Showing papers on "Coating published in 2000"

Transparent Superhydrophobic Thin Films with Self-Cleaning Properties

Abstract: Transparent superhydrophobic thin films with TiO2 photocatalyst were prepared by utilizing a sublimation material and subsequent coating of a (fluoroalkyl)silane. The transparency of the films decreased with increasing TiO2 concentration, which was attributed to the size difference of the starting materials. The film with only 2 wt % TiO2 maintained higher contact angle than the film without TiO2 after 1800-h outdoor exposure, the accumulation of stain being avoided due to TiO2 photocatalysis. The films prepared in this study are the first ones that satisfy the requirements of transparency, superhydrophobicity, and long lifetime simultaneously.

Novel LiCoO2 Cathode Material with Al2O3 Coating for a Li Ion Cell

Abstract: A high-performance LiCoO2 cathode was successively fabricated by a sol−gel coating of Al2O3 to the LiCoO2 particle surfaces and subsequent heat treatment at 600 °C for 3 h. Unlike bare LiCoO2, the ...

Controlling droplet deposition with polymer additives

Abstract: Controlling the impact of drops onto solid surfaces is important for a wide variey of coating and deposition processes--for example, the treatment of plants with herbicides and pesticides requires precise targeting in order to meet stringent toxicological regulations. However, the outer wax-like layer of the leaves is a non-wetting substrate that causes sprayed droplets to rebound; often less than 50% of the initial spray is retained by the plant. Although the impact and subsequent retraction of non-wetting aqueous drops on a hydrophobic surface have been the subjects of extensive experimental and theoretical work, non-newtonian rheological effects have not been considered in any detail. Here we report that, by adding very small amounts of a flexible polymer to the aqueous phase, we can inhibit droplet rebound on a hydrophobic surface and markedly improve deposition without significantly altering the shear viscosity of the solutions. Our results can be understood by taking into account the non-newtonian elongational viscosity, which provides a large resistance to drop retraction after impact, thereby suppressing droplet rebound.

Compliant tissue sealants

Abstract: An improved barrier or drug delivery system which is highly adherent to the surface to which it is applied is disclosed, along with methods for making the barrier. In the preferred embodiment, the system is compliant, in that it is capable of conforming to the three dimensional structure of a tissue surface as the tissue bends and deforms during healing processes. The barrier or drug delivery systems is formed as a polymeric coating on tissue surfaces by applied a polymerizable monomer to the surface, and then polymerizing the monomer. The polymerized compliant coating preferably is biodegradable and biocompatible, and can be designed with selected properties of compliancy and elasticity for different surgical and therapeutic applications.

Superhydrophobic−Superhydrophilic Micropatterning on Flowerlike Alumina Coating Film by the Sol−Gel Method

Abstract: A novel route to form superhydrophobic−superhydrophilic micropatterned coating film has been developed UV light was irradiated on the superhydrophobic coating film which consists of three layers, a flowerlike Al2O3 gel film, a very thin TiO2 gel layer, and a FAS layer, to cleave the fluoroalkyl chain in FAS selectively, and well-defined superhydrophobic and superhydrophilic regions were formed

Oil Palm Fibre Reinforced Phenol Formaldehyde Composites: Influence of Fibre Surface Modifications on the Mechanical Performance

Abstract: Oil palm fibres have been used as reinforcement in phenol formaldehyde resin. In order to improve the interfacial properties, the fibres were subjected to different chemical modifications such as mercerisation, acrylonitrile grafting, acrylation, latex coating, permanganate treatment, acetylation, and peroxide treatment. The effect of fibre coating on the interface properties has also been investigated. Morphological and structural changes of the fibres were investigated using scanning electron microscopy and IR spectroscopy. Mechanical properties of untreated and treated fibres were studied. Changes in stress–strain characteristics, tensile strength, tensile modulus and elongation at break of the fibres upon various modifications were studied and compared. The incorporation of the modified fibres resulted in composites having excellent impact resistance. Fibre coating enhanced the impact strength of untreated composite by a factor of four. Tensile and flexural performance of the composites were also investigated. Finally, inorder to have an insight into the failure behaviour, the tensile and impact fracture surfaces of the composites were analysed using scanning electron microscope.

