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Topic: Pyrolytic carbon

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	15.3.3.2
		Originally developed in the early 1960s by Gulf General Atomic as a coating for nuclear fuel rods [938, 1038-1040], pyrolytic carbon is formed in a fluidized bed by the pyrolysis of a gaseous hydrocarbon such as methane depositing carbon onto a preformed substrate such as polycrystalline graphite at 1000-1500 K [903, 955].
		For example, in one experiment [813] mechanical heart valves with pyrolytic carbon surface were implanted in the mitral position of sheep without the administration of post-operative anticoagulants or antiplatelet agents for 2, 4, and 6 weeks, then were removed and examined by scanning electron microscopy.
		Pyrolytic carbon is also a biologically compatible material for arthroplasty of diseased finger joints [817].
	www.nanomedicine.com /NMIIA/15.3.3.2.htm (1440 words)

	Pebble bed reactor - Wikipedia, the free encyclopedia
		Instead of water, it uses pyrolytic graphite as the neutron moderator, and an inert or semi-inert gas such as helium, nitrogen or carbon dioxide as the coolant, at very high temperature, to drive a turbine directly.
		The concept was enabled by the realization that engineered forms of silicon carbide and pyrolytic carbon were quite strong, even at temperatures as high as 2000 °C (3600 °F).
		The precipitation of the pyrolytic graphite is by a mixture of argon, propylene and acetylene in a fluidized-bed coater at about 1275 °C. The fluidized bed moves gas up through the bed of particles, "floating" them against gravity.
	en.wikipedia.org /wiki/Pebble_bed_reactor (4292 words)

	Process for producing articles of carbon-silicon carbide composite material and carbon-silicon carbide composite ...
		At the crystallization step of pyrolytic carbon deposited in the coke matrix pores and on the fibers, there occurs an increase in the pyrolytic carbon reactivity required for a rapid formation of SiC while siliconizing, and thereby for preventing the silicon access to the carbon fibers, which are not intended to convert into silicon carbide.
		Generally, the pyrolytic carbon densification parameters are chosen depending on the methane content in the city gas, the furnace size, and the charge amount, as well as on the required degree of the preform infiltration with pyrolytic carbon.
		The pyrolytic carbon deposited in the pore space of the carbonized preform consists of stacks of graphitic layers disposed along the pore perimeters, in the material coke matrix, and in the intertow space of the fibrous basis.
	www.freepatentsonline.com /5635300.html (3440 words)

	OhioLINK ETD: VAN WINKLE, MICHAEL
		The intent of the project is to determine the feasibility of using pyrolytic carbon as a suitable material for a left ventricle assist device (LVAD).
		On average, the titanium alloy cable interface caused 2.155 x10-5cm3 of wear on the pyrolytic carbon chip during the course of experimentation.
		Pyrolytic carbon was found to be a suitable material for a LVAD using the appropriate cable interface.
	www.ohiolink.edu /etd/view.cgi?ucin1085776125 (277 words)

	Power transmission and energy absorbing systems - Patent 4291794
		Carbon composite friction membrane--a thin membrane consisting of a fibrous material, the fibers of which may be carbonized or graphitized; a pyrolytic material deposited interstitially of the fibrous material; and, for certain applications, a supplementary carbonaceous binder material impregnated into the fibrous material.
		Various pyrolytic materials may be used in densifying the starting substrate of the present invention including pyrolytic carbon, pyrolytic graphite, certain nitrides such as boron nitride, certain refractory metals such as tantalum, tungsten, molybdenum and columbium, as well as certain carbides including tantalum carbide, niobium carbide, zirconium carbide, hafnium carbide and silicon carbide.
		As earlier discussed, the nature of material with which the carbon composite friction material of the invention interfaces comprises one of the criteria for determining the manner in which the substrate is infiltrated and the manner in which the composite thus formed is subsequently worked or treated.
	www.freepatentsonline.com /4291794.html (4935 words)

