Showing papers on "Antimony published in 1983"

High temperature embrittlement of NI and Ni-Cr alloys by trace elements

Abstract: The effects of Sb, Sn, and Zr additions on the creep properties of Ni and Ni + 20 pct Cr are reported. Antimony and tin additions (~1 wt pct) induce extensive grain boundary cavitation in nickel, while smaller antimony additions had little effect on Ni + 20 pct Cr. Addition of 0.11 pct Zr to Ni + 20 pct Cr greatly inhibited grain boundary cavitation and reduced its Coble creep rate. Auger electron spectroscopy of cavitated specimens provided direct evidence of impurity segregation to cavity surfaces. Residual sulfur segregated most strongly, and was observed on cavity surfaces in all cavitated specimens. Tin segregated somewhat less intensely than sulfur, and antimony segregated only slightly. Segregation of antimony and sulfur to uncavitated portions of Ni + 1 pct Sb grain boundaries was also observed. These results are discussed in terms of segregation effects on energetic and transport properties of the grain boundaries and cavity surfaces.

Influence of sulfur, phosphorus, and antimony segregation on the intergranular hydrogen embrittlement of nickel

Abstract: The effectiveness of sulfur, phosphorus, and antimony in promoting the intergranular embrittlement of nickel was investigated using straining electrode tests in IN H2SO4 at cathodic potentials. Sulfur was found to be the critical grain boundary segregant due to its large enrichment at grain boundaries (104 to 105 times the bulk content) and the direct relationship between sulfur coverage and hydrogen-induced intergranular failure. Phosphorus was shown to be significantly less effective than sulfur or antimony in inducing the intergranular hydrogen embrittlement of nickel. The addition of phosphorus to nickel reduced the tendency for intergranular fracture and improved ductility because phosphorus segregated strongly to grain interfaces and limited sulfur enrichment. The hydrogen embrittling potency of antimony was also less than that of sulfur while its segregation propensity was considerably less. It was found that the effectiveness of segregated phosphorus and antimony in prompting intergranular embrittlementvs that of sulfur could be expressed in terms of an equivalent grain boundary sulfur coverage. The relative hydrogen embrittling potencies of sulfur, phosphorus, and antimony are discussed in reference to general mechanisms for the effect of impurity segregation on hydrogen-induced intergranular fracture.

El chichon: composition of plume gases and particles.

Abstract: Aircraft measurements were made of trace gases, atmospheric particles, and condensed acid volatiles in the plume of El Chichon volcano, Chiapas, Mexico, in November 1982. Hydrogen sulfide was the primary gaseous sulfur species in the plume at the time of collection. Concentrations of 28 elements were determined by neutron activation analysis of particulate material from the plume. Rates of trace element emission to the atmosphere for each species were estimated by normlization to the simultaneously determined total sulfur emission rate. The volatile elements sulfur, chlorine, arsenic, selenium, bromine, antimony, iodine, tungsten, and mercury were enriched relative to bulk pyroclastic material by factors of 60 to 20,000. Arsenic, antimony, and selenium were associated predominantly with small (>/= 3 micrometer) particles. Calcium and sodium were present almost exclusively on larger particles and aluminum and manganese were bimodally distributed. Ashladen particulate material injected into the stratosphere during the early violent eruptions was enriched by factors of 10 to 30 relative to ash in some of the same elements observed in the quiescent plume.

X-ray photoelectron spectroscopy study of uranium and antimony mixed metal-oxide catalysts

Abstract: X-ray photoelectron spectra of the mixed oxides USb3O10 and USbO5 have been studied and compared with the spectra of the pure oxides β-Sb2O4, Sb2O3, Sb2O5 and β-UO3, U3O8, UO2. The results of this study support the view that the metals in the two compounds are in the states UV and SbV.We also discuss composition, homogeneity and finally changes in USb3O10 after its use as a catalyst in the selective oxidation of propene, and after treatment with propene and oxygen. The compound is partly reduced and can be written as UVSb(III + V)3O7, 5–9. As no cation migration was detected in the depth analysed, the initial structure of USb3O10 is not destroyed. The evolution corresponds to the formation of oxygen vacancies and to a change in the coordination of the two cations. The reduction of the initial compound is non-reversible. Our results show that oxygen mobility through the oxide is low, since reoxidation affects only the surface antimony species which are detected by Auger photoelectron spectra.

Antimoniosis: a particular form of pneumoconiosis. I. Etiology, clinical and X-ray findings.

Abstract: The occupational exposure, clinical findings, lung function and radiological characteristics of 51 workers in an antimony smelting plant are presented. The workers were exposed to the airbone dust containing a high concentration of antimony trioxide (up to 88%) and antimony pentoxide.

