Showing papers on "Coating published in 1995"

The Science and Engineering of Thermal Spray Coatings

Abstract: Preface to the Second Edition. Preface to the First Edition. Acronyms, Abbreviations and Symbols. 1 Materials Used for Spraying. 1.1 Methods of Powders Production. 1.1.1 Atomization. 1.1.2 Sintering or Fusion. 1.1.3 Spray Drying (Agglomeration). 1.1.4 Cladding. 1.1.5 Mechanical Alloying (Mechanofusion). 1.1.6 Self-propagating High-temperature Synthesis (SHS). 1.1.7 Other Methods. 1.2 Methods of Powders Characterization. 1.2.1 Grain Size. 1.2.2 Chemical and Phase Composition. 1.2.3 Internal and External Morphology. 1.2.4 High-temperature Behaviour. 1.2.5 Apparent Density and Flowability. 1.3 Feeding, Transport and Injection of Powders. 1.3.1 Powder Feeders. 1.3.2 Transport of Powders. 1.3.3 Injection of Powders. References. 2 Pre-Spray Treatment. 2.1 Introduction. 2.2 Surface Cleaning. 2.3 Substrate Shaping. 2.4 Surface Activation. 2.5 Masking. References. 3 Thermal Spraying Techniques. 3.1 Introduction. 3.2 Flame Spraying (FS). 3.2.1 History. 3.2.2 Principles. 3.2.3 Process Parameters. 3.2.4 Coating Properties. 3.3 Atmospheric Plasma Spraying (APS). 3.3.1 History. 3.3.2 Principles. 3.3.3 Process Parameters. 3.3.4 Coating Properties. 3.4 Arc Spraying (AS). 3.4.1 Principles. 3.4.2 Process Parameters. 3.4.3 Coating Properties. 3.5 Detonation-Gun Spraying (D-GUN). 3.5.1 History. 3.5.2 Principles. 3.5.3 Process Parameters. 3.5.4 Coating Properties. 3.6 High-Velocity Oxy-Fuel (HVOF) Spraying. 3.6.1 History. 3.6.2 Principles. 3.6.3 Process Parameters. 3.6.4 Coating Properties. 3.7 Vacuum Plasma Spraying (VPS). 3.7.1 History. 3.7.2 Principles. 3.7.3 Process Parameters. 3.7.4 Coating Properties. 3.8 Controlled-Atmosphere Plasma Spraying (CAPS). 3.8.1 History. 3.8.2 Principles. 3.8.3 Process Parameters. 3.8.4 Coating Properties. 3.9 Cold-Gas Spraying Method (CGSM). 3.9.1 History. 3.9.2 Principles. 3.9.3 Process Parameters. 3.9.4 Coating Properties. 3.10 New Developments in Thermal Spray Techniques. References. 4 Post-Spray Treatment. 4.1 Heat Treatment. 4.1.1 Electromagnetic Treatment. 4.1.2 Furnace Treatment. 4.1.3 Hot Isostatic Pressing (HIP). 4.1.4 Combustion Flame Re-melting. 4.2 Impregnation. 4.2.1 Inorganic Sealants. 4.2.2 Organic Sealants. 4.3 Finishing. 4.3.1 Grinding. 4.3.2 Polishing and Lapping. References. 5 Physics and Chemistry of Thermal Spraying. 5.1 Jets and Flames. 5.1.1 Properties of Jets and Flames. 5.2 Momentum Transfer between Jets or Flames and Sprayed Particles. 5.2.1 Theoretical Description. 5.2.2 Experimental Determination of Sprayed Particles' Velocities. 5.2.3 Examples of Experimental Determination of Particles Velocities. 5.3 Heat Transfer between Jets or Flames and Sprayed Particles. 5.3.1 Theoretical Description. 5.3.2 Methods of Particles' Temperature Measurements. 5.4 Chemical Modification at Flight of Sprayed Particles. References. 6 Coating Build-Up. 6.1 Impact of Particles. 6.1.1 Particle Deformation. 6.1.2 Particle Temperature at Impact. 6.1.3 Nucleation, Solidification and Crystal Growth. 6.1.4 Mechanisms of Adhesion. 6.2 Coating Growth. 6.2.1 Mechanism of Coating Growth. 6.2.2 Temperature of Coatings at Spraying. 6.2.3 Generation of Thermal Stresses at Spraying. 6.2.4 Coatings Surfaces. 6.3 Microstructure of the Coatings. 6.3.1 Crystal Phase Composition. 6.3.2 Coatings' Inhomogeneity. 6.3.3 Final Microstructure of Sprayed Coatings. 6.4 Thermally Sprayed Composites. 6.4.1 Classification of Sprayed Composites. 6.4.2 Composite Coating Manufacturing. References. 7 Methods of Coatings' Characterization. 7.1 Methods of Microstructure Characterization. 