	Pebble bed reactor -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-22)
		The concept was enabled by the realization that engineered forms of silicon carbide and pyrolytic carbon were quite strong, even at temperatures as high as 2000 °C. The natural geometry of close-packed spheres then provides the ducting (the spaces between the spheres) and spacing for the reactor core.
		The layer of porous pyrolytic graphite right next to the fissionable ceramic absorbs the radioactive gases (mostly (A colorless odorless inert gaseous element occurring in the earth's atmosphere in trace amounts) xenon) emitted when the heavy elements split.
		The silicon carbide coating is precipitated from a mixture of (A nonmetallic univalent element that is normally a colorless and odorless highly flammable diatomic gas; the simplest and lightest and most abundant element in the universe) hydrogen and methyltrichlorosilane.
	www.absoluteastronomy.com /encyclopedia/p/pe/pebble_bed_reactor.htm (4014 words)

	[No title] (Site not responding. Last check: 2007-10-22)
		The phosphate is reduced by the carbon reductant to elemental phosphorus, which is evolved as a vapor from the molten reaction mass.
		Various carbons, especially pyrolytic carbons such as coal and petroleum cokes in particulate form, are suitable for use as the carbon reductant.
		Excess carbon and ash are continuously removed from the bottom of the reactor using a double air lock.
	www.wipo.int /cgi-pct/guest/getbykey5?KEY=01/25147.010412&ELEMENT_SET=DECL (3549 words)

	[No title] (Site not responding. Last check: 2007-10-22)
		is porous and of low density ; densifying the carbonized component by depositing carbon in the pores of the component ; and heating the densified carbonized component in an inert atmosphere for graphitizing and removing impurities from the component, wherein the component has a coefficient of friction in the range of 0.
		Carbon reinforcements may also take the form of continuous filament yarn, chopped yarn, or tape made from continuous filaments and which are referred to as unidirectional arrays of fibers.
		The carbonized or pyrolyzed component is processed by the addition of pyrolytic carbon using chemical vapor infiltration of hydrocarbon gases (methane, ethane, propane, and the like and mixtures thereof) under conditions sufficient to achieve a final density of preferably from about 1.
	www.wipo.int /cgi-pct/guest/getbykey5?KEY=00/35669.001130&ELEMENT_SET=DECL (3984 words)

	United States Patent Application: 0030099836
		A thermal management device comprising anisotropic carbon encapsulated in an encapsulating material that is applied directly to the anistropic carbon and improves the rigidity of the carbon, preferably wherein the encapsulating material is polyimide or epoxy resin or acrylic or polyurethane or polyester or any other suitable polymer.
		The carbon plate may have a thickness in the range of 200-250.mu.m or 250-300.mu.m or 300-350.mu.m or 350-400.mu.m or 400-450.mu.m or 450-500.mu.m.
		This is typically thermalised pyrolytic graphite with mosaic or full ordering, with an in plane thermal conductivity (indicated by arrow A) of 1550-1850W/mK and a thermal conductivity of 825W/mK in the orthogonal direction (indicated by arrow B), with both directions having low values of tensile strength.
	appft1.uspto.gov /netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=/netahtml/PTO/search-bool.html&r=1&f=G&l=50&co1=AND&d=PG01&s1=20030099836.PGNR.&OS=DN/20030099836&RS=DN/20030099836 (6344 words)

	SwRI Summer 1999 Technology Today Article
		But for a reason yet to be known, pyrolytic carbon and other so-called blood-compatible coatings are unrecognized by the body and accepted.
		Pyrolytic Properties) by which the material is created generates, as a by-product, small (micrometer scale) internal cracks within the PyC near the parent graphite substrate.
		Small disks of pyrolytic carbon on graphite substrates, of the same composition, overall size, and substrate-coating dimensions as that characteristic of commercial heart valves, were used to simulate crack initiation in such valves.
	www.swri.org /3pubs/ttoday/summer99/valve.htm (2452 words)

	Mingxuan Jiang (Site not responding. Last check: 2007-10-22)
		Pyrolytic carbon coatings were successfully deposited on graphite and molybdenum substrates from benzene and cyclohexane precursors.
		The goal was to demonstrate the feasibility of using the liquid reagent CVD process to deposit pure pyrolytic carbon that possesses the microstructures and properties required for mechanical heart valves.
		The crystallite size of the pyrolytic carbon was about 20-30 Å for a deposition temperature range of 950-1150°C. TEM micrographs revealed that the deposit was of the desired turbostratic nodular structure with low texture.
	www.me.gatech.edu /me/theses/Jiang2.html (215 words)

