Showing papers on "Coating published in 1998"

Drug coating with topcoat

Abstract: A coating and method for a coating an implantable device or prostheses are disclosed. The coating includes an undercoat of polymeric material containing an amount of biologically active material, particularly heparin, dispersed therein. The coating further includes a topcoat which covers less than the entire surface of the undercoat and wherein the topcoat comprises a polymeric material substantially free of pores and porosigens. The polymeric material of the topcoat can be a biostable, biocompatible material which provides long term non-thrombogenicity to the device portion during and after release of the biologically active material.

Progress in coatings for gas turbine airfoils

Abstract: The development of ever more efficient gas turbines has always been paced by the results of research and development in the concurrent fields of design and materials technology. Improved structural design and airfoil cooling technology applied to higher strength-at-temperature alloys cast by increasingly complex methods, and coated with steadily improved coating systems, have led to remarkably efficient turbine engines for aircraft propulsion and power generation. For first stage turbine blades, nickel-based superalloys in various wrought and cast forms, and augmented by coatings since the 1960s, have been singularly successful materials systems for the past 50 years—and still no real world substitutes are on the horizon. This paper traces the history of protective coatings for superalloy airfoils beginning with the simple aluminides, followed by modifications with silicon, chromium and platinum, then MCrAlY overlay coatings, and finally the elegant electron beam vapor deposited ceramic thermal barrier coatings recently introduced to service. The publicly available results of several decades of research supporting these advances are highlighted. These include generic research on oxidation and hot corrosion mechanisms of superalloys and coatings, the intricacies of protective oxide adherence, mechanisms of low temperature (Type II) hot corrosion, and of aluminide coating formation and mechanical properties of alloy–coating systems. With no promising turbine materials beyond coated nickel-base superalloys apparent in the foreseeable future, continued progress will likely be made by further refinement of control of thermally grown oxide adherence, and by more cost effective manufacturing processes for contemporary types of protective coatings.

Drug-releasing coatings for medical devices

Abstract: The invention is directed to medical devices having a drug-releasing coating and methods for making such coated devices. The coating permits timed or prolonged pharmacological activity on the surface of medical devices through a reservoir concept. Specifically, the coating comprises at least two layers: an outer layer containing at least one drug-ionic surfactant complex overlying a reservoir layer containing a polymer and the drug which is substantially free of an ionic surfactant. Upon exposure to body tissue of a medical device covered with such coating, the ionically bound drug in the outer layer is released into body fluid or tissue. Following release of such bound drug, the ionic surfactant binding sites in the outer layer are left vacant. To maintain the pharmacological activity after delivery of the ionically bound drug, additional amounts of the drug are embedded or incorporated in the reservoir layer in a manner which allows the drug, which is substantially free of ionic surfactants, to complex with the vacant binding sites of the ionic surfactant of the outer layer. As a result, the surface of the medical device is enriched with the drug to provide sustained pharmacological activity to prevent the adverse reaction due to the presence of the medical device. The invention is further directed to medical devices with stabilized drug-releasing coatings. The coatings are stabilized by exposure to a low energy, relatively non-penetrating energy source, e.g., gas plasma or an electron beam energy source.

Ink jet recording sheet

Abstract: PROBLEM TO BE SOLVED: To provide an ink jet recording sheet excellent in image concealability and coating film strength and suitable for a use of an outdoor advertisement such as a poster, a suspension curtain, a banner or a signboard, an indoor ornament or a dupulicating picture. SOLUTION: An ink absorbing layer consisting of an inorg. filler and a binder is laminated on the surface of a fiber base material and an image concealing layer is laminated to the rear surface thereof through an adhesive layer. In the ink absorbing layer, the compounding amt. of the binder is 50-200 pts.wt., pref., 80-150 pts.wt. per 100 pts.wt. of the inorg. filler and the binder is used much as compared with a conventional amt. to enhance coating film strength and to improve weatherability and water resistance.

Insecticidal seed coating

Abstract: The present invention relates to an insecticidal coating for a seed comprising one or more binders selected from the group consisting of polymers and copolymers of polyvinyl acetate, methyl cellulose, polyvinyl alcohol, vinylidene chloride, acrylic, cellulose, polyvinylpyrrolidone and polysaccharide and an insecticide and filler wherein the binder forms a matrix for the insecticide and filler resulting in a substantially non-phytotoxic seed coating; methods for producing said coating and the seed treated with the above described coating. Additionally the invention concerns a method of controlling soil-borne insect pests, particularly from the order of Coleoptera, such as Diabrotica spp., comprsing applying to a seed an insecticidal coating as described above.