7.1.1 Methods of Chemical Analysis. 7.1.2 Crystallographic Analyses. 7.1.3 Microstructure Analyses. 7.1.4 Other Applied Methods. 7.2 Mechanical Properties of Coatings. 7.2.1 Adhesion Determination. 7.2.2 Hardness and Microhardness. 7.2.3 Elastic Moduli, Strength and Ductility. 7.2.4 Properties Related to Mechanics of Coating Fracture. 7.2.5 Friction and Wear. 7.2.6 Residual Stresses. 7.3 Physical Properties of Coatings. 7.3.1 Thickness, Porosity and Density. 7.3.2 Thermophysical Properties. 7.3.3 Thermal Shock Resistance. 7.4 Electrical Properties of Coatings. 7.4.1 Electrical Conductivity. 7.4.2 Properties of Dielectrics. 7.4.3 Electron Emission from Surfaces. 7.5 Magnetic Properties of Coatings. 7.6 Chemical Properties of Coatings. 7.6.1 Aqueous Corrosion. 7.6.2 Hot-gas Corrosion. 7.7 Characterization of Coatings' Quality. 7.7.1 Acoustical Methods. 7.7.2 Thermal Methods. References. 8 Properties of Coatings. 8.1 Design of Experiments. 8.2 Mechanical Properties. 8.2.1 Hardness and Microhardness. 8.2.2 Tensile Adhesion Strength. 8.2.3 Elastic Moduli, Strengths and Fracture Toughness. 8.2.4 Friction and Wear. 8.3 Thermophysical Properties. 8.3.1 Thermal Conductivity and Diffusivity. 8.3.2 Specific Heat. 8.3.3 Thermal Expansion. 8.3.4 Emissivity. 8.3.5 Thermal Shock Resistance. 8.4 Electric Properties. 8.4.1 Properties of Conductors. 8.4.2 Properties of Resistors. 8.4.3 Properties of Dielectrics. 8.4.4 Electric Field Emitters. 8.4.5 Properties of Superconductors. 8.5 Magnetic Properties. 8.5.1 Soft Magnets. 8.5.2 Hard Magnets. 8.6 Optical Properties. 8.6.1 Decorative Coatings. 8.6.2 Optically Functional Coatings. 8.7 Corrosion Resistance. 8.7.1 Aqueous Corrosion. 8.7.2 Hot-medium Corrosion. References. 9 Applications of Coatings. 9.1 Aeronautical and Space Industries. 9.1.1 Aero-engines. 9.1.2 Landing-gear Components. 9.1.3 Rocket Thrust-chamber Liners. 9.2 Agroalimentary Industry. 9.3 Automobile Industry. 9.4 Ceramics Industry. 9.4.1 Free-standing Samples. 9.4.2 Brick-Clay Extruders. 9.4.3 Crucibles to Melt Oxide Ceramics. 9.4.4 Ceramic Membranes. 9.5 Chemical Industry. 9.5.1 Photocatalytic Surfaces. 9.5.2 Tools in Petrol Search Installations. 9.5.3 Vessels in Chemical Refineries. 9.5.4 Gas-well Tubing. 9.5.5 Polymeric Coatings on Pipeline Components. 9.5.6 Ozonizer Tubes. 9.6 Civil Engineering. 9.7 Decorative Coatings. 9.8 Electronics Industry. 9.8.1 Heaters. 9.8.2 Sources for Sputtering. 9.8.3 Substrates for Hybrid Microelectronics. 9.8.4 Capacitor Electrodes. 9.8.5 Conductor Paths for Hybrid Electronics. 9.8.6 Microwave Integrated Circuits. 9.9 Energy Generation and Transport. 9.9.1 Solid-oxide Fuel Cell (SOFCs). 9.9.2 Thermopile Devices for Thermoelectric Generators. 9.9.3 Boilers in Power-generation Plants. 9.9.4 Stationary Gas Turbines. 9.9.5 Hydropower Stations. 9.9.6 MHD Generators. 9.10 Iron and Steel Industries. 9.10.1 Continuous Annealing Line (CAL). 9.10.2 Continuous Galvanizing Section. 9.10.3 Stave Cooling Pipes. 9.11 Machine Building Industry. 9.12 Medicine. 9.13 Mining Industry. 9.14 Non-ferrous Metal Industry. 9.14.1 Hot-extrusion Dies. 9.14.2 Protective Coatings against Liquid Copper. 9.14.3 Protective Coatings against Liquid Zirconium. 9.15 Nuclear Industry. 9.15.1 Components of Tokamak Device. 9.15.2 Magnetic-fusion Energy Device. 9.16 Paper Industry. 9.16.1 Dryers. 9.16.2 Gloss Calender Rolls. 9.16.3 Tubing in Boilers. 9.17 Printing and Packaging Industries. 9.17.1 Corona Rolls. 9.17.2 Anilox Rolls. 9.18 Shipbuiding and Naval Industries. 9.18.1 Marine Gas-turbine Engines. 9.18.2 Steam Valve Stems. 9.18.3 Non-skid Helicopter Flight Deck. References. Index.

