Showing papers on "Coating published in 1997"

Partially coated electrodes, manufacture and use

Abstract: A partially coated electrosurgical electrode has a portion of a medical grade metallic material as a substrate for energy application. Conductive of sites of metallic material or alloys thereof pass energy through peaks that define valleys nearby. A partial coating in the valleys has a low surface free energy. A treated surface across the peaks and generally over the filled valleys is relatively smooth for non stick characteristics during application of electrosurgery to tissue and bodily fluids. Openings in the treated surface through the partial coating are at the peaks of conductive sites to expose the metallic material or alloys thereof. The partial coating is a fluorinated polymer. The treated surface is a relatively even level that is not flat. The metallic material substrate is an alloy of stainless steel or nickel chrome. A mechanically deformed surface finish, plasma or vapor deposition on the substrate forms the conductive sites. A method of manufacturing the electrode has steps including preparing it the metallic conductor, making it with the conductive material having peaks above the valleys as conductive sites, applying the partial coating to it and treating the surface across the peaks and generally over the filled valleys of the partially coated electrically conductive electrode. Locating the openings among the valleys is a step. Treating may be mass finishing, such as vibratory or tumbling the partially coated electrodes with or without abrasive material media or polishing, buffing, surface grinding, abrasive belt grinding or sanding with abrasive material. Making the peaks and valleys can be by stamping, coining, burnishing, embossing, threading, tumbling, vibrating, shot peening, wire brushing, grit blasting, thermal spraying, with powder, with wire supplied to melt and be distributed, or with high velocity oxygen fuel and a nickel, cobalt alloy, stainless steel or a nickel chrome alloy. A manufacturing method for the electrode has coating a strip of metal with the low surface energy polymer and forming it in a stamping operation with a raw edge metal edge.

Medical devices with long term non-thrombogenic coatings

Abstract: A coating and method for implantable open lattice metallic stent prostheses are disclosed. The coating includes a relatively thin layer of biostable elastomeric material containing an amount of biologically active material, particularly heparin, dispersed in the coating in combination with a non-thrombogenic surface. In one embodiment, the surface is provided with sites of high electronegativity species by coating with fluorosilicone which aid in controlling elution, particularly the initial release rate, and reduced thrombogenic activity. Other non-thrombogenic outer layers for heparin such as covalently bound polyethylene glycol (PEG) are also disclosed.

Solid phase microextraction

Abstract: Solid Phase Microextraction (SPME) uses a small volume of sorbent dispersed typically on the surface of small fibres, to isolate and concentrate analytes from sample matrix. After contact with sample, analytes are absorbed or adsorbed by the fibre phase (depending on the nature of the coating) until an equilibrium is reached in the system. The amount of an analyteextracted by the coating at equilibrium is determined by the magnitude of the partition coefficient of the analyte between the sample matrix and the coating material. After the extraction step, the fibres are transferred, with the help of a syringe-like handling device, to analytical instrument, for separation and quantitation of target analytes. This technique integrates sampling, extraction and sample introduction and is a simple way of facilitating on-site monitoring. Applications of this technique include environmental monitoring, industrial hygiene, process monitoring, clinical, forensic, food, flavour, fragrance and drug analyses, in laboratory and on-site analysis.

Method of applying drug-release coatings

Abstract: The invention is directed to a method of applying drug-release coatings whereby a polymer can be dissolved in a first solvent (solvent A) to form a polymer system and a drug can be dissolved or suspended in a second solvent (solvent B) to form a drug system. The coating or layer of coating so formed comprises a substantially uniform combination of the drug and polymer. Solvent B can be the same as or different than solvent A. The coating can be applied on a stent body by separately spraying or dipping the polymer system and the drug system onto the devices. The coating can be accomplished by either applying the polymer and drug systems sequentially or simultaneously. In certain embodiments, a drug can be suspended in solvent B. In some cases, three or more systems can be utilized. For instance, a third system containing pure solvent A or B can smooth the coating surface, if the solvent of the third spraying system is compatible with the polymer matrix.

Thermal management system for L.E.D. arrays

Abstract: A method of manufacturing an electrically driven L.E.D. lamp assembly (10) comprising the steps of screen printing an electrically insulating coating (16) which can be of less than two hundred microns thickness over an electrically and thermally conductive heat sink, i.e., aluminum, and printing circuit traces 18 of a resin with metal dispersed therein in end to end relationship on the routes of insulating coating 16 to establish discrete and electrically conductive paths for electrically interconnecting light emitting diodes 20. The light emitting diodes 20 are adhesively secured to the ends of adjacent circuit traces 18 with an electrically conductive adhesive 26 comprising an organic polymeric material compounded with a metal.