Recent progress on the tribology of doped diamond-like and carbon alloy coatings: a review

Abstract: Diamond-like carbon (DLC) coatings have been widely recognized as being a wear-resistant solid lubricant with a low friction coefficient. Its tribological behavior strongly depends both on the tribotesting conditions and the nature of the coating, which in turn depends on the technique used for film deposition. Recently, there have been several attempts to improve the tribological behavior of DLC coatings by the addition of elements, such as silicon, nitrogen, fluorine and various metals. The paper will present an updated review of the tribological properties of doped DLC, in comparison with the conventional hydrogenated and non-hydrogenated carbonaceous films.

Controlled method for silica coating of silver colloids. Influence of coating on the rate of chemical reactions

Abstract: The preparation and chemical reactivity of Ag@SiO2 particles have been investigated using UV−vis spectroscopy, laser Doppler electrophoresis, and electron microscopy. The factors governing the depo...

Drug release stent coating

Abstract: A method of coating implantable open lattice metallic stent prosthesis is disclosed which includes sequentially applying a plurality of relatively thin outer layers of a coating composition comprising a solvent mixture of uncured polymeric silicone material and crosslinker and finely divided biologically active species, possibly of controlled average particle size, to form a coating on each stent surface. The coatings are cured in situ and the coated, cured prosthesis are sterilized in a step that includes preferred pretreatment with argon gas plasma and exposure to gamma radiation electron beam, ethylene oxide, steam.

Slippery, tenaciously adhering hydrophilic polyurethane hydrogel coatings, coated metal substrate materials, and coated medical devices

Abstract: A process for the preparation of slippery, hydrophilic polyurethane hydrogel coating compositions, and materials composed of a polymeric plastic or rubber substrate or a metal substrate with a coating of a slippery, hydrophilic polyurethane hydrogel thereon, such that the coating composition tenaciously adheres to the substrate, are disclosed. The coating compositions and coated materials are non-toxic and biocompatible, and are ideally suited for use on medical devices, particularly, catheters, catheter balloons and stents. The coating compositions, coated materials and coated devices demonstrate low coefficients of friction in contact with body fluids, especially blood, as well as a high degree of wear permanence over prolonged use of the device. The hydrogel coating compositions are capable of being dried to facilitate storage of the devices to which they have been applied, and can be instantly reactivated for later use by exposure to water.

Immobilisation of TiO2 powder for the treatment of polluted water

Abstract: TiO2 powder was immobilised on solid support substrates (stainless steel, titanium alloy, titanium metal, and tin oxide coated glass) using electrophoretic coating and spray coating. Electrochemical anodisation of titanium metal was also carried out to give a thin film of TiO2 on the surface. The coated substrates were annealed in air at elevated temperatures to improve the adhesion of the catalyst to the supporting substrates. The photocatalytic efficiency of the TiO2 coatings was compared using the degradation of phenol in aqueous solution as a standard test system. In the case of the powder derived films, the photocatalytic efficiency was found not to be markedly dependent upon either the substrate used or the annealing temperature employed in the coating process. Surface analysis of the immobilised TiO2 showed no significant differences in the elemental composition or in band gap energies. The electrophoretic coating method was found to be the most reproducible resulting in highly fractured thick films with high photocatalytic activity. (C) 1998 Elsevier Science B.V.

Microporous covered stents and method of coating

Abstract: A coated microporous stent and method of coating are disclosed The inventive stent consists of a tubular member made from a flat sheet assembled together in a tube with the ends of the sheet assembled together through a technique such as surface fusing Preferably, the stent is made up of a plurality of spaced rows of slots with spaces between adjacent slots within a row staggered with respect to corresponding spaces on adjacent rows In a first embodiment of a coated stent, a coating is attached to the stent only at a single area of line contact on the outer surface of the stent with the remainder of the coating being larger than the unexpanded stent, but being made of dimensions designed to snugly receive the outer surfaces of the stent when it is expanded within a blood vessel In a second embodiment, the present invention also contemplates coating of a stent of the type known as a "self-expanding" stent that is programmed to self-expand at a particular temperature by either using the shape memory properties of the metal or by using the flexibility and elasticity of the metal In this embodiment, prior to programming the formed stent, the stent is placed in a container of coating material and is coated Thereafter, the stent is programmed in the desired manner and is subsequently physically compressed and kept inside a sheath The stent is placed within the blood vessel still within the sheath, and the sheath is then removed, allowing the stent to expand to its desired configuration Methods of making such coated stents are disclosed