Surgical staples with plated anvils

Abstract: The present invention relates to anvils for surgical fastener applicators having a fastener forming surface for forming surgical fasteners, an intermediate surface formed of a metallic alloy disposed on at least a portion of the fastener forming surface and a polytetrafluorethylene coating disposed on the intermediate surface. The polytetrafluorethylene coating is provided to reduce the force necessary to form the fasteners.

Characterization and Chemical Modification of the Silica Surface

Abstract: Part 1 The silica surface: silica - preparation and properties physical characterization of the silica surface the surface chemistry of silica quantification of the silanol number the distribution of the silanol types and their desorption energies the effect of surface morphology on the dehydroxylation behaviour related materials - silicates Part 2 Chemical modification of the silica surface: chemical modification of silica - applications and procedures modification with silicon compounds mechanistic studies modification with boron compounds modification with other compounds ammoniation of modified silica - introduction of functional groups Part 3 Chemical surface coating: coating techniques chemical surface coating Appendices - surface analysis techniques: FTIR-PAS, fourier transform infrared spectroscopy with photoacoustic detection XPS, X-Ray photoelectron spectroscopy 29Si CP MAS NMR, Cross polarization magic angle spinning nuclear magnetic resonance surface science techniques

Use of electrochemical impedance spectroscopy for the study of corrosion protection by polymer coatings

Abstract: A discussion of the requirements for hardware and software necessary for collection and analysis of electrochemical impedance spectroscopy data for polymer coated metals is presented. Most authors agree that a simple model can describe the frequency dependence of impedance spectra for polymer coated metals exposed to corrosive environments. The water uptake of the coating can be estimated from the time dependence of the coating capacitance C c, The pore resistance R po depends both on the resistivity ρ of the coating and the disbonded area A d. The polarization resistance R P of the corroding area under the coating and the corresponding capacitance C dl both depend on A d. The breakpoint frequency method is discussed in detail and the dependence of the breakpoint frequency f b on ρ and A d is derived. In addition to f b other parameters can be obtained which depend on the ratio A d/ρ or only on A d or ρ. Since these parameters can be obtained at frequencies exceeding 1 Hz without the need for an analysis of the impedance spectra in the entire frequency region, this approach is considered especially useful for corrosion monitoring. The concepts proposed for the analysis and interpretation of EIS data for polymer coated metals are illustrated using data for Al alloys, Mg and steel exposed to NaCl. For an alkyd coating on cold rolled steel the time dependence of A d and ρ during exposure to 0.5 m NaCl has been determined qualitatively using the modified breakpoint frequency method.

