Advanced Materials Research Vols. 83-86

Abstract: Verification testing of two model technologies in pilot scale to remove arsenic and antimony based on reverse osmosis and chemical coagulation/filtration systems was conducted in Spiro Tunnel Water Filtration Plant located in Park City, Utah, US. The source water was groundwater in abandoned silver mine, naturally contaminated by 60-80 ppb of arsenic and antimony below 10 ppb. This water represents one of the sources of drinking water for Park City and constitutes about 44% of the water supply. The failure to remove antimony efficiently by coagulation/filtration (only 4.4% removal rate) under design conditions is discussed in terms of the chemistry differences between Sb (III, V) and As (III, V). Removal of Sb(V) at pH > 7, using coagulation/filtration technology, requires much higher (50 to 80 times) concentration of iron (III) than As. The stronger adsorption of arsenate over a wider pH range can be explained by the fact that arsenic acid is tri-protic, whereas antimonic acid is monoprotic. This difference in properties of As(V) and Sb(V) makes antimony (V) more difficult to be efficiently removed in low concentrations of iron hydroxide and alkaline pH waters, especially in concentration of Sb < 10 ppb.

Abstract: Glass fiber reinforced polymer (GRP) and needle reinforced polymer (NRP) composites have been used to produce a new kind of thin cross section liner for rehabilitation of in ground sewer pipes. The liner made from resin impregnated glass fiber woven (or plastic needle felt) is in-placed and cured for the rehabilitation of deteriorated pipe. This technique is entitled as cured in place pipe (CIPP) and penetrating to all over the world. Among the renovation technologies, CIPP appears less expensive and more promising than other techniques. CIPP liners are made up of several reinforcement layers impregnated with various thermosetting resins such as epoxy, vinyl ester and unsaturated polyester. Different woven geometries can be used for the felt and tube. In this study, the experimental results obtained from cured composites are given. The mechanical characteristics of CIPP tubes manufactured with different materials were given. Specifically glass fiber and synthetic felt impregnated in thermosetting unsaturated polyester resin were investigated. Standard three point flexural tests were carried out on specimens cut out from the cured liners. Beside these three point flexural tests, abrasive and erosive wear tests were also performed on these samples.

Abstract: Aluminum has experienced significant growth in several sectors over the last decade as a result of its properties and performance attributes. Aluminum is being recognized by different sectors such as automotive, construction, aerospace, etc. as a one of the best candidate material for various applications. Increasing demand for aluminum-based products and further globalization of the aluminum industry have contributed significantly to the higher consumption of aluminum scrap for re-production of aluminum alloys. In automotive applications, for example, the opportunities for continued growth in powertrain and suspension applications plus lightweighting of body structures offer the potential for considerable further growth. Today, a large amount of the aluminum going into new products is coming from recycled products. This represents a growing "energy bank" of aluminum that will become available for recycling at the end of vehicles' lives, and thus recycling is becoming a major issue, and it is essential to tackle this problem before it is too late. The future growth offers opportunity for new recycling technologies and practices to maximize scrap quality, improve efficiency and reduce cost. The present paper highlights some of the current development work in recycling, the challenges facing the implementation of recycling technologies and the future prospective of the idea.

Abstract: Chemicals play an important role in the enhancement of oil and gas production and processing. They control corrosion, prevent organic and inorganic deposits, aid in phase separation and control microbial problems. Several factors can have significant impact on the safety, maintenance, operation, and service life of the chemical injection point. Failures encountered in the high pressure retrievable chemical injection points are presented. This paper also provides guidelines for materials selection and design of chemical injection points in upstream facilities.

Abstract: A novel technique for depositing thick DLC based films on the inside of cylindrical substrates, like pipes, tubes and valves, has been developed. A plasma enhanced chemical vapour deposition (PECVD) technique has been used to engineer and optimize the above mentioned films for maximum coating performance. Of particular importance is the corrosion and wear resistant qualities of these films. Changes in film chemistry, structure and thickness are attributed to the improved corrosion and wear resistance. Details will be given of the corrosion testing which has taken place, such as exposure to HCL (hot and ambient temperature), NaCl and H2S environments. One such test is a very aggressive sour autoclave test where the film is exposed to an aqueous, organic and gas phase over a 30 day period and no damage to the film was found. In depth details of this sour autoclave test will be shown including photographs of the film before and after testing. Wear testing has also been carried out in dry and wet sand slurry environments where very low coefficient of friction (COF) and wear rates were found. It is believed that this thick DLC based film can increase the component life in applications where internal surfaces are exposed to highly corrosive and abrasive media, in particular the oil and gas industry. Examples of such applications are mud pump sleeves, deep well components, directional drilling, abrasive flow spools, pump barrels and in sour fields (H2S).

