Advanced Materials Research Vols. 712-715

Abstract: By using self-designed non-thermal plasma reactor, the influences of discharge power, initial concentration of C₃H₆ and O₂ concentration on NO pro-oxidation in C₃H₆/NO/N₂/O₂ mixture were studied. The obtained results indicate that with the increasing of discharge power, NO₂/NO_x ratio grows firstly and then decreases after reaching a peak value, while NO_x conversion efficiency and N₂O concentration gradually rise. Increasing initial concentration of C₃H₆ or O₂ concentration would help to enhance NO oxidation efficiency. With the same discharge power, NO_x conversion efficiency grows with the increasing of C₃H₆ initial concentration while reduces with the increasing of O₂ concentration. Controlling the concentration of C₃H₆ and O₂ in exhaust gas can lead the NO₂/NO_x ratio to reach 50%, which is benefit to NO_x conversion with SCR system.

Abstract: In this study, the optimized manufacturing process of Shrub Scrimber has been researched by using orthogonal experiment. The dynamic mechanical properties of Shrub Scrimber were measured by Fast Fourier Transform (FFT) nondestructive testing method, and the reliability of this method was verified by the linear regression between the static mechanical properties and the dynamic one. The results showed that shrub Scrimber had excellent mechanical properties, and can be used as structure replaced natural wood. The flexural vibration test were confirmed reliable to predict the mechanical properties of Shrub Scrimber.

Abstract: Composite SiN_x/DLC films were deposited on silicon substrate by co-deposition system. The carbon plasma was generated by filtered cathodic arc source, simultaneously incorporated with silicon nitride from RF magnetron sputtering. The silicon nitride sputtering rate was maintained by fixed RF power at 100W while the arc current of FCA was varied from 20 to 80A.The SiN_x/DLC film composition and optical properties were investigated by X-ray photoelectron spectroscopy and spectroscopic ellipsometry respectively. The results revealed that the atomic concentration of carbon increased while those of silicon and nitrogen decreased with increasing arc current. The oxidation was found on the film surface and related to the atomic concentration of silicon. The optical properties can be changed as a function of carbon concentration by setting different arc current. In this work, the volume percentage of carbon obtained from spectroscopic ellipsometry using Bruggeman EMA model showed good numerical correlation with the atomic percentage of carbon from XPS analysis with the range spanning across 75-95 at. %.

Abstract: Pear-shaped needle is a special tool to processing microporous on the spinneret, which is critical to the quality of the spinneret. Existing processing methods of pear-shaped needle has many disadvantages, this paper put forward a method to processing pear-shaped needle with hone grinding, and validated it by experiment.

Abstract: As withstanding very high loads, thermal cycling leading to thermal fatigue, and severe environmental in the steel industry, rolls with long service life are specially required. High speed steel with high vanadium content is a newly-developed wear-resistance material that has been studied and used in some countries for making steel rolls. As a surface treatment technology, laser cladding can fabricate coating to improve the wear resistance of substrate. In this paper, the substrates for laser cladding were nodular cast iron rolls, Nd: YAG solid pulsed laser was used to explore the feasibility of preparation high vanadium high speed steel (HVHSS) coatings. The Nd: YAG laser cladding results that the coated layers combined metallurgically with the substrate with a lot of microcracks. The average microhardness up to 650 HV is more than 2 times as high as that of the substrate. After laser remelting, a fully dense and crack free HVHHS coating with an excellent metallurgical bonding was deposited. The presence of VC in the coating mainly improves the microhardness of coating up to about 650 HV.

Abstract: With the development of machinery and mold manufacturing industry, there is a great significance of using composite manufacturing technology on surface hardening products to improve the quality and longevity. With the example of hot forging the automobile brake supporting frames, this paper explores to introduce hot forging die nc welding method, aiming to reduce the forging manufacturing costs and improve the reuse efficiency.

Abstract: Based on FEM, the paper presents a reasonable four teeth end mill model to simulate the process of metal milling, which uses the adaptive meshing criteria.This model simulates a typical work-piece chip breaking process with different cutting speed and feed ratio, which gets the cutting forces curves and the total status of residual stress distribution.

Abstract: 3-mm thick Al-12.7Si-0.7Mg alloy plates were cut from the hot extrusion profiles. A butt-welding joint was made by gas metal arc welding (GMAW). The microstructures and mechanical properties of welded joint were studied by scanning electron microscope and tensile test methods. The results show that weld bead with good appearance and internal quality was obtained under the optimized welding parameters. The ultimate tensile strength for base material and welded joints of hot extrusion Al-12.7Si-0.7Mg alloy are much higher than that of 6063 alloy in T4 condition.

Abstract: Aiming at the disadvantages of low utilization ratio of steel ingot, uneven microstructure properties and long production period in the solid steel ingot forging process of heavy cylinder forgings such as reactor pressure vessel, a new shortened process using hollow steel ingot was proposed. By means of modeling of lead sample and DEFORM-3D numerical simulation, the deformation law and grain refinement behavior for 162 ton hollow steel ingot upsetting at different reduction ratios, pressing speeds and friction factors were investigated, and the formation rule of inner-wall defects in upsetting of hollow steel ingots with different shape factors was further analyzed. Simulation results show that the severest deformation occurs in the shear zone of meridian plane in the upsetting process of hollow steel ingot, and the average grain size in the shear zone is the smallest. As pressing speed increases, the forming load gradually increases and the deformation uniformity gets worse, while the average grain size decreases. An increase in friction factor can increase the peak value of effective strain, but it significantly reduces the deformation uniformity, increases the forming load and goes against grain refinement. Moreover, the four kinds of defects on the inner wall of steel ingot can be eliminated effectively by referring to the plotted defect control curve for hollow steel ingot during high temperature upsetting.

Abstract: The rock broken process was simulated by using finite element method based on the hob broken rock mechanism. The rock broken shape was analyzed by adjustment numbers of hobs and angles of hob. The destruction of rock was the presence of both compressive failure and shear failure. The main destruction of rock was compressive failure with single hob. The main destruction of rock was shear failure with multiple hobs. It could be found that the main destruction of hard and brittle rock was shear failure but shear failure of softer rock was relatively small through rock breaking process of three hob in different sequentially angles.