Papers by Keyword: Removal Mechanism

Abstract: In drilling the ultra-slim small diameter deep hole of titanium alloy, the problem of chip breaking and chip removal is common. When the drill is working normally, the ultrasonic vibration can be applied for the drill bit to cut the bit in the vibration to form a pulse. The cutting force waveform in drilling, should select the reasonable vibration frequency, amplitude, feed amount, workpiece rotation and other parameters to match, control the size and shape of the chip, get satisfactory chips, and avoid chip clogging. In this study, the ANSYS finite element simulation software was used to simulate the TC4 drilling process, and the difference between ultrasonic vibration drilling and ordinary drilling was analyzed. Drilling experiments were carried out. The experimental results show that compared with conventional drilling, ultrasonic vibration drilling has better surface quality, reduced tool wear and increased material removal rate.

Abstract: Eutrophication as a result of uncontrolled phosphorus (P) concentration that is released in wastewater has emerged as a major problem nowadays. Treatment of P demands high costs specifically to its chemical and maintenance needs. A lot of efforts were undertaken to find the most economical material that can treat P such as Electric Arc Furnace Slag (EAFS), a by-product from steel industry and Limestone (LS), and a natural resource that can be easily obtained from sedimentary rock. Despite numerous study conducted previously, the mechanism of P removal between these two materials have not been explored yet in detail. Therefore, an experimental work had been designed to evaluate the performance of P removal mechanism between the EAFS and LS lab-scale filter systems which can offer the best removal in overall. In this study a column lab scale of vertical rock filters in 100 mm diameter × 400 mm height were constructed for both EAFS and LS filters. The observation period was conducted for 2.5 months utilizing synthetic phosphorus concentration of 25 mg/L as its initial concentration. Working condition of the experiment was adjusted at pH 4.5 to 7.5 under 26.8±0.64 °C. X-ray fluorescence (XRF) analysis was also performed in order to determine chemical composition of EAFS and LS media. Results revealed that EAFS showed a significant effect on the removal of P mechanism compared to the LS filter system. The highest removal of P for both filter systems were observed to achieve 90% (pH 5) in the EAFS compared to only 68% (pH 4.5) in the LS system. This may be associated with the dissolution of Ca, Fe and Al elements in the EAFS that promotes precipitation process and hence gave higher removal compared to the LS element (only Ca has the highest percentage = 91%). At lower pH (acidic) condition the soluble metal salts react with phosphate ion to form phosphate hydrolysis product thus promoting precipitation in the system. In conclusion, it is predicted that precipitation may occur within the filter systems predominantly in the EAFS filter as pH was change from acidic to alkaline (4.5 – 7.5) due to dissolved (Al³⁺, Ca²⁺, Fe³⁺) within the filter system. Nevertheless, it is recommended that future study should be carried out on the precipitates salts through X-ray diffraction (XRD) analysis so as the existence of phosphate and metal salts as a result of precipitation can be finally confirmed.

Abstract: In this paper, the salinity domestication and mechanism of nitrite nitrogen removal ofAcinetobacter lwoffii were studied. The results showed that the optimum domestication salinityof the bacteria was 0.5% NaCl. It was speculated that the bacteria might have both oxidase andreductase, transform the nitrite nitrogen into ammonium nitrogen and nitrate nitrogen, and then usethem to synthesis the body protein. It also found that high concentrations of sodium nitrite hadinhibition effect on the bacteria growth.

Abstract: The electrolytic in-process dressing (ELID) grinding technology was adopted for precision grinding experiments of volume fraction of 40% of SiCp/Al composites, obtaining the machined surface roughness of Ra0.030μm. Studying the forming mechanism of processed surface, analyzing several typical grinding surface defects, summarizing the grinding characteristics and removal mechanism of SiCp/Al composites.

Abstract: Magnetorheological finishing (MRF) is an advanced machining technology can achieve high efficiency and smoother surfaces. This study discusses the material removal mechanism of MRF, and proposes a kind of magnetorheological fluid with the nano-diamond abrasives. A series of experiments on the BK7 optical glass were conducted to investigate effects of the concentration of nano-diamond abrasives on surface quality and removal efficiency.

