Advanced Materials Research Vols. 156-157

Abstract: An MG-2000 high-speed and high-temperature friction-abrasion testing machine was used to evaluate the friction and wear behaviors of AISI1045 steel sucker rod sliding against J55 tubing string and J55 tubing strings coated with spray-welded wear-resistant coatings of various thicknesses in a ring-on-ring configuration and under the lubrication of oilfield wastewater as the lubricating medium. The worn surface morphologies of the sucker rod specimens coupled with the J55 tubing string and the J55 tubing string coated with the wear-resistant coating were observed with a scanning electron microscope. As the results, it was effective to increase the wear-resistance of the frictional pair with the addition of the wear-resistant coatings on the tubing string surface. The wear-resistant coating of a proper thickness also contributed to reducing the friction coefficient to some extent, which was helpful to reduce the friction force between the sucker rod and tubing string pair and increase the service lifetime of the pair. The decreased wear rates of the sucking rod specimens coupled with the tubing string specimens coated with the wear-resistant coating of a proper thickness were attributed to the action of the coating in decreasing adhesion wear. Moreover, the tubing string specimen recorded little difference in wear rate at normal temperature and 60°C. However, the sucker rod specimen registered as lightly larger wear rate at 60°C than at room temperature, which could be attributed to the enhanced adhesion wear and mild corrosive wear at elevated temperature. It was imperative to properly control the thickness of the wear-resistant coating on the tubing string surface so as to bring its friction-reducing and antiwear action into effect.

Abstract: Activated carbon was prepared from blue coke powder by physical activation. The results show that the specific surface area (BET) is 697.05m2/g, the total pore volume is 0.4569cm3/g and the average pore size is 2.6221nm. The adsorption properties of Cr( ) onto blue coke powder activated carbon are discussed from the kinetics and thermodynamics viewpoints. The pseudo-second-order kinetic model shows the best correlation with experimental data. Langmuir and Freundlich models are used to fit the equilibrium, and it is indicated that Freundlich best fits these data. The adsorption of Cr( ) onto blue coke powder activated carbon is found to be an endothermic process in nature.

Abstract: Aiming at the lack of the traditional design method of the forging die, the response surface methodology based on design of experiments is proposed to optimize the parameters of flash gutter in forging die. According to the central composite inscribed experiment design, numerical simulation was carried out. On this basis, the quadratic polynomial response surface model was built by regressive analysis. The optimized flash gutter sizes are obtained by analyzing the response surface model with an objective of minimizing flash volume. The forging die of automobile flange has been studied as an illustration to validate the application of the response surface methodology. Finally, the comparison was done using genetic algorithms and the results show that the response surface methodology is better than the genetic algorithms with shorten time and better effect when the factor is small.

Abstract: Traditional probability statistics theory is impossible to obtain failure lifetime data by accelerated test for expensive and complex systems or equipments for real-time work. Due to the variety of system failure modes and the randomness of system deterioration process and the fuzziness of system maintenance threshold, it is difficult to estimate the random deterioration process of a complex repairable system by single parameter. In order to describe system performance deterioration more subjectly, it proposes generalized proportional intensity model(GPIM). considering the effects of various covariates such as performance parameters, environment stress, failure types and maintenance history simultaneously. This method provides a new method to solve the maintenance decision-making problem of complex repairable system. CF6-80C2A5 aero-engine is illustrated as an example for case study to indicate the obvious practical value by the method proposed herein.

Abstract: In this paper,the ball screw feeding system’s dynamic characteristics of a numerical remanufacture grinding machine is analyzed using the FEM. Discusses the modeling method of ball screw system into the finite element model and established the combination of finite element model. Through the modal analysis and the harmonious response analysis, the nature frequency and vibration mode of the feeding system and typical operating conditions of excitation in the harmonic responsehave have been gotten,thus the dependable basis for the construction’s optimization and dynamic function’s increasing of the feeding system is provided, ensure the numerical remanufacture will be success.

