Thin metallic

The use of thin metal foils (Be, Cu, Ti) reduces the radiation attenuation in the window or serves as pre-filtration for various measurement set-ups. 

Another important application area is the non-destructive defectoscopy of electronic components. Fig.2a shows an X-ray shadow image of a SMC LED. The 3-dimensional displacement of internal parts can only be visualized non-destructively in the tomographic reconstmction. Reconstructed cross sections through this LED are shown in Fig.2b. In the same way most electronic components in plastic and thin metal cases can be visualized. Even small electronic assemblies like hybrid ICs, magnetic heads, microphones, ABS-sensors can be tested by microtomograpical methods. 

Instead of an absorbing dye layer between the mica. Levins et al [57] used thin metallic films and developed a method for FECO analysis using an extended spectral range. 

Turbadar T 1959 Complete adsorption of light by thin metal films Proc. Phys. See. 73 40-4... 

If pres.sure tubing is used, it is advisable to insert a short length of thin metal wire e.g.. copper wire, 22 gauge) to prevent the tubing being closed completely by the screw clip. 

Because of its small size and portabiHty, the hot-wire anemometer is ideally suited to measure gas velocities either continuously or on a troubleshooting basis in systems where excess pressure drop cannot be tolerated. Furnaces, smokestacks, electrostatic precipitators, and air ducts are typical areas of appHcation. Its fast response to velocity or temperature fluctuations in the surrounding gas makes it particularly useful in studying the turbulence characteristics and rapidity of mixing in gas streams. The constant current mode of operation has a wide frequency response and relatively lower noise level, provided a sufficiently small wire can be used. Where a more mgged wire is required, the constant temperature mode is employed because of its insensitivity to sensor heat capacity. In Hquids, hot-film sensors are employed instead of wires. The sensor consists of a thin metallic film mounted on the surface of a thermally and electrically insulated probe. 

Writing by Bubble Forming. Bubble formation occurs under thin metal layers on polymeric substrate films, caused by local evaporation when hit by a focused laser beam (see Fig. 3c). Bubble formation occurs as in the DIP concept in dye-in-polymer films which are covered by a thin metal (mostiy gold) or ceramic layer (6) (see Fig. 3d). 

Transport of France reduces dimensional change by using a thin inner liner of Invar. Another patented French system accommodates this change by means of the flexibility of thin metal which is creased. The creases run in two direc tions, and the form of the crossings of the creases is a feature of the system. 

Conveyor-Belt Devices The metal-belt type (Fig. 11. 55) is the only device in this classification of material-haudhug equipment that has had serious effort expended on it to adapt it to indirecl heat-transfer seiwice with divided solids. It features a lightweight construction of a large area with a thin metal wall. ludirect-coohiig applications have been made with poor thermal performance, as could be expected with a static layer. Auxihaiy plowlike mixing devices, which are considered an absolute necessity to secure any worthwhile results for this seiwice, restrict applications. 

Stainless steel is susceptible to sensitization when it is heated to the range of 900 to 1550°F (480 to 850°C). Since any welding operation involving stainless steel will produce such temperatures in the metals being joined, it would appear that all welded stainless steel would sensitize. However, sensitization is a function of both time and temperature, occurring most rapidly at temperatures near 1250°F (675°C). Metals that cool rapidly through this temperature range will not sensitize. Consequently, thin metal sections, which cool rapidly, are less susceptible to sensitization than thick sections. 

The capacitor element in this case is made up of extremely thin metallic films. When a dielectric failure occurs in any of the elements, the current passes through the film. The film, being too thin to sustain the current, fuses only at the point of dielectric puncture clearing the fault quickly. The external fuses remain intact, and so remains the affected element in service. Some manufacturers claim that 10000 such failures and healings may reduce the rating of the element or the unit made up of such elements by barely I %. 

A composite material consists of flat, thin metal plates of uniform thickness glued one to another with a thin, epoxy-resin layer (also of uniform thickness) to form a multi-decker-sandwich structure. Young s modulus of the metal is Ej, that of the epoxy resin is E2 (where E2 < Ej) and the volume fraction of metal is Vj. Find the ratio of the maximum composite modulus to the minimum composite modulus in terms of Ej, E2 and V. Which value of gives the largest ratio ... 

The nature of the interface formed between very thin metallic films and substrates of various types has been studied extensively by AES, just as it has by XPS... 

Ellipsometry in the vacuum UV (< 190 nm) enables the analysis of materials for the next generation lithography (photoresist, AR coatings) at the latest exposure wavelengths (157 nm and 193 nm). The short wavelengths increase the sensitivity of ellipsometric measurements of ultra thin films (<10 nm). New prospects are expected for the analysis of thin metallic and dielectric layers. 

The advent of the integrated circuit and its foundry has now firmly integrated materials scientists into modern electronics, their function both to optimise production processes and to resolve problems. To cite Just one example, many materials scientists have worked on the problem of clectronugraiion in the thin metallic conductors built into integrated circuits, a process which eventually leads to short circuits and circuit breakdown. At high current densities, migrating electrons in... 

Another recently discovered form of epitaxy is graphoepitaxy (Geis et al. 1979). Here a non-crystalline substrate (often the heat-resistant polymer polyi-mide, with or without a very thin metallic coating) is scored with grooves or pyramidal depressions the crystalline film deposited on such a substrate can have a sharp texture induced by the geometrical patterns. More recently, this has been tried out as an inexpensive way (because there is no need for a monocrystalline substrate) of preparing oriented ZnS films for electroluminescent devices (Kanata et al. 1988). 

Coutts, T.J. (1974) Electrical Conduction in Thin Metal Films (Elsevier, Amsterdam). DeCristofaro, N. (1998) Amorphous metals in electric-power distribution applications, MRS Bull. 23(5). 50. 

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