Developing new industrial applications for gold: Gold nanotechnology

Nanotechnology has transformed gold from a marginal into a very effective catalyst with unique properties. The astounding growth in gold nanoparticle research, as reflected in publications and patents, now promises new materials applications for gold nanotechnology and some possibilities are indicated in this article.     

Beyond TCNE: new building blocks for molecule-based magnets

Several new examples of organic one-electron acceptors have been discovered to be viable and versatile alternatives to tetracyanoethylene as building blocks for the synthesis of charge-transfer salt/charge-transfer polymer molecule-based magnets. Guidelines for the identification of new acceptor candidates as well as several examples of compounds derived from these acceptors will be described. The observed magnetic properties include glassy ferromagnetism, metamagnetism and ferrimagnetism.     

New derivatives of phenylamine as novel building blocks of conducting polymers

A novel phenylamine substituted derivatives possessing different photochromic groups were investigated. Using the electrochemical and spectroelectrochemical measurements the electrochemical activity of the monomers and polymers have been studied. The results indicate good film forming properties most of the monomers and stability of the forming films. The polymeric films include diphenylamine or triphenylamine unit and five member heterocycle ring moieties.     

Printed gold for electronic applications

Molecular and nanoparticulate gold precursors for application in inkjet printing onto flexible substrates are discussed. The choice of stabilising ligands and the size of the nanoparticles influence the solution stability of the ink and their ability to form decorative or conductive functional films.     

Thermal barrier coatings for industrial gas turbine applications: An industrial note

Thermal barrier coatings (TBCs) have been used in high-thrust aircraft engines for many years to pro-vide thermal protection and increase engine efficiencies. TBC life requirements for aircraft engines are typically less than those required for industrial gas turbines. This paper describes current and future ap-plications of TBCs in industrial gas turbine engines. Early testing and applications of TBCs are reviewed. Areas of concern from the engine designer’s and materials engineer’s perspective are identified and evaluated. This paper focuses on the key factors that are expected to influence utilization of TBCs in ad-vanced industrial gas turbine engines. It is anticipated that reliable, durable, and highly effective coating systems will be produced that will ultimately improve engine efficiency and performance.     

X-ray modeling for industrial applications

A computer package for the simulation of the X-ray imaging process in nondestructive evaluation (NDE) is presented. The components of the radiographic inspection system are considered independently, i.e. the characteristics of the source, the geometry and the material properties of objects and defects, as well as the imaging process itself. The model is based on a ray tracer technique describing the attenuation of the radiation. The scattering effect is included in terms of built-up factors. A CAD-interface provides the opportunity to arrange independent CAD objects, e.g. the component geometry or defect shapes, defining a testing scheme. Complicated defect shapes are created by a preprocessor, the built-up factors can be received from experiments or from a separate model using an efficient solution of the scattering problem based on the theory of Markovian processes with random structure.     

High-current metal ion implantation for industrial applications

Ion implantation, as an efficient surface processing technique, has developed to include the implantation of various metallic ions for improving not only wear properties, but also such other surface properties as solid lubrication, fatigue, chemical stability, and engineering reliability. The high-dose metal ion implantation that can be accumulated in a short time over a relatively large implanting area makes metal vapor vacuum arc (MEVVA) source ion implantation well suited to practical surface engineering modification applications.     

Coordination polymers with [Au(CN)4]- building blocks: a 1-d chain of molecular NiII2AuIII2 squares

A new coordination polymer utilizing the neglected cyanoaurate anion [Au(CN)₄]- building block is reported. Reaction of a Ni(II) salt, diethylenediamine (dien) and K[Au(CN)₄] yields Ni(dien)[Au(CN)4]₂, which consists of a unique bimetallic Ni(II)₂/Au(III)₂ supramolecular square through cis N(cyano) bridging of the [Au(CN)₄]- building block to [Ni(dien)]²⁺ cations. These squares further aggregate into a 1-D chain via Au-N(cyano) interactions; no Au(III)-Au(III) interactions are observed. Within the square, the magnetic coupling between the Ni(II) centres is very weak, indicating that the [Au(CN)₄]- unit is a poor mediator of magnetic exchange in this system.     

