Gilley K.L.,University of Florida |
Nino J.C.,University of Florida |
Riddle Y.W.,Diamond Materials , Inc. |
Hahn D.W.,University of Florida |
Perry S.S.,University of Florida
ACS Applied Materials and Interfaces | Year: 2012
The effects of annealing temperature on the tribological properties of electroless nickel-boron coatings have been investigated. The coatings were annealed in a tube furnace under a flow (0.0094 N m 3/min) of oxygen gas at temperatures of 250, 400, 550, and 700 °C for 3 h. Using scanning electron microscopy, images of the annealed coatings documented changes in surface morphology. From this it was seen that the higher annealing temperatures produced marked changes, moving from the nodular structure of nickel-boron coatings to a flaked surface morphology. The chemical effect of the annealing temperature was studied via X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The XPS data indicated that after annealing at the temperatures of 550 and 700 °C, an accumulation of boron oxide species could be seen at the surface as well as a complete loss of nickel signal. An analysis of Raman spectra collected across the surface further identified the predominant species to be boric acid. The tribological response of the coatings was studied with a pin-on-disk tribometer with 440C stainless steel balls run against the coatings in ambient air. It was seen that the as received sample and the sample annealed at 250 °C samples exhibited modest friction properties, while the 400 °C sample had increased friction due to wear debris from the ball. The 550 and 700 °C samples showed remarkably low friction coefficients between 0.06 and 0.08, attributable to the presence of boric acid. The wear tracks were analyzed using scanning white light interferometry and from this data wear rates were obtained for the coatings ranging from 10 -8 to 10 -7 mm 3/Nm. © 2012 American Chemical Society.
Rath P.,Karlsruhe Institute of Technology |
Gruhler N.,Karlsruhe Institute of Technology |
Khasminskaya S.,Karlsruhe Institute of Technology |
Nebel C.,Fraunhofer Institute for Applied Solid State Physics |
And 3 more authors.
Optics Express | Year: 2013
Wide bandgap dielectrics are attractive materials for the fabrication of photonic devices because they allow broadband optical operation and do not suffer from free-carrier absorption. Here we show that polycrystalline diamond thin films deposited by chemical vapor deposition provide a promising platform for the realization of large scale integrated photonic circuits. We present a full suite of photonic components required for the investigation of on-chip devices, including input grating couplers, millimeter long nanophotonic waveguides and microcavities. In microring resonators we measure loaded optical quality factors up to 11,000. Corresponding propagation loss of 5dB/mm is also confirmed by measuring transmission through long waveguides. © 2013 Optical Society of America.
Voronov O.A.,Diamond Materials , Inc. |
Street Jr. K.W.,NASA
Diamond and Related Materials | Year: 2010
Samples of a new carbon material, Diamonite-B, were fabricated under high pressure from a commercial carbon black - identified as mixed fullerenes. The new material is neither graphite-like nor diamond-like, but exhibits electrical properties close to graphite and mechanical properties close to diamond. The use of Raman spectroscopy to investigate the vibrational dynamics of this new carbon material and to provide structural characterization of its short-, medium- and long-range order is reported. We also provide the results of investigations of these samples by high resolution electron microscopy and X-ray diffraction. Hardness, electrical conductivity, thermal conductivity and other properties of this new material are compared with synthetic graphite-like and diamond-like materials, two other phases of synthetic bulk carbon. © 2009 Elsevier B.V.
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 600.00K | Year: 2004
DMI has produced functionally-graded diamond-TiC-Ti cutters for machining lightweight mirror optics, particularly those made of SiC, with high precision and with minimal wear of the cutting edge. The improved wear (relative to commercial diamond tools) is achieved by orienting diamond crystals on the tips of specially designed cutter inserts, so as to exploit the anisotropy in diamond hardness. The reduction in tip wear enhances the precision of machining in uninterrupted cuts. The advantage is most clearly seen when hard ceramics, such as SiC, are machined, but the new cutter technology also provides benefits in machining certain metallic systems. Another innovation is the fabrication of a set of spherically-shaped Diamonite? smoothers, which improve the quality of the finishing operation; thus, for the first time, giving an ultra-smooth surface finish. The combined innovations should enable the optics industry to enhance the performance of large telescopes and interferometers. In Phase I, we designed a special diamond cutting tool for SiC, manufactured samples of cutters and smoothers, conducted research on machining and smoothing of mirror materials, and proved the validity of the concept. In Phase II, we propose to develop ultra-smooth diamond tooling and diamond tool fabrication techniques. The deliverables are diamond-TiC-Ti cutters to achieve higher precision of turning and Diamonite? smoothers to realize better surface finish. In addition, procedures for the reproducible fabrication of mirror optics will be defined. In Phase III, we will implement our developed tools and techniques with end-user companies, and produce machined parts to NASA specifications. This new class of tools should also have wide applications in the machining of structural and functional ceramics.
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 100.00K | Year: 2007
New carbon materials and composites with 1-10 nm crystallite sizes are low-cost, lightweight, and scalable, and have unique wear and high temperature characteristics. These materials have been incorporated in newly-developed coatings, which have been applied to gas turbine components (nozzles, vanes, liners, and blades) to improve performance. This project will develop a new carbon-fiber/nano-carbon matrix composite ¿ coated with a fabric-reinforced, nanostructured, oxidation protective layer ¿ which will enhance the performance and life span of high temperature gas turbines. The new composite will be lightweight; have high surface hardness; withstand high temperature; be wear-, shock-, and vibration-resistant; and be shaped into stiff or flexible structures with equal success. Phase I will conduct experiments to prove feasibility in stator turbine applications. Phase II will demonstrate: (1) the engineering scale-up of the proposed carbon nanocomposite ceramic under its nanostructured coating, and (2) its applicability for high temperature turbine stator and rotor components. Commercial Applications and other Benefits as described by the awardee: The new ceramic matrix composites should prevent cracking and delamination, and enhance the efficiency of gas turbines and energy efficiency. Potential applications include high temperature gas turbine nozzles, vanes, liners, and blades, as well as non-lubricated sliding fits, rotors and cases. Other commercial and defense applications include: (1) heat shields and boost motor components, (2) internal combustion and jet engines (as a replacement for steel and other metallic components), and (3) coating of components with very high surface hardness (since the method will increase surface hardness up to 10 on the Mohs scale, the hardness of diamond).