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Full-Text Articles in Engineering Science and Materials

Utilizing Gis Technology For Brownfields Redevelopment, Jeffrey J. Duteau Aug 1998

Utilizing Gis Technology For Brownfields Redevelopment, Jeffrey J. Duteau

Theses

Typically, when developers, banks and other organizations have an interest in a piece of property they perform an extensive information search to determine if the site is worth purchasing. This search could consist of tax and title information, the location of utilities and major roadways in the area, information on population demographics and environmental contaminant data. An information search of this type could take days, weeks or even months to compile. With a geographic information system (GIS), this search could take a matter of minutes and is displayed in an easy to understand graphic or map form along with a ...


Trifluoroiodomethane As An Environmentally Friendly Gas For Water Patterning By Plasma Etching Process, Krit Aryusook Dec 1996

Trifluoroiodomethane As An Environmentally Friendly Gas For Water Patterning By Plasma Etching Process, Krit Aryusook

Theses

Trifluoroiodomethane (CF3I), a non-global warming gas, has been investigated with study as a substitute for typical CFC etchants, such as CF4 and C2F6, used in wafer pattering technology. This investigation was carried out by exposing dielectric films of silicon oxide (SiO2) and silicon nitride (Si3N4) in CF3I and C2F6/O2 (used as a reference) plasma environments. The etch rate of these films was ascertained as function of applied rf power, etchant gas flow rate, reaction chamber operating pressure, and O2 to CF3 ...


Microporous Silicon Dioxide/Vycor Membranes For Gas Separation, Justin R. Barone Dec 1996

Microporous Silicon Dioxide/Vycor Membranes For Gas Separation, Justin R. Barone

Theses

This study focused on producing membranes for molecular sieving of gases by reducing the pore size of an already existing membrane structure. To do this, SiO2 was deposited inside the pores of a Vycor tube with initial pore diameter of 4 nm. The film deposition took place by a low pressure chemical vapor deposition (LPCVD) process where diethylsilane (DES) and nitrous oxide (N2O) were used as precursor gases. A counterflow reactant geometry was used where the precursor gases were flowed on both sides of the porous membrane. This deposition geometry gave higher selectivities and better mechanical stability ...


Synthesis And Characterization Of Silicon Dioxide Thin Films By Low Pressure Chemical Vapor Deposition, Sutham Niyomwas Dec 1996

Synthesis And Characterization Of Silicon Dioxide Thin Films By Low Pressure Chemical Vapor Deposition, Sutham Niyomwas

Theses

Ditertiarybutylsilane ( DTBS ) and oxygen have been used as precursors to produce silicon dioxide films by low pressure chemical vapor deposition. These films were synthesized in the temperature range of 600°C to 800°C at constant pressure, and at different gas flow composition. The films were found to be uniform with a composition that varied with deposition temperature and gas flow ratio. The growth rate was found to follow an Arrhenius behavior with an apparent activation energy of 2.62 kcal/mol. The growth rate was seen to increase with higher distance between wafers and to vary as a function ...


Low Pressure Chemical Vapor Deposition Of Silicon Dioxide And Phosphosilicate Glass Thin Films, Vijayalakshmi Venkatesan Oct 1996

Low Pressure Chemical Vapor Deposition Of Silicon Dioxide And Phosphosilicate Glass Thin Films, Vijayalakshmi Venkatesan

Theses

Silicon dioxide thin films were synthesized on silicon and quartz wafers using Ditertiarybutylsilane(DTBS) and oxygen as precursors. Trimethylphosphite (TMP) was injected to obtain phosphosilicate glass. The films were processed at different temperatures between 700°C and 850°C at a constant pressure, and at different flow ratios of the precursors. The films deposited were uniform, amorphous and the composition of the films varied with deposition temperature and precursor flow ratios. The deposition rate increased with increasing temperature and with increasing TMP flow rate. The stresses were very low tensile in the case of undoped silicon dioxide film and tended ...


