Engineering Commons^™

Microwave Pretreatment Of Corn Stover For Anaerobic Digestion, Abhishek D. Saxena

Masters Theses

Anaerobic digestion is one of the several technologies used for biomass conversion to electricity or heat. This thesis focused on microwave irradiation of corn stover as a pretreatment for anaerobic digestion, and studies its impact on methane production.

The first run comprised three sets of stover soaked overnight in water, dilute sulfuric acid and dilute acetic acid, and each treated to three different levels of microwave irradiation. The results indicated a high variability in the data of the water set, which showed that there was no clear impact of microwave pretreatment on methane production. The dilute sulfuric acid and dilute …

Nanoscale Materials Processing: Electron Beam-Induced Etching Of Silicon And Silicon Dioxide, Steven Jeffrey Randolph

Masters Theses

Both silicon and silicon dioxide can be etched with an electron beam in the presence of a xenon difluoride atmosphere in a process known as electron beam-induced etching (EBIE). In order to study the EBIE process, a Hitachi S-3500N scanning electron microscope (SEM) was modified to accept a vapor delivery system. Evidence has been presented regarding the fundamental mechanisms by which EBIE occurs, as well as the microscope variables that effect the etch process.

The effects of beam current and beam energy on the EBIE process were examined for both materials. On silicon, it was observed that the increased current …

Combinatorial Design Of Nickel-Chromium Alloys By Physical Vapor Deposition And Electron Beam Welding, Jaret James Frafjord

Masters Theses

Combinatorial methods, which include high efficiency and high throughput methods to create a large compositional range of materials, have proven to be highly effective and efficient in research and development in the chemical and pharmaceutical industries. In this thesis, similar methods for the development and optimization of metals and alloy systems are explored. Combinatorial Ni-Cr alloy samples were developed by physical vapor deposition (PVD) of a wedged film on a bulk material, and then locally melting the two by electron beam welding (EBW). A combinatorial alloy gradient was thus created along the length of the weld. The samples were rapidly …

Laser-Dressing Of Alumina For Grinding Wheels, Abhijeet Ashok Khangar

Masters Theses

Higher the number of effective cutting edges on the surface of a grinding wheel, the higher is the grinding efficiency. However due to continuous grinding, efficiency is reduced as the effective cutting edges on wheel surface get worn out and blunt. Moreover, the wheel also gets loaded with metal chips during machining. Both geometric and functional characteristics of the grinding wheel have to be restored periodically. Dressing is a sharpening operation designed to generate a particular surface topography on the cutting face of the wheel. The conventional processes, like diamond dressing, do not produce consistent grinding results due to dresser …

The Effects Of The Surface Nanocrystallization And Hardening (Snh) Process On Fatigue Resistance, Yuan Wei

Masters Theses

Nanocrystalline and coarse-grained materials have shown high resistances for the fatigue-crack initiation and growth, respectively. In this thesis, the surface- mechanical-attrition (SMA) treatment has been employed for the surface- nanocrystallization and hardening (SNH) process to produce engineered materials with coarse grains in the interior and grain-refinement progressively down to the nano-size on the surface.

The effects of the different processing parameters of the SMA treatment, including the ball size, materials, and treatment time, on the SNH process of the Ti-6Al- 4V and Ni-based Hastelloy® C-2000 Alloys were investigated from the viewpoints of the microstructure, microhardness, surface roughness, and fatigue behavior, …

Measurement Of Material Creep Parameters Of Amorphous Selenium By Nanoindentation And The Relationship Between Indentation Creep And Uniaxial Creep, James Anthony Lamanna Jr.

Masters Theses

ὲ_I= BP_ⁿm

The purpose of this work was to measure the indentation creep parameters of amorphous selenium and to begin to develop a relationship between indentation creep and uniaxial creep. The data for this study was obtained by creating three different indentation creep experiments to test amorphous selenium under multiple loading conditions at multiple temperatures. The testing temperatures included 40°C, 35°C, 30°C, and 25°C. These specific temperatures were chosen to collect creep data above and below the glass transition temperature of 31°C. This indentation data was used to accomplish several objectives.

The first objective was to …

Laser In-Situ Combinatorial Carbide Coating On Steel, Anshul Kumar Singh

Masters Theses

The potential for synthesizing an in-situ grown ultra-fine carbide composite coating on the surface of steel during laser surface engineering was investigated. A 2.5 KW Nd:YAG laser was employed to modify the surface of a AISI 1010 steel deposited with a precursor powder mixture of Fe, Ti, Cr and C. With the help of laser surface engineering, carbide composite coating on the surface of plain C steel was achieved. It is envisioned that such a coating will offer superior tribological properties.

Energy Dispersive Spectroscopy in supplement with X-ray Diffractometery indicated the evolution of TiC, Fe-Cr, and M_{7C3 as major …}

Ti-8mo As An Alternative To Ti-6al-4v In Hip Replacement Implants, Brandice Annette Green

Masters Theses

In the present research, the wear and corrosion properties of a heat treated Ti-8Mo alloy are compared to that of a Ti-6Al-4V, an alloy commonly used as the material for the stem component of hip prosthesis. Ti-6Al-4V has the attractive properties of high strength to weight ratio and excellent corrosion resistance. However, the alloy has poor wear resistance and there have been biocompatibility concerns with Al and V. The heat treated Ti-8Mo is an alloy that has not yet been examined for biomaterial applications. However, the low toxicity of Mo and the possibility of improved wear resistance due to heat …