Advanced Materials Research Vol. 815

Abstract: The CdS films were deposited on soda lime glass (SLG) substrate by Chemistry Bath Deposition (CBD). The influence of cadmium concentration on structure and properties of CdS films had been investigated. The phase compositions of the films were characterized by X-ray diffraction (XRD). The microstructure of the films was observed by Scanning Electron Microscope (SEM). The transmittance of the films was measured by Ultraviolet-visible Spectrophotometer. The results show that the cadmium concentration has great influence on Crystallite structure and grain size of the films. Under the condition of Cd²⁺ concentration of 0.006mol/L, the crystalline degree of the film is higher and the crystal growth is more remarkable, which help to make great progress on transmittance and optical band gap of the films.

Abstract: The crystal structure of wollastonite is triclinic. Electronic structures and optical properties of wollastonite were studied using a quantum mechanical first principles approach. The geometric parameters, electric and optical properties of wollastonite are investigated by using the plane-wave ultrasoft-pseudopotential method (PWP).The equilibrium lattice constants are in good agreements with experimental data. The electronic structures reveal that wollastonite has a indirect band (5.4eV) gap and a direct band (5.5eV).Optical properties have been studied and the calculated optical dielectric constant (ε_op) is about 2.68.

Abstract: Under the condition of high dynamic, there is a pixel shift phenomenon which is called smear in the star image sampled by star sensor. The recovery algorithm of star energy distributing for star sensor is presented in the paper. The quaternion of next frame is calculated with the previous continuous quaternion. All the ideal star coordinates of star image in the FOV is calculated with the quaternion of next frame. Then the angle between the two previous continuous axis directions is calculated with the previous continuous axis directions calculated with the previous continuous quaternion. The radius of threshold scan window of star image is calculated according to the angle. Finally, within the star image radius of the threshold scan window, shift the original star image to make the shifted star energy distribution continuous. So the star image distribution subjects to 2-D Gaussian distribution, and the star coordinates is obtain with centroiding algorithm. A star sensor featuring a recovery algorithm of star energy distributing for star sensors proposed in this paper was for demonstration at night sky experiment.

Abstract: The effect of hypereutectic Al-22%Si alloys prepared by means of Controlled Diffusion Solidification (CDS) followed by subsequent heat-treatment on the microstructure and sliding abrasive wear behaviors is investigated. The results show that the primary silicon morphology, size and distribution can be improved by CDS, especially for the case of liquid-liquid mixing. After heat-treatment, the eutectic silicon can be spheroidized. Under the same load, the wear rates for the identically mixed and heat-treated Al-22%Si alloys are lower than those unheat-treatment, and the wear rate of liquid-liquid mixed and heat-treated Al-22%Si alloy reach its minimum. The wear mechanism of traditional cast Al-22%Si alloy includes adhesive wear and fatigue breaking-off, while the liquid-liquid mixing can effectively restrain flaking on the worn surface and avoid the fatigue breaking-off, the wear mechanism is changed into abrasion wear.

Abstract: soprene can be polymerized into three types of isomeric units, cis-1, 4, trans-1, 4 and 3, 4-units. Dyad or triad sequences of these units were investigated by ¹³C-NMR, which the signals are assigned for the sequences as well as the special linkages, head-to-head and head-to-tail structures. The crystallization ability of polyisoprene was mainly dependent on these sequence structures and was studied in this paper, including cold crystallization and stress-induced crystallization. As a result, the samples with regular sequence structure had better crystallized ability which will be as the guidance for the polymerization.

Abstract: The hot ductility behavior of test steel was investigated by Gleeble-3500 thermo-mechanical simulator through high temperature tensile test. The reduction in area (RA) and tensile strength (TS) were acquired to draw hot ductility curve and hot strength curve. SEM fractograph and microstructure of the tensile samples were analyzed. The results show that the third brittle zone of test steel is between 700°C and 800°C and the occurrence of the third brittle zone is mainly related to the formation of film-like ferrite along the prior austenite grain boundary and the precipitation of second phase. Moreover, the drop of hot ductility at 900°C is rooted in the reduction of grain boundary strength owing to the precipitation of sulfides. Therefore, it is advised that the straightening temperature of test steel should be kept over 900°C.

Abstract: Steel framed structures have been increasingly built in Korea since the early 1970s and the use of submarine structural steel is being increased thanks to the easiness in welding and superior seismic performance. But, the risk of fire outbreak goes up because of the increase in fire load density. The evaluation of the structural stability of the structural frames at high temperatures can be done based on the mechanical properties of the applied steel at the high temperatures. In this paper, in order to get the fundamental data as to the structural stability of the steel frames built with submarine structural steel at high temperatures, coupon tests for SM 400, SM 490 and SM 520 at high temperatures were conducted and the results were compared with each other and with those of the euro-code for verification.

Abstract: In order to detect the diffusion law of alloying elements in 0.95c-1.45cr-0.35mn-0.25si bearing steel during annealing process,the database of tcfe7 and mobfe of dictra software were used to calculate the diffusion kinetics. The results show that c atoms diffuse rapidly in single fcc phase field and at last uniform,temperature and holding time have no significant influence on them;cr,si,and mn has the same diffusion mechanism,the initial solidifying field has lower solute than the subsequent,and has slight change after solidification. The improvement of segregation factor (cr) at 1300°C for 5h is better than at 1050°C, 1200°C for 10h.

Abstract: Cu-coated carbon fiber cloth/Ti-6Al-4V composite (Cu-C_f/TC4) and uncoated-C_f/TC4 were fabricated by spark plasma sintering (SPS) method. The microstructure and dynamic compression properties of the C_f/TC4 composites were investigated. Results show that the matrix-fiber interfacial bonging in uncoated-C_f/TC4 is weaker than in Cu-C_f/TC4. Moreover, lamellar TiC exists throughout the TC4 matrix in uncoated-C_f/TC4, while there is no TiC generated in TC4 matrix of Cu-C_f/TC4. Dynamic compressive tests indicate the stress-strain curves of Cu-C_f/TC4 and uncoated-C_f/TC4 show no difference at a strain rate of 2500 s^-1, while show significant difference at a strain rate of 4800 s^-1. Further investigations find: (1) at a strain rate of 2500 s^-1, the reinforcement effect of C_f on Cu-C_f/TC4 is similar to TiC on uncoated-C_f/TC4, explaining the exact similarity in compressive property of Cu-C_f/TC4 and uncoated-C_f/TC4; (2) at a strain rate of 4800 s^-1 the reinforcement effect of C_f on Cu-C_f/TC4 is far more than TiC on uncoated-C_f/TC4, explaining the higher compressive strength of Cu-C_f/TC4; moreover, multiple debonding of carbon fiber and its squeezing into TC4 matrix constitute an important energy absorption mechanism for uncoated-C_f/TC4, explaining the better plasticity of uncoated-C_f/TC4.

Abstract: The experiment program was carried out to investigate strength performance and flexural properties of concrete containing recycled crumb rubber. The rubber contents of 10,20,30 and 40% by volume were selected to partially replace the fine aggregate with crumb rubber of 20 mesh, and sodium hydroxide (NaOH) solution was employed to modify the rubber surface, enhancing adhesion between rubber particles and cement paste. Uniaxial compression and four point bending tests showed that both compressive and flexural strength reduced as crumb rubber inclusion increasing. It is notable that surface modification by NaOH solution have positive effects on strength properties of crumb rubber concrete, and the failure mode tends to become ductile failure due to the rubber inclusion rather than brittle failure of normal concrete.