Platinum Bath Research Articles

What Cleopatra Sees

What Cleopatra Sees Meena Alexander (bio) Cleopatra in dark glasses turns a cornerAnd comes upon Morris Gittell Insurance Broker She hides behind a pillarSo he will not see her, the child loitering, close to the sign— We Help You in Obtaining Your Birth CertificateEspecially If You Were Born in the South. Why is the boy standing there?Dressed in his hooded sweatshirt He ducks his head, murmuring yes, yes, yesTo that other life, not yet come. Something floats between her skinAnd glass, a cluster of risky hieroglyphs Rare Almagest, the mysteries of birth and deathCut from a platinum bath. Haunted by light a man stood for hours,Hands soaked, getting it just right. She watched him with his camera,Scarf to his throat, lens glinting. Dear Damage—she writes in her own head—My soul knows rivers. She adjusts her glasses, watches the boyNaked, gleaming with Nile water,Then torn apart, Osiris, all his flesh thrownInto the pitch drunk Mississippi, [End Page 31] Then cheeks stung with rock rose and eglantine,Miraculously whole, racing through plots Of bullwhips and manacles.She sees him step out of the C train, Strolling up Sugar Hill in dun colored flannels,Houndstooth jacket slung over his shoulder, A grown man, hair white, smoldering in sunlight:The children of Gaza sing in his veins. I cannot get him out of my mind, she whispersTo no one in particular. He is that lad and he is Osiris,Come to live in me, part of the speckled glory of things. [End Page 32] Meena Alexander Meena Alexander was born in India and grew up there and in Sudan. She has published six volumes of poetry including Illiterate Heart (winner of the PEN Beyond Margins Award). Forthcoming this fall is her new volume Birthplace with Buried Stones (TriQuarterly Books/ Northwestern UP, 2013). Her book of essays Poetics of Dislocation appeared in the Michigan Poets on Poetry Series. She has received awards from the Guggenheim, Fulbright, and Rockefeller foundations and the Arts Council of England. She is Distinguished Professor of English at CUNY Graduate Center and Hunter College. Footnotes * Inspired by Roy DeCarava's Gittel, 1950 Copyright © 2013 The Johns Hopkins University Press

Preparation and methanol oxidation catalysis of Pt-CeO 2 electrode

An electrochemical methodology to prepare platinum/cerium oxide electrodes by using glassy carbon substrates has been developed. The method involves an “occlusion deposition” of CeO 2 particles at glassy carbon electrodes from a platinum bath in acid solution at an applied constant potential. The depositions were made by applying a controlled potential of −200 mV vs. Ag/AgCl in 0.5 M H 2SO 4 containing K 2PtCl 6 and CeO 2 suspensions. The deposition was done at different concentrations of K 2PtCl 6 and constant supersaturation concentrations of CeO 2. The final composite electrodes were characterized by using X-ray fluorescence/energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. The catalytic properties of the composite electrodes were tested for the electrooxidation of methanol in acid solution by chronoamperometry and were compared to Pt only deposits on glassy carbon.

Electroless deposition of platinum on titanium substrates

The use of an electroless platinum bath based on chloroplatinic acid and hydrazine for depositing adherent and uniform layers on titanium panels is demonstrated. The conditions were optimised for a new set of additives. The effect of concentrations of platinum metal in the bath on thickness of the deposit was studied. The deposition rates on titanium and gold-plated titanium are evaluated. Dispersed platinum coatings on titanium powder were successfully obtained.

Features of determination of the oxygen and nitrogen contents in aluminum nitride and oxide powders by the method of reduction extraction

