Advanced Materials Research Vols. 875-877

Abstract: Steel alloyed by nickel, chromium and molybdenum reach according to normative standards (EN) yield point about 900 MPa and contraction about 25% after heat treatment. Authors of this paper noticeably increase the strength properties of that steel without changes in plastic properties with using of electroslug remelting refining technology (ESR). Subject of research are forgings of very large mass and dimensions. The forgings are used in special armament technology as (tank gun barrels). Very negative influence on mechanical properties of final product has content of nanodimensioned impurities.

Abstract: ntegral impeller geometries are complex and its material is also particularly difficult to machine, what makes conventional machining cannot process the integral impeller in the high quality, low cost way. The article study on the groove of the integral impeller is processed by the way of NC electrochemical machining. By orthogonal experiments, based on analyzing the factors such as cathode width, machining voltage, electrolyte pressure and spindle speed, and the optimal parameters was obtained. The test results show that using NC electrochemical machining of integral impeller has an irreplaceable superiority.

Abstract: The current status of technical development of annular shaft kiln for limestone calcination production is described in this paper. Based on the existing technological accumulation, a new type annular shaft kiln with capacity of 600t/d has been developed independently by Beijing Shougang International Engineering Technology Co. Ltd. A number of key technologies of the new type large annular shaft kiln are researched and integrated, include thermal process system determination, lining refractory structure optimization, heat-exchanger configuration etc. The major advanced characteristics of new type annular shaft kiln are energy saving, higher efficiency, lower environmental pollution, lower emission, lower engineering investment, and lower operation cost. The excellent performances and application results in production have been achieved at Shougang Qiangang steel plant.

Abstract: This work contributes to a better understanding of wear mechanisms of ultrafine cemented carbide cutting tools used in turning operation of superalloy and high strength steels at high cutting speeds. The main objective of this work is to verify the influence of grain size and the cobalt content of ultrafine cemented carbide tools on tool life and tool wear mechanism. The main conclusions are that grain size and the cobalt content of ultrafine cemented carbide tools strongly influence tool life and tool wear involve different mechanisms. The wear mechanisms of different grain size and the cobalt content of ultrafine cemented carbide tools observed on the rake face at these conditions were adhesion and notch, at the end of tool life, adhesion was the main wear mechanism at higher cutting speeds.

Abstract: Blind-via plays a crucial role in interlayer interconnection of printed circuit board. To get the blind via metallized a direct electroplating process has been put forward by the way of a inducing CO₂ laser beam irradiating the copper in the bottom of blind via. The method for direct electroplating of copper onto a non-copper platable layer has been investigated in blind via metalization. The regression analysis was used to discuss the laser beam energy in different parameters. The results of electroplated blind via showed that the copper in the bottom of blind via can be induced by CO₂ laser, and the induced copper particles ejected to the hole wall plays a role of the conductive film layer that mainly composed of copper by electroless plating or carbon black conductive film during electroplating, plasma used in cleaning blind via can promote the sorption of induced copper particles onto the via wall.

Abstract: A lot of literature sources are devoted to nitrides heterostructures for LEDs, not less to the designing problems of converters of their radiation to white light. In our present work we are focused only on optimization of phosphor's properties. New multiligand photoluminophores for white light emitting diodes, solar batteries and x-ray detectors as well as original technological methods of their manufacturing and some obtained results are described.

Abstract: A novel hybrid process (2D scanner + LASER + CNC machining) was used to join transparent and opaque polymers. A 30W diode laser and a 3-axis CNC machining center were combined to accommodate a 2D scanning system for high flexibility and productivity. The scanning speed, the number of repetitions and the laser power were selected as parameters for the weld test. By combining CNC and laser, the productivity and accuracy were improved and manufacturing cost decreased accordingly. The maximum speed of 1130 mm/min was achieved with minimum power of 2Watt. The developed system demonstrated the joining of transparent PC and opaque ABS polymers by using 2 dimensional laser beam motion. The air gap could be minimized by using constant force on the upper holding plate, and preheating by the first run of the laser system. The weld bead decreased at the lower laser power and the higher laser scanning speed.

Abstract: The atomistic-scale cold welding processes for metallic nanowires (NWs) are studied using embedded-atom molecular dynamics (MD) simulations. The mechanical behavior and structural evolution of the FCC metallic nanowires, including Au, Ag, and Cu materials, that experienced a mechanical stretching break and solid-phase pressure welding process, were investigated. The welding temperatures (T_w) ranging from 100 to 900 K were systemically investigated on the effects of welding strength. The ratio of welding strength, R_ws, defined as the ratio between the welding strength and the original yield strength of NWs, was employed to identify the welding quality. Simulation results show that the R_ws of Au NWs is better than those of Ag and Cu welded at room temperature; however, for welding at high temperatures (600~900 K) the R_ws value of Ag NWs is the best. The R_ws values of Au NWs using cold welding show less variance than with high temperature welding, reflecting that the application of cold-welding on the Au NWs is highly feasible. The R_ws values for NWs with small diameters are generally higher than those with large diameters. The breaking places of the tensile test for the post-welded NWs didnt occur at the welding region, indicating that the broken wires can be robustly reconnected through solid-phase mechanically-assisted welding methods.

Abstract: In this paper, the ZnO crystal was synthesized using hydrothermal method through 24 hours reaction with 35 % filling factor at 430°C. When the mineralizer concentration is rather low (eg. lmol/L NaOH), only ZnO microcrystal is produced. The mineralizer concentration increases, the larger crystal was present. When 5 mol/L NaOH served as mineralizer, the extent of the synthesized crystal was nearly 500m. The ZnO cryslals with length of 1500m were present when 3ml/L KOH served as mineralizer. Respectively when 3mol/L NaOH and lmol/L KBr were used as mineralizer, the extent of the synthesized crystal was nearly 700m , the diameter was 200m and the exposed faces m { 100}, p { 101 } was complete , so we obtained the higher quality crystals. Besides the larger crystal, a great deal of microcrystal and nanocrystallites cluster was also present in the product.

Abstract: This paper analyzes the existing problems of acting lapping pressure in lapping internal holes of main cylinder of brake-pump with solid abrasives, proposes a new type of solid abrasives supporting method, namely, three supportting points acting lapping pressure method. The method improves pressure distribution between solid abrasives and the surface of the machined workpiece,which is favorable to increase cylindricity of machined hole.Through actual machining process, new method is demonstrated increasing cylindricity accuracy of machined holes of main cylinder significantly.