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Full-Text Articles in Engineering

Oxidation Studies On Small Atom Doped Ti5si3 , Andrew Jason Thom Jan 1995

Oxidation Studies On Small Atom Doped Ti5si3 , Andrew Jason Thom

Retrospective Theses and Dissertations

Several Ti5Si3Zx compositions (Z = B,C,N,O and 0 ≤ x ≤ 1) were arc-melted, and powder x-ray diffraction indicates the materials maintain the Mn5Si3-type structure of undoped Ti5Si3. Single crystal x-ray diffraction verifies that the ternary additions occupy the normally vacant interstitial sites in the Mn5Si3-type structure. Interstitial nitrogen and oxygen also significantly increase the density of Ti5Si3;Coefficient of thermal expansion (CTE) of Ti5Si3 was measured by the method of high temperature x-ray diffraction. CTE along the c-axis is substantially larger than along the a-axis ([alpha] a = 8.68 ± 0.14 and [alpha] c = 20.4 ± 0.4 ppm ...


Oxidation And Creep Behavior Of Mo5si3 Based Materials , Mitchell Karl Meyer Jan 1995

Oxidation And Creep Behavior Of Mo5si3 Based Materials , Mitchell Karl Meyer

Retrospective Theses and Dissertations

Mo[subscript]5 Si[subscript]3 shows promise as a high temperature creep resistant material. The high temperature oxidation resistance of Mo[subscript]5 Si[subscript]3 has been found to be poor, however, limiting its use in oxidizing atmospheres. Mo [subscript]5Si[subscript]3 exhibits mass loss during oxidation at 800°-1200° C due to volatilization of molybdenum oxide, indicating that the silica scale that forms does not provide a passivating layer. Catastrophic 'pest' oxidation occurs at 800° C. The oxidation rate at 1200° C is on the order of 10[superscript]3 mg cm[superscript]-2 hr[superscript ...


Preparation And Characterization Of B2s3-Based Chalcogenide Glasses , Jaephil Cho Jan 1995

Preparation And Characterization Of B2s3-Based Chalcogenide Glasses , Jaephil Cho

Retrospective Theses and Dissertations

The discovery of the fast ion conducting B[subscript]2S[subscript]3-based glasses has been one of the most significant development in the field of solid electrolytes. Considerable experimental studies have been done to maximize conductivities and chemical stabilities of these glass systems. Recently, the study of the structure and properties of these glasses compared to their oxide analog has become important;The IR spectra of M[subscript]2S + B[subscript]2S[subscript]3 (M = Li, K, Rb and Cs) and MS + B[subscript]2S[subscript]3 (M = Sr and Ba) thioborate glasses have shown the monotonic increase in tetrahedral ...


Synthesis, Characterization And Physical Properties Of Al-Cu-Fe Quasicrystalline Plasma Sprayed Coatings , Daniel J. Sordelet Jan 1995

Synthesis, Characterization And Physical Properties Of Al-Cu-Fe Quasicrystalline Plasma Sprayed Coatings , Daniel J. Sordelet

Retrospective Theses and Dissertations

The phases and microstructures of Al-Cu-Fe powders and coatings were investigated in this study. Powders were prepared by grinding a chill cast ingot and by high pressure gas atomization. The contrasting solidification rates of these two processes yielded very different solidification structures. The cast ingot was very inhomogeneous and contained icosahedral ([psi]), cubic ([beta]), monoclinic ([lambda]) and tetragonal ([theta]) phases. The gas atomized powder had a finer scale of phase segregation and consisted primarily of the [psi] and [beta] phase; a small fraction of the [lambda] phase was present as well;Plasma arc sprayed (PAS) coatings were formed using the ...