Advanced Materials Research Vol. 900

Abstract: The composite coatings were obtained on a magnesium alloy by micro-arc oxidation (MAO) and sol-gel technique. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to evaluate the corrosion behavior of MAO coating and composite coatings in a 3.5% Na₂SO₄ solution. The results show that corrosion behavior of the MAO coating and composite coatings are different at different immersion times. The corrosion resistance of composite coatings is good than that of MAO coating.

Abstract: The composite coatings were obtained on a magnesium alloy by micro-arc oxidation and sol-gel technique. Electrochemical impedance spectroscopy (EIS) was used to evaluate the corrosion behavior of MAO coating and composite coatings in a simulated seawater solution. The results show that corrosion behavior of the MAO coating and composite coatings are different at different immersion times. Corrosion protection of the MAO coating gradually weaken with the extension of soaking time, but corrosion protection of the composite coatings become stronger first and then weaken.

Abstract: Electrospraying (ES) is of great interest in research for its finely controlled delivery of biomaterials. This study investigated mechanisms involved in the electrospraying of biological macro-molecules which may cause spraying instabilities. Hyaluronan (HA) solutions with concentrations ranging from 1 to 5 w/v % (w in g and v in 100 ml) were prepared for spraying trials using nozzles with a size of 30 μm. In electrifying HA solutions with a high molecular weight of 2.1 MDa, controllable jets can be achieved only at the lowest concentration of 1 w/v %. Generally, further use of a sonication method to reduce the molecular size, stable cone jets can be performed relatively easily than using HA solutions of higher concentrations. The improvement of spray stabilities can be attributed to the reduction in viscosity of the solutions after the sonication. Steady micro-sized jets were observed during the ES process and the jet size was found to increase with the increase of both the molecular size and the concentration. Both parameters can be directly ascribed to the rheological property of the solutions. Results show that a suitable viscosity is critically important in stabilizing the electrospray of macro-molecules. A concentration reduction of HA molecules also happens during electrospraying, which indicates that there is a partial reflection of macro-molecules inside the Taylor-cone with the fluid motions during the spraying process. This partial reflection process is affected by molecular sizes, solution concentrations and spraying time.

Abstract: (Ti,Al)N coatings possess superior hardness, good thermal and chemical stability. To further study the oxidation resistance, the arc-deposited AlTiN bulk material was collected from the substrate shutter of a commercial coating system deposited for over 100 batches. The thermal behaviour of the materials was studied by TGA/DSC with different annealing temperature or different atmospheres. The results show that AlTiN bulk material annealed in nitrogen exhibits the denser structure and thermal stability up to 1000°C. The oxidation resistance of the AlTiN can reach to 800°C. Annealed at 600 ~ 700°C proceed the recrystallization process which denser the structure. New phase of TiO₂ is formed by incorporate oxygen in exchange of nitrogen. nanoscaled 1D wire formation occurred at the 1000°C for 3 hours in air.

Abstract: The gas permeability of polymer modified mortar coating add steel fiber concrete compound structure was studied by thickness-wall cylinder structure experiment. The coatings were characterized by scanning electron microscope,energy-dispersive X-ray spectroscopy.the gas permeability of steel fiber concrete is 6.85×10^-15 m². applying the coating can reach 10^-17 m². The intrinsic gas permeability of polymer modified cement based materials is 1.36×10^-17 m² using regression calculate analysis method .Coating thickness is constant, raw materials composition and structure is the fundamental factors affecting permeability.

Abstract: It is difficult to capture a completely clear image of nonwoven web which is thicker than the depth of field of a light microscope. This phenomenon will leads to the data loss and the test error. In this paper, a region-based image fusion algorithm based on fibers natural boundaries was proposed. First, the one-pixel-wide boundaries were extracted from the point-based image fusion process. Then, the image fusion regions were formed by the sharpness diffusion from the source points which have the highest sharpness at local gradient within the boundaries of fibers. Finally, a fused clear image of the nonwoven web was constructed by replacing the regions with the corresponding regions which have the highest sharpness gradient from the series images at different focus positions of the light microscope.

Abstract: The adhesion property of oxide film has great effects on the grinding quality and efficiency of ELID grinding. In this paper, adhesion strength model of oxide film is established, ELID grinding is conducted to nanometric cemented carbide and ordinary cemented carbide, ELID grinding force is measured, adhesive stress is calculated and the correctness of adhesion model is verified. The results show that the adhesion strength of oxide film is relatively greater, the transition from γ-Fe₂O₃ to α-Fe₂O₃ in the oxide film is relatively fuller and the polishing performance is relatively better while the grinding depth is smaller; with the deepening of grinding, the adhesion strength of oxide film reduces, the composition of the oxide film that transforms into α-Fe₂O₃ is less and the polishing ability reduces. The adhesion model of oxide film well reflects the adhesion property of oxide film, and the application of this model can represent the distribution, shedding and updating of the oxide film on the surface of grinding wheel.

Abstract: Based on the thought of incremental forming, a new kind of sheet metal bending process has been described and investigated in this article. The software of the control system for the specific machine is developed combining motion control card and servo motors. Both single point and multi-points bending are taken into consideration from experimental and finite element analysis. Curved sheet and hyperbolic sheet metal are examined through experiments to extend the application for more smoothed and complicated curved sheet metal. The effectiveness of the process to deal with complex curved sheet metal is shown by all the experiments.

Abstract: The metal transfer behavior in hyperbaric GMAW process was investigated by using a high speed camera system with infrared laser as backlight. The metal transfer mode at 1-12bar argon environment shows different characteristics. Three kinds were observed: large droplet repelled transfer, projected repelled transfer and hyperbaric streaming transfer. Large droplet repelled transfer occurs mostly in the welding process with low feeding speed and relatively low welding voltage. Projected repelled transfer appears at middle feeding speed and high ambient pressure. Transfer tracks of former two modes deviate from the axial direction of welding wire. The spatter is produced more frequently in the projected repelled transfer mode. Hyperbaric streaming transfer is found meanly at high feeding speed and relatively high voltage. Because of its stability reflected from metal transfer process, hyperbaric GMAW process with hyperbaric streaming transfer mode should be employed preferentially.

Abstract: Igneous rocks of Junggar Basin are hard, strong abrasive and poor drillability. ROP is low in drilling these rocks, and drilling cycle is long, which seriously affect the process of exploration and development in the Carboniferous reservoir. Considering the igneous rock formation characteristics and the drilling problems, using PDC impregnated diamond high strength, super abrasion as the main rock breaking device, a new type of cutting and grinding of diamond impregnated bit was developed. This bit has the following characteristics: Compound cutting structure with blades and cylindrical Impregnated cutters; big nozzle in the center + deep radiation water slot hydraulic structures; Natural diamond and TSP lengthened gauge design; Selection of 40/50 mesh diamond grit, mix two kinds of inserts with diamond concentration 70%.The bit has the combination of impregnated bit and PDC drill bit technical advantages, which improve the bit adaptability to the formations. Hassan3 Carboniferous igneous formations field test shows that: average ROP is 0.71m / h, single bit footage is 86.5m, which increased by about 20% and 302% respectively compared with high efficient three-roller bits. The success usage of this bit in Hassan 3 provide an effective means for high quality fast drilling in Junggar Basin igneous rock formation.