http://SaturnianCosmology.Org/ mirrored file For complete access to all the files of this collection see http://SaturnianCosmology.org/search.php ========================================================== Glassy carbon From Wikipedia, the free encyclopedia *Glassy carbon*, also called *vitreous carbon*, can be fabricated as different shapes, sizes and sections, is a non-graphitizing carbon which combines glassy and ceramic properties with those of graphite. The most important properties are high temperature resistance, hardness (7 Mohs ), low density, low electrical resistance, low friction, low thermal resistance, extreme resistance to chemical attack and impermeability to gases and liquids. Glassy carbon is widely used as an electrode material in electrochemistry , as well as for high temperature crucibles and as a component of some prosthetic devices. Contents [hide <#>] * 1 Production <#Production> * 2 Structure <#Structure> * 3 Electrochemical properties <#Electrochemical_properties> * 4 See also <#See_also> * 5 References <#References> * 6 External links <#External_links> [edit ] Production It was first observed in the laboratories of The Carborundum Company , Trafford Park, Manchester, UK, in the mid 1950's by Bernard Redfern (BR) the inventor, a materials scientist and diamond technologist. He noticed that Sellotape he used to hold ceramic (rocket nozzle) samples in a furnace maintained a sort of structural identity after firing in an inert atmosphere. He searched for a polymer matrix to mirror a diamond structure and discovered a resole resin that would, with special preparation, set without a catalyst. Using this phenolic resin, crucibles were produced. Crucibles were distributed to organisations such as UKAEA Harwell. BR left the Carborundom Co., which officially wrote off all interests in the glassy carbon invention. Whilst working at the Plessey Company laboratory (a disused church!) in Towcester, UK, BR received a glassy carbon crucible for duplication from UKAEA. He identified it as one he had made from markings he had engraved into the uncured precursor prior to carbonisation. (It is almost impossible to engrave the finished product.) The Plessey Company set up a laboratory first in a factory previously used to make briar pipes, in Litchborough, UK, and then a permanent facility at Caswell, near Blakesly, UK. Caswell became the Plessey Research centre and then the Alan Clark research Centre. Glassy carbon arrived at the Plessey Company Limited as a fait accompli. BR was assigned J. C. Lewis, as a laboratory assistant, for the production of glassy carbon. F. C. Cowlard was assigned to BR department later, as an laboratory administrator. Cowlard was an administrator who previously had some association with Silane (Silane US Patent assignee 3,155,621 3 Nov 1964). Neither he nor Lewis had any previous connection with glassy carbon. Large sections of the precursor material were produced as castings, moldings or machined into a predetermined shape. Large crucibles and other forms were manufactured. Carbonisation took place in two stages. Shrinkage during this process is considerable (48.8%) but is absolutely uniform and predictable. A nut and bolt can be made to fit as the polymer, processed separately and subsequently give a perfect fit. UK patent application were filed in 11 Jan.1960 and US patent filed 9 Jan. 1961 (finalised as US patent 3,109,712). This prior art is not referenced in US patent 4,668,496, 26 May 1987 for Vitreous Carbon. Some of the first ultrapure samples of Gallium Arsenide were zone refined in these crucibles. (Glassy carbon is extremely pure and unreactive to GaAs). Doped/impure glassy carbon exhibited semiconductor phenomena. Uranium carbide inclusions were fabricated (using U238 carbide at experimental scale). Patents were filed "Bodies and shapes of carbonaceous materials and processes for their production" and the name "Vitreous Carbon" presented to the product by the son of BR. Glassy/Vitreous Carbon was under investigation used for components for thermonuclear detonation systems and at least some of the patents surrounding the material were rescinded (in the interests of national security) in the 1960s. Despite his majority contribution to the research, invention, development and production of glassy / Vitreous carbon, references to Bernard Redfern were not obvious in subsequent publications by Mssrs F. C. Cowlard and J. C. Lewis.^[1] <#cite_note-0> Original boat crucibles and precursor samples exist. [edit ] Structure The structure of glassy carbon has long been a subject of debate. Early structural models assumed that both sp^2 - and sp^3 -bonded atoms were present, but it is now known that glassy carbon is 100% sp^2 . However, more recent research has suggested that glassy carbon has a fullerene -related structure.^[2] <#cite_note-1> Note that glassy carbon should not be confused with amorphous carbon . This from IUPAC: "Glass-like carbon cannot be described as amorphous carbon because it consists of two-dimensional structural elements and does not exhibit ‘dangling’ bonds."^[3] <#cite_note-2> It exhibits a conchoidal fracture . [edit ] Electrochemical properties Glassy carbon electrode (GCE) in aqueous solutions is considered to be an inert electrode for hydronium ion reduction:^[4] <#cite_note-Sawyer-3> H_3 O^+ _(aq) + e^- \rm \stackrel{GCE} {\rightleftharpoons} H\cdot_(aq) E^o = −2.10 V versus NHE at 25 °C Comparable reaction on platinum: H_3 O^+ _(aq) + Pt_(s) + e^- \rightleftharpoons Pt:H_(s) E^o = 0.000 V versus NHE at 25 °C The difference of 2.1 V is attributed to the properties of platinum which stabilizes a covalent Pt-H bond.^[4] <#cite_note-Sawyer-3> [edit ] See also * Graphite * Electrochemistry * Fullerenes [edit ] References 1. *^ <#cite_ref-0>* Cowlard, F. C.; Lewis, J. C. (1967). "Vitreous carbon — A new form of carbon". /Journal of Materials Science/ *2* (6): 507–512. doi :10.1007/BF00752216 . 2. *^ <#cite_ref-1>* Fullerene-related structure of commercial glassy carbons , P.J.F. Harris, 2003. 3. *^ <#cite_ref-2>* The entry for "Glass-like carbon" in IUPAC Goldbook. 4. ^ ^/*a*/ <#cite_ref-Sawyer_3-0> ^/*b*/ <#cite_ref-Sawyer_3-1> D.T. Sawyer, A.Sobkowiak, J.L. Roberts Jr., "Electrochemistry for Chemists, Second Edition", John Wiley & Sons, Inc., 1995. [edit ] External links * HTW, supplier's website , for Glassy Carbon SIGRADUR