Implantable substrate sensor

Abstract: An implantable substrate sensor has electronic circuitry and electrodes formed on opposite sides of a substrate. A protective coating covers the substrate, effectively hermetically sealing the electronic circuitry under the coating. Exposed areas of the electrodes are selectively left uncovered by the protective coating, thereby allowing such electrodes to be exposed to body tissue and fluids when the sensor is implanted in living tissue. The substrate on which the electronic circuitry and electrodes are formed is the same substrate or “chip” on which an integrated circuit (IC) is formed, which integrated circuit contains the desired electronic circuitry. Such approach eliminates the need for an hermetically sealed lid or cover to cover hybrid electronic circuitry, and allows the sensor to be made much thinner than would otherwise be possible. In one embodiment, two such substrate sensors may be placed back-to-back, with the electrodes facing outward. As required, capacitors that form part of the sensor's electronic circuits are formed on the substrate by placing metalization layers and a dielectric in vacant areas of the substrate surface.

Reinforcement coatings and interfaces in aluminium metal matrix composites

Abstract: The interface between the matrix and reinforcement plays a crucial role in determining the properties of metal matrix composites (MMC). Surface treatments and coating of the reinforcement are some of the important techniques by which the interfacial properties can be improved. This review reports the state of art knowledge available on the surface treatments and coating work carried out on reinforcements such as carbon/graphite, silicon carbide (SiC) and alumina (Al2O3) and their effects on the interface, structure and properties of aluminium alloy matrix composites. The metallic coatings improved the wettability of reinforcement but at the same time changed the matrix alloy composition by alloying with the matrix. Ceramic coatings reduce the interfacial reaction by acting as a diffusion barrier between the reinforcement and the matrix. Multilayer coatings have multifunctions, such as wetting agent, diffusion barrier and releaser of thermal residual stress. The roles of reinforcement coating as a means of “in situ hybridising” and “in situ alloying” are described.

Fast-setting latex coatings and formulations

Abstract: A fast-setting coating material can be prepared by contacting a stable acqueous dispersion of a polymer that contains strong cationic groups and weak acid groups onto a substrate that is basic or rendered to be basic. Alternatively, the coating material can be prepared by contacting in either order or concurrently, the surface of a substrate with two separate polymers, one of which contains strong cationic groups, and the other of which contains weak acid groups. In this case, the substrate need not be basic for the coating to quickly set.

Bonding layers for medical device surface coatings

Abstract: A medical device is coated with a thin coherent bond coat of acrylics, epoxies, acetals, ethylene copolymers, vinyl polymers, polymers containing hydroxyl, amine, carboxyl, amide, or other reactive groups, and copolymers thereof. Outer layers may be applied and remain adherent to the substrate in water for an extended period. The bond coat may comprise cross linkers such as urea resins, melamines, isocyanates, and phenolics. Preferred polymers include vinylpyrrolidone-vinyl acetate, styrene acrylic polymer, ethylene acrylic acid copolymer, carboxyl function acrylic polymer, hydroxyl function acrylic polymer, and acrylic dispersion polymer. The coatings may be applied to inert metal or plastic surfaces of medical devices such as needles, guide wires, catheters, surgical instruments, equipment for endoscopy, wires, stents, angioplasty balloons, wound drains, arteriovenous shunts, gastroenteric tubes, urethral inserts, laparoscopic equipment, pellets, and implants. Methods of coating and coating liquids are provided.

Adherent, flexible hydrogel and medicated coatings

Abstract: The adherent coating of the invention comprises a stabilizing polymer together with an active agent (a hydrophilic polymer and/or a bioactive agent) in a layer bonded to the surface of a medical device. This invention encompasses the coating liquids used for coating medical devices, methods of coating the devices, and the coated devices. The stabilizing polymer is selected to entrap the active agent in a coating that has a high degree of flexibility and has improved bonding to a wide variety of substrates. Preferred stabilizing polymers are cross-linkable acrylic and methacrylic polymers, ethylene acrylic acid copolymers, styrene acrylic copolymers, vinyl acetate polymers and copolymers, vinyl acetal polymers and copolymers, epoxy, melamine, other amino resins, phenolic polymers, copolymers thereof, and combinations.