Thermodynamic activity of magnesium in several highly-solvating liquid alloys

Abstract: An emf technique is reported using porous alumina tubes to contain reference metals and alloys in a molten salt electrolyte. Data are reported for the activity of magnesium and its temperature derivative in several liquid metal solvents. These include lead (650 °C), tin (800 °C), bismuth (850 °C), antimony (850 °C), and mixtures of tin and antimony (800 °). In all cases, the solvents show strong negative deviations from ideal thermodynamic behavior, due to the effects of strong solvation caused by the formation of intermetallic compounds. The extent of this effect is Pb < Sn < Bi < Sb. The data reported are useful in evaluating solvents for the possible carbothermic reduction of magnesium oxide.

The effects of certain impurities and their interactions on zinc electrowinning

Abstract: The effects of germanium, antimony, arsenic, cobalt, glue, and free acid concentration were studied on both commercial and synthetic electrolytes. The effects of a single factor and the combined effects of multiple factors were elucidated. The temperature, zinc concentration, and current density were varied for some of the tests. It was found that the acid content was the most critical factor when impurity levels were at normal plant solution concentrations. The ranges where the effect of the impurity became apparent were: greater than 20 ppb (parts per billion) for antimony; 40 ppb for germanium; 120 ppb for arsenic; and 7 to 8 mg/1 for cobalt for a solution containing 65 g/1 zinc and 100 g/1 free sulfuric acid. At higher levels of acid, the acceptable level of impurity declined markedly. Glue additions were found to counteract the effects of antimony and germanium, but did little to counteract the effects of cobalt and arsenic. The level of acid was found to be especially critical when cobalt and arsenic were in the electrolyte. Cobalt and arsenic exhibited synergism, and lower current efficiencies were obtained for arsenic-cobalt combinations than expected. A factorially designed experiment was conducted to quantify the effects observed by one-factor-at-a-time testing. The structures and morphologies of the deposits were examined using X-ray diffraction and scanning electron microscopy.

Synthesis of a phospha-arsene and a phosphastibene; the first compounds with phosphorus–arsenic and phosphorus–antimony double bonds

Abstract: The reaction of (Me3Si)2CHMCl2(M = As or Sb) with (2,4,6-But3C6H2)PH2 in the presence of 1,5-diazabicyclo[5.4.0]undec-5-ene affords the double-bonded compounds, (2,4,6-But3C6H2)PMCH(SiMe3)2(M = As or Sb)

Silicon self-interstitial supersaturation during phosphorus diffusion

Abstract: The effect of phosphorus introduction and diffusion on the diffusivities of boron, arsenic, and antimony in silicon was studied using arsenic and antimony buried layers in a boron‐doped silicon substrate It was found that the diffusivity of boron and arsenic was enhanced, while that of antimony was retarded directly under the silicon surface exposed to phosphorus Since antimony diffuses primarily via a vacancy mechanism while the other two elements via a combination of vacancy and interstitialcy mechanisms, these results suggest that phosphorus predeposition enhances the silicon self‐interstitial concentration and reduces the concentration of vacancies

The Determination of the Chemical Species of Some of the “Hydride Elements” (Arsenic, Antimony, Tin and Germanium) in Seawater: Methodology and Results

Abstract: A number of elements in the fourth, fifth and sixth group of the periodic system form hydrides upon reduction with sodium borohydride, which are stable enough to be of use for chemical analysis (Ge, Sn, Pb, As, Sb, Se, Te). Of these elements, we have investigated in detail arsenic, antimony, germanium and tin. The inorganic and organometallic hydrides are separated by a type of temperature-programmed gas-chromatography. In most cases it is optimal to combine the functions of the cold trap and the chromatographic column in one device. The hydrides are quantified by a variety of detection systems, which take into account the specific analytical chemical properties of the elements under investigation. For arsenic, excellent detection limits (≅40 pg) can be obtained with a quartz tube cuvette burner which is positioned in the beam of an atomic absorption spectrophotometer. For some of the methylarsines, similar sensitivity is available by an electron capture detector. The quartz-burner/AAS system has a detection limit of 90 pg for tin; for this element much lower limits (≅10 pg) are possible with a flame photometric detection system, which uses the extremely intense emission of the SnH molecule at 609.5 nm. The formation of GeO at the temperatures of the quartz tube furnace makes this device quite insensitive for the determination of germanium. Excellent detection limits (≅140 pg) can be reached for this element by the combination of the hydride generation system with a modified graphite furnace/AAS.

Antimony Content and Speciation in the Water Column and Interstitial Waters of Saanich Inlet

Abstract: A hydride generation method was developed for the determination of Sb(III), Sb(III)-S and Sb(V) species in natural waters, and has been applied to the waters and interstitial waters of Saanich Inlet. In the oxic waters, dissolved antimony exists primarily as Sb(V) (1.2–1.4 nM) with a few percent Sb(III) (.01–.07 nM). Sb(III) production occurs in the photic zone and probably accounts for its concentration at levels greater than those predicted from equilibrium considerations. Even in the low H2S bottom waters, there is no significant reduction of Sb(V) and Sb(III). However, up to 0.15 nM Sb(III)-S species is found there. In the upper 10 cm of the reducing interstitial waters there is a very large release of Sb from the particulate matter. At least 50% of the Sb exists as Sb(III) + Sb(III)-S. The remainder most probably exists as a thioantimonate. This dissolved Sb diffuses to the overlying waters where it is rapidly oxidized to Sb(V). In the deeper portions of the sediment, Sb is resedimented perhaps as a sulfide or associated with iron sulfide precipitation.

Asbestos-free friction materials

Abstract: An asbestos-free friction material characterized by good friction and wear properties. It comprises the combination of a binder resin, copper oxide, antimony sulfide and an aromatic polyamide resin. Barytes is also a valuable additive in the combination.

Structural and Biological Characterization of Antimony(V) Polyamines

Abstract: The condensation of organoantimony(V) dihalides with diamines forming antimony(V) polyamines employing the interfacial technique is described. Structural characterization was accomplished by employing elemental analysis, light-scattering photometry, infrared spectroscopy, control reactions, and mass spectroscopy. The products exhibit mild inhibition to a wide range of bacteria and to HeLa, BHK-21, and L929 cancer-related cell lines.

Oxidation catalyst, especially for the preparation of methacrylic acid by gas phase oxidation of methacrolein

Abstract: OF THE DISCLOSURE Oxidation catalysts which in addition to oxygen ions, with or without NH4+ ions, con-molybdenum, tungsten, phosphorus and antimony as basic components, in the atomic ratio Mo:W:P:Sb =12:0.1-3: 0.1-4:0.1-3, and which are prepared in a conventional manner by combining molybdenum, phosphorus, antimony and tungsten compounds in aqueous solutions or suspensions, removing the water and calcining the residues, the com-bination being carried out at chloride ion concentra-tions of less than 0.3 mole per mole of molyb-denum and in the presence of ions of monocarboxylic acids of 1 or 2 carbon atoms, dicarboxylic acids or hydroxy-carboxylic acids, are particularly suitable for the gas phase oxidation of methacrolein to methacrylic acid.

Structural investigations of the vanadium–antimony–oxygen system

Abstract: The structural properties and thermally induced behaviour of non-stoicheiometric vanadium antimonate and antimony tetroxide which are formed during solid-state reactions between antimony(III) oxide and vanadium(V) oxide in nitrogen have been investigated. The β-Sb2O4 phase which is formed at temperatures exceeding 800 °C as large hexagonal plate-type crystals is more accurately described as a solid solution of ca. 5% vanadium in β-Sb2O4. The formation of this ‘β-Sb2O4’ phase and the conversion of α- into β-Sb2O4 in the presence of vanadium at lower temperatures than those normally required for the transformation is associated with the incorporation of vanadium into the β-Sb2O4 structure. The oxidative decomposition of monophasic vanadium antimonate at temperatures exceeding 800 °C also gives ‘β-Sb2O4’ which, when subjected to continued thermolysis, generates an outgrowth of vanadium antimonate from the hexagonal crystalline faces. It is proposed that this results from the recombination of ‘β-Sb2O4’ with the vanadium(V) oxide formed in the initial reversible decomposition of vanadium antimonate.

Reactivity of tin oxide and some antimony–tin oxide catalysts for the oxidation of methane and the isotopic exchange of oxygen. An examination of the role of adsorbed and lattice oxygen in catalytic oxidation

Abstract: The oxidation of methane with oxygen-18 to carbon dioxide and water at 400 °C has been examined on a series of antimony–tin oxide catalysts containing up to 17.9% antimony. The otherwise high rates of exchange of oxygen between the products and catalysts were suppressed by freezing out the former as they were generated. This technique permitted the application of the isotope kinetics described in the previous paper. Thus the participation of both adsorbed and lattice oxygen in the formation of carbon dioxide has been confirmed and the relative activities of the two forms measured. It was found that utilisation of adsorbed oxygen, substantial on tin oxide, decreased sharply with increasing antimony content in the mixed-oxide catalysts, being completely suppressed on the 17.9% antimony-containing catalyst.Rates of exchange of oxygen with the same catalyst series, measured at 580 °C, were also found to decline with increasing antimony content, as did the relative importance of the heteromolecular exchange process between a molecule of oxygen and one lattice oxygen atom compared with exchange with two lattice atoms.The results obtained in the oxidation and exchange experiments are compared and possible mechanisms advanced for the interaction of oxygen with antimony–tin oxide catalysts.