Advanced Materials Research Vols. 418-420

Abstract: Abstract. Using the correlation between the measure value and measured value in the indirect detection, the whole presumption method and theoretical formula of the confidence intervals for measured value are put forward. Based on the different detection methods, the confidence interval of high confidence and high accuracy can be given by the proposed method according to random measurement results. Through the Monte Carlo simulation, using the deducing method and the related theory, it may be concluded that the true value is included within the confidence interval which is obtained by this method. The traditional method can only get the point estimation but not give the confidence intervals in the practical engineering. According to the method, the interval estimation of concrete strength can be give. Moreover, this method is used not only in test concrete strength, especially in the evaluation of earthquake, but also in strength detecting for bridges, the pressure vessel, aircraft wing etc.

Abstract: In order to study the influences of aggregate size on CO₂ laser absorption property, several special absorbing coatings were prepared from four kinds of different particle sizes (45 μm, 13 μm, 6.5 μm and 1.6 μm) TiO₂ powder. The CO₂ laser absorption capacities of these coatings were studied by comparative analysis of the surface morphology and laser heated areas. The results show that the absorbing capacity increases with particle size dwindling. In all samples, the 1.6 μm specimens display the best performance with the largest laser heated area on cross section. The analysis indicate that, the decreasing of particle size will lead to an increase on absorbing surfaces, which is benefit for improving the absorbing capacity. Furthermore, smaller size particles also can cause the temperature increased faster than large particles, which lead to a further increase on absorbing performance for the positive feedback effects between the temperature and the absorbing capacity. Finally, the effects of particle size variety on designing absorbing coatings are also discussed.

Abstract: Polyurethane foams (PUFs) filled with several halogen-free flame retardants and composite halogen-free flame retardants were prepared. The flame retardant, thermal stable and mechanical properties of the PUFs were investigated. The results of limiting oxygen index (LOI) and thermogravimetric analysis (TGA) revealed that PUFs filled with dimethyl methylphosphonate (DMMP) had better flame retardancy compared with other flame retardants and DMMP degraded at a low temperature to form several phosphorated acids which accelerated the formation of char layer. Composite flame retardant of DMMP and melamine (MA) had a synergistic effect between phosphorus and nitrogen. The combination of DMMP and MA slightly altered the density of the PUFs. Results from the mechanical analysis revealed that with the increase in concentration of MA in the composite flame retardant of DMMP and MA, the tensile strength of PUFs reduced firstly and then increased up to a constant.

Abstract: In this work, one self-invented closed single screw dehydrator was used to dehydrate wet natural rubber, instead of current three opened crepers and one hammer mill at home and abroad. The dehydration technology and the properties of the obtained dry natural rubber were studied. The results show that single screw dehydrator can simplify dehydration process. The water consumption of single screw dehydrator is 20% of current productive technology, meaning a lower wastewater discharge and treatment cost of wastewater. The moisture content of dehydrated natural rubber is lower than 20%, a good dehydration effect. The dry natural rubber dehydrated with single screw dehydrator has an improved thermal-oxidation ageing resistance whether dried by hot-air or microwave. The thermal-oxidation ageing resistance of natural rubber dried by microwave is better than that of hot-air drying, the value of initial plasticity (P₀) and plasticity retention index (PRI) are 29.3 unit value and 19.26 unit value greater than that of SCR5 in GB/T 8081, respectively.

Abstract: This paper discusses the assembly time and assembly success rate which are two important indexes of one flexible assembly system. The assembly process is conducted to a two dimension random process passage through a rectangle objective domain. The faster and slower transition probability matrices are used to deduce approximatively the distribution of assembly time and the assembly success rate. The assembly time is a PH (phase-type) distribution which is the function of correlation coefficient and variance of random process. The assembly success rate increases with the increment of assembly time. At last, an illustrated example demonstrates the results.

Abstract: Abstract. Bismuth oxide is an important metal-oxide semicondutor, the interest in developing methods which can prepare Bi₂O₃ with unique properties has been a hot issue recently. In this paper, paralled flaw precipitation method has been employed to synthesize nanostructured Bi₂O₃. It is found that the bandgap and photocatalytic performance of Bi₂O₃ has a strong dependence on the pH value of precipitation reaction.The prepared photocatalysts were characterized by BET, XRD and UV-Vis diffuse reflectance. The results show that Bi2O3 prepared under pH value 8.5 has the highest BET surface area, pore volume, the smallest pore size and the average crystal size. Bi₂O₃ prepared under pH value 8.5 exhibits the best photocatalytic activity. The results of further experiments show that bandgap and the specific surface area all play an important role in promotion of photocatalytic activity of Bi₂O₃ prepared under pH 8.5.

Abstract: The effects of modified SiC nano-powders on the microstructures and the work-hardening properties of shot peening treatment on high manganese steel have been carried out by means of microstructure observation, x-ray diffraction analysis and hardness testing. The results are showed that compared with the samples without modified SiC nano-powders, the microstructure of ZGMn13 are finer and markedly improved rate of work hardening. The micro-hardness of surface is enhanced significantly after the shot peening. Its strengthening mechanism is mainly twinning and dislocation, but no Martensite strengthening.

Abstract: Abstract. For efficiently performing the numerical simulation of electromagnetic continues casting (EMCC) with finite element method (FEM) and finite volume method (FVM) combined scheme, a program integrates with data-format conversion and post-processing was proposed. The conversion of data format realized by linear interpolating, and the post processor developed on a Visual Fortran 6.6A platform using Fortran-95 language and the QuickWin module. Both 2-D and 3-D EM-FEM data calculated by a general-purpose FEM software, ANSYS, could be converted into FVM-data format using this program, and all FVM-data whether scalar quantities or vector ones could be displayed in the manners of cabinet drawing and normal axonometric drawing, which promises the correctness for data format conversion process of FEM/FVM-joint and the convenient analysis of transport phenomena during EMCC numerical simulation. The results of transport simulations and data format conversions indicate that the format-conversion method as well as the post processing is effective and convenient in numerical simulation with FEM/FVM-joint under various EM fields.

Abstract: Gas permselective packaging film is an emerging material which enables it with gas selective permeation functions so as to keep the preservation atmosphere of inner packages and thus extends the shelf-life of fresh fruits. In this work, Hexamethyldisilazane and Hexamethyldisiloxane were applied as the precursors to comparatively investigate the behavior on the preparation of gas permselectivy film, respectively. Also, Different reaction parameters such as plasma input power, deposition time and monomer proportions were investigated respectively. The film properties were analyzed by Water Contact Anglemeter, Surface Profiler thickness test, Fourier Transform Infrared Spectroscopy (FTIR), water vapor transmission rate test (WVTR) and oxygen transmission rate test (OTR). The results showed that HMDS is better than HMDSO to be the precursor for the formation of gas permselectivity films.The film formed from the monomer of HMDS changed the gas permeability of the film reversely which is more suitable for the preparation of such materials.

Abstract: Due to the shortage of traditional pre-cross linked particulate, such as suspension property, temperature and salt tolerance, and injectivity, this paper developed hydrophobic association polymer pre-cross linked particulate based on hydrophobic association polymer. The performance evaluation of rheological behavior, microstructure and mobility control ability demonstrate that hydrophobic association polymer pre-cross linked particulate can partly dissolved in water, and has certain viscosity thickening and suspension property; it partly cross linking forming mesh structure, and has strong resilience; it can deform through the porous media after swelling, and has good mobility control ability.