	General Atomics News
		Pyrolytic carbon, the premier material for artificial heart valves was discovered in 1966 at General Atomics by Dr. Jack Bokros and by Dr. Vincent Gott, then at the University of Wisconsin.
		Bokros was using pyrolytic carbon to coat nuclear fuel particles for the GA gas-cooled nuclear power reactors more than 30 years ago.
		This endeavor was successful and the biomedical grade of pyrolytic carbon, known as Pyrolite¨, was rapidly incorporated into the existing heart valve designs.
	www.ga.com /news.php?subaction=showfull&id=988790400&archive=&start_from=&ucat=& (547 words)

	Pyrolytic Carbon for Biomedical Applications
		Pyrolytic carbon belongs to the family of turbostratic carbons, which have a similar structure to graphite.
		Pyrolytic carbon and other turbostratic carbons differ in that the layers are disordered, resulting in wrinkles or distortions within layers.
		Pyrolytic carbon coatings are made by co-depositing carbon and silicon carbide onto suitable substrates using chemical vapour deposition processes.
	www.azom.com /details.asp?ArticleID=1463 (428 words)

	Carbon. (Site not responding. Last check: 2007-10-22)
		Reznik, K.J. Hüttinger, On the terminology for pyrolytic carbon, Carbon 40 (4) (2002) pp.
		Xavier Bourrat, Jerome Lavenac, Francis Langlais, Roger Naslain, The role of pentagons in the growth of laminar pyrocarbon, Carbon 39 (15) (2001) pp.
		A.M. Puziy, O.I. Poddubnaya, The properties of synthetic carbon derived from nitrogen- and phosphorus-containing polymer, Carbon 36 (1-2) (1998) pp.
	www.elsevier.com /cdweb/journals/00086223/viewer.htt?viewtype=keywords&rangeselected=15 (2260 words)

	Carbon Rods for Carbon Evaporation, Carbon Rod Sharpener
		Carbon films are uniformly amorphous and highly transparent to electrons because carbon has a low atomic weight.
		This may be explained by the deflection of light carbon atoms out of straight-line flight by collisions with gas molecules and with the walls or obstructions in a vacuum chamber.
		Carbon and graphite rods are offered in either spectroscopic or technical grades for standard microscopy evaporation requirements and for carbon coaters.
	www.tedpella.com /carbon_html/carbon1.htm (638 words)

	Graphite intercalation compound electrodes for rechargeable batteries and a method for the manufacture of the same - ...
		This invention relates to electrodes of a rechargeable battery, wherein an active material for said electrode is pyrolytic graphite into which alkali metals, alkaline earth metals, rare earth metals, or transition metals are intercalated as an electron-donor type dopant, or halogens, halogen compounds, or oxygen acids are as an electron-acceptor type dopant.
		It may be possible to deposit pyrolytic carbon on a conductive substrate of aluminium, copper, etc., by the chemical vapor-deposition (CVD) method, etc., so as to form an electrode.
		In this example, 1 M lithium perchlorate was used as an electrolyte and propylene carbonate was used as a solvent for the electrolyte.
	www.freepatentsonline.com /4863818.html (2789 words)

	Method for making a carbon-carbon composite - US Patent 5837081 (Site not responding. Last check: 2007-10-22)
		The method of the present invention is cost-effective and efficient as the use of vapor grown carbon fiber mats eliminates the need to mechanically weave individual grown fibers into a mat prior to their use as reinforcements in a carbon composite.
		Densification of the vapor grown carbon fiber mat preform with pyrolytic carbon may be accomplished by conventional methods including chemical vapor infiltration and pitch infiltration.
		The formation of pyrolytic carbon is characterized by development of basal graphitic planes in the same method orientation as the carbon fibers.
	www.patentstorm.us /patents/5837081.html (3378 words)

	Articles - Graphite (Site not responding. Last check: 2007-10-22)
		In its pure glassy (isotropic) synthetic forms, pyrolytic graphite and carbon fiber graphite is an extremely strong, heat-resistant (to 3000 Â°C) material, used in reentry shields for missile nosecones, solid rocket engines, high temperature reactors, brake shoes and electric motor brushes.
		Carbon fiber and carbon nanotubes are also used to graphite reinforced plastics, and in heat-resistant composites such as reinforced carbon-carbon (RCC)).
		The mechanical properties of carbon fiber graphite-reinforced plastic composites and grey cast iron are strongly influenced by the role of graphite in these materials.
	www.cbasket.com /articles/Graphite (549 words)