Fracture Mechanics of Functionally Graded Materials

Abstract: In today's highly demanding technological environment, one of the main challenges in new material design is combining seemingly irreconcilable thermomechanical properties in the same component (e.g., high heat and corrosion resistance, high strength in elevated-temperature applications and high resistance to wear, and high toughness in load-bearing elements). In many cases, the problem may be solved by using coatings or by layering dissimilar materials. From a structural viewpoint, a major disadvantage of these techniques, particularly in ceramic coating of metals, has been the resulting high thermal and residual stresses and relatively poor bonding strength. Thus, in thin films, coatings, and layered materials, surface cracking and debonding or delamination have been common forms of mechanical failure. One effective way of reducing residual and thermal stresses and enhancing bonding strength has been to eliminate material-property discontinuities by grading the material composition near the interfaces or through the coating. These new materials, with continuously varying compositions or volume fractions, are known as functionally graded materials (FGMs).In developing FGMs, research on the mechanics, and particularly on the fracture mechanics of these inhomogeneous materials, is needed to provide technical support to materials scientists and to manufacturing and design engineers. In the past, fracture mechanics has been useful both as a screening tool during material processing and as a design and maintenance tool for service-life assessment. Broadly speaking, fracture mechanics involves studying the effect of the applied loads, the component/flaw geometry, and the environmental conditions on the fracture of engineering materials.

Effect of surface topology on the osseointegration of implant materials in trabecular bone.

Abstract: The importance of surface topology and implant material composition on osseointegration in trabecular bone was investigated using three commercially used implant materials and surface-texturing procedures which included blasting, high temperature acid etching, and hydroxyapatite (HA) coating. Surface roughness and spacing parameters were measured for each implant group with a laser interferometric profilometer. Cylindrical implants were press-fit into trabecular bone sites in the knee of mature miniature pigs. After 12 weeks in situ, osseointegration was evaluated by (1) mechanical pushout tests to measure bone-implant interface strength and (2) quantitative morphometric measurements of the percent implant surface covered by bone. We found that HA-coated implants showed superior osseointegration in terms of both pushout failure load and surface coverage by bone measurements. An excellent correlation (r2 = .90) was found between the average roughness of the implant surface and pushout failure load. New methods for altering the local topologic and/or chemical state of the implant surface (i.e., by acid etching) may provide an important new avenue of research for improving the osseointegrative properties of orthopedic materials. © 1995 John Wiley & Sons, Inc.

Decorative panel and production thereof

Abstract: PURPOSE:To provide excellent abrasion resistance by applying a thermoplastic synthetic resin to the surface of the fancy veneer bonded to the surface of a substrate through an adhesive not only to infiltrate a part thereof into the fancy veneer but also to form a thermosetting synthetic resin layer and forming a film layer containing an abrasive material on the synthetic resin layer. CONSTITUTION:Substrate treatment is applied to the surface of a substrate 1 if necessary and an adhesive 4 is applied to the treated surface of the substrate 1 by a coating device. Next, fancy veneer 2 coated with a thermosetting resin is placed on the substrate 1 and the fancy veneer 2 and the substrate 1 are pressed between upper and lower clamp plates under pressure by a flat plate press not only to infiltrate the thermosettlng resin in the fancy veneer 2 under pressure but also to cure the thermosetting resin to form a thermosetting resin layer 3 on the surface of the fancy veneer 2 while forming a thermosetting resin impregnated part 3a in the fancy veneer 2 on the surface side thereof. Further, a film layer 6 having abrasion resistance is formed on the thermosetting resin layer 3 by applying paint mixed with an abrasive material 5 to the resin layer 3.

Multilayer PVD coatings for wear protection

Abstract: The PVD technology is well suited to realize new and advanced coating concepts like gradient coatings, metastable coatings, multicomponent coatings, multilayer or superlattice coatings. Among these coating concepts the multilayer coatings seem to be the most promising concept because it meets many requirements (e.g. multifunctional character, moderate residual stresses, good adherence to metallic substrates, proper hardness to toughness ratio and low friction coefficients) for a composite exposed to complex wear conditions. Further the concept allows metastable and multicomponent materials to be introduced in a graded multilayer arrangement. By this way different layer concepts can be realized simultaneously. A functional and a structural design, taking into account the material selection for the individual layers, the adjustment of the interface volume and constitution and the optimization of the individual layer sequence and thickness, allows a tailoring of properties and performance. Covalent or ionic materials like B 4 C, SiC, Si 3 N 4 or Al 2 O 3 can be introduced as intermediate layers in the multilayer arrangement, raising hardness and high temperature strength without reducing adherence or toughness of the coating. New results concerning constitution, properties and application characteristics for multilayer coatings mainly based on TiC/TiN are presented.

Coatings on glass

Abstract: A method of producing mirrors comprising depositing onto a ribbon of hot glass during the production process a coating comprising at least one pyrolytic reflecting layer and at least one color modifying layer whereby the mirrors exhibit color in reflectance and have a visible light reflection of at least 35 % and less than 70 %. There is also provided a mirror having such a coating.

Quantitative Extraction Using an Internally Cooled Solid Phase Microextraction Device

Abstract: Solid phase microextraction (SPME) is a new extraction technique which uses a fused silica fiber coated with polymeric coating to extract organic compounds from their matrix and directly tranfer analytes into a gas chromatograph (GC) by thermal desorption in a GC injector. SPME has been proven to be simple, time efficient, and sensitive. By sampling from the headspace above sample matrices, SPME can be used to extract target analytes from very complex matrices such as sludge, wastewater, and soil. In this paper, we develop a new approach for headspace SPME sampling. By heating the sample matrix while simultaneously cooling the fiber coating, we not only facilitate the mass transfer and the release of analytes into the headspace but also create a temperature gap between the cold fiber coating and the hot headspace which significantly increases the partition coefficients of analytes

Method for making an electronic module

Abstract: A multi-chip module is provided which utilizes benzocyclobutene as a laminate adhesive for bonding the upper dielectric films in a high density interconnect structure. The benzocyclobutene thermosetting polymer is spin coated on a polyimide film, and baked at low temperature to remove any solvent to leave a B-staged coating on the polyimide film. The composite film can be laminated to an underlying electrical structure using a vacuum laminator and heat. As the heat is applied, the BCB layer softens, flows and then cures to bond the polyimide film to the underlying electrical structure.

Development and Optimization of a TiO2-Coated Fiber-Optic Cable Reactor: Photocatalytic Degradation of 4-Chlorophenol.

Abstract: We have developed, characterized, and utilized a photochemical reactor system that employs an optical fiber cable as a means of light transmission to solid supported TiO_2. Light energy is transmitted to TiO_2 particles, which are chemically anchored onto quartz fiber cores, via radial refraction of light out of the fiber. Operational factors that influence the efficiency of the bundled-array optical fiber reactor are as follows: the uniformity and extent of light propagation down the fiber, the degree of light absorption by the TiO_2 coating of the refracted light, and the ability of the chemical substrates to diffuse into the TiO_2 coating. A TiO_2 coating layer that minimizes the interfacial surface area of the quartz core and TiO_2 particles and operation with incident irradiation angles near 90" enhance light propagation down the fibers. A maximum quantum efficiency of Φ = 0.011 for the oxidation of 4-chlorophenol was achieved. This can be compared to a maximum quantum efficiency of Φ = 0.0065 for 4-chlorophenol oxidation in a TiO_2 slurry reactor operated under similar conditions.

Electroless plating process for the manufacture of printed circuit boards

Abstract: There is disclosed a process for electroless plating of a conductive metal layer onto the surface of a non-conductive substrate, in which the substrate surface is prepared for receiving a coating of activator using conventional methods, and the coating of activator is applied by contacting the substrate surface with a stabilized sensitizing solution comprising ions of at least one Group VIII and IB transition metal, preferably palladium chloride, stannous ions in a molar concentration in excess of that of the transition metal ions, an acid, and a buffering salt; followed by contacting the sensitized substrate surface with a noble metal activating solution to catalyze the substrate surface for subsequent electroless plating. The sensitized and activated substrate is then contacted with an aqueous dry film photoresist, which is then imaged and developed to form a predetermined electrical circuit pattern, using conventional methods. The cleaned and imaged substrate is then immersed in an acidic electroless nickel metal depositing solution, for a time, at a concentration, and at a temperature sufficient to prepare the substrate for subsequent pattern electroplating, said acidic electroless metal depositing solution comprising ions of nickel, a complexing agent, a reducing agent capable of reducing said metal ions to a metallic state in an acidic medium, provided that said reducing agent does not include formaldehyde or a formaldehyde generating composition, one or more stabilizers, and water.

Poly(3, 4-ethylenedioxythiophene): Conductive coatings, technical applications and properties

Abstract: Poly(3, 4-ethylenedioxythiophene) (PEDT) is a new polymeric organic conductor which, when combined with polystyrene sulphonic acid, produces a system that can be processed as an aqueous solution and yields effective antistatic coatings for films. The antistatic effect is achieved with coating weights of just a few mg PEDT/m2, resulting in films with a surface resistivity of 106 ω/□.

Ion beam process for deposition of highly abrasion-resistant coatings

Abstract: An ion beam deposition method is provided for manufacturing a coated substrate with improved abrasion resistance, and improved lifetime. The substrate is first chemically cleaned to remove contaminants. Secondly, the substrate is inserted into a vacuum chamber (1) on holder (3), and the air therein is evacuated via pump (2). Then the substrate surface is bombarded with energetic ions from ion beam source (4) supplied from inert (5) or reactive (6) gas inlets to assist in removing residual hydrocarbons and surface oxides, and activating the surface. After sputter-etching the surface, a protective, abrasion-resistant coating is deposited by ion beam deposition where reactive gas inlets (7, 8 and 9) may be employed. The ion beam-deposited coating may contain one or more layers. Once the chosen coating thickness is achieved, deposition is terminated, vacuum chamber pressure is increased to atmospheric pressure and the coated substrate products having improved abrasion-resistance are removed from the chamber. These coated products may be plastic sunglass lenses, ophthalmic lenses, bar codes scanner windows, and industrial wear parts needing protection from scratches and abrasion.

New generation of plasma-sprayed mullite coatings on silicon carbide

Abstract: Mullite is promising as a protective coating for silicon-based ceramics in aggressive high-temperature environments. Conventionally plasma-sprayed mullite on SiC tends to crack and debond on thermal cycling. It is shown that this behavior is due to the presence of amorphous mullite in the conventionally sprayed mullite. Heating the SiC substrate during the plasma spraying eliminated the amorphous phase and produced coatings with dramatically improved properties. The new coating exhibits excellent adherence and crack resistance under thermal cycling between room temperature and 1000 to 1400 C. Preliminary tests showed good resistance to Na2CO3-induced hot corrosion.

Medical device with lubricious coating

Abstract: A medical balloon and catheter in which the balloon (14) is wrapped and folded upon itself tortuously and tightly so outer surfaces (12) contact each other for insertion into the body and in whic the balloon is free of bridging and adhesion between abutting surfaces. The balloon has a base of a continuous polymeric surface (10) expandable from a folded, wrapped configuration with surfaces touching each other into a balloon when inflated. A lubricious, bio-compatible, hydrogel coating (11) is disposed on the polymeric surface and a thin, lubricious, blood-compatible coating (12) is disposed upon the hydrogen coating and adheres to it to prevent abutting surfaces of the folded polymeric surfaces from adhering to each other during inflation and to prevent delamination of the hydrogel coating and/or rupture of the balloon. Preferably the blood-compatible coating (12) is polyethylene glycol, methoxy polyethylene glycol or mixtures thereof having a molecular weight between about 100 and 20,000 grams per gram mole.

Colour deformable mirror device having optical thin film interference colour coatings

Abstract: A semiconductor device comprises a plurality of coloured deformable mirrors controllable by electrical circuitry. Groups of mirrors, responsive to the electronic signals, are selectably operable to reflect incident light. The deformable mirrors are coated with an optical thin film interference colour coating having at least a layer that is substantially transparent to the visible light. As well the optical thin filminterference colour coating includes at least one further layer that is partially absorbing with respect to the visible light. The spectral reflectance and absorptance of the deformable mirror is modified in order to obtain a desired reflectance colour by the process of optical interference enhanced absorption in the optical thin film interference colour coating. The optical thin film interference colour coating has predetermined layer thicknesses and materials; the substantially transparent layer substantially determines the desired reflected colour.

Precursor solutions for forming coatings

Abstract: An electrochromic coating is produced by adding an organic moiety to a solution of an electrochromic precursor, said organic moiety having a decomposition temperature greater than, or a vapor pressure sufficiently low at, the temperature at which solution solvent is removed, such that said organic moiety remains integral with the electrochromic precursor coating on said substrate after said solvent evaporates, and said organic moiety having a decomposition temperature lower than, or a vapor pressure sufficiently high at, the temperature at which said electrochromic precursor coating is converted to an electrochromic coating that said moiety is substantially removed from said coating before or during said conversion.