Abstract: Trend of the high-speed and high efficiency machining has pushed the continuous demand of higher spindle speed and power for the machining center application. However, Conventional steel spindles are not appropriate for high speed operation because of their high rotational inertia and low damping ratio. Moreover, heat generation and dynamic loading caused by high speed rotation have been obstacles for increasing the speed limit in many conventional steel spindles applications. Apart from optimizing lubrication, the application of new materials is an interesting alternative to increase the boundary speed and life-span of roller bearings for machine-tool spindles. In this study, a high speed grinding motorized spindle equipped with hot isostatically pressed silicon nitride (HIPSN) fully-ceramic ball bearings without inner rings and yttria partially stabilized tetragonal zirconia polycrystal (Y-TZP) ceramic spindle shaft was designed for higher speed, rigidity, precision and longer operating life. Furthermore, the characteristics of ceramic motorized spindle, such as temperature increase, vibration, power, rigidity, noise and so on, were investigated by the experimentation. The results show that the ceramic motorized spindles have good behaviors under low load, high speed grinding conditions.

Abstract: The polyphenol and flavonoid contents and antioxidation capabilities, including total reducing power, DPPH radical scavenging capability and lipid peroxidation inhibition, of ethanol extracts of water hyacinth (Eichhomia crassipes) were investigated and compared with those extracted from red tide seaweed (Enteromorpha prolifera) and from the most common seaweed (Porphyra haitanensis). Results showed that E. crassipes contained higher amounts of polyphenols [6.68 mg gallic acid equivalents (GAE)/g] in the leaf than in the stem (4.37 mg GAE/g) or in P. haitanensis (4.27 mg GAE/g). The E. crassipes also contained higher contents of flavonoids [1524 and 453 mg rutin equivalents (RE)/g in leaf and stem, respectively] than did E. prolifera (233 mg RE/g). Accordingly, both the leaf and stem of E. crassipes had relatively higher reducing power [118.35 and 47.21 100μg ascorbic acid equivalents (AscAE)/g, respectively] and DPPH radical scavenging capability (74.6% for leaf and 62.7% for stem) when compared with E. prolifera (reducing power of 16.5 and DPPH radical scavenging capability of 42.96%). Statistical analysis showed that the antioxidation capabilities, especially reducing power, of extracts of the three aquatic plants were positively correlated with their total polyphenol contents, but not with the contents of flavonoids. The correlation coefficient (r) of the content of polyphenols and reducing power of those extracts was r=0.9028, that for DPPH scavenging and lipid peroxidation inhibition was r=0.9311 and 0.9099, respectively. These results indicated that phenolic compounds are the main compounds contributing to the antioxidation activities of seaweed extracts. E. crassipes can be a source for extracting natural antioxidants.

Abstract: Heavy water is a class of highly contaminated waste water, even if the concentration is small, it can cause harm, and the toxicity is long-term sustainability.In this paper, Aureobasidium pullulans secretion of melanin were used for adsorption of Cr6+ ions in waste water.Aureobasidium pullulans strain were activated, cultured for seed and fermented, so that secreted melanin. The Aureobasidium pullulans secretion of melanin were made of dry cell, four factors such as pH, time, amount of bacteria,temperature and three level orthogonal experimental made for adsorption of chromium metal.Results showed, adsorption of chromium metal by dry cells for the best conditions: control temperature 30 , pH 3, the adsorption time was 2 hours, the absorption rate was 27%; and reached the four factors on the adsorption of Cr6+ for Aureobasidium pullulans followed the order: pH> bacteria amount> of time> temperature. In the best adsorption conditions were wet cell assay for adsorption of chromium metal. With 4% (V/V) hydrogen peroxide of 0.01ml/mg bleaching for the dry and wet cell, then for its adsorption of chrome metal. The results showed that the order of effect on adsorption of heavey metal ions by Aureobasidium were: the dry cells secretion of melanin> the wet cells secretion of melanin > decolorized dry cells> decolorized wet cells. It showed that adsorption ability of heavy metals by Aureobasidium pullulans was related to its secretion of melanin.

Abstract: First-principles calculations using the plane-wave pseudo-potential (PWPP) method based on the density functional theory (DFT) is employed to study the crystal structure, band gap, density of states of anatase TiO2 doped with gadolinium (Gd). The generalized gradient approximation (GGA) based on exchange-correlation energy optimization is employed to calculate them. The calculated results demonstrate that the mixing of gadolinium dopants induces states with original titanium 3d and oxygen 2p valence band attributes to the band gap narrowing. This can enhance the photocatalytic activity of anatase TiO2.

Abstract: The TRIZ theory and technology is applied to solv the problems of pasted honeycomb paperboard production process. Aiming at the drawback of pasted honeycomb paperboard production process the analysis of technology contradiction is carried out. Applying technology contradiction solve matrix, through the innovation principles of the Spheroidality and Asymmetry and combined with the characteristics of the production process, innovative design of the spiral forming process has been made.