Advances in polymers for PLEDs: from a polymerization mechanism to industrial manufacturing

The recent development of polymer light emitting diodes (PLEDs) has triggered a lot of interest for their use in displays, backlights, and for lighting applications. Their high efficiency and ease of manufacturing make PLEDs especially attractive. Various conjugated polymers have been employed, but especially soluble phenyl-poly-p-phenylene vinylene(s) show excellent properties.The chemical as well as the structural purity of the polymers has proven to be essential for high performance, long lifetime PLEDs. Mechanistic investigations allowed the identification of one major polymerization defect in PPVs, the so called tolane–bisbenzyl moiety. This in turn has enabled us to eliminate the most significant failure mechanism of these PPVs during device operation.The newly developed polymers are manufactured on an industrial scale. A combination of a glass lined 370/560 L vessel cascade allows manufacturing in kilogram scale quantities while still maintaining high purity levels. A significant extension of this facility is now in use and ensures availability of large quantities ready-to-use solution of various light emitting polymers with photo-resist type purity.     

One-step fabrication of hierarchical polypyrrole microspheres with nanofibers as building blocks

Hierarchical polypyrrole microspheres, which have nanofibers as building blocks, the size of several microns and a conductivity of 0.8 S cm^?1, were prepared simply and directly via a one-step self-assembly approach in the presence of (NH₄)₂S₂O₈ (APS), cetyltrimethylammonium bromide (CTAB) and sulfonated polyaniline (SPANI). It was found that the formation probability of hierarchical polypyrrole microspheres depended on the (NH₄)₂S₂O₈/CTAB and SPANI/CTAB molar ratio. Bulk quantities of hierarchical polypyrrole microspheres can be obtained readily under the optimal conditions such as (NH₄)₂S₂O₈/CTAB molar ratio >2.8 and SPANI/CTAB molar ratio >4.7 × 10^?3. The precipitate [(CTA)₂S₂O₈] of CTAB and (NH₄)₂S₂O₈ was proposed to act as a “template” to promote the formation of PPY nanofibers, while the dopant SPANI was suggested to play a “rope-like” or “bridge-like” role in the subsequent self-assembly of nanofibers into PPY hierarchical microspheres. The experimental results and our investigation for the formation of PPY hierarchical microspheres may shed some light on preparing of other conductive hierarchically materials by proper molecular design and experimental condition optimization.     

Cold spraying: Innovative layers for new applications

In recent years, results of many studies have been published that enhance understanding of the fundamental mechanisms of cold-spray coating generation and bonding as well as coating characteristics. From the points of view of a job shop in thermal spraying and of a user of cold-spraying equipment, a procedure, being used in development of new applications is presented herein. In addition to the technical requirements, some general factors determining the success of industrial use of spraying are shown. Examples of coldsprayed coatings are described to shos both the possibility of rapid integration of this new technique in established coating jobs as wells as exploration and use of new possibilities in cold spraying and development of applications that have not yet been a focus of thermal spray techniques. Suggestions for further research and development activities are made on the basis of practical cold-spray experience. The original version of this paper was published in the CD ROM Thermal Spray Connects: Explore Its Surfacing Potential, Internaltional Thermal Spray Conference, sponsored by DVS, ASM International, and IIW International Institute of Welding, Basel, Switzerland, May 2–4, 2005, DVS-Verlag GmbH, Düsseldorf, Germany.     

Ultrafast laser manufacturing: from physics to industrial applications

Modern ultrafast lasers are enabling better operative performances in micro and nano-fabrications of materials, benefited from their ease of use, robustness, and reliability. The purpose of this paper is to bridge the gap between the knowledge of ultrafast optics and the modern industrial applications. The paper introduces main phenomena in ultrafast laser-matter interactions by reviewing relevant theoretical models and simulation techniques. The operation of ultrafast lasers is based on nonlinear optics phenomena, fully described only in the framework of quantum-mechanics. Current trends in the development of modern ultrafast system are given. It also presents a review of the latest advances in ultrafast laser-based manufacturing processes, some of the most interesting industrial applications, and a discussion on future trends and challenges.     