Fabrication Of Integrated Optic Sensor To Monitor Pollutant Concentration In Effluents, Kiran Chatty Oct 1996

Fabrication Of Integrated Optic Sensor To Monitor Pollutant Concentration In Effluents, Kiran Chatty

Theses

An attempt has been made to fabricate an integrated optic sensor to monitor pollutant concentration in effluents. Optic fiber has to be coupled to the waveguide in order to send light through the waveguide. In order to facilitate the easy coupling of the fiber to the waveguide, V-grooves were formed in the silicon substrate. In order to achieve this Silicon nitride was deposited to serve as an etch mask. An attempt was made to obtain low stress silicon nitride films.

This work also attempted to synthesize the materials required to fabricate the waveguide. LPCVD processes were developed to produce undoped ...


Synthesis And Characterization Of Silicon Dioxide Thin Films By Low Pressure Chemical Vapor Deposition Using Ditertiarybutylsilane And Oxygen, Sung-Jun Lee Oct 1996

Synthesis And Characterization Of Silicon Dioxide Thin Films By Low Pressure Chemical Vapor Deposition Using Ditertiarybutylsilane And Oxygen, Sung-Jun Lee

Theses

This study is focused on the synthesis and characterization of silicon dioxide thin films deposited on silicon wafers by Low Pressure Chemical Vapor Deposition (LPCVD), using ditertiarybutylsilane (DTBS) as a precursor and oxygen as the oxidant. The dependence of film growth rate on various process parameters were studied. The growth rate was found to follow an Arrhenius curve with the variation in the temperature with an activation energy of 12.6 kcal/mol. The growth rate was found to be inversely proportional to the temperature in the range 550-750 °C. The refractive index and density were observed to be close ...


Effect Of Lamellar Microstructure On The Permeability Of Polyethylene Films, Yufu Li Oct 1996

Effect Of Lamellar Microstructure On The Permeability Of Polyethylene Films, Yufu Li

Theses

Lamellar microstructures can decrease the permeability to gases and vapors by increasing the diffusive path in plastic films, or the so-called "tortuosity" which depends on the aspect ratio, orientation, and the volume fraction of the dispersed material. In this research, different types and percentages of mica with relatively high aspect ratio are used as oxygen barrier materials in blown films. Both high and low density polyethylenes (HDPE and LDPE), as well as their blends are used as the matrix materials.

A decrease in permeability of both LDPE and HDPE films to oxygen is achieved with increasing volume fraction of the ...


Dynamic Mechanical Analysis Of Particulate Dental Composites, Minu Parekh May 1996

Dynamic Mechanical Analysis Of Particulate Dental Composites, Minu Parekh

Theses

Typically, dental composites are used in different configurations and situations. When a cavity forms at the occlusal surface of a posterior tooth, a class I and class II filling is used, depending on the extent and nature of the cavity formed. These fillings have to be designed to resist mechanical abrasion and occlusal stress during chewing, bruxing and other tooth functions. Class IV fillings are also designed to resist biting stress. In these applications composites with high filler loading with filler particles of size >0.6μm are used. These composites are typically known as minifill or midifill composites. When more ...


Plasma Enhanced Chemical Vapor Deposition Of Stress Free Tungsten Films, David Perese May 1996

Plasma Enhanced Chemical Vapor Deposition Of Stress Free Tungsten Films, David Perese

Theses

This study focuses on PECVD to make tungsten film for X-ray absorber for use in X-ray lithography applications. The previous LPCVD study was used for comparison of film properties. A cold wall, single wafer, Spectrum 211 CVD reactor was used for the deposition of tungsten from H2 and WF6. The growth kinetics were determined as a function of temperature, pressure and flow rate ratio. The deposition rate was found to follow an Arrehnius behavior between 300-500°C with an activation energy of 55.7 kJ/mol. The growth rate increased linearly with total pressure and H2 partial pressure. In the ...


Characterization Of Low Pressure Chemically Vapor Deposited Boron Nitride Films As Low Dielectric Constant Materials, Manish Narayan Dec 1995

Characterization Of Low Pressure Chemically Vapor Deposited Boron Nitride Films As Low Dielectric Constant Materials, Manish Narayan

Theses

Boron nitride thin films were synthesized on Si and quartz wafers by low pressure chemical vapor deposition using borane triethylamine complex and ammonia as precursors. The films were processed at 400°C, 475°C and 550°C at a constant pressure of 0.5 Torr and at different precursor flow ratios.

