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Arsenic speciation using high performance liquid chromatography-inductively coupled plasma-mass spectrometry

Description: A method has been developed by Argonne National Laboratory to identify and quantify As(III), As(V), and organoarsenic compounds in environmental samples. A arsenic species were separated by reversed-phase, ion-pairing, HPLC using a microbore Inertsil-ODS{trademark} column. Only 1 {micro}L of sample was injected on the column, and the mobile phase flow rates were typically on the order of 40 {micro}L/min. The HPLC mobile phase was a mixture of methanol and tetrabutylammonium hydroxide (TBAH), and the column effluent was introduced into an ICP-mass spectrometer using direct injection nebulization. Detection limits of less than 1 pg As (as injected on the column) were easily obtained for each arsenic species. The effect of changes in mobile phase composition and ICP-MS conditions will be described, as well as quality control measures, e.g., the use of surrogates, internal standards, and matrix spikes. Precision and accuracy information will be presented from the analysis of aqueous standards and soil extracts that were spiked with arsenic oxide [As(III)], sodium arsenate [As(V)], dimethylarsinic acid (DMAA), or chlorovinyl arsenious acid (CVAA). The authors believe that these data demonstrate the utility of this technique for the sensitive determination of arsenic species present in water or soil.
Date: August 1995
Creator: Bass, D. A.; Yaeger, J. S.; Crain, J. S.; Kiely, J. T.; Parish, K. J.; Gowdy, M. J. et al.
Partner: UNT Libraries Government Documents Department

The growth of InAsSb/InAsP strained-layer superlattices for use in infrared emitters

Description: We describe the metal-organic chemical vapor deposition growth of InAsSb/InAsP strained-layer superlattice (SLS) active regions for use in mid-infrared emitters. These SLSs were grown at 500{degrees}C, and 200 torr in a horizontal quartz reactor using TMIn, TESb, AsH{sub 3},and PH{sub 3}. By changing the layer thickness and composition we have prepared structures with low temperature ({le}20K) photoluminescence wavelengths ranging from 3.2 to 4.4 {mu}m. Excellent performance was observed for an SLS LED and both optically pumped and electrically injected SLS lasers. An optically pumped, double heterostructure laser emitted at 3.86 {mu}m with a maximum operating temperature of 240 K and a characteristic temperature of 33 K. We have also made electrically injected lasers and LEDs utilizing a GaAsSb/InAs semi-metal injection scheme. The semi-metal injected, broadband LED emitted at 4 {mu}m with 80 {mu}W of power at 300K and 200 mA average current. The InAsSb/InAsP SLS injection laser emitted at 3.6 gm at 120 K.
Date: June 1, 1997
Creator: Biefeld, R.M.; Allerman, A.A. & Kurtz, S.R.
Partner: UNT Libraries Government Documents Department

Spectral ellipsometry of GaSb and GaInAsSb: Experiment and modeling

Description: The optical constants {epsilon}(E)[={epsilon}{sub 1}(E)+i{epsilon}{sub 2}(E)] of single-crystal GaSb at 300K have been measured using spectral ellipsometry in the range of 0.3-5.3 eV. The {epsilon}(E) spectra displayed distinct structures associated with critical points (CPs) at E{sub 0} (direct gap), spin-orbit split E{sub 0}+{Delta}{sub 0} component, spin-orbit split (E{sub 1}, E{sub 1}+{Delta}{sub 1}) and (E{sub 0}{prime}, E{sub 0}{prime}+{Delta}{sub 0}{prime}) doublets, as well as E{sub 2}. The experimental data over the entire measured spectral range (after oxide removal) has been fit using the Holden model dielectric function based on the electronic energy-band structure near these CPs plus excitonic and band-to-band Coulomb enhancement effects at E{sub 0}, E{sub 0}+{Delta}{sub 0} and the E{sub 1}, E{sub 1}+{Delta}{sub 1} doublet. In addition to evaluating the energies of these various band-to-band CPs, information about the binding energy (R{sub 1}) of the two-dimensional exciton related to the E{sub 1}, E{sub 1}+{Delta}{sub 1} CPs was obtained. The value of R{sub 1} was in good agreement with effective mass/k{sup {rightharpoonup}}{center_dot}p{sup {rightharpoonup}} theory. The ability to evaluate R{sub 1} has important ramifications for recent first-principles band structure calculations which include exciton effects at E{sub 0}, E{sub 1}, and E{sub 2}. The experimental results were compared to other evaluations of the optical constants of GaSb.
Date: June 30, 1999
Creator: Charache, G.W.; Mu {tilde n}oz, M.; Wei, K.; Pollak, F.H. & Freeouf, J.L.
Partner: UNT Libraries Government Documents Department

Multi-staged, InAsSb mid-infrared lasers and light-emitting diodes, grown by MOCVD