Sol-gel coating technology for the preparation of solid-phase microextraction fibers of enhanced thermal stability.

Abstract: A novel sol-gel method is described for the preparation of solid-phase microextraction (SPME) fibers. The protective polyimide coating was removed from a 1-cm end segment of a 200 μm o.d. fused-silica fiber, and the exposed outer surface was coated with a bonded sol-gel layer of poly(dimethylsiloxane) (PDMS). The chemistry behind this coating technique is presented. Efficient SPME-GC analyses of polycyclic aromatic hydrocarbons, alkanes, aniline derivatives, alcohols, and phenolic compounds in dilute aqueous solutions were achieved using sol-gel-coated PDMS fibers. The extracted analytes were transferred to a GC injector using an in-house-designed SPME syringe that also allowed for easy change of SPME fibers. Electron microscopy experiments suggested a porous structure for the sol-gel coating with a thickness of ∼10 μm. The coating porosity provided higher surface area and allowed for the use of thinner coatings (compared with 100-μm-thick coatings for conventional SPME fibers) to achieve acceptable stationary-phase loadings and sample capacities. Enhanced surface area of sol-gel coatings, in turn, provided efficient analyte extraction rates from solution. Experimental results on thermal stability of sol-gel PDMS fibers were compared with those for commercial 100-μm PDMS fibers. Our findings suggest that sol-gel PDMS fibers possess significantly higher thermal stability (>320 °C) than conventionally coated PDMS fibers that often start bleeding at 200 °C. This is due, in part, to the strong chemical bonding between the sol-gel-generated organic-inorganic composite coating and the silica surface. Enhanced thermal stability allowed the use of higher injection port temperatures for efficient desorption of less-volatile analytes and should translate into extended range of analytes that can be handled by SPME-GC techniques. Experimental evidence is provided that supports the operational advantages of sol-gel coatings in SPME-GC analysis.

Biodegradable coating with inhibitory properties for application to biocompatible materials

Abstract: A method is disclosed for coating a biomaterial to be placed in contact with a patient's blood flow to inhibit blood coagulation from adhering to the biomaterial that would otherwise result from such contact. A biodegradable material of liquid state compatible with the blood and tissue of the human body is prepared, and an anti-coagulant drug is incorporated into the liquid state of the biodegradable material to form a liquid coating material. The liquid coating material is adhesively applied to a surface of the biomaterial in a substantially continuous overlying layer having a formulation, pattern and thickness selected according to the period of time over which the coating material is to perform its anti-coagulant action. Thereafter the coating material is dried to a layer thickness less than about 100 microns for continuous disintegration thereof as a function of time when the layer is in contact with flowing blood. The method is utilized in an exemplary embodiment in which the biomaterial is a vascular stent.

Sol-gel coatings on metals

Abstract: Sol-gel derived films can be deposited on metals to improve their resistance to oxidation and corrosion or to modify their surface properties. However, practical applications are limited by problems intrinsic to sol-gel processing or specific of coating/metal systems. Coatings aimed to improve oxidation and wet corrosion resistance have been the most studied. The results published in the literature show that sol-gel coatings may offer good protection against oxidation. More difficult is to achieve a protection against wet corrosion. An important aspect of the application of the sol-gel method for coating metallic objects is also the deposition technique.

Time-specific controlled release dosage formulations and method of preparing same

Abstract: The present invention provides a method of achieving the time-specific delivery of a pharmaceutically active agent to a patient in need of the therapeutic effects of the pharmaceutically active agent. The method includes administering a pharmaceutical formulation comprising (a) a core including the pharmaceutically active agent to be delivered, and (b) a swellable polymeric coating layer substantially surrounding the core. The swellable polymeric coating layer delays the release of the pharmaceutically active agent from the core for a predetermined period of time dependent upon the thickness of the swellable polymeric coating layer. The swellable polymeric coating layer surrounding the core is provided by a new method which includes alternately (I) wetting the core with a binder solution, and (ii) coating the core with powdered polymeric particles a sufficient number of times to produce a time-specific dosage formulation having the desired thickness of swellable polymeric coating layer.

