14,669 research outputs found
Insulating diamond coatings on Tungsten electrodes
No full textS.293-297Insulating diamond layers of 5-20 mm thickness are deposited by hot filament-chemical vapor deposition (HF-CVD) on tungsten electrodes. These electrodes of about 150 mm length and 2 mm diameter are used for level sensors in hostile environments like water at 350°C. The increase of the resistivity due to N-doping is compared to resistivity of undoped layers. Studies of the homogeneity and quality of the layers are performed by scanning electron microscopy (SEM) and micro-Raman spectroscopy. The electrical characterization is performed by impedance spectroscopy at room temperature and at elevated temperatures up to 83°C in aqueous NaCl solution (3%). The reduction of pores and pin holes is important in arriving at high values of electrical impedance (|Z| > 1 MO, 30 Hz), which is essential for a level sensor working in poorly conductive liquids (swater ≈ 0.1 mS cm−1). Several cleaning procedures are necessary to reduce the pore density from about 1 per 20 mm2 to less than 1 per 1000 mm2. Highest resistivity values of N-doped diamond layers, averaged over the electrode length and film thickness, amounted to 5 × 1012O· cm.6Nr.2-
A study on PDC drill bits quality
No full textThe quality of innovating PDC (Polycrystalline Diamond Compact) bits materials needs to be determined with accuracy by measuring cutting efficiency and wear rate, both related to the overall mechanical properties. An original approach is developed to encompass cutting efficiency and wear contribution to the overall sample quality. Therefore, a lathe-type test device was used to abrade specific samples from various manufacturers. Post-experiment analyzes are based on models establishing coupled relationships between cutting and friction stresses related to the drag bits excavation mechanism. These models are implemented in order to evaluate cutting efficiency and to estimate wear of the diamond insert. Phase analysis by XRD and finite element simulations were performed to explain the role of physicochemical parameters on the calculated quality factor values. Four main properties of PDC material were studied to explain quality results obtained in this study: cobalt content in samples that characterizes hardness/fracture toughness compromise, undesired phase as tungsten carbide weakening diamond structure, diamond grains sizes and residual stresses distribution affecting abrasion resistance
Ms. Courtney Chartier, RWWL AUC, August 2011
No full textThis video is a conversation with Ms. Courtney Chartier. Ms. Chartier talks about her work on the "New Georgia Encyclopedia" and "Online Voter Education Project." Andrea Jackson, AUC Woodruff Library, is the interviewer
Ms. Neely Terrell, RWWL AUC, March 2012
No full textThis video is a conversation with Ms. Neely Terrell. Ms. Terrell talks about her book, "Super Singles Activate". Anthony Kinsey and Jahnesta Horney, AUC Woodruff Library, are the interviewers
Personal Papers (MS 80-0002)
No full textLetter from William M. Hynds to Rough Diamond Co., Inc. discussing H. Kempner Cotton Company's cotton exports
Personal Papers (MS 80-0002)
No full textLetter from William M. Hynds to Rough Diamond Co., Inc. discussing H. Kempner Cotton Company's cotton exports
Personal Papers (MS 80-0002)
No full textLetter from William M. Hynds to the Rough Diamond Co., Inc. discussing payment due to H. Kempner Cotton Company under a barter contract
A study of unusual diamonds from the George Creek K1 Kimberlite dyke, Colorado
No full textCathodoluminescence photomicrographs of diamonds from the George Creek Kl (section 28) kimberlite dyke in Colorado reveal complex intergrowth relationships between CO?-free and CO?-bearing diamond growth generations. The distribution of the CO?-bearing diamond in some specimens suggests that this generation is younger than the CO?-free diamond growth generation, although the age relationships are mostly ambiguous. CO?-bearing diamond appears to have crystallized from fluids which invaded fractures and etched embayments in the CO?-free diamond growth generation, which shows evidence of plastic deformation. The CO?-free diamond growth generation commonly exhibits features caused by extreme plastic deformation during mantle residence time. Abundant yellow-green plastic slip planes transect zones of customary blue cathodoluminescence in many diamonds, and raised lamination lines have been recognized on resorption surfaces. The complexity and intensity of surface etch features in most George Creek diamonds, including the CO?-bearing growth generation, suggests that the diamonds were subjected to multiple episodes of etching and resorption. Extensive development of hexagonal and trigonal etch pits resulted from the action of oxidizing CO?-H?O fluids, and some late-stage etching is believed to have occurred in the hypabyssal dyke system prior to kimberlite eruption
Ms. Felesha Love, Spelman College, January 2016
No full textThis video is a conversation with Felesha Love. Ms. Love talks about her book, "Brave Leap to Freedom: Integrating Mind, Body, and Spirit to Cultivate Healthy Relationships". Jordan Moore, AUC Woodruff Library, is the interviewer
Personal Papers (MS 80-0002)
No full textInvoice from Diamond Tailors for repair to a coat lining. Total charges are listed
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