Description: Due to lower nonradiative rates, mid-infrared (2-6 micron) lasers with strained, narrow bandgap, Sb-based active regions have the potential to operate at lower current density and higher temperature than competing devices. Superior performance may be achieved through the {open_quotes}band structure engineered{close_quotes} reduction of Auger recombination and the implementation of multi-stage (or {open_quotes}cascaded{close_quotes}) active regions. We describe the first lasers and LEDs utilizing strained InAsSb, multi-stage active regions. An (n)InAs / (p)GaAsSb semimetal layer is incorporated into each stage as an internal electron-hole source. To date, 2-stage LEDs and 2-stage lasers have been demonstrated. Our multi-stage devices were grown by MOCVD.
Date: September 1, 1997
Creator: Kurtz, S.R.; Allerman, A.A.; Biefeld, R.M. & Baucom, K.C.
Partner: UNT Libraries Government Documents Department

Composition for detecting uranyl

Description: The present invention relates to an indicator composition for use in spectrophotometric detection of a substance in a solution, and a method for making the composition. Useful indicators are sensitive to the particular substance being measured, but are unaffected by the fluid and other chemical species that may be present in the fluid. Optical indicators are used to measure the uranium concentration of process solutions in facilities for extracting uranium from ores, production of nuclear fuels, and reprocessing of irradiated fuels. The composition comprises an organohalide covalently bonded to an indicator for the substance, in such a manner that the product is itself an indicator that provides increased spectral resolution for detecting the substance. The indicator is preferably arsenazo III and the organohalide is preferably cyanuric chloride. These form a composition that is ideally suited for detecting uranyl.
Date: January 1, 1994
Creator: Baylor, Lewis C. & Stephens, Susan M.
Partner: UNT Libraries Government Documents Department

InGaAsN Solar Cells with 1.0eV Bandgap, Lattice Matched to GaAs

Description: The design, growth by metal-organic chemical vapor deposition, and processing of an In{sub 0.07}Ga{sub 0.93}As{sub 0.98}N{sub 0.02} solar Al, with 1.0 ev bandgap, lattice matched to GaAs is described. The hole diffusion length in annealed, n-type InGaAsN is 0.6-0.8 pm, and solar cell internal quantum efficiencies > 70% arc obwined. Optical studies indicate that defects or impurities, from InGAsN doping and nitrogen incorporation, limit solar cell performance.
Date: November 24, 1998
Creator: Allerman, A.A.; Banas, J.J.; Gee, J.M.; Hammons, B.E.; Jones, E.D. & Kurtz, S.R.
Partner: UNT Libraries Government Documents Department

The unusual conduction band minimum formation of Ga(As{sub 0.5{minus}y}P{sub 0.5{minus}y}N{sub 2y}) alloys

Description: The conduction band minimum formation of GaAs{sub 0.5{minus}y}P{sub 0.5{minus}y}N{sub 2y} is investigated for small nitrogen compositions (0.1% < 2y < 1.0%), by using a pseudopotential technique. This formation is caused by two unusual processes both involving the deep-gap impurity level existing in the dilute alloy limit y {r_arrow} 0. The first process is an anticrossing with the {Gamma}{sub Ic}-like extended state of GaAs{sub 0.5}P{sub 0.5}. The second process is an interaction with other impurity levels forming a subband. These two processes are expected to occur in any alloys exhibiting a deep-gap impurity level at one of its dilute limit.
Date: May 11, 2000
Creator: BELLAICHE,L.; MODINE,NORMAND A. & JONES,ERIC D.
Partner: UNT Libraries Government Documents Department

Measurement of Stibine and Arsine Generation from the Exide 3100-Ah Lead-Acid Module

Description: Stibine and arsine evolution from lead-acid cells in a 36-kWh Exide load-leveling module was measured as this module approached 1900 cycles of operation. A specially prepared gas-collection apparatus enabled us to determine the maximum and average rates for evolution of both toxic hydrides. Hydride generation began once the cell voltage exceeded 2.4 V. The maximum rate for arsine occurred just above 2.5 V and consistently preceded the peak rate for stibine for each sampled cell. When adjusted for size effects, the degree of stibine and arsine evolution was greater than found in a continuous overcharge study conducted by Exide. The average rates of hydride generation were found to be 175 microgm/min for stibine and 12.6 microgm/min for arsine. The former rate proved to be the critical value in determining safe ventilation requirements for cell off-gases. The minimum airflow requirement was calculated to be 340 L/min per cell. Projections for a hypothetical 1-MWh Exide battery without an abatement system indicated that the normal ventilation capacity in the Battery Energy Storage Test facility provides nearly five times the airflow needed for safe hydride removal.
Date: January 1987
Creator: Marr, J. J. & Smaga, J. A.
Partner: UNT Libraries Government Documents Department

Arsenic speciation in soil using high performance liquid chromatography/inductively coupled plasma/mass spectrometry