To a great degree an improvement in the properties of aluminum nitride-base ceramics is related to an increase in purity of the raw material, particularly to a reduction in the quantity of oxygen, the impurity most strongly influencing the thermal conductivity and mechanical and other properties of the material. In addition, methods of determination of the oxygen content in nitrides, as in other aluminum compounds, are very inadequate. For these purposes the method of reduction extraction of oxygen by carbon in the form of carbon monoxide, which is distinguished by high sensitivity and rapidity, is normally recommended [1]. However, for aluminum compounds this method has poor reproducibility and accuracy and also low reliability of the results. This is the result of difficulty in reduction of aluminum oxide by carbon, formation of A10 gaseous suboxide not recorded by this method, intense dissociation of aluminum nitride during the analysis, and the fact that the particles of the unreacting substance are carried off by the liberated nitrogen from the reaction zone. In order to eliminate these processes in analysis of oxygen in the nitride and other aluminum compounds, the authors of [1] recommend that platinum or tin capsules with the weighed portion be dropped into a graphite crucible with a platinum bath heated to 2700 K. It is clear that, for largescale analyses, the necessity of which is the result of the wider use of aluminum nitride ceramics, such recommendations are inapplicable. Reference has been made to the possibility of determination of nitrogen in refractory nitrides [2] and in mixture of aluminum and vanadium nitrides [3], and of oxygen in mixtures of aluminum and calcium oxides [4] with use of the TN314, TC-136, and RO-316 instruments (Leco, USA) but the conditions of the analyses are not described. In order to establish the possibility of determination of the oxygen content in aluminum nitride and other aluminum compounds in this work, the temperature and time relationships of extraction of oxygen from aluminum nitride and oxide and mixtures of them under different conditions, including in the presence of a molten nickel---copper mixture and with sealing of the opening of the graphite crucible with a partially fused metal stopper, were studied. The method of the experiment consisted of measurement of the temperature and time relationships of the degree of extraction of oxygen and nitrogen (share of extracted gas in relation to its total content in %) from aluminum oxide and nitride and also of proportioned mixtures of them in pulsed heating of the substances being analyzed in a graphite crucible in a flow of helium. The design of the instrument for pulsed reduction extraction with chromatographic separation of the gases and recording with a detector based on thermal conductivity, the dimensions of the graphite crucibles, and the basic stages of preparation of the samples and conducting the analysis, are similar to those described in [5, 6]. The investigations were made in the 500-4300 K range and one heating pulse for a 5--30 mg sample lasted 3--30 sec. The LKhM-80 chromatograph (model No. 2) was operated with a column thermostat temperature of 333 K, a thermal conductivity detector thermostat temperature of 383 K, a thermal conductivity detector current of 120 mA, and helium consumptions through the measuring column of 1.5" 10 -4 and through the comparison column of 3" 10 -5 m3/min. With the use of the metal bath 1--4 mg of carbonyl nickel powder was added to the graphite crucible together with the sample before analysis. The crucible was covered with well-matched copper plugs (diameter 3 mm, weight about 0.35 g). In turning on of heating a portion of the copper plug adjoining the water-cooled electrode of the pulse furnace remains infused while the opposite portion fuses earlier than interaction of the plug with the graphite starts. The copper--nickel alloy wets the graphite well, and with the help of capillary forces closes the lack of tightness close to the plug, envelops the sample, and covers the inner surface of the crucible, decreasing the gas permeability of its walls. In this way carrying away of the dispersed particles of the sample by the liberated gas is prevented. Powder substances with known oxygen (standard specimens of No. 471, R21 iron powder, tungsten and erbium oxides) and nitrogen (S41b and $44b standard specimens, and also titanium nitride powders, the quantity of nitrogen in which was determined by the Kjeldahl method) were used for calibration of the instrument. The nitrogen content in the aluminum nitride powders was determined by the same method.

The determination of oxygen in molybdenum by the inert gas fusion method using a limited platinum bath

The determination of oxygen in molybdenum by the inert gas fusion method using a limited platinum bath

Dosage de l'azote dans le vanadium par fusion reductrice sous vide

A study of the conditions for the determination of nitrogen in vanadium by vacuum fusion in a platinum bath has shown that ( a) the amount of nitrogen extracted depends on the ratio ( R) of the weights of platinum and vanadium, and ( b) the amount extracted passes through a maximum value for a particular R value depending on the temperature. With R values of ca. 2 and extraction temperatures above 1900°, results were in reasonable agreement with those obtained by the Kjeldahl method, the reproducibility being 2–3%.

Determination of oxygen and Hydrogen in tungsten and other metals by a vacuum-fusion gas-chromatographic method

A gas-chromatographic method has been developed for the analysis of gas evolved from tungsten and tungsten-base alloys in the vacuum-fusion process. The method is suitable for determining 5–3,000 p.p.m. of oxygen and 0.2–300 p.p.m. of hydrogen, and can be applied to other metals. Above 50 p.p.m. of oxygen and 3 p.p.m. of hydrogen, the values found compare favourably with those obtained by alternative methods; below these levels, no reliable alternative procedures are readily available. In the proposed method, the sample is submitted to vacuum fusion in a molten platinum bath in a graphite crucible, and an aliquot of the evolved gas is transferred by means of a specially modified Drallim valve, to a stream of high-purity helium. The components are separated on a column of molecular-sieve 5A at 100° and detected with a radioactive-type ionization detector. Calibration and operation of the system are described in detail, and the effects of variables are discussed. Evidence was obtained that hydrogen recoveries by the conventional vacuum-fusion method are sometimes slightly low, because of methane formation. An important advantage of the method is that the evolved gases are positively identified by their retention volumes.