The films deposited were uniform, amorphous and the composition of the films varied with deposition temperature and precursor flow ratios. The thickness of the film increased with increasing flow ratio, but, decreased with increasing temperature. The stresses in the film were either mildly tensile or compressive.

The least dielectric ...


Synthesis Of Boron Nitride/Vycor Composite Membrane Structures By An Optimized Lpcvd Process, Chenna Ravindranath Oct 1995

Synthesis Of Boron Nitride/Vycor Composite Membrane Structures By An Optimized Lpcvd Process, Chenna Ravindranath

Theses

Since the advent of the idea of ultrafiltration, microporous membranes have come through a long way in establishing a niche as an efficient technology for gas separation applications. More and more research is aimed at reducing pore size towards nanolevels, when separation factor is the criterion rather than the permeability. This work is focused at synthesizing and characterizing microporous inorganic membranes for gas separations by molecular sieving. BN was deposited on mesoporous vycor tubes using triethylamine borane complex (TEAB) and ammonia as precursors. Effect of temperature and deposition geometry on permeability of various gases has been studied. Very high selectivities ...


Low Pressure Chemical Vapor Deposition Of Tungsten As An Absorber For X-Ray Masks, Hongyu Chen Oct 1995

Low Pressure Chemical Vapor Deposition Of Tungsten As An Absorber For X-Ray Masks, Hongyu Chen

Theses

Tungsten film is one of promising materials for X-ray absorber in X-ray Lithography technology because of its high X-ray absorption and refractory properties. This study focus on CVD method to make tungsten film for X-ray absorber.

In this work, a cold wall, single wafer, Spectrum 211 CVD reactor was used for the deposition of tungsten from H, and WF6. The growth kinetics were determined as a function of temperature, pressure and flow ratio. The deposition rate of as deposited tungsten films was found to follow an Arrehnius behavior in the range of 300-500°C with an activation energy of 55 ...


Low Pressure Chemical Vapor Deposition Of Copper Films From Cu(I)(Hfac)(Tmvs), Wei-Shang King Dec 1994

Low Pressure Chemical Vapor Deposition Of Copper Films From Cu(I)(Hfac)(Tmvs), Wei-Shang King

Theses

Recently, copper has been found as a possible substitute for Al alloys because of its low resistivity (1.67 μΩ • cm) and potentially improved resistance to electromigration. Conventional physical vapor deposition (PVD) method do not provide the conformal deposition profile for the high density integrated circuit, therefore, chemical vapor deposition (CVD) has become the most promising method for the resulting conformal profile.

In this work, a cold wall, single wafer, CVD tungsten reactor was used for the deposition of copper with Cu(I)(hfac)(tmvs). Film growth rates were between 100 to 800 A/min depending on processing conditions, and ...


Aeration And Operation Of An Immobilized Cell Oxidative Bioreactor, James Joseph Woods Dec 1994

Aeration And Operation Of An Immobilized Cell Oxidative Bioreactor, James Joseph Woods

Theses

The primary purpose of this work is to help define the optimum window of operations for an immobilized cell oxidative bioreactor. The analytical technique employed requires no outside verification (such as G.C. analysis) and is independent of liquid flow rate. Method of aeration has been determined to be an important parameter for optimizing bioreactor efficiency, and optimization of the quantity of hydrogen peroxide added to provide oxygen during bio-oxidation has been investigated. Ammonium hydroxide as a fixed nitrogen source can be used to restore the vitality of the bioreactor under certain conditions.

The effects of several different methods of ...


Synthesis Of Silicon Oxide/Vycor Composite Membrane Structures By An Optimized Lpcvd Process, Abhijit Datta Dec 1994

Synthesis Of Silicon Oxide/Vycor Composite Membrane Structures By An Optimized Lpcvd Process, Abhijit Datta

Theses

This study is focused on development of highly selective ceramic membrane structures consisting of silicon dioxide films synthesized by low pressure chemical vapor deposition (LPCVD) on mesoporous Vycor substrates. The ability of easily altering the composition of such films by varying the LPCVD processing parameters affords the opportunity of microengineering the pore structure by reducing the diameters of pre-existing pores in the support. The process parameters investigated include, deposition temperature, total pressure, and flow rate of oxygen. Both the kinetics and select properties of the deposits were examined. The growth rate as a function of temperature was seen to follow ...


