Novel Carbon Films for Next Generation Rotating Equipment Applications

This report describes the results of research performed on a new generation of low friction, wear resistant carbon coatings for seals and bearings in high speed rotating equipment. The low friction coatings, Near Frictionless Carbon (NFC), a high hydrogen content diamondlike carbon, and Carbide Derived Carbon (CDC), a conversion coating produced on the surfaces of metal carbides by halogenation, can be applied together or separately to improve the performance of seals and bearings, with benefits to energy efficiency and environmental protection. Because hard carbide ceramics, such as silicon carbide, are widely used in the seals industry, this coating is particularly attractive as a low cost method to improve performance. The technology of CDC has been licensed to an Illinois company, Carbide Derivative Technologies, Inc. (CDTI) to implement the commercialization of this material

Nano-structured carbide-derived carbon films and their tribology

Tsinghua Science and Technology, 10(6): pp. 699-703. Retrieved March 13, 2006 from http://nano.materials.drexel.edu/Papers/CDC_Tibology_TSINGHUA.pdf. DOI: http://dx.doi.org/10.1016/S1007-0214(05)70138-3Carbide-derived carbon (CDC) is a form of carbon produced by reacting metal carbides, such as SiC or TiC, with halogens at temperatures high enough to produce fast kinetics, but too low to permit the re-arrangement of the carbon atoms into an equilibrium graphitic structure. The structure of CDC is derivative of the original carbide structure and contains nanoscale porosity and both sp2 and sp3 bonded carbon in a variety of nanoscale structures. CDC can be produced as a thin film on hard carbides to improve their tri-bological performance. CDC coatings are distinguished by their low friction coefficients and high wear resis-tance in many important industrial environments and by their resistance to spallation and delamination. The tribology of CDC coatings on SiC surfaces is described in detail

Fluid dynamics and mass transfer in vertical submerged gas jets.

Thesis. 1977. Ph.D.--Massachusetts Institute of Technology. Dept. of Materials Science and Engineering.MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE.Vita.Includes bibliographical references.Ph.D

Investigation of Dynamic Oxygen Adsorption in Molten Solder Jetting Technology

Surface tension forces play a critical role in fluid dynamic phenomena that are important in materials processing. The surface tension of liquid metals has been shown to be very susceptible to small amounts of adsorbed oxygen. Consequently, the kinetics of oxygen adsorption can influence the capillary breakup of liquid-metal jets targeted for use in electronics assembly applications, where low-melting-point metals (such as tin-containing solders) are utilized as an attachment material for mounting of electronic components to substrates. By interpreting values of surface tension measured at various surface ages, adsorption and diffusion rates of oxygen on the surface of the melt can be estimated. This research program investigates the adsorption kinetics of oxygen on the surface of an atomizing molten-metal jet. A novel oscillating capillary jet method has been developed for the measurement of dynamic surface tension of liquids, and in particular, metal melts which are susceptible to rapid surface degradation caused by oxygen adsorption. The experimental technique captures the evolution of jet swells and necks continuously along the jet propagation axis and is used in conjunction with an existing linear, axisymmetric, constant-property model to determine the variation of the instability growth rate, and, in turn, surface tension of the liquid as a function of surface age measured from the exit orifice. The conditions investigated so far focus on a time window of 2-4ms from the jet orifice. The surface properties of the eutectic 63%Sn-37%Pb solder alloy have been investigated in terms of their variation due to O2 adsorption from a N2 atmosphere containing controlled amounts of oxygen (from 8 ppm to 1000 ppm). The method performed well for situations where the oxygen adsorption was low in that time window. The value of surface tension for the 63Sn-37Pb solder in pure nitrogen was found to be 0.49 N/m, in good agreement with previously published work. A characteristic time of O(1ms) or less was determined for the molten-metal surface to be saturated by oxygen at 1000 ppm concentration in N2

Effect Of Hydrogen On The Physical And Mechanical Properties Of Silicon Carbide-Derived Carbon Films

In this study, the effect of hydrogen on the structure and mechanical properties of carbon films produced by selective etching of monolithic SiC was examined. The process to produce carbon films from SiC (i.e., SiC-derived carbon, CDC) was carried out in a gas mixture of Cl2 and H2 at 1000 °C for 20 h. The Raman intensity ratio, ID/IG, where subscripts D and G refer to diamond and graphite, decreased as the hydrogen concentration in the gas mixture increased, indicating a decrease in the sp2 carbon cluster. XRD analysis also showed that the fraction of graphitization decreased as the hydrogen concentration increased. The addition of hydrogen that prevented the formation of graphite (sp2 bonding) also resulted in a reduction in the film thickness. The hardness and elastic modulus of the carbon films tended to decrease as the H2 content increased owing to the contribution from the C-H bond and the nano-size pore. © 2009 Elsevier B.V. All rights reserved

Nano-structured carbide-derived carbon films and their tribology

Das US-Holocaust-Museum in Washington hat eine neue Online-Datenbank in Betrieb genommen, die den Zugang zu den Dokumenten seines Archivs erleichtern soll. Die Internetseite http://WorldMemoryProject.org solle den Zugang zu Informationen über jüdische und nicht-jüdische Opfer des Holocaust verbessern, teilte das Museum mit. Das Archiv des Museums umfasst demnach Dokumente zu 17 Millionen Menschen, die von den Nationalsozialisten verfolgt wurden."Das World Memory Project wird die Zugänglichkei..