Advanced Materials Research Vols. 550-553

Abstract: In this paper, a new porous coating was formed directly on the surface of titanium metal via anodic oxidation. And by the SEM, the morphology of the coating, which is composed of well-ordered perpendicular nanotubes, was characterized. Moreover, taking deionized water as the test fluid, a visualization study of the coating on its pool boiling heat transfer performance was made. The results demonstrated that compared with the smooth surface, the nucleate boiling heat transfer coefficient can increase 3 times while the nucleate boiling super heat was reduced 30%.

Abstract: Kaolin is a mineral composition of water cut aluminum silicate collection of words, used widely. But since most kaolin contain quality score 0.5% ~ 3% of iron oxide or hydrogen ferric oxide, restricted its use. With reduction and complexation method to kaolin bleach, which can effectively reduce the content of iron in the clay. The low pH in with organic acid(citric acid, acid, oxalic acid, also sugar) refined bleached high content of coal kaolin ferric oxide. The results show that, citric acid and also the sugar acid in iron effect is poor, does not meet the industrialized production, oxalic acid can remove kaolin can dip in iron, when pH lower than 1.2, the temperature of 80 °C on the bleaching, white degree of more than 80%, to adapt to the industrial application of coal kaolin basic conditions. At the same time, because of the difference of shading minerals, different sources of kaolin bleaching and the white degree stability condition is different, the actual production of should according to the specific of the sources, after the test to be sure.

Abstract: Through the study on influence factors of the carbonic acid reaction of phosphogypsum decomposition slag in the three-phase fluidized bed, the effect of different factors on the transformation of CaS in the phosphogypsum decomposition slag was discussed. Experiments show that Increasing CO2 gas flow and extending reaction time have benefit for the transformation of CaS. The conversion rate of CaS was increased firstly and then tended to flatten with the increase of the liquid-solid ratio. The rise of reaction temperature has a weak inhibitory effect for the transformation of CaS. Comparing with tank reactor, three-phase fluidized bed reactor is more advantageous to the carbonic acid reaction of phosphogypsum decomposition slag.

Abstract: This paper establishes a model of thermal checking calculation of heat supply network based on graph theory and thermodynamic calculation, by analyzing directly buried installation of thermal network utilizing the heat-transfer mechanism and principle of thermal equilibrium. Take the directly buried heat supply network for instance, in which hot water is as a heat medium. The establishment of the spatial database and attribute database of thermal network based on GIS and Microsoft Access respectively, as well as the thermodynamic calculation of thermal networks based on GIS developed by object oriented programming language VB is done .Thus enables point-and-click query, update on property and thermal calculation functions. Finally, through comparative study on the calculation results and actual operation of the system, we find the relative error of the thermodynamic temperature is less than 10%.

Abstract: PLA has excellent processing property and good thermal stability, which are closely related to the processing technology, and the general processing temperature can be controlled in 170~230°C. Effects of different processing conditions (internal mixing temperature, internal mixing time and internal mixing speed) on the properties of PLA were discussed. The results show that the mechanical properties and other performance of PLA can be obviously enhanced by internal mixing. Internal mixing time and internal mixing speed have little effects on the performance of PLA, but the internal mixing temperature has obvious effect on the properties of PLA. PLA has the optimum properties when the internal mixing time is 5min, internal mixing speed is 20r/min and internal mixing temperature is 190°C. The spherocrystal size and spherocrystal rate of PLA are influenced strongly by the mixing conditions.

Abstract: The particle concentration signals of silicon powder in the fluidizing gas i.e. air under different operating conditions were determined. The diameter of silicon particles, operating velocity, radial distance and axial distance are used as input vector; the mean value of particle concentration signal in the silicon power fluidized bed is used as a target vector. The RBF neural network is applied to build the predicted model of the mean value in silicon power fluidized bed. The result shows that the prediction of mean value through the RBF neural network is prior to that by BP neural network, and its error is less than 0.2%.

Abstract: The chemical industrial park’s quick development has brought out many security and environment problem. For the common leakage accidents, it is urgently needed to build emergency response decision support system. The analysis of the accident is the crucial part of the system, in this paper the method of integrating GIS with diffusion model was used to simulate the three-dimensional diffusion process and predict the impact scope of the accident. The Pasquill-Gifford model and Gaussian diffusion model was introduced; Gaussian plume model was applied through the example to illustrate the method. The system is not just convenient for drawing up critical situation pre-arranged planning, but could offer timely assistant decision for emergency command.

Abstract: Until recently, the potential of biodegradable polymers obtained from agro-resources have long been recognized. In particular, poly-D-lactic acid (PDLA) is a very promising biodegradable polymer because its melting point is 40 °C higher than the melting point of standard PLA, making it as resistant to heat as the petroleum-derived polybutylene terephthalate (PBT). In this work, a fermentation broth containing D-(-)-lactic acid was pretreated with microfiltration and nanofiltration in order to remove cells and color prior to start the esterification reaction with ethanol. A highly efficient fractionating column designed in our laboratory was employed to distill 95 wt% ethanol from the esterification reaction. A vapor permeation technique using NaA zeolite membrane was employed to remove water allowing the dehydrated ethanol to be recycled. This integrated esterification-dehydration process results in a complete conversion of D-(-)-lactic acid to ethyl-D-lactate. For distillation, experimental result showed that more than 98% pure ethyl lactate was obtained by controlling the temperature of ethyl lactate vapor at the exit point of the fractionating column. After hydrolysis, the purity of D-(-)-lactic acid product was obtained at 98.89% with more than 87.8% optical purity.

Abstract: The BaTi₄O₉ submicron powders were synthesized by a sol-gel method, and the sintering behavior and microwave dielectric properties of BaTi₄O₉ ceramics prepared from powders with different particle sizes were also investigated. The particle size of powders calcined at 700 °C, 800 °C, 900 °C and 1000 °C were 8-10 nm, 70-90 nm, 100-120 nm and 140-170 nm, respectively. The 70-170 nm powders benefited the sintering process and microwave dielectric properties, whereas nanoparticles with the size of 8-10 nm damaged the sintering behavior due to the more amorphous phases and lower green density introduced by the large surface area. Sintered at 1175 °C, the BaTi₄O₉ ceramic prepared from 100-120 nm size nanoparticles had compact structure and exhibited good microwave dielectric properties of εr = 36.91 and Q×f = 29,833 GHz.

Abstract: Overfilling or full liquid is the main cause of liquefied gas cylinder explosion accidents; great volume expansion ratio (VER) of cylinder can efficiently prevent explosion accidents arising from overfilling or full liquid. This paper studies the change in pressure in overfilled or full-liquid liquefied gas cylinders as a function of temperature and the relationship between temperature and VER, and puts forward measures of increasing the VER of liquefied gas cylinders.