Advanced Materials Research Vols. 295-297

Abstract: The effect of the thickness on the dielectric and ferroelectric properties of poly(vinylidene fluoride trifluoroethylene) [P(VDF-TrFE)] copolymer thin films were investigated. The results show that the dielectric constant and tunability increase while the coercive field decreases with increasing film thickness. The film thickness also affects both the reversible and irreversible Raleigh parameters in the ac field dependence of dielectric constant. The observed phenomenon can be explained by the existence of interfacial layers between electrodes and film. No obvious thickness-dependent microstructure and ferroelectric transition temperature was observed.

Abstract: The cohesive zone plays very important role in the operation of COREX melter gasifier, up to now, definition of the cohesive boundary has always been a challenging task. In this paper, a two-dimensional hot model of melter gasifier, in which paraffin and corn are used to simulate DRI, coke and lump coal respectively, has been established to study the cohesive boundary in this paper. While the whole experimental process is recorded by the high-speed camera, the image processing method is put forward to define the cohesive boundary quantificationally.

Abstract: NiCr nano oxides have been synthesized by impregnation method and were used as the anode electrocatalysts for direct methanol fuel cell(DMFC). The catalysts were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM). The activity of catalysts with different metal molar ratios and calcination temperatures on the methanol oxidation reaction were investigated by cyclic voltammetry(CV) and bulk electrolysis with coulometry. The results show that the NiCr nano oxides calcined at 500°C for 6h gave an excellent electrocatalytic performance in the anodic oxidation of methanol.

Abstract: The stress superimposing testing method of residual stress is different from the stress releasing way. A new stress field is introduced adding on the initial state. The residual stress is indentified by the strain increment differences of the material detected in the stress superimposing process. The traditional stress superimposing testing method including hardness and indentation method are reviewed. The principle and application of two new type of stress superimposing testing methods of residual stress are introduced, their disadvantages are also indicated.

Abstract: This paper takes the boom of truck-mounted concrete pump from a company as the study subject. After analyzing its working station, it can be found that the fourth boom is in the most dangerous working conditions when extending horizontally. Select this operating mode, carry on the stress analysis and three dimensional entity modeling with the project software Solid Works to it, then realize the boom's statics finite element analysis with Solid Works plug-in unit Cosmos Works.

Abstract: To introduce the situation of removal phosphorus from steel slag at present, the existence of phosphorus in the steel slag was analyzed. The technical concept that steel slag was used as a sintering raw material in sintering process was proposed by the thermodynamic analysis on the base of adding ferrous manganese ore.The technology has reference value for making steel slag be the raw material of sintering and can control the content of phosphorus in the sintering to a certain extent.

Abstract: Process of the separation of waste polyester-cotton fiber with dilute hydrochloric acid was studied. Acid mass fraction, reaction time, reaction temperature and solid-liquid ratio were studied on the effect of separation with the method of Orthogonal experiment. The results showed that the priority order of the factors was reaction time > acid mass fraction > reaction temperature > solid-liquid ratio. The optimal conditions through serious research on such factors were: acid mass fraction 10%, solid-liquid ratio 4g/100ml, reaction temperature 95°Cand reaction time 90 minutes. Through the microscope, polyester and cotton fibers were separated completely in which polyester into fibrous and cotton fibers were hydrolyzed into tiny powder.

Abstract: Using low placement temperature and proper water pipe cooling water, the cracks are rarely appears in the interior of the dam, but the surface of the dam is prone to cracking. During the construction, the surface of the dam may be wet due to several factors such as creep, maintenance and so on, so the effect of the heat preservation is always been over-estimated. For those concrete blocks constructed in cold season, without proper heat preservation, the cracks are easy to appear soon after construction. For those concrete blocks constructed in hot period, under the influence of air temperature, the temperature of those concrete within about 5.0m of the dam surface are hard to control. So the key point to prevent the dam surface constructed in cold period is to take heat preservation measure suiting the on-the-spot situation. And for those dam blocks constructed in hot period, water cure on the surface of the dam can greatly reduce the risk of dam surface cracking.

Abstract: Taking into account the initial damage and the accumulation of damage of concrete, Mazars damage model was modified. Based on the modified Mazars damage model, combined with finite element software ANSYS, the fracture failure process of the three-point bending notched beam of concrete was simulated. The initiation load P_ini and maximum load P_max of the three-point bending beam were determined with the damage criterion, and the full relation curve of the load P versus the loading point displacement Δ of the fracture failure process of the three-point bending beam was obtained. The results show that the method of numerical simulation of concrete fracture failure process is feasible, and based on the initiation load of the crack determined by numerical simulation, the initiation toughness of the beam can be easily calculated, and the problem of calculation of the initiation toughness caused by the initiation load can not be accurately determined in the actual experiment is resolved.

Abstract: Ultrasonic vibration friction and wear experiments were carried out by MFT-R4000 reciprocating friction and wear tester bonded with ultrasonic device. The surface morphologies of wear scars were examined by scanning electron microscope (SEM). The influences of ultrasonic vibration on friction reduction and anti-wear properties of GCr15/45# steel frictional pairs under different loads were discussed. The experimental results showed that, the friction of GCr15/45^# steel frictional pairs could be reduced by ultrasonic vibration, and the reduction of friction coefficient became more obvious as the loads increasing. The friction coefficient measured under ultrasonic vibration is 12% lower than it measured without ultrasonic vibration when the load was 50N. However, the wear of frictional pairs increased under ultrasonic vibration, and the amplitude of wear volume enlarged with the loads increase, which is 63% at the load of 50N.