Surface coatings for catheters, direct contacting diagnostic and therapeutic devices

Abstract: A catheter including a distal end assembly having an external surface coating. Where the distal end assembly includes electrodes or other electrical components, the coating is preferably electrically conductive. Such an electrically conductive coating is formed from a material comprising regenerated cellulose, although other materials such as a hydrogel or a plastic having an electrically conductive component are utilizable. Where the distal end assembly includes optical or ultrasonic components, the regenerated cellulose coating is suitable. The robustness of the surface coating permits the manufacture and utilization of electrode configurations that are formed on a non-conductive base member by processes such as pad printing, vapor deposition, ion beam assisted deposition, electroplating and other printed circuit manufacturing processes. Additionally, because the surface coating produces a smooth outer surface to the distal end assembly, lead wires and temperature sensing devices can be bonded to the exterior surface of electrodes and then coated to produce a smooth outer surface; thus providing a simple, inexpensive manufacturing method for the attachment of such components to the electrodes.

A study of high velocity oxy-fuel thermally sprayed tungsten carbide based coatings. Part 1: Microstructures

Abstract: The microstructures of two tungsten carbide–cobalt (WC–Co) coatings, deposited using high velocity oxy-fuel (HVOF) thermal spraying method in different conditions, are studied. They are compared with that of the WC–Co powder grains injected in the flame, in an attempt to understand the transformations that occur during deposition. For this purpose, various imaging and analytical techniques in electron microscopy are used, in addition to global characterization methods such as X-ray diffraction and fluorescence. These methods reveal that the coatings are made of distinct islands, elongated along the substrate direction, which exhibit a nano-crystalline matrix containing tungsten, cobalt and carbon. The fraction of WC grains in the coating is smaller than that in the powder and fluctuates throughout the coating. A net loss in carbon is evidenced in the coatings as compared to the powder grains. New phases, W2C and W, appear in specific locations in the microstructure in relation with the local composition of the matrix. Very little metallic cobalt is retained. The extent of the transformation is related to the spraying conditions. Some processes that account for the change in microstructure and composition during spraying are proposed.

Transparent barrier coatings on polyethylene terephthalate by single- and dual-frequency plasma-enhanced chemical vapor deposition

Abstract: Transparent barrier coatings on polymers are receiving much attention in industry, for pharmaceutical, food and beverage packaging applications. Plasma-enhanced chemical vapor deposition (PECVD) is among several competing techniques which can produce thin layers of inorganic glassy barrier materials. In this article we describe the performance of silicon compounds (SiO2 and Si3N4) on 13 μm polyethylene terephthalate (PET) substrates, the barrier coatings being deposited in a dual-frequency (microwave/radio frequency) pilot-scale PECVD reactor for continuously moving flexible webs up to 30 cm in width. The volatile silicon compound used for SiO2 deposition is HMDSO (C6H18Si2O), while SiH4 serves to deposit Si3N4. Coating thicknesses, d, in the range 8 nm⩽d⩽200 nm, are measured using a variety of techniques, namely stylus profilometry, continuous wavelength optical interferometry, x-ray fluorescence, variable angle spectroscopic ellipsometry, and transmission electron microscopy, while film compositions are...

Effect of Chain Length on the Protection of Copper by n-Alkanethiols

Abstract: Self-assembled monolayers (SAMs) formed by the adsorption of n-alkanethiols [CH3(CH2)n-1SH; n = 8, 12, 16, 18, 20, 22, and 29] onto copper provide a flexible method for producing coatings that can protect the underlying metal against corrosion The ability to tailor the thickness of the coatings at the angstrom-level by choice of adsorbate allows examination of the effect of angstrom-level variations in film thickness on the performance of the SAM as a barrier layer A combination of infrared (IR) spectroscopy and electrochemical impedance spectroscopy (EIS) was used to correlate the structure of the SAM with its barrier properties during extended exposures to 1 atm of O2 at 100% relative humidity (RH) EIS results reveal that the coating resistances provided by SAMs with chain lengths of 16 carbons or more (ie n ≥ 16) exhibit a linear increase with chain length and are orders of magnitude greater than those provided by SAMs with n ≤ 12 due to the more crystalline nature of the thicker films Upon expos

Method and apparatus for providing a conductive, amorphous non-stick coating

Abstract: A conductive, non-stick coating (62) is provided using a ceramic material which is conductive, flexible and provides a surface which exhibits the property of lubricity. A room or near room temperature manufacturing process produces a coating of titanium nitride on a substrate, where the coating is amorphous if the substrate is a solid material including plastics, composites, metals, magnets and ceramics, enabling the substrate to bend without damaging the coating. The coating can also be applied as a conformal coating on a variety of substrate shapes, depending upon the application. The coating is biocompatible and can be applied to a variety of medical devices.

