Coatings tantalum

R.E. Buxbaum and A.B. Kinney, Hydrogen Transport Through Tubular Membranes of Palladium-coated Tantalum and Niobium, Ind. Eng. Chem. Res. 35, 530 (1996). 

Buxbaum R.E., Kinney A.V. Hydrogen transport through tubular membranes of palladium-coated tantalum and niobium. Ind.Eng.Chem.Res. 1996 35 530-537. 

Use Refractory for aircraft and rocket applications, thermocouple protection tubes, high temperature electrical conductor, cutting tool component, coating tantalum, cathode in high-temperature electrochemical systems. 

Na S04. The calibration factor has been determined as the composite of two factors. For the first factor 1 ml of a standard solution was dried on an albumen-coated tantalum disk, and the disk was counted. The average coating of salt on the disk was much less than 1 mg/cm. A fiber was then placed on the disk and dissolved with concentrated HNOj solution, and the disk was dried and again counted. The first factor is the ratio of the first count to the second. A value of 1.12 with a coefficient of variation of the mean of 1.2 % was obtained from 11 determinations. 

EINECS 234-963-5 Zirconium boride Zirconium boride (ZrB2) Zirconium diboride Zirconium diboride (ZrB2). Refractory for aircraft and rocket applications, thermocouple protection tubes, high-temp, electrical conductor, cutting-tool component, coating tantalum, cathode in high-temp, electrochemical systems oxidation-resistant composites. Atomergic Chemetals Cerac Noah Cham. 

Buxbaum and the group at NETL have reported permeabilities for palladium coated tantalum of between 1.07 x 10 and 1.45 x 10 mol m i s Pa for temperatures 623-693 K (350-420 °C) [41]. Weekly backflushes with hydrogen to remove coke and other impurities were recommended [35]. Buxbaum and Marker have reported a permeability for Pd coated Nb of 3.2 x 10 mol m i s i Pa at 698 K (425 °C), which was only one-third of the theoretical value due to gas phase resistance [42]. The Buxbaum group has achieved a permeabihty for Zr of 2.2 X 10 mol m l s i Pa - at 698 K (425 °C) [42]. They state that hydrcgen transport through zirconium is 100 times better than through Pd under similar conditions [42]. 

Rosenblatt, E.F. Cohn, J.G. (1955) Platinum-metal-coated tantalum anodes. US Patent 2,719,797 October 4, 1955. 

The range of electrical conductivity of various materials is illustrated in Figure 18. Many of the semiconductive or conductive polymer membrane applications involve optoelectronic applications discussed in the next section. Other applications where these polymer membranes are utilized include antistatic coatings, tantalum capacitor electrodes. 

MIBK is a highly effective separating agent for metals from solutions of their salts and is used in the mining industries to extract plutonium from uranium, niobium from tantalum, and zirconium from hafnium (112,113). MIBK is also used in the production of specialty surfactants for inks (qv), paints, and pesticide formulations, examples of which are 2,4,7,9-tetramethyl-5-decyn-4,7-diol and its ethoxylated adduct. Other appHcations include as a solvent for adhesives and wax/oil separation (114), in leather (qv) finishing, textile coating, and as a denaturant for ethanol formulations. 

Cathodic Protection Systems. Metal anodes using either platinum [7440-06 ] metal or precious metal oxide coatings on titanium, niobium [7440-03-17, or tantalum [7440-25-7] substrates are extensively used for impressed current cathodic protection systems. A prime appHcation is the use of platinum-coated titanium anodes for protection of the hulls of marine vessels. The controUed feature of these systems has created an attractive alternative... 

Some metals used as metallic coatings are considered nontoxic, such as aluminum, magnesium, iron, tin, indium, molybdenum, tungsten, titanium, tantalum, niobium, bismuth, and the precious metals such as gold, platinum, rhodium, and palladium. However, some of the most important poUutants are metallic contaminants of these metals. Metals that can be bioconcentrated to harmful levels, especially in predators at the top of the food chain, such as mercury, cadmium, and lead are especially problematic. Other metals such as silver, copper, nickel, zinc, and chromium in the hexavalent oxidation state are highly toxic to aquatic Hfe (37,57—60). 

Antireflection coatings are used over the silicon surface which, without the coating, reflects ca 35% of incident sunlight. A typical coating consists of a single layer of a transparent dielectric material with a refractive index of ca 2, which is between the index of siUcon and ait or cover material. Materials such as titanium dioxide, tantalum pentoxide, Ta20, or siUcon nitride, Si N, ca 0.08-p.m thick are common. The coating and a physically textured... 

Another example is the siliciditing of tantalum, basically an oxidation— reduction reaction. The packing is sodium duoride and siUcon. After deposition, the coating diffuses continuously into the substrate, according to the following reactions ... 

Aluminide and sUicide cementation coatings such as TaAl on tantalum and MoSi2 on molybdenum oxidize at slow rates and possess some inherent self-repair characteristics. Fine cracks that appear and are common to these coatings can be tolerated because stable, protective oxides form within the cracks and seal them. Thermal cycling, however, accelerates faUure because of thermal expansion mismatch that ultimately dismpts the protective oxide coating. 

Bromine reacts with essentially all metals, except tantalum and niobium, although elevated temperatures are sometimes required, eg, soHd sodium does not react with dry bromine but sodium vapor reacts vigorously. Metals such as lead, magnesium, nickel, and silver react with bromine to form a surface coat of bromide that resists further attack. This protective coating allows lead and nickel to be used as linings in bromine containers. Metals tend to be corroded by bromine faster in the presence of moisture than without, probably because of the formation of hydrobromic and hypobromous acids. 

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