Determination of Oxygen in Titanium by Isotopic Dilution

AbstractTwo specimens of titanium which had been analyzed independently by vacuum fusion and inert-gas fusion were analyzed for oxygen by an isotope-dilution technique which employed a platinum bath and allowed the dilution to be followed with time. With graphite crucibles which had been degassed at 1850°C for 2 1/2 hours or longer, the exchange was linear with time for both the blank and analysis. Extrapolation to zero time permitted the oxygen content to be measured with a standard deviation of ±0.004 per cent for specimens of weight 0.5 gram. The results were in agreement with or slightly higher than those obtained by vacuum fusion. Suspected segregation in one of the specimens rendered an exact comparison between the methods uncertain. Resume Deux specimens de titanium, qui avaient ete analyses separement par fusion dans le vide et fusion dans un gaz inerte, ont ete analyses Quant a l' oxygene par une technique de dilution d'lsotope, utilisant un bain de platine et permettant de suivre la dilution ave...

The Determination of Oxygen in Metals with High Melting Points by the Inert Gas Fusion Method: A Silicon Fusion Technique

Abstract The determination of oxygen in metals with high melting points is important for the development of metallurgy. This paper will describe a very simplified apparatus and a procedure which gives precise results almost without a blank test. A silicon fusion technique developed by the present authors is used instead of the platinum bath method for the purpose of decomposing oxides in metals. It enables us to determine oxygen in a small quantity of a sample by the use of a highly-sensitive gas chromatograph. The amount of oxygen in the purified tantalum and niobium was determined within a standard deviation of 0.0038%. The precision established in tests of titanium samples containing 0.074% of oxygen was 0.0018%; this observed value is in good agreement with that obtained by the vacuum fusion method.

Determinaton of Micro-Gases in Molybdenum. II

Vacuum fusion gas extraction techniques using platinum-nickel bath at 1800°C and platinum baths at various temperatures from 1900°C to 2050°C were examined to determine microgases in molybdenum and the maximum permissible molybdenum content in fluid platinum for effective gas extraction. And microscopic examination was also carried out in order to see the graphite precipitated from bath alloys.Gases were extracted out of electrolytically polished one-gram samples cut off from a sintered, swaged molybdenum rod used in the previously described nickel bath technique and others, in which gaseous impurities might be distributed homogeneously. And, in the 2050°C platinum bath technique, two- or four-gram samples from arc-melted molybdenum ingots were also used to determine the maximum permissible molybdenum content in platinum bath at this temperature. Extracted gases were analyzed by means of the fractional freezing under low pressure, and the sensitivity of measurement was, in these experiments too, O.5 micron-liter for both oxygen (as carbon monoxide) and hydrogen analyses, and 0.05 micron-liter for nitrogen.The allawance for reproducibility of analysis of experimental one-gram samples was +1 part per million by weight for both oxygen and nitrogen below about 30 ppm. and 10 ppm. respectively and ± 0.1 ppm. for hydrogen below about 1.0 ppm., same as the experiments described in the paper I. And the following results were found : (1) Oxygen analyses by using the platinum bath technique gave the results which were by about 10 ppm. (about 11 micron liters of carbon monoxide evolved from one gram sample) greater than about 18 ppm. obtained by using the platinum-nickel, nickel, and nickel-tin baths, these facts suggesting the sorption of evolved carbon monoxide on the film or vapor of nickel evaporated from baths ; (2) Each result of nitrogen and hydrogen analyses by using the platinum bath technique agreed with that by the solid extraction technique mentioned before, within errors of 1 ppm. and 0.1 ppm. respectively ; (3) The maximum permissible molybdenum contents in a fluid platinum bath for extracting gases were about 70 per cent by weight at 2050°C, about 20 per cent at 2000 °C, and about 10 per cent at 1950°C ; (4) Accordiding to the microscopic examination of bath alloys, graphite flakes precipitated from fluid platinum-carbon or platinum-molybdenum-carbon alloy were so much less than those from fluid nickel-carbon or nickel-molybdenum-carbon alloy, that the control of carbon content in platinum bath by addition of pure platinum was unnecessary, in contrast with the case of nickel or iron bath.From these experiments following the previous ones, it can be concluded that the vacuum fusion gas extraction technique by platinum bath at 2050°C is the most reliable and useful one for micro-gas analysis of molybdenum.

