Papers by Keyword: Removal Rate

Abstract: Abrasive Waterjet Machining (AWJM) has significant advantages, such as being environmentally friendly, used for machining hard-to-cut materials, and do not cause a heat-affected zone. More machining tests are needed to understand the concept of material machinability in AWJM to increase process flexibility and produce parts with higher productivity, better accuracy, and surface quality. This paper presents drilling and slotting experiments through different metallic materials at fixed machining conditions to evaluate their machinability using AWJM. It introduces new machinability indices that arrange the tested materials concerning their machinability rating. Drilling indices include volumetric removal rate (VRR), penetration rate (PR), specific removal rate (SRR), and taper angle (TA). The paper correlates VRR, PR, drilling power, and Young’s modulus of the tested materials. In the case of slotting, VRR, kerf taper angle (TA), and the average surface roughness, Ra, were measured and used as indices of machinability. Cost analysis was also performed to introduce an economical index of machinability for both AWJ drilling and slotting AWJM operations.

Abstract: Shallow trench isolation via chemical mechanical polishing (CMP-STI) tests of Si wafers using CeO₂ slurry were studied. The impact of CeO₂ slurry's solid concentration on the SiO₂ removal rate and the selectivity ratio The effects of the solid concentration of CeO₂ slurry on the removal rate of SiO₂ and selectivity (SiO₂/Si₃N₄) were investigated. The CeO₂ abrasive was well matched to the XRD standard pattern, confirming that it had a cubic phase and the absence of any impurities. The SEM image showed that CeO₂ primary particles had a spherical-like shape with a size within 30-60 nm. Additionally, the prepared CeO₂ slurry showed a relatively high dispersion level. The wettability degree of the CeO₂ slurry on top of the Si wafer surface was also sufficient. Furthermore, results from polishing tests indicated that both the SiO₂ removal rate and the selectivity increased linearly with a rise in CeO₂ solid concentration.

Abstract: A novel add-on hardware device is placed near the point of slurry dispense that can instantaneously activate slurry performance during polishing via megasonic irradiation. This new technology (Flucto-CMP® is able to overcome the inherent polisher-slurry weaknesses such as wafer-level defects, process vibrations, cost of ownership, slurry waste, remval rate (RR), and RR selectivity. Flucto-CMP® has been successfully applied to various types of CMP slurries resulting in significant increases in the removal rates of copper, SiC, borosilicate hard mask, ILD, TiN, and silicon carbide through chemical alteration of the passivation layer needed for material removal. Specifically, for copper CMP, using Flucto-CMP®, we see an up to 31% boost in RR which is well correlated with the amount of reactive oxidizing species generated through irradiation as well as the measured relative indentation depth of the passivation layer. In addition to boosts in RR, for copper, we see a 50X drop in the variance of shear force and a 5X drop in the variance of normal force when Flucto-CMP® is used. This dramatic reduction in process vibration for copper soft-landing processes ought to reduce wafer-level defects. Much greater rate improvements are observed when polishing SiC, and borosilicate hard masks.

Abstract: The removal of heavy metals in waste pickling acid by iron powder reduction was studied. The effects of reaction time, reaction temperature and dosage of iron powder on the removal efficiency of Zn, Cr, Ni and Pb in waste pickling acid were investigated. The results showed that, the removal rate of Cr tended to be stable after 2 h of reaction under magnetic stirring. After 4 hours, the removal rate of Zn,Ni and Pb tended to be stable. The temperature was increased from 20°C to 90 °C, the removal rates of Ni and Pb could be increased by 9.09% and 11.6%, while the removal rates of Zn and Cr were only increased by 1.15% and 2.85%; Increasing the dosage of iron powder was beneficial to the removal of heavy metals in waste pickling acid, and the combined amount of free acid in the waste acid would affect the removal efficiency of heavy metals. The research results had important guiding significance for the practical application of iron powder reduction method in the heavy metal purification project of waste pickling acid.

Abstract: The hydrolytic properties of LiAlO₂ (LAO) are important factors for its applications on LED fabrication. During soft pad polishing process, the H₂O in the slurry is deleterious for LAO surface polishing results. The current study develops a material removal rate model for materials with hydrolysis reaction to predict the result of polishing process.The current research conducts the experimental studies to investigate the material removal rate and its mechanism during the soft pad polishing process. In the experimental study, the hydrolytic properties of LAO have been tested to understand the hydrolysis speed with different operation parameters to assist the development of the theoretical model. Also the material removal rates of LAO with hydrolytic property have been measured under different soft pad polishing operating conditions. The experimental results provide the hydrolytic properties of LiAlO₂ to understanding of the mechanism on polishing process.