Stable Cationic Capillary Coating with Successive Multiple Ionic Polymer Layers for Capillary Electrophoresis

Abstract: A coated capillary modified with a cationic polymer was developed by using a novel coating procedure, successive multiple ionic−polymer (SMIL) coating The SMIL coating was achieved by first attaching the cationic polymer to the capillary inner wall, and then the anionic polymer to the cationic polymer layer, and finally the cationic polymer to the anionic polymer layer The stability of Polybrene (PB)-modified capillary made by SMIL coating was remarkably improved in comparison with a conventional PB-modified capillary It endured during 600 replicate analyses and also showed strong stability against 1 M NaOH and 01 M HCl The relative standard deviation of the run-to-run, day-to-day, and capillary-to-capillary coating was all below 1%, and good reproducibilities were obtained The PB-modifed capillary made by SMIL coating was applied to the basic protein analyses It gave good performances for the protein analyses even when the pH of the electrolyte was near the isoelectric point (pI) of the protein I

Thermal processing of hydroxyapatite for coating production

Abstract: Thermally processed hydroxyapatite coatings used on dental implants and hip prostheses for enhanced fixation may typically consist of a number of chemical and structural phases. These phases affect coating performance and tissue attachment. Hydroxyapatite was plasma sprayed to examine the phase evolution during processing. Coatings were examined with X-ray diffraction and elemental analysis. Results indicate that phase transformations are produced by (a) preferential removal of hydroxyl and phosphate leading to a change in melt composition, and (b) the high cooling rate due to the thermal spray process. Hydroxyl group removal promotes the amorphous phase and oxyapatite. Further heating produces a less viscous melt facilitating decomposition of hydroxyapatite to tricalcium and tetracalcium phosphate. Phosphate removal during flight produces a more calcium-rich melt preferring tetracalcium phosphate and calcium oxide formation. A proposed model shows the phase location within the lamellae of these coatings. Coating processes must thus prevent removal of hydroxide and phosphate during processing to maximize the hydroxyapatite content.

Amorphous phase formation in plasma-sprayed hydroxyapatite coatings.

Abstract: The amorphous phase content of air plasma-sprayed hydroxyapatite coatings is dependent upon spraying and deposition conditions. X-ray diffraction and optical microscopy were used to investigate the influence of spray parameters on the formation of the amorphous phase. Results show three factors which most influence the formation of the amorphous phase: dehydroxylation of the molten particle during flight, the cooling rate as it impinges onto the metal substrate, and the substrate temperature. Crystalline regions were identified as unmelted particles and elongated recrystallized areas. Amorphous phase regions vary throughout the coating but are more commonly found at the coating-substrate interface, i.e., the regions decrease toward the surface of the coating. Such an inhomogeneous distribution of phase content is expected to affect the clinical process of bone deposition, and therefore successful implant fixation.

State of the art in hard coatings for carbide cutting tools

Abstract: The majority of carbide cutting tools in use today employ hard coatings because coatings offer proven benefits in terms of tool life and machining performance. Continuing development of the chemical vapor deposition (CVD) coating process, the most widely used technique, has produced complex multilayer coatings tailored for specific applications and workpiece materials. These coatings include alumina layers of different crystal structures, and TiCN layers applied by high- or moderate-temperature (MT-CVD) processes. Over the last decade, coatings applied by physical vapor deposition (PVD) have gained acceptance in applications requiring sharp edges or those featuring interrupted cuts. Originally limited to TiN coatings, the PVD offering now includes TiCN and TiA1N coatings which provide better high-speed performance and increased abrasive wear resistance. In the area of superhard coatings, improvements in deposition processes and coating adhesion have resulted in diamond-coated carbide tools that have begun to play an important role in machining non-ferrous and non-metallic materials. This paper presents the state of the art in hard coatings for carbide cutting tools including discussion of coating characteristics and applications.