Polymer, Metal, and Hybrid Nano‐ and Mesotubes by Coating Degradable Polymer Template Fibers (TUFT Process)

Abstract: ). Selective reaction with the silver atoms at the interface of the particles occurred and the coated particles were then extracted from reverse micelles. The powder of coated nanocrystals thus obtained was then dispersed in hexane, giving an optically clear solution. The size distribution was still rather large (30 %), and to reduce it a size-selected precipitation process [20] was used. In this process two solvents, such as hexane and pyridine, are mixed. The first is a good solvent and the second a poor solvent for the alkyl chains. With this solvent mixture, the larger coated particles flocculated whereas the smaller ones remain in the solution, thus providing size selection. By repeating this process several times, a homogenous clear colloidal solution of dispersed 4.3 nm nanocrystals is obtained. The concentration of nanocrystals with final size distribution around 13 % was controlled.

Deposition of layered bioceramic hydroxyapatite/TiO2 coatings on titanium alloys using a hybrid technique of micro-arc oxidation and electrophoresis

Abstract: Titanium alloys have been used with some success in several bioimplant applications. However, they can suffer certain disadvantages, such as poor osteoinductive properties and low corrosive-wear resistance. Attempts to overcome the first of these drawbacks have involved coating the metal with the bioceramic material hydroxyapatite (HA), a primary component of bone and a very good osteoinductor. Since TiO 2 coatings are also known to be effective as chemical barriers against the in-vivo release of metal ions from the implants, a double layer HA–TiO 2 coating on titanium alloys with HA as the top layer and a dense TiO 2 film as the inner layer should possess a very good combination of bioactivity, chemical stability and mechanical integrity. This paper describes efforts to improve implant biocompatibility and durability by applying a hybrid treatment of micro-arc discharge oxidation (MDO) and electrophoretic deposition. The most common structural titanium alloy (Ti-6Al-4V) was used as the substrate material. A phosphate salt solution and an HA powder aqueous suspension were used as the electrolyte for micro-arc oxidation and the solution for HA electrophoretic deposition, respectively. It is shown that a relatively thick and hard TiO 2 coating can be produced by anodic micro-arc oxidation of titanium, and an HA coating incorporated on top of the TiO 2 layer can simultaneously be formed using a combination of plasma electrolysis and electrophoresis, with the suspension held at high values of pH. X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) have been used to investigate the microstructure and morphology of the coatings. The adhesive strength between the coating and substrate has been assessed using scratch adhesion testing. The corrosion resistance of the specimens was examined using potentiodynamic tests in a buffered physiological solution. The results indicate that a hybrid combination of micro-arc oxidation and electrophoretic deposition can provide a phase-pure HA top layer and anticorrosive TiO 2 interlayer, which should show good mechanical and biochemical stability in the corrosive environment of the human body.

Mechanical factors favoring release from fouling release coatings.

Abstract: For some twenty years the marine coatings industry has been intrigued by polymer surfaces with low adhesion to other materials, especially to the biological glues used by marine organisms. Polymers with fouling release surfaces have been made from sundry materials, and their resistance to marine fouling in both static and dynamic tests has been evaluated in the world's oceans. Although the polymer surface property most frequently correlated with bioadhesion is its critical surface tension (γ?), resistance to fouling is also influenced by other bulk and surface properties of the polymer. This paper reviews the types of bonding associated with polymeric materials used in fouling resistant coatings, describes the removal process in terms of fracture mechanics, and discusses the importance of surface energy, elastic modulus and coating thickness in the release of biofoulants.

Self-assembled monolayers as anti-stiction coatings for MEMS: characteristics and recent developments

Abstract: Despite significant advances in surface micromachining technology, stiction remains a key problem, severely limiting the realization and reliability of many micro-electro-mechanical systems (MEMS) devices. In this article, we focus on self-assembled monolayers as release and anti-stiction coatings for MEMS. Their formation mechanism, the microstructure coating process, and the characteristics of the coated microstructures are described, followed by a discussion of the current limitations, areas for improvements and recent progress for this coating technology.

Methods of coating an implantable device having depots formed in a surface thereof

Abstract: The present invention provides methods of coating an implantable device, such as a stent or a graft, having a plurality of depots formed in a surface thereof. An exemplary method includes applying a composition including a polymer and a solvent to the implantable device proximate to the depots. Such application of the composition is performed at a first gas pressure. The method also includes applying a second gas pressure, which is greater than the first gas pressure, to the composition-coated device so that air pockets in the depots are eliminated, or at least reduced in size. The method also includes the act of removing the solvent from the composition to form a coating. An implantable device coated in accordance with the method is also provided. The compositions employed in the methods may include one or more therapeutic substances such as antineoplastics, antimitotics, antiinflammatories, antiplatelets, anticoagulants, antifibrins, antithrombins, antiproliferatives, antibiotics, antioxidants, antiallergics, radioisotopes, and combinations thereof.