Description: A method has been developed to identify and quantify As(III), As(V), and organoarsenic compounds in soil samples from the Rocky Mountain Arsenal (RMA) by high performance liquid chromatography/inductively coupled plasma/mass spectrometry (HPLC/ICP/MS). The soils were extracted using tetrabutylammonium hydroxide (TBAH) and sonication. The percentages of As(III), As(V), and organoarsenic species extracted from soil samples were 30, 50, and 100 respectively. The arsenic species were not altered during the extraction process. They were separated by reversed-phase, ion-pairing, HPLC using a microbore Inertsil-ODS{trademark} column. The HPLC column effluent was introduced into an ICP/MS system using a direct injection nebulizer (DIN). Detection limits of less than 1 pg were readily obtained for each arsenic species. Internal standards are recommended to increase accuracy and precision. Soil samples spiked with arsenic oxide, sodium arsenate, dimethylarsinic acid (DMAA), and chlorovinyl arsenious acid (CVAA) were extracted, identified and quantified with the HPLC/ICP/MS system. The soil samples were analyzed in support of the analytical needs of a thermal desorption treatability study being conducted at the RMA.
Date: August 1, 1996
Creator: Bass, D. A.; Yaeger, J. S.; Parish, K. J.; Crain, J. S.; Kiely, J. T.; Gowdy, M. J. et al.
Partner: UNT Libraries Government Documents Department

Development of a field-portable air monitor for Lewisite

Description: The focus of this research is the development of a prototype field-portable ambient-air monitor for measuring trace levels of volatile organoarsenicals. Lewisite (dichloro[2-chlorovinyl]arsine) is a chemical warfare agent developed during World War I and stockpiled on a large scale by the former Soviet Union. A continuous air monitor for Lewisite at the eight-hour time-weighted-average concentration (3 {mu}g/m{sup 3}) is necessary to protect the safety and health of arms control treaty inspectors. Flow injection is used to integrate an air sampling device based on liquid-phase extraction with a flow-through detector based on potentiometric stripping analysis. We describe a method for the sampling and preconcentration of organoarsenicals from ambient air by using a gas permeation membrane sampler. The sampler is designed to selectively preconcentrate analyte that permeates a silicone rubber membrane into a caustic carrier stream. Instrument design is described for the sampling and detection methodologies.
Date: March 1, 1996
Creator: Aldstadt, J.H.; Martin, A.F. & Olson, D.C.
Partner: UNT Libraries Government Documents Department

Microstructural evaluation of Sb-adjusted Al{sub 0.5}Ga{sub 0.5}As{sub 1{minus}y}Sb{sub y} buffer layer systems for IR applications

Description: The authors report on a transmission electron microscopy (TEM) study of Sb-adjusted quaternary Al{sub 0.5}Ga{sub 0.5}As{sub 1{minus}y}Sb{sub y} buffer-layers grown on <001> GaAs substrates. A series of structures were grown by MBE at 470 C that utilize a multilayer grading scheme in which the Sb content of Al{sub 0.5}Ga{sub 0.5}As{sub 1{minus}y}Sb{sub y} buffer-layers grown on <001> GaAs substrates. A series of structures were grown by MBe at 470 C that utilize a multilayer grading scheme in which the Sb content of Al{sub 0.5}Ga{sub 0.5}As{sub 1{minus}y}Sb{sub y} is successively increased in a series of 125 nm thick layers. Post growth analysis using conventional bright field and weak beam dark field imaging of these buffer layers in cross-section reveals that the interface misfit dislocations are primarily of the 60{degree} type and are distributed through out the interfaces of the buffer layer. When optimized, the authors have shown, using plan view and cross-sectional TEM, that this approach can reduce the threading defect density to below the detectability limit of TEM (< 10{sup 5}/cm{sup 2}) and preserve growth surface planarity. The Sb-graded approach was used to fabricate two 2.2 {micro}m power converter structures fabricated using InGaAs grown on Sb-based buffer layers on GaAs substrates. A microstructural and electrical characterization was performed on these device structures and the results are contrasted with a sample in which InP was selected as the substrate. Microstructure, defect density and device performance in these not-yet-optimized Sb-based buffer layers compares favorably to equivalent devices fabricated using InP substrates.
Date: June 1, 1998
Creator: Chen, E.; Paine, D.C.; Uppal, P.; Ahearn, J.S.; Nichols, K. & Charache, G.W.
Partner: UNT Libraries Government Documents Department

In-situ monitoring of GaSb, GaInAsSb, and AlGaAsSb

Description: Suitability of silicon photodiode detector arrays for monitoring the spectral reflectance during epitaxial growths of GaSb, AlGaAsSb, and GaInAsSb, which have cutoff wavelengths of 1.7, 1.2, and 2.3 {micro}m, respectively, is demonstrated. These alloys were grown lattice matched to GaSb in a vertical rotating-disk reactor, which was modified to accommodate near normal reflectance without affecting epilayer uniformity. By using a virtual interface model, the growth rate and complex refractive index at the growth temperature are extracted for these alloys over the 600 to 950 nm spectral range. Excellent agreement is obtained between the extracted growth rate and that determined by ex-situ measurement. Optical constants are compared to theoretical predictions based on an existing dielectric function model for these materials. Furthermore, quantitative analysis of the entire reflectance spectrum yields valuable information on the approximate thickness of overlayers on the pregrowth substrate.
Date: June 1, 1998
Creator: Vineis, C.J.; Wang, C.A.; Jensen, K.F. & Breiland, W.G.
Partner: UNT Libraries Government Documents Department

Interfaces in InAsSb/InGaAs strained-layer superlattices grown by MOCVