Metals processing resistance

It is claimed that the cured materials may be used continuously in air up to 300°C and in oxygen-free environments to 400°C. The materials are of interest as heat- and corrosion-resistant coatings, for example in geothermal wells, high-temperature sodium and lithium batteries and high-temperature polymer- and metal-processing equipment. 

In these processes, a special base coat is applied to the surface of the plastic product to be metallized. The product is then placed in a vacuum chamber in which a metallic vapor is created and deposited on the product. A protective clear top coat is then applied over the thin metal layer for abrasion and environmental resistance. The simplest vacuum metallizing processes use resistance heating to melt and vaporize the metal. 

Debiasing of emitter-base pn junction can be minimized by using a double metal process. A simplified cross section of a 4H-SiC power BJT with double metal process is shown in Figure 6.11. In this structure, the emitter electrode covers most of the active area and is connected to emitter fingers through vias, whereas the base electrode is placed outside of the active area. Use of this structure eliminates most of the resistive voltage drop in the emitter fingers at an increased cost of the fabrication process. 

A double metal process can be used to reduce the cell pitch and minimize parasitic resistance and capacitance, which can be critical for 4H-SiC BJTs intended for high-frequency operations. The finished structure in Figure 6.12(e) can be covered with an intermetallic dielectric layer. Via holes are then opened, and a thick metal... 

An interesting property of HNO3 is its ability to passivate some metals, such as iron and aluminum. This property is of significant industrial importance, since modem processes for producing the acid depend on it. Modern suitability formulated stainless sleel alloys are usefully resistant to nitric add through a wide range of conditions. The acid s passivity or the metal s resistance to attack is attributed to the formation of a protective oxide layer on the surface of the metal. 

Although scattering processes in both semiconductors and metals increase with rising temperamre, thereby decreasing the mobility of the carriers, the scattering is more than offset in a semiconductor by an increase in the charge carrier concentration. Thus, the electrical resistivity of a semiconductor decreases with increasing temperamre, dp/dT < 0. In a metal, the resistivity has the opposite temperamre dependency dp/dT > 0. 

MOCVD process as well as the oxidation problem of the diffusion barrier, the low temperature MOCVD process is required which usually results in amorphous or weekly crystallized as-deposited thin films. Therefore, high temperature post-annealing is an absolute necessity. The upper limit temperature of the post-annealing is about 800°C considering the interdiffusion between the BST and electrodes at higher temperature and process integration issues such as degradation of the metal contact resistance. 

Corrosion resistant masonry lined metallic process equipment combine three vital components that must be designed to complement each other and function as a whole. 

Fig. 39 The process sequence for the lift-off process (the planarized metallization process) (a) a resist film is patterned on a dielectric film, (b) dielectric patterning, (c) thin catalytic film layer (PVD or CVD Ti, Al) is deposited, (d) a lift-off technique removes the excess material, leaving the catalytic layer in the trench only,...

Related Compounds sumably some antibiotics are delicately balanced so as to be able to compete successfully with the metal-binding agents of the bacteria while not disturbing the metal processing by the host. There is evidence that at least some bacteria have developed resistance to antibiotics through the development of altered enzyme systems that can compete successfully with the antibiotic.133 The action of the antibiotic need not be a simple competitive one. The chelating properties of the antibiotic may be used in metal transport across membranes or to attach the antibiotic to a specific site from which it can interfere with the growth of bacteria. 

Liquid-phase oxidations of alcohols in the presence of supported metal catalysts are potentially very attractive reactions for the preparation of intermediates and fine chemieals because high selectivities can be obtained with environmentally clean processes. Indeed, they proceed under mild conditions, with molecular oxygen as oxidizing agent and water as solvent. Supported catalysts, based mainly on platinum-group metals, are resistant to leaching, are recyclable, and are readily available from catalyst manufacturers in various compositions and forms. 

Processes developed for the injection molding of circuit boards include PCK Technology s mold-n-plate process uses two shots, the first being one of catalytic resins, to form paths on plastic parts that are then processed in a copper bath to form circuitry. Special grades of polysulfone, polyethersulfone, and polyarylsulfone are used for the process. In the in-mold metallization process, various conductive, resistive, capacitive, or inductive components are embedded directly into the plastic part in the tool. 

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