Many Kinds Of Defects Research Articles

K-0637 遮熱コーティング皮膜のナノキャラクタリゼーション(S06-2 遮熱コーティングの強度評価)(S06 コーティング材の力学特性と損傷機構)

Nano-characterization of ceramic top-coat/metallic bond-coat interface was conducted for the plasma sprayed thermal barrier coating (TBC) systems subjected to different kinds of reheat treatment conditions by means of an electron probe micro analysis and transmission electron microscopy and so forth, in order to find out the optimum coating processing condition. Reheat treatment was applied to the TBC specimen with different temperature in air or inert Ar gas. It was found that in air the thermally grown oxide (TGO) at interface was composed of the double oxide layers; one was Al_2O_3 layer on the bond-coat and another was mixed oxides layer consisting of Co, Ni, Cr, Al on the Al_2O_3 layer. This TGO layer was discontinuous and imperfect layer with many kinds of defects. But TGO layer formed by reheat treatment in Ar appeared much more protective with continuous and homogeneous morphology.

Single-particle selection and alignment with heavy atom cluster-antibody conjugates.

A method is proposed for selecting and aligning images of single biological particles to obtain high-resolution structural information by cryoelectron microscopy. The particles will be labeled with multiple heavy atom clusters to permit the precise determination of particle locations and relative orientations even when imaged close to focus with a low electron dose, conditions optimal for recording high-resolution detail. Heavy atom clusters should also allow selection of images free from many kinds of defects, including specimen movement and particle inhomogeneity. Heavy atom clusters may be introduced in a general way by the construction of "adaptor" molecules based on single-chain Fv antibody fragments, consisting of a constant framework region engineered for optimal cluster binding and a variable antigen binding region selected for a specific target. The success of the method depends on the mobility of the heavy atom cluster on the particle, on the precision to which clusters can be located in an image, and on the sufficiency of cluster projections alone to orient and select particles for averaging. The necessary computational algorithms were developed and implemented in simulations that address the feasibility of the method.

Specialized techniques in holographic non-destructive testing of composites

Holographic interferometry is a very efficient technique used in non-destructive testing and characterizing of composites. Many kinds of defects may be simultaneously detected over large areas, without any contact with the tested material. All the defects appear as local distortions of a regular fringe pattern covering the holographic image of the tested object. Seeing a complicated fringe pattern with a large number of local distortions in a single image might be confusing for the operator, who is often interested in detecting a particular type of defect. In such cases, in order to apply the holographic technique, specialized testing techniques have to be established. This paper describes two such techniques, one for testing the metallic insertions in the belt area of rubber tyres, the other for testing pasteboard-epoxy composites, and detecting fiber direction and interactions.

Carrier traps in a GaAs/AlxGa1−xAs single electron transistor

We study carrier traps in a single electron transistor fabricated from a GaAs/AlxGa1−xAs heterostructure. In the heterointerface, there are many kinds of defects, which induce various trap levels in the band gap of AlxGa1−xAs or GaAs. The current through the transistor switches between two states because of trapping and detrapping of a single electron. The gate voltage dependencies of the switching indicate how the traps are spatially distributed. The possibility of the existence of a trap with multilevels is also discussed.

Overview of Cast Multicrystalline Silicon Solar Cells

Worldwide environmental problems such as the greenhouse effect and acid rain have been caused by the human race's continuous reliance on the combustion of petroleum for fuel.Solar energy, which is clean and practically unlimited, is expected to be a desirable alternate energy source to conventional power supplies, and demand for the photovoltaic system has increased throughout the world, especially in Europe and the United States.Photovoltaic cells are probably the most effective method for capturing solar energy, since they are easy to use and are the most effective means of directly generating electricity.Many kinds of solar cells have been developed in past years, especially since the first oil crisis in 1973. Among them, solar cells from cast multicrystalline silicon (also refereed to as (cast) polycrystalline silicon or semicrystalline silicon) are considered to be one of the most promising types, capable of achieving both high efficiency and low cost.In 1975, Wacker proposed a new manufacturing method for silicon substrates, using the casting method. Since then, many organizations have been involved in the research and development of multicrystalline ingots and solar cells using multicrystalline silicon substrates.Multicrystalline silicon substrates contain many kinds of defects compared to single-crystal silicon substrates, so the efficiency of multicrystalline silicon solar cells has been inferior to that of single-crystal cells. Recent research on multicrystalline silicon solar cells has resulted in substantial improvements and in the demonstration of high-efficiency cells.

A structural investigation of the crystallization products of an amorphous Ni-P alloy

Abstract The crystallization product of an amorphous ni80P20 alloy has been studied using X-ray diffraction and transmission electron microscopy (TEM). The crystallization product is composed of two phasese: body-central tetragonal (b.c.t.) Ni3 P compound and face-central cubic (f.c.c.) Ni austenite, and a new set of orientation relationships between them has been obtained: <001> b.c.t. // <110> f.c.c., <110> b.c.t.// <111> f.c.c. According to the orientation relationships, a possible interface model between Ni3 P and Ni crystals was proposed. An observation of the cyrstals was carried out by means of high-resolution electron microscopy (HREM). The morphology of the products is characterized by separated cyrstalline blocks of the two phases, in which Ni3 P blocks contain many kinds of defects. Different kinds of Ni-phase morphology were also analysed. Such a crystallization product which is difficult to interpret by suing the classical atom-diffusion mechanism can be understood according to the newly developed cyrstallization micromechanism. The structure relationship between the coordination clusters (in amorphous state) and the crystallization products was also discussed.

Multi-functional visual inspection system for assembled PCBs using digital signal processor.

The production number of printed circuit boards (PCBs) is increasing very rapidly. To automize the PCB production, a visual inspection system for assembled PCB has been developed.The system inspects many kinds of defects on assembled PCBs, such as parts missing, improper parts on PCBs, polarity error of diodes and capacitors and improper insertion of leads, using image processing techniques. The multi-step similarity vector method has been developed to read various character patterns of IC names from many manufacturers. To inspect polarity marks on movable parts with long leads, the flexible window system has been installed. The slitted light is casted on leads backside of PCB to inspect parts missing and improper insertion of leads.To execute these variety of image processing at high-speed, the inspection system is equipped with a micro-programmable digital signal processor for image processing, the DSP-i. The DSP-i enables the system to inspect the various inspection functions 25 times faster than general purpose 16 bits microcomputers.