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- <p>Aluminum-silver alloys -- Metallurgy<br />Grain boundaries<br />Metals -- Heat treatment</p> (1)
- <p>Kirkendall effect -- Mathematical models<br />Grain boundaries<br />Ionic crystals</p> (1)
- <p>Steel alloys -- Fatigue<br />Steel alloys -- Effect of high temperatures on<br />Materials at high temperatures<br />Chromium-plating</p> (1)
- Ferrites (Magnetic materials) -- Synthesis<br />Ferrites (Magnetic materials) -- Properties<br />Cadmium compounds<br />Manganese compounds (1)
- Zinc -- Electrometallurgy<br />Electrolysis<br />Extraction (Chemistry) (1)
Articles 1 - 6 of 6
Full-Text Articles in Engineering
Synthesis And Properties Of Cadmium Manganese Ferrites, B. W. Jong
Synthesis And Properties Of Cadmium Manganese Ferrites, B. W. Jong
Doctoral Dissertations
"The formation sequence of (Cd,Mn,Fe) (Mn,Fe)₂O₄ from the individual oxides,x CdO + (1-x) MnCO₃ + α-Fe₂O₃,was found by X-Ray diffraction. Cd(Mn,Fe)₂O₄ was formed completely from CdO·Fe₂O₃ and CdO·Fe₂O₄ at 900°C and reacted with MnFe₂O₄ for 0 < x < 0.5 and with α-Fe₂O₃ for 0.5 < x < 1.0 to form a single phase of (Cd,Mn,Fe) (Mn,Fe)₂O₄ at 1150°C. This is the first time that the details involved in the formation sequence of CdMn-ferrite have been shown. A mixture of 0.5 CdO + 0.5 MnCO₃ + α-Fe₂O₃ was calcined at 900°C for 2 hrs forming Cd(Mn,Fe)₂O₄ with no Cd present in the other phases. Sintering was accomplished at 1150°C for 30 minutes forming a single phase of Cd₀.₅Mn₀.₅Fe₂O₄ with a bulk sintered density of 98-99% of the X-Ray density. The rate of changing density followed the relationship, p = K ln t + c, at temperatures between 1050°C and 1300°C. Magnetic properties of CdₓMn₁₋ₓFe₂O₄ were affected by composition x. A relationship, B = gx + h, was found between maximum magnetic flux density B and composition x at room temperature for 0 <̲ x <̲ 0.3. This was rationalized by a modification of Néel's theory. The maximum magnetic flux density decreased with increasing cadmium concentration for 0.3 < x <̲ 0.5. This decrease was attributed to the changing direction of the magnetic moment in the octahedral site sub-lattice according to the superexchange theory. No magnetic properties were observed due to the formation of a compensated antiferromagnetic phase for 0.5 < x <̲ 1.0. Maximum magnetic flux density increased with bulk density, while the coercive force decreased with the grain growth and the initial permeability increased with the bulk density and grain size. A stator core used for a-c electric motor application was formed by pre-sintering at 900⁰C for 2 hrs. Slots were then sawed with a tungsten carbide blade and final sintering was accomplished at 1150⁰C for 1 hr"--Abstract, pages iii-iv.
Effects Of Cr-Plating And Environment On The Cracking Of Low Alloy Steels At High Temperatures, Robert C. Tooke
Effects Of Cr-Plating And Environment On The Cracking Of Low Alloy Steels At High Temperatures, Robert C. Tooke
Doctoral Dissertations
"The cracking of low alloy Cr-Mo-V steels under cyclic stress at 1000-1100°C. was studied using a specially designed test apparatus. The results obtained from specimens plated with hard chromium are compared to those of unplated specimens. Tests conducted in gas mixtures of carbon monoxide and carbon dioxide showed that a high CO/CO2 ratio retards cracking in both plated and unplated specimens. Both external and internal oxidation are used to explain these results. Inherent microcracks in the hard chromium plating promoted cracking in all CO/CO2 environments. It was also found that these steels are severely embrittled in the presence …
The Effect Of Impurities And Additives On The Electrowinning Of Zinc, Haruhisa Fukubayashi
The Effect Of Impurities And Additives On The Electrowinning Of Zinc, Haruhisa Fukubayashi
Doctoral Dissertations
"The effect of various impurities, commonly found in zinc electro-winning solutions, on the surface morphology of deposited zinc was investigated. Individual additions of the impurities Al, Ag, Cd, Co, Cr, Cu, Ge, Mn, Ni, Sb, Sn, Ti, PbO₂ , PbSO₄, and HCl were studied. In a few cases additives of animal glue, gum arabic, and Na₂SiO₃, were used individually or in combination, to determine their effect on the surface structure of the deposited zinc. Comparisons were then made with deposits from a pure electrolyte consisting of H₂SO₄ and Zn⁺², 200 and 65 g/l, respectively. The zinc was deposited on a …
A Study Of The Solid Regions In The System Zr-Te, Frances Dolores Jenkins
A Study Of The Solid Regions In The System Zr-Te, Frances Dolores Jenkins
Doctoral Dissertations
"Relative intensity measurements of X-ray powder diffraction lines were made of compositions in the region ZrTe₀.₅ to ZrTe₂.₀, fired between 600º and 817ºC in evacuated sealed tubes. The experimental relative intensities of samples between ZrTe and ZrTe₂ were compared with values calculated for several theoretical models with different Zr vacancy ordering schemes and Te vacancy concentrations. The most probable structural model for compositions in the range ZrTe to ZrTe₁.₅ is one in which the number of Zr vacancies located at z = 0 ranges from 0% to 30%, with the concentration of Te vacancies ranging from 0 to 35%. A …
The Morphology Of Cellular Precipitation In Aluminum Rich Aluminum-Silver Alloys, Santiago Ibarra Jr.
The Morphology Of Cellular Precipitation In Aluminum Rich Aluminum-Silver Alloys, Santiago Ibarra Jr.
Doctoral Dissertations
"The morphology of cellular precipitation in Al-29.8wt%Ag alloy has been investigated in bulk specimens by transmission electron microscopy and in solution treated specimens by means of hot stage microscopy. Both cellular and general precipitation were observed to occur simultaneously in quench-aged and isothermally aged alloys. By studying the early stages of precipitation in the hot stage, the mechanism for the growth of cells in Al-Ag alloys was developed. According to this mechanism, the grain boundary allotriomorphs begin to form, the boundary then interacts with the allotriomorphs by bowing, and then either trailing precipitation forms on the allotriomorphs or new lamellae …
Grain Boundary Diffusion In Ionic Crystals, Kulwant Singh Sabharwal
Grain Boundary Diffusion In Ionic Crystals, Kulwant Singh Sabharwal
Doctoral Dissertations
"The diffusion of ¹³¹I in single crystals and along the tilt grain boundaries of pure and calcium chloride doped (142±5 ppm) bicrystals of sodium chloride, grown by Czochralski technique, was investigated using a microtome sectioning technique. Results on bulk diffusion in pure NaCl agree well with the results of earlier investigators and are represented by the D=(504 cm²/sec)exp (-2.27 ev/kT). Enhanced diffusion of ¹³¹I is observed along the grain boundaries and the presence of the dopant lowers the grain boundary diffusivity over the entire temperature range of 430ºC - 570ºC studied in the present investigation. Thermal activation and electrical polarization …