Industrial applications of CrN (PVD) coatings, deposited at high and low temperatures

Abstract: Industrial applications of CrN (PVD) coatings are entering an expanding but selective range of mass manufactured goods. They may be prepared as single, low and high temperature CrN coatings and double TiN+CrN coatings. In this work, depositions of CrN at high temperatures were performed by a low voltage thermionic arc in a BAI 730M apparatus, while at low temperatures (below 250 °C), the plasma-beam sputtering process in a SPUTRON apparatus was used. We studied the following critical parameters that influence the quality of the coatings and applied the performance tests used in industrial practice: adhesion and scratching coefficient, microhardness, surface topography, oxidation and corrosion resistance. The performance tests were made with the assistance of technicians as well as in 12 Slovenian factories. CrN coatings were deposited at 480 °C for wear and corrosion protection in cold forming and cutting of copper in commutator manufacturing, in forming of aluminium components in automotive production and for surface improvement of moulds (made of H11 steel) in Al-Si die casting under pressure. Deposition temperatures of 180–220 °C, obtained in the SPUTRON apparatus, were required to improve cold forming tools made of alloyed tool steels (e.g. D2 and D3). The lowest obtainable temperature of 140 °C in the SPUTRON gave a CrN coating of high quality for practical use. These coatings were used to protect electrodeposited and electropolished nickel moulds (models) in artificial teeth production. Double TiN+CrN coatings were used as a highly abrasive resistant coating in the production of rotors (in the electromotor industry), and in cold forming and forging in mass manufacturing of screws. The results and performance tests were compared with the available data, mostly published on forming, milling, deep drawing of copper, nickel and titanium and their alloys, and on die casting of aluminium and Al-alloys.

Compositions and methods for coating medical devices

Abstract: The present invention provides compositions and methods for coating medical devices with pharmaceutical agents and devices coated with the compositions. The coated devices provide controlled or sustained release of pharmaceutical agents for the treatment of wounds or disease.

A review of methods for improving the interfacial adhesion between carbon fiber and polymer matrix

Abstract: The interfacial properties between carbon fibers and surrounding matrix of a composite are drastically affected by interfacial structure. This structure mainly relates to the surface physico-chemistry of the fiber, which includes its surface chemical groups and microstructure, morphology, surface area, and surface free energy. These properties can be changed by various surface treatments, including various dry and wet oxidation steps, plasma treatment, electrodischarge, and fiber sizing or coating. These methods improve the interfacial properties significantly and synergistically, although each treatment has its specific application area.

Method of providing a substrate with a bio-active/biocompatible coating

Abstract: Disclosed is a method of enhancing the biocompatibility of a substrate by providing the substrate with a continuous bio-active surface coating. This method includes applying to the substrate a first coating which includes an aqueous dispersion or emulsion of a polymer containing an organic acid functional group and an excess of a polyfunctional cross-linking agent which is reactive with the organic acid groups of the polymer. A continuous bio-active surface coating is then formed over the dried first coating by applying thereover a bio-active agent containing an organic acid functional group or metal salt thereof. The first and second coatings are then dried to covalently bond the organic acid functional groups of the bio-active agent to the polymer through the excess unreacted polyfunctional cross-linking agent.

Friction control of diamond-like carbon coatings

Abstract: The friction reduction of contacting surfaces in relative motion may be achieved through the use of solid lubricant coatings. The control of friction and wear through diamond-like carbon (DLC) coatings strongly depends on both the environmental conditions and the nature of the coating, as determined by the deposition process. The paper presents and discusses friction results linking the structure and composition of DLC coatings prepared by PACVD and varying precursor and bias, with physical and mechanical properties and tribological behavior in controlled environments. The wide range of the friction coefficients observed, from less than 0.01 to more than 0.5, and the different mechanisms involved are explained by the effects of the deposition process and tribological parameters.

LED structure with ultraviolet-light emission chip and multilayered resins to generate various colored lights

Abstract: The innovative LED structure of the present invention mixes certain materials which can change the wave length of light in the resin of a LED and enables the LED to generate a white light and lights of various other colors as well. The shortcomings of conventional LEDs may be improved upon. By coating different fluorescent materials on the surface of a ultra violet light LED chip, it is possible to obtain a LED able to emit various colored light.

Polypropylene–wood fiber composites: Effect of treatment and mixing conditions on mechanical properties

Abstract: Polypropylene/wood fiber composites were prepared at three different temperatures: 170°C, 180°C, and 190°C. The surface of wood fibers was modified through the use of silane coupling agents and/or coating with polypropylene or maleated polypropylene. The fiber coating was performed by propylene polymerization in the presence of wood fibers or by immersion in an o-dichlorobenzene polypropylene (or maleated polypropylene) solution. Tensile and three-point bending tests were performed in order to evaluate the adhesion between matrix and wood fibers. Evidence shows that 180°C is the best mixing temperature, while the use of vinyl-tris (2-methoxy ethoxy) silane with or without maleated polypropylene coating is the best surface treatment. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1227–1235, 1997

Implantable medical device formed from a refractory metal having a thin coating disposed thereon

Abstract: An implantable medical device formed from a drawn refractory metal and having an improved biocompatible surface is described. The method by which the device is made includes coating a refractory metal article with platinum by a physical vapor deposition process and subjecting the coating article to drawing in a diamond die. The drawn article can be incorporated into an implantable medical device without removing the deposited metal.