Residual/thermal stresses in FGM and laminated thermal barrier coatings

Abstract: The plane strain elasticity problem for a functionally gradient material (FGM) and a multi-layered homogeneous coating bonded to a metal substrate due to a uniform temperature change is considered. The substrate is assumed to be a nickel-based alloy-Rene-41. The FGM coating is a particulate composite of Rene-41 and zirconia with volume fractions continuously varying through the thickness. The multi-layered coating consists of one, two or four homogeneous layers with stepwise changing volume fractions. With a possible failure mechanism of surface cracking or edge debonding in mind, the relevant stresses on the surface of the coating and along the interfaces are evaluated. For the piecewise homogeneous coating the power of singularity and the corresponding stress intensity factors at the points of intersection of the interfaces and the free ends are calculated. It is shown that by using the FGM coating the stress singularities are eliminated and the stress distribution is smoothed considerably. Sample results for the displacements and for the contour plots of an effective stress governing the yield behavior of the material are given and the asymptotic behavior of the stress state around the singular point is examined.

Diesel particulate filter apparatus

Abstract: According to the present invention, a filter body for collecting particulates is constituted of a fiber laminate material produced by laminating a fiber material comprising a core material in the form of a fiber, and a covering layer of a material different from that of the core material formed around the outer periphery of the core material by coating. The core material of the fiber material is selected from among inorganic fibers such as glass or ceramic fibers containing alumina, and heat-resistant alloy fibers each made of a heat-resistant alloy selected from among Ti-Al alloys, Fe alloys containing at least one of Mo, Cr and Ni, and Fe-Cr-Al-Y alloys. The covering layer is made of a material selected from among silicon carbide ceramics respectively derived from polytitanocarbosilane, polysilazane and polycarbosilane, thermoplastic materials, silicon carbide ceramics such as Si-C, Si-Ti-C-O and Si-C-O or silicon nitride ceramics such as Si-N-C-O, alumina ceramics, and zirconia ceramics.

Characterization of Sol‐Gel‐Derived TiO2 Coatings and Their Photoeffects on Copper Substrates

Abstract: In accordance with the corrosion protection of Cu by coating under illumination, the relation between the structural characterization and the photoelectrochemical properties of sol‐gel‐derived coating has been investigated utilizing glow discharge spectroscopy, x‐ray diffraction, and x‐ray photoelectron spectroscopy analysis techniques. As a result of the well‐known shrinkage of the gel under heat‐treatment, the thickness of the coating decreased with increasing heating temperature, about a 50% decrease from 200 to 800°C. Amorphous gel was found to be crystallized above 400°C, which gave rise to a great enhancement of the photocurrent of the coating. In relating these results to the photoelectrochemical behavior of Cu, it was revealed that both the significant change in the photocurrent and the existence of Cu oxides in the coating were not the direct reasons which accounted for the critical temperature for to impose its photoeffect on the Cu substrate. The dramatic change in the photopotential of Cu would be explained by the change of Schottky barrier at the interface in terms of the Fermi level pinning at the Ti3+ defect level. Nevertheless, the increase in the photocurrent of coating was beneficial to move the photopotential of coated Cu to a much less noble level. The degradation of the photoeffect of coating heated above 800°C was due to the significant diffusion of Cu into the coating.

Method for manufacturing a semiconductor package

Abstract: A method for manufacturing a semiconductor package, including providing a lead frame in which die pad and side rail areas of the lead frame are mechanically interconnected to, and electrically isolated from each other so that the exposed bottom surface of the die pad does not become coated with a metal plating film during surface treatment for coating outer leads of the lead frame.

Atomic oxygen resistant coatings for low earth orbit space structures

Abstract: This review presents research in the area of polymeric coatings developed for protecting low earth orbit (LEO) space structures from atomic oxygen. Following a brief description of the LEO environment, ground-based simulation facilities for atomic oxygen and evaluation of protective coatings are discussed. Atomic oxygen resistant coatings based on different polymeric systems such as fluorinated polymers, silicones, poly (carborane-siloxane)s and decarborane-based polymers are presented. Finally, the performances of different coating systems are compared and the scope for further research to improve the performance of some of the coating systems is discussed.