The Photolithographic Patterning Of Porous Silicon Using Silicon Nitride And Silicon Carbide Films As Masks, Hong Wang Dec 1994

The Photolithographic Patterning Of Porous Silicon Using Silicon Nitride And Silicon Carbide Films As Masks, Hong Wang

Theses

In this study, a simple photolithographic pattern process for porous silicon is described. The process utilizes silicon nitride or silicon carbide coated on the top of silicon wafer as a masks. Then a test pattern was projected on the sample by illumination during anodic etching in HF:ethanol solution which produced microcracks in regions illuminated during anodization. Creation of these microcracks resulted in formation of porous silicon in the underlying regions. The cracking is related to the stress in the thin film. The films with tensile stress exhibit cracking while compressive stress samples do not. Compared to silicon carbide films ...


Agitation Requirements For Complete Dispersion Of Emulsions, Dun-Huang Tsai May 1988

Agitation Requirements For Complete Dispersion Of Emulsions, Dun-Huang Tsai

Theses

An investigation on the minimum agitation speed required to achieve complete dispersion in liquid-liquid systems has been carried out. A model based on the momentum balance for a droplet and on Kolmogoroff's theory of isotropic turbulence was used for the prediction of the role of the most important variables on the minimum agitation speed. The equation so derived can be expressed in terms of a number of non- dimensional groups (such as Re, Ar, and Su). For geometrically similar systems the equation contains only one adjustable parameter ( to be determined experimentally) in the form of the proportionality constant correlating ...


Analysis Of Combustion Products Of Kynol And Nomex, Abdul Halim Hassan Housny May 1977

Analysis Of Combustion Products Of Kynol And Nomex, Abdul Halim Hassan Housny

Theses

The gaseous products generated by flaming combustion of Kynol and Nomex fibers under the same conditions (temperature 300-700°C, natural air) were quantitatively analyzed by infrared spectrophotometry, gas chromatography, mass spectrometry and a colorimetric tube method. The four techniques were chosen to examine the wide range of volatile and condensable products expected due to their different capabilities and sensitivities.

The main gases generated were carbon monoxide, carbon dioxide, methane and benzene.

The mass spectrometer was used to identify the condensed vapors. These were mainly phenol, methyl phenol and dimethyl phenol from the Kynol fiber and benzene, aniline, diaminobenzene, benzoic acid ...


Thermal Decomposition Products Of Kynol And Nomex With Reference To Structure And Toxicity, Shaker H. El-Sherbini May 1977

Thermal Decomposition Products Of Kynol And Nomex With Reference To Structure And Toxicity, Shaker H. El-Sherbini

Theses

The purpose of this investigation was to study the combustion products of KYNOL and NOMEX as a fire retardant fibers. From the quantitative analysis data of the combustion products, the polymer structure is discussed and the property of thermal stability is explained.

From the analysis of the combustion products, the toxicity indices for the two fibers are determined. It is found to be 0.1 for KYNOL and 0.71 for NOMEX. This can be interpreted to mean that, if one gram of MIDI, is decomposed and the combustion products were diffused in one cubic meter of air, the probability ...


An Analysis Of The Geneva Mechanism As A Timing Device, Hubert W. Meyer May 1973

An Analysis Of The Geneva Mechanism As A Timing Device, Hubert W. Meyer

Theses

A mathematical analysis of the Geneva mechanism was conducted to determine the potential of this device as a tinting mechanism, and the feasibility of replacing the widely used pallet and starwheel escapement with a Geneva mechanism.

The primary objective of the study was to determine if the Geneva mechanism will attain a terminal velocity, and if so, how much time is required to reach this velocity.

To accomplish this objective, the differential equation of motion for the system was derived using Lagrangian dynatos. The equation was programmed and solved on a digital computer.

The study indicated that the Geneva mechanism ...