Abstract: Electrical discharge phenomena in EDM occur in a very short time period and in a very narrow space, thus making both observation and theoretical analysis extremely difficult. For this reason, the material removal mechanism in EDM has yet to be understood clearly. EDM is a thermal process. Thermal energy is generated by a pulse discharge between the workpiece and the tool electrode. It results in melting and evaporating followed by removal of both the workpiece and tool electrode, forming a discharge crater on both surfaces. In this paper, the hydrostatic pressure distribution in melting area was simulated by Molecular Dynamics (MD) methods. The analysis shows that after discharge is ignited, extremely high pressure is generated inside the melting area. The pressure distribution along the central axis of the melting area at different times indicates that during the discharge duration, the hydrostatic pressure quickly increases to a peak value along the depth direction of melting area and then reduced to 0 GPa in the unaffected area. It was also found that with the passage of time, the depth of the point where the pressure peaks increases with the formation of the discharge crater, accompanied by the decrease in the peak pressure. In addition, the ejected material atoms at different times during the removal process were also analyzed. It was found that the material ablation occurs mostly during the discharge duration.

Abstract: In this paper, poly aluminium chloride (PAC) was used to remove phenol and aniline from the aqueous phase .The adsorption properties of this process was investigated by zeta potential measurement, infrared spectroscopy and the analysis of pollutants structure and adsorption kinetic. The results described that not only electrostatic attraction but hydrogen adsorption were the main mechanism of both the phenol adsorption and the aniline adsorption. The pseudo second-order kinetic equation could best describe these two adsorption kinetics. The calculated activated energy of adsorption processes of phenol and aniline were 47.2KJ/mol and 44KJ/mol, respectively, which indicated that the adsorption process was chemisorption. Friedrich model was fitter to describe the adsorption isotherm of these two adsorption processes.

Abstract: Silicon Carbide is a ceramic material with extraordinary properties. Not only does it excel in mechanical properties, such as very high hardness and flexural strength, but also shows excellent thermal properties with a low thermal expansion and operating temperatures above 1000°C. These properties predestine silicon carbide for applications in harsh environments. Structuring silicon carbide in the sintered state with conventional methods is not feasible due to its hardness. A non-conventional process to structure materials independent of their mechanical properties is electrical discharge machining (EDM). A certain conductivity is however required for this process. To fulfill this requirement, the method of an assisting electrode (AE) is used. During the process, an intrinsic AE is generated from the cracked dielectric oil and deposited on the ceramic surface. The process can therefore continue even after the applied AE has been penetrated. For a deeper understanding of the present removal mechanism EDM of non-conducting ceramics, especially in the area of micro EDM, an investigation of the influence of conductivity is necessary. Therefore three silicon carbide ceramics with different electrical conductivity (S-SiC: 1 10^-7 S/cm; LR-SiC: 10 S/cm; HO-SiC: 5 10^-9 S/cm) have been microstructured and analysed. It is found that the conductivity of the silicon carbide materials has no influence on the machinability, all samples can be microstructured. The microsections of the machined samples show that the near-surface structure of the SiC materials is not negatively influenced by the EDM process. The analysis of the surface revealed indications that for S-SiC and for HO-SiC, thermal spalling is the present removal mechanism. The LR-SiC surface shows melting structures. The material removal rate of LR-SiC is 8 × 10^-3 mm3/min, whereas the material removal rate of the S-SiC and the HO-SiC ranges at 3 × 10^-3 mm3/min. The high MRR of the LR-SiC indicates a removal mechanism analog to Silicon infiltrated Silicon carbide (SiSiC), with removal of a conductive phase.

Abstract: Constructed wetland is a mode of economical and highly effective system applied in wastewater treatment with special removal mechanism function, which has drawn much attention over the world constantly. On the basis of study from abroad, this article makes the brief induction of removal mechanism, influential factors and combined technique of constructed wetlands, for the further research works were also put forward in the next future.

Abstract: The material removal mechanisms for Cu electrochemical mechanical planarization (ECMP) including 5-Methyl-1H-Benzotriazole (TTA), hydroxyethylidenedi phosphoric acid (HEDP), and tribasic ammonium citrate (TAC) were investigated by electrochemical techniques, X-ray photoelectron spectrometer (XPS) analysis, and polishing of Cu-coated blanket wafers. The experimental results show that the main factor affecting the thickness of the oxide layer formed during ECMP process is the applied potential. This understanding is beneficial for optimization of ECMP processes.