Engineering Commons^™

Corrosion Inhibitor For Reinforcing Steel In Concrete, Hanan Abdel Aziz Elnouhy

Archived Theses and Dissertations

No abstract provided.

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 to 1.47 …

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 …

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 …

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 towards being less …

Residual Strength After Fatigue Of Unidirectional And Cross-Ply Metal Matrix Composites At Elevated Temperature, Sen-Tzer Chiou

Theses and Dissertations

This study investigated the residual strength of the unidirectional and cross-ply laminates of SCS-6 / Ti-15-3, metal matrix composite at elevated temperature 427°C (800°F) after under tension-tension load controlled mode. For this purpose, several specimens were fatigued to various fractions of the fatigue life and then loaded monotonically to failure. The purpose of this study was to determine the effects of different levels of fatigue damage on the composite's strength. The unidirectional specimens were cycled at a 900 MPa maximum stress at a frequency of 10 Hz, while, the cross-ply specimens were tested at both 300 MPa and 450 MPa …

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 than …

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 H2/WF6 ratio studies …

Waste Steel Chips From Workshops As A Substitute For Fiber Reinforcement In Concrete, Alaa Abdultawab Abulella

Archived Theses and Dissertations

No abstract provided.

Modeling Of Progressive Damage In Fiber-Reinforced Ceramic Matrix Composites, James P. Solti

Theses and Dissertations

An analytic methodology is developed to model the response of fiber-reinforced ceramic matrix composites (CMOs) when subjected to monotonic and fatigue loadings. The analysis requires the formulation of (1) a micromechanics model which defines the laminate's geometry and constitutive relationship; (2) failure criteria which estimate the extent of microstructural damage, and, finally, (3) a means of analyzing frictional slip, fiber pull-out, interfacial wear and laminate failure. For the present study, the behavior of unidirectional and crossply CMOs is investigated using modified shear-lag theory in conjunction with a set of failure criteria with a minimum reliance on empirical data. The damage …

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 constant for the films …

Thermal Behavior Of Energy Storage System In A Cylindrical Tank, Walid Wagih Darwish

Archived Theses and Dissertations

No abstract provided.

Growth And Properties Of Chemically Deposited Cds Thin Films, Edward A. Gluszak

Theses : Honours

Polycrystalline thin films of undoped CdS and In doped CdS (i.e. CdS:In) have been deposited by chemical bath on glass slides and high purity silicon wafers. The effect of different processing conditions (e.g. substrate temperature, doping and air annealing) on film growth, optical transmittance and electrical properties were correlated with the film microstrucutre. The mechanism of chemical bath deposition of CdS thin films from the ammonia-thiourea system is studied. The influence of reaction parameters (i.e. concentration of reactants and pH) on film growth were determined and modeled. Thin film growth is thermally activated with an energy ≈ 5 x 10 …