Surface protection method for stents and balloon catheters for drug delivery

Abstract: A medical device, such as a stent or balloon of a balloon catheter which includes a body portion which has an exterior surface which contacts, at least in part, a vessel wall during treatment. The body portion is expandable from a first position, wherein the body portion is sized for insertion into the vessel lumen, to a second position, wherein at least a portion of the exterior surface is in contact with the lumen wall. The medical device includes a first coating disposed over at least a portion of the exterior surface of the body portion with the first coating including a drug or therapeutic substance which is intended for controlled release from the surface. The medical device further includes a second coating overlying at least a substantial portion of the first coating. The second coating includes a material that is generally impervious to elution of the drug or therapeutic substance therethrough when the body portion is in a first position when inserted into the vessel lumen. The material of the second coating is relatively inelastic so that the second coating fractures during expansion of the body portion to the second position to allow elution of therapuetic substance through a multiplicity of fissures fromed through the second coating.

A review of investigations on biocompatibility of diamond-like carbon and carbon nitride films

Abstract: This paper reviews the present status of studies of biocompatibility of diamond-like carbon (DLC) and carbon nitride (CN) coatings. DLC and CN coatings, due to their novel mechanical and tribological properties, chemical inertness, electrical and optical properties, and biocompatibility, are excellent candidates for biomedical applications. A number of clinical applications for DLC are now being considered by commercial manufacturers of surgical implants. Preliminary studies have shown that DLC coating can be adherent on a range of biomaterials with desirable bulk properties, no toxicity toward living cells, no inflammatory response or loss of cell integrity, as well no cellular damage. Despite only a few reports about biocompatibility of CN coating, which, with its mechanical and chemical properties comparable with DLC, is a very attraction coating material for future biomedical applications. This paper outlines the present level of research and suggests areas for future research, these include in vivo tests and a more detailed investigation of coating bond structure or properties.

Coating medical devices using air suspension

Abstract: Methods and apparatuses for coating medical devices and the devices thereby produced are disclosed. In one embodiment, the invention includes a method comprising the steps of suspending the medical device in an air stream and introducing a coating material into the air stream such that the coating material is dispersed therein and coats at least a portion of the medical device. In another embodiment, the medical devices are suspended in an air stream and a coating apparatus coats at least a portion of the medical device with a coating material. The coating apparatus may include a device that utilizes any number of alternative coating techniques for coating the medical devices. This process is used to apply one or more coating materials, simultaneously or in sequence. In certain embodiments of the invention, the coating materials include therapeutic agents, polymers, sugars, waxes, or fats. By using air suspensions to coat medical devices, the methods of the present invention result in coatings having minimal defects and uniform thicknesses and mechanical properties. Further, the methods of the present invention are time efficient and cost effective because they facilitate the coating of numerous medical devices in a single batch, resulting in numerous medical device units containing substantially the same coating.

Coating compositions having improved scratch resistance, coated substrates and methods related thereto

Abstract: Compositions are provided which contain (a) one or more polysiloxanes comprising at least one reactive functional group; a plurality of particles; and, optionally, one or more curing agents comprising at least one functional group that is reactive with any reactive functional group of polysiloxane (a). Additionally, a process for applying the multi-component composite coatings described above to a substrate and coated substrates are provided. A process for preparing the coating compositions also is provided. The multi-component composite coating compositions of the invention provide highly scratch resistant color-plus-clearcoatings capable of retaining scratch resistance after weathering.

Stent having antimicrobial agent

Abstract: A medical stent having an inorganic antimicrobial agent on a surface, the agent preferably being a zeolite. The stent can be of metal or a polymer and the agent being in a coating that is applied to one or both of the surfaces of the stent. The stent can be of a polymer resin incorporating the agent.

Porosity evaluation of protective coatings onto steel, through electrochemical techniques

Abstract: Various electrochemical techniques, usually used to characterise the corrosion resistance of coated steel, are compared in order to evaluate the porosity of various protective coatings (Al, Ti, TiN or CrN). The porosity significantly influences the corrosion behaviour of the coated steel, tested in saline environment, and some gaps are evident in the porosity values determined from these techniques. These heterogeneous data are interpreted in terms of intrinsic behaviour of each coating and of galvanic effects between the relevant coating and the substrate. The advantages and drawbacks of each electrochemical technique are underlined in correlation with the type of tested coating.