Determination of oxygen in titanium by vacuum fusion analysis with platinum bath technique

Determination of oxygen in titanium by vacuum fusion analysis with platinum bath technique

Separation of Thorium from Rare Earths, Zirconium, and Other Elements by Cation Exchange Chromatography

Thorium has a high affinity for the Dowex 50 cation exchange resin and it is not eluled tom a column of the resin even by relatively concentrated hydriochloric acid. Semiquantitative affinities for AG 50 resins in hydrochloric acid were investigated for 23 cations, and ''single element'' elution curves were prepared for those with high affinities. A method was developed a separate thorium quantitatively, even in small amounts. from zirconium and the rare earths. (auth) l599l An investigation was made of the reproducibility of the platinum bath technique for determining oxygen in titanium and its alloys. Although several variations of the platinum-bath technique were tried, the results were not satisfacarily reproducible. However, a modified technique, platinum aux, was developed. The accuracy of the dry-crucible and the platinum-flux techniques as applied to unalloyed titanium, and one alloy, Ti-6A14V, was determined by using standard samples. Both techniques appeared capable of recovering at lesst 92% of the oxygen in unalloyed titanium standards. In most cases the recovery was much better. Average oxygen recovery from Ti-6Al-4V alloy standards was 93% by both the platinum-flux and the dry-crucible techniques. Studies on the reproducibility of analytical values made on three other alloys, Ti-8Mn, Ti-2Fe- 2Cr-2Mo, and Ti-5Al-2.5Sn,more » indicated that satisfactory results could be obtained by both techniques. (auth) l5992 Tantalum and niobium are separated and determined gravmetrically by precipitation with selenious acid from highly acidic solutions in the absence of complex ing agents. Hydrogen peroxide is used in the preparation of the solution and later catalytically destroyed during digestion of the precipitate. From 0.2 to 30 mg, separately or in mixtures, of niobium or tantalum pentoxide can be separated from mixtures containing 100 mg each of the oxides of scandium, yttrium, cerium, vanadium, molybdenum, iron, aluminum, tin, lead, and bismuth with a single precipitation; and iron 30 mg of titanium dioxide. and 50 mg each of the oxides of antimony and therium, when present separately, with three precipitations. At least 50 mg of uranium(VI) oxide can be separated with a single precipitation when present alone; otherwise, three precipitations may be needed. Zirconium does not interfere when the tantalum and niobium contents of the sampls are small, but in general, zirconium as well as tunssten interfere. The method is applied to the determination of the earth acids in tantaloniobate ores. (auth)« less

Determination of gases in plutonium, uranium and zirconium by vacuum fusion

A vacuum fusion system suitable for routine'analysis of gases present in plutonium, uranium, and zirconium was built and acceptable results were obtained with the exception of the determination of nitrogen in zirconium. Hydrogen is evolved by heating the metal in a vacuum while all gaaua are released by fusing the sample at 1900° in a metal bath contained in a graphite crucible. Tho gases evolved from each sample are collected in individual bulbs for later mass spcctrometric analyses. Hydrogen values within 5% and oxygen values within 10% are obtained on zirconium. standards. The results for plutonium samples analyzed by the iron and platinum bath techniques are in satisfactory agreement. The apparatus and techniques described provide a method whereby the gases present in 5 separate metallic samples may be collected in one melting operation of leas than two hours duration.

Determination of Oxygen in Titanium. Modified Vacuum Fusion Apparatus and Platinum Bath Technique

An improved vacuum fusion apparatus for determination of oxygen in titanium incorporates an improved furnace section, a sample entry port, and an analytical system. Use of platinum bath results in simplified operation, giving fast and reliable oxygen determinations. Thirty samples can be analyzed before opening system to atmosphere. (auth)

The determination of oxygen in titanium: Vacuum fusion with a platinum bath

Oxygen can be determined in titanium accurately by vacuum fusion with a platinum bath. The platinum bath is preferred to an iron bath or dry bath since more samples can be analysed in a bath without interference from gettering and solidification of the bath. The blank from adding iron or tin with the sample is eliminated.