Abstract: Silicon carbide (SiC) is widely used in terrestrial and space applications because of its good mechanical, thermal and optical properties. Nevertheless, traditional grinding and polishing technologies cannot meet the machining requirements due to the high hardness and brittleness. In this paper, Inductively Coupled Plasma (ICP) is utilized to process the SiC optics. The effects of different processing recipes on the removal rate and temperature are investigated. The results show that the removal rate almost keeps stable with processing time and changes with the flow rate of plasma gas, reaction gas, the ratio of CF₄/O₂ and the power. The input power and processing time are the two main influence factors on the processing temperature.

Abstract: In order to establish a low cost and high efficiency immobilized microorganism system to treat Cr (VI) wastewater, the effects to removal capacity to Cr (VI) of microbe strain, additives and medium were investigated. These strains were immobilized with SA (sodium alginate) by immobilized microorganism technology combined with three additives CNTs (carbon nanotubes), activated carbon, straw and nutrient source, respectively. The results showed that three kinds of additives could improve the removal effect to Cr (VI), and the removal rate up to 30% when Cr (VI) concentration was 10mg/L. There was not a significant difference among these additives. The solution contains 40% medium could significantly improve the removal capacity to Cr (VI). The removal rate could reach more than 98% when Cr (VI) concentrations were 10mg/L-20mg/L. Therefore, efficient strains, additives and medium could improve the removal capacity to Cr (VI) of immobilized microorganism technology. It can be widely used in chromium contaminated wastewater.

Abstract: Rice husk was used as an adsorbent to study the adsorption of Cr (VI) from wastewater, Based on the experimental studies on influences of the particle size of rice husk, solution pH value, adsorption time, temperature and rice husk dose, the optimal conditions of the adsorption were determined as follows: temperature of 35°C, pH of 2, the particle size of rice husk in the range of 80-100 mesh, adsorption time of 3h, dose of 30g/0.2g. Under the optimal conditions, the removal rate of chromium from wastewater by rice husk can reach 91%.

Abstract: Treatment of actual coking wastewater considered to be difficult by traditional systems. The present study is related to treatment of actual coking wastewater through microaerobic EGSB reactor. The study showed the EGSB reactor could attain about 75% high COD removal. Increasing V_up could strength COD removal. Moreover, high sludge concentration and profound communal synergism existing within the dense granules were very important. As a result of the kinetic analysis of the EGSB reactor treating actual coking wastewater for COD removal using a modified Stover–Kincannon model, the maximum substrate utilization rate, v_max, half saturation constant, K_S, inhibitor constant, K_I, actual pollutant removal rate, , and the actual inhibition degree, K_S /K_I were determined as 2.65×10^-3h^-1, 39.57mg.L^-1, 415.82mg.L^-1, 6.7×10^-5h^-1.mg^-1.L and 0.1(before increasing V_up), 7.34×10^-3h^-1, 19.53mg.L^-1, 197.76mg.L^-1, 3.7×10^-4 h^-1.mg^-1.L and 0.1(after increasing V_up), and 9.35×10^-3h^-1, 6.38mg.L^-1, 162.81mg.L^-1, 1.47×10^-3 h^-1.mg^-1.L and 0.04 (after increasing V_up and X), respectively. The inhibition of toxic contaminants in the actual coking wastewater would cause the decreasing of pollutant removal rate, however, enhancing and X (simultaneously optimizing sludge aggregate structure) could strengthen the performance effect.

Abstract: The desulphurization experiment of oil-soluble oxidant tert-amyl hydroperoxide with dibenzothiophene dissolved in decalin as model-oil was researched. Characterisation on oxidation product was made, and dibenzothiophene removal rate was computed. The influence factors of the oxidative reaction regent amount and the condtions of reaction temperature and reaction time were optimized and compared. The best reaction condition was reaction temperature 90°C, reaction time 3 h, ratio of oxygen to sulfur 4:1, catalyst amount 0.12 g. Dibenzothiophene removal rate reached 97% in this reaction condition.