The dependency of microstructure and properties of nanostructured coatings on plasma spray conditions

Abstract: In this paper, Al2O3-13 wt.% TiO2 coatings formed via a plasma spray approach using reconstituted nanosized Al2O3 and TiO2 powder feeds are described. Effects of various plasma spray conditions on the microstructure, grain size, phase content and microhardness of the coatings have been evaluated. It is found that phase transformation of nanosized Al2O3 and TiO2 during heat treating, sintering and thermal spraying is, in general, identical to that of micrometer-sized counterparts. Furthermore, the particle temperature during thermal spray could be divided into three regimes, i.e. low, intermediate and high temperature regimes, according to the characteristics of the coating produced from the nanopowder. The hardness and density of the coating increase with the spray temperature. The phase content and grain size of the coating also exhibits a strong dependency on the spray temperature. The coating sprayed using nanopowder feed displays a better wear resistance than the counterpart sprayed using commercial coarse-grained powder feed. The observed phenomena are discussed in terms of physics of thermal spraying, mechanisms of coating growth and phase transformation of the oxides.

Reduced electromigration and stressed induced migration of Cu wires by surface coating

Abstract: The idea of the invention is to coat the free surface of patterned Cu conducting lines in on-chip interconnections (BEOL) wiring by a 1-20 nm thick metal layer prior to deposition of the interlevel dielectric. This coating is sufficiently thin so as to obviate the need for additional planarization by polishing, while providing protection against oxidation and surface, or interface, diffusion of Cu which has been identified by the inventors as the leading contributor to metal line failure by electromigration and thermal stress voiding. Also, the metal layer increases the adhesion strength between the Cu and dielectric so as to further increase lifetime and facilitate process yield. The free surface is a direct result of the CMP (chemical mechanical polishing) in a damascene process or in a dry etching process by which Cu wiring is patterned. It is proposed that the metal capping layer be deposited by a selective process onto the Cu to minimize further processing. We have used electroless metal coatings, such as CoWP, CoSnP and Pd, to illustrate significant reliability benefits, although chemical vapor deposition (CVD) of metals or metal forming compounds can be employed.

Mechanical buckling instability of thin coatings deposited on soft polymer substrates

Abstract: Deformation of rubber and poly(ethylene terephthalate) coated with a platinum or a gold film was studied. The thickness of the coating film was approximately ten nanometers. The polymer substrates were 104 to 105-fold softer than the coating. Folding of the coating leading to the appearance of a wave-like pattern on an originally smooth surface was observed both in tension and after shrinkage. In tension the wave crests are oriented along the elongation direction. After shrinkage the wave crests are perpendicular to the shrinkage direction. For rubber substrates, the appearance of the wave is explained by a mechanical buckling instability of the coating under compressive force. The length of the surface wave depends on the thickness of the coating layer and the rigidity of the polymer substrate. In addition to folding, regular fragmentation of the coating film on long and comparatively narrow bands is observed. The cracks are perpendicular to the wave crests both in tension and after shrinkage.

Methods of forming a coating for a prosthesis

Abstract: Methods of forming a coating onto an implantable device or endoluminal prosthesis, such as a stent, are provided. The coating may be used for the delivery of an active ingredient. The coating may have a selected pattern of interstices for allowing a fluid to seep through the coating in the direction of the pattern created.

Designing oxidation-resistant coatings

Abstract: This article examines the historical development of high-temperature, oxidation- and corrosion-resistant coatings, demonstrating how diffusion surface treatments, modified diffusion coatings, the design of M-Cr-Al-X corrosion-resistant overlay coatings, and the application of thermal-barrier coatings can be used to reduce the scaling (oxidation) rate of coated components. Future trends in high-temperature coating design are also reviewed, including the custom design of corrosion-resistant alloys, smart overlay coating concepts, diffusion barriers, and the use of layered thermal-barrier coating structures.

Hydrophobic coating including DLC on substrate

Abstract: A substrate is coated with a hydrophobic coating that includes highly tetrahedral amorphous carbon that is a form of diamond-like carbon (DLC). In certain embodiments, the coating is deposited on the substrate in a manner to increase its hydrophobicity (e.g. so that the coating has an initial contact angle θ of at least about 100 degrees; and/or a surface energy of no more than about 20.2 mN/m). In certain embodiments, the coating is deposited in a manner such that it has an average hardness of at least about 10 GPa, more preferably from about 20-80 GPa.