	SPI Supplies® Brand Pyrolytic Graphite Planchets
		The particular type of pyrolytic graphite offered presently by SPI Supplies is of the type that is "substrate nucleated" or sometimes referred to as "SN Grade".
		Most forms of carbon have associated with them high background radiation levels in an EDS spectra, thereby reducing the sensitivity for a high precision analysis.
		A good alternative would be the SPI Diamond Planchets, since carbon in the form of diamond has a very low level of Bremsstrahlung radiation, and approaches that of beryllium.
	www.2spi.com /catalog/mounts/pyrolytic.shtml (312 words)

	ATS MEDICAL INC - ATSI Quarterly Report (10-Q) ITEM 2. Management's Discussion and Analysis of Financial ...
		Pyrolytic carbon, which is the substrate used in manufacturing our valves, has been the only material used to manufacture mechanical heart valves for humans for many years and remains the most advanced raw material for our products.
		We purchased pyrolytic carbon components under a long-term supply agreement with Carbomedics, Inc. (formerly Sulzer Carbomedics, Inc.) through June 2002 and we are required to resume purchases of such components in 2007.
		Because the pyrolytic carbon components are made to meet the unique specifications of the ATS heart valve, our inventory may have little, if any, value in the open market.
	sec.edgar-online.com /2004/05/10/0000950134-04-007063/section8.asp (5907 words)

	Method for producing a ceramic matrix composite material having improved toughness - US Patent 5079039 (Site not responding. Last check: 2007-10-22)
		The method of claim 7 wherein the step of depositing the layer comprised of material selected from the group consisting of pyrolytic carbon and boron nitride further includes changing the heat and pressure in said oven.
		It is particularly advantageous to use for the lower-rigidity interfacial layer(s) a material chosen among boron nitride and pyrolytic carbon, especially laminar pyrolytic carbon, since such a material has a high elastic shear stress.
		In the present example, the matrix is obtained by successive depositions of a silicon carbide (SiC) layer on the fibers of the reinforcement fiber, followed by a laminar pyrolytic carbon (PyC) interfacial layer and, finally, a new SiC layer.
	www.patentstorm.us /patents/5079039.html (2365 words)

	Refs800-899
		Neugebauer, L. Claes, “The biological reaction of the tissues to carbon fibre ligament prosthesis in sheep-knees,” Aktuelle Probl.
		Wolter, “Biocompatibility of carbon fibre and carbon fibre microparticles,” Aktuelle Probl.
		E.M. Attwood, D.J. Weich, J.M. Oosthuizen, “Influence of carbon particles on superoxide and hydrogen peroxide radical release during the killing of Mycobacterium bovis by alveolar macrophages,” Tuber.
	www.nanomedicine.com /NMIIA/Refs800-899.htm (2196 words)

	Carbon in Heart Valves (Site not responding. Last check: 2007-10-22)
		Pyrolytic carbon is a form of carbon originally developed for the nuclear fuels industry in the 1960's.
		These pyrolytic carbons have been alloyed with silicon carbide to maintain consistent hardness.
		With the invention of pure On-X carbon, the silicon biocompatibility compromise is a thing of the past.
	www.mcritx.com /carbon_valves.htm (243 words)

	Carbon-Carbon Composites, Carbon Fiber Overcoated - The Pyrogenics Group (Site not responding. Last check: 2007-10-22)
		Carbon-Carbon composites are various forms of carbon fiber based preforms,which are reinforced by chemical vapor infiltration (CVI), using high temperature vacuum furnaces.
		Another area is glass forming and handling, where carbon composites, in addition to being glass friendly, have low porosity and high thermal stability.
		Being a high purity carbon material, it does not leave a residue.
	www.pyrographite.com /carb.htm (202 words)

	OST1997AR (Site not responding. Last check: 2007-10-22)
		A model to assess the potential for degradation of implant materials in an in vitro oxidizing environment was developed using pyrolytic carbon as a test material.
		Pyrolytic carbon was chosen because of its importance in cardiovascular applications.
		The model involves treating the pyrolytic carbon with various oxidative chemicals that occur as a result of cell activation, such as bleach, superoxide, and hydrogen peroxide, as well as, human monocyte-derived macrophages.
	www.fda.gov /CDRH/ost/rpt97/OST1997AR44.HTML (269 words)

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