Service life of Ti/SnO2-Sb2O5 anodes

Abstract: The service life of SnO2–Sb2O5 coated anodes prepared by the spray pyrolysis technique using Ti or Ti/IrO2 substrate, was studied under galvanostatic conditions (100mAcm–2 in 1m H2SO4 at 25°C. The results showed that the presence of an IrO2 interlayer between the Ti substrate and the SnO2–Sb2O5 coating (Ti/IrO2/SnO2–Sb2O5 anode) strongly increases the service life of the anode. This beneficial action of the IrO2 interlayer was attributed to its high anodic stability and its isomorphous structure with TiO2 and SnO2. Cyclic voltammetry and steady-state polarization curves showed that the electrochemical behaviour of the Ti/IrO2/SnO2–Sb2O5 electrode lies between the behaviour of the Ti/IrO2 and the Ti/SnO2–Sb2O5 electrodes due to incorporation of IrO2 in the SnO2–Sb2O5 coating during its preparation.

Derivatization/Solid-Phase Microextraction: New Approach to Polar Analytes

Abstract: Trace analysis of fatty acids in water and/or air was enhanced by coupling solid-phase microextraction (SPME) with derivatization of the target analytes to less polar and more volatile species prior to GC analysis. Derivatization was performed in three ways: in the sample matrix, in the SPME fiber coating, and in the GC injector port. Derivatization converts polar analytes into less polar analogues, therefore increasing their coating/water or coating/gas partition coefficients and improving SPME efficiency and method sensitivity. Derivatization changes analytes with low volatilities into more volatile derivatives, thus improving their GC separations, detection, and quantitation. Pentafluorobenzyl bromide and (pentafluorophenyl)diazoethane (PFPDE) were used to derivatize short-chain fatty acids directly in sample matrices for selective and sensitive ECD detection. Diazomethane and pyrenyldiazomethane (PDAM) were used for effective in-fiber derivatization of long-chain and short-chain fatty acids, respecti...

Hydrophilic, swellable coatings for biosensors

Abstract: Methods for reducing the electrode impedance of implantable biosensors by coating the surface of the biosensor with a uniform hydrogel which allows unimpeded water movement around the sensor are provided. The surface coatings are compositions which are biocompatible and are capable of water uptake of at least 120% of their weight, more preferably at least 200% of their weight. Upon the uptake of water, the hydrogels used in the present invention will also swell and provide a layer of water around the electrodes to which the hydrogels are attached. The hydrogels can be prepared from (a) a diisocyanate, (b) a hydrophilic polymer which is a hydrophilic diol, a hydrophilic diamine, or a combination thereof, and optionally, (c) a chain extender.

A thermal barrier coating for a superalloy article and a method of application thereof

Abstract: A multi-layer thermal barrier coating (42) for a superalloy article (40) comprises a platinum enriched superalloy layer (44), an MCrAlY bond coating (46) on the platinum enriched superalloy layer (44), a platinum enriched MCrAlY layer (48) on the MCrAlY bond coating (46), a platinum aluminide coating (50) on the platinum enriched MCrAlY layer (48), an oxide layer (54) on the platinum aluminide coating (50) and a ceramic thermal barrier coating (56) on the oxide layer (54). The platinum aluminide coating (50) and the platinum enriched MCrAlY layer (48) reduce movement of transition metals from the superalloy substrate (40) and the MCrAlY bond coating (46) to the oxide layer (54) so that the oxide layer is very pure alumina. The platinum enriched superalloy layer (44) reduces movement of aluminium from the MCrAlY bond coating (46) to the superalloy substrate (40) so that the oxide layer (54) remains pure alumina to improve long term adhesion of the ceramic thermal barrier coating (56), and additionally reduces movement of transition metals from the superalloy substrate (40) to the oxide layer (54).

Liquid film coating : scientific principles and their technological implications

Abstract: Part I: Physics of coating processes: capillary hydrodynamics and interfacial phenomena wetting: static and dynamic contact lines surfactancy coating rheology setting, drying and curing: heat and mass transfer and phase behavior. Part II: Methods of investigating coating processes: experimental methods and flow visualization asymptotic methods of mathematical analysis computational methods. Part III: Theory and practice of coating processes: analysis and design of coating dies pre-metered coating processes self-metering coating processes free-meniscus coating processes elasto-hydrodynamic coating systems flow after coating analysis and design of drying equipment optimization and control of coating processes.