Abstract: Applying mechanical vibration with subsonic frequencies during permanent mold casting enhances nucleation and improves mold-casting heat transfer. Despite the several published papers in this field, little attention was given to correlating the vibration parameters of frequency and amplitude with the casting microstructure. In this paper microstructure examination and numerical simulation are used to explain the microstructure refinement using mold-vibration. A 1-D numerical model is used to explain the different mechanisms that mold-vibration has at different frequencies of 100 Hz, 500 Hz, and 2000 Hz. Microstructure examination for samples of Al-12.6wt%Si are presented and a correlation with the numerical results using inverse heat conduction method is attempted. Results show that increasing the value of the apparent thermal diffusivity of the casting is as a result of vibration is a major factor in achieving the desired refinement. Improving the mold-casting heat transfer coefficient showed significant influence on the process only at high frequency of 2 kHz due to the low vibration amplitude used.

Abstract: Laser welding of steel 316L sheets is considered and the effects of laser welding parameters on the laser weld quality and metallurgical changes in the weld section are presented. The laser weld quality is assessed through careful examination of weld geometrical features, and the resulting weld microstructure. Metallurgical changes in the weld sites are examined using optical, and electron scanning microscope (SEM). Two levels of heat inputs are used-1500W and 2000W; and two scanning speeds of 2cm/s and 4cm/s are used to laser weld 316L sheets. It is found that at the high laser power intensities, evaporation takes place in the irradiated region and as the laser power intensity increases further, a cavity is formed at the top surface of the welding cross section. A similar situation is also observed as the laser scanning speed reduces. The low diffusivity of the alloying elements at high temperatures preserves the segregation profile. The scattered partitioning of the cells and dendrite boundaries are observed due to the presence of Cr and Mo.

Abstract: The quality of breast prostheses dependant on homogeneous mixing of materials during the manufacturing process. This research endeavoured to investigate the mixing of two silicones that are widely used in the production of breast prostheses. The effect of impeller design on obtaining a homogeneous mixture was investigated. Four different types of impellers were used to investigate the effect of stirrer type, diameter, speed, position and time to obtain a homogeneous mixture. Stirring speeds of 500 rpm, 800 rpm and 1100 rpm were investigated together with stirring height and stirring diameter. Percentage of homogeneity of the mixture was investigated ranging from 10 to 60 minutes with a 10 minutes interval. The effect of stirring time and speed on viscosity was also examined. It was found that a four blade radial impeller gives the best result for mixing in all cases.

Abstract: Although the low yield rate of ITO thin-film during the production of semiconductor techniques is easily seen. Current work presents a new modus of electrochemical machining using a design rolling tool as electrodes constructs a precision recycle process offering faster performance in removing the color filter surface’s ITO thin-film. Through establishing an ultra-precise recycling process to remove the thin-film microstructure, this helps the semiconductor optoelectronic industry to reduce both production costs and pollution. The design features of the removal processes for a thin-film and the tool design of rolling electrodes are of major interest. Higher electrical current is not required when an effective feeding electrodes is used to reduce the response area. In the current experiment, the author utilizes a 5th Generation TFT-LCD. The design electrodes (rolling tool) are used with continuous and pulsed direct current in the electrochemical machining experiment. A displays’ color filter with a fast feed rate is combined with enough electric power to provide highly effective removal. High rotational speed of the rolling tool and high flow velocity of the electrolyte elevates the discharge mobility and improves the removal effect. A larger diameter of the fictitious rotation circle of the cathode and a small end radius of the cathode provide better removal effect. A precision recycling process is presented using an effective rolling tool in the electrochemical machining. It only needs a short period of time to remove the ITO thin-film easily and cleanly.

Abstract: The objective of this study is to determine the optimal ball grinding parameters of the bio-ceramics ZrO2 by executing the Taguchi’s L18 orthogonal array experiment, analysis of variation (ANOVA), and the full factorial experiment on a PC-based multi-axis CNC engraving machine. The manufacture of a ZrO2 coping using the optimal ball grinding parameters has also been studied based on a tooth plaster model via reverse engineering technique. The 3D data points of a tooth plaster model were digitized by the developed on-machine measurement system on a PC-based CNC multi-axis engraving machine by integrating a circular triangulation laser probe with the machine and a PC. A CAD model of a coping could then be constructed by Pro/Engineer software, based on the digitized 3D data points. With the help of the PowerMill CAM software, the machining path of a coping has been simulated, and the correspondent NC codes have been generated to fabricate the ZrO2 coping using the determined optimal ball grinding parameters, on the CNC multi-axis engraving machine. The average surface roughness of Ra=0.49 um for the ground ZrO2 ceramics coping could be obtained by utilizing the optimal flat surface grinding parameters.