Computed tomography part I: Introduction and industrial applications

X-ray computed tomography (CT) provides quantitative, readily interpretable data and enables the inspection of structures that are not amenable to any other nondestructive evaluation technique. As a result, CT has become well established as an inspection, evaluation, and analysis tool in industry. Many of the applications have been in the aerospace industry, where the high cost and performance requirements of components justifies the cost of CT inspection, but use in other industries is growing as equipment becomes increasingly available.     

Platinum colloid catalyzed etchingless gold electroless plating with strong adhesion to polymers

Echingless electroless plating (ELP) process that can produce gold thin film with strong adhesion to various polymer films has been developed. We have found that platinum (Pt) colloidal nanoparticles have excellent catalytic activity for ELP. The Pt colloidal nanoparticles can be immobilized via electrostatic interactions on a substrate simply by dipping it into a Pt colloid. Owing to the excellent catalytic property of the Pt nanoparticles, continuous gold thin films can be produced at room temperature using a simple cyanide-free gold electroless plating solution composed of chloroauric acid and hydrogen peroxide. The process requires no surface modifications for the immobilization of the catalyst, and by simple post-annealing the adhesion of the plated films to various polymer films can be improved by three orders of magnitude in comparison to that of “as-deposited” film. The process developed in this work is expected to be an environment-friendly thin metal film deposition process without the use of toxic and hazardous substances.     

Polyfuran conducting polymers: Synthesis,properties, and applications

In this review, polyfuran (PFu) synthesis methods and the nucleation mechanism; the electrochemical, structural, morphological, and magnetic properties of PFu; thermal behavior; theoretical calculations on PFu, as well as its applications reported to date, have been compiled. Not only PFu homopolymers have been reviewed, but also PFu co-polymers, PFu bipolymers, and PFu composites. The results are listed, discussed, and compared. It is hoped that this assembly of all the relevant data might enhance knowledge about this conducting polymer and lead to new research fields.     

The use of gold mercaptides for decorative precious metal applications

An overview of the use of soluble gold mercaptide compounds as precursors in Decorative Precious Metal (DPM) ink formulations, for application onto ceramic, glass and plastic substrates, is given. Synthetic, thermal, structural and metallisation properties are highlighted, together with the advantages that these precursors show for DPM ink applications. The literature reviewed covers the period 1960 to 2001. Mechanistic studies are described and likely future trends indicated.     

Controlled placement of nanoscale building blocks: Toward large-scale fabrication of nanoscale devices

Much effort has been made recently to develop future devices or sensors comprising nanoscale building blocks such as nanowires, carbon nanotubes, DNA, proteins, and nanoparticles. One of the key requirements to realize these devices/sensors is the capability to place individual nanoscale building blocks onto exact substrate locations. This article will review recent progress in various approaches exploited to place or assemble nanoscale building blocks in a controlled way.     

Creep behaviour of a cast TiAl-based alloy for industrial applications

The creep behaviour of a cast TiAl-based alloy with nominal chemical composition Ti–46Al–2W–0.5Si (at.%) was investigated. Constant load tensile creep tests were performed in the temperature range 973–1073 K and at applied stresses ranging from 200 to 390 MPa. The minimum creep rate is found to depend strongly on the applied stress and temperature. The power law stress exponent n is determined to be 7.3 and true activation energy for creep Q is calculated to be 405 kJ/mol. The initial microstructure of the alloy is unstable during creep exposure. The transformation of the α₂(Ti₃Al)-phase to the γ(TiAl)-phase, needle-like B2 particles and fine Ti₅Si₃ precipitates and particle coarsening are observed. Ordinary dislocations in the γ-matrix dominate the deformation microstructures at creep strains lower than 1.5%. The dislocations are elongated in the screw orientation and form local cusps, which are frequently associated with the jogs on the screw segments of dislocations. Fine B2 and Ti₅Si₃ precipitates act as effective obstacles to dislocation motion. The kinetics of the creep deformation within the studied temperature range and applied stresses is proposed to be controlled by non-conservative motion of dislocations.