressure, and burn-off length on microstructure and mechanical properties of the welds. This work consolidates information on the aspects of diffusion joining of steel, copper and Aluminum component with wrought materials for practical execution. In the view point of tensile strength, the highest tensile strength between AlCu and AISI 4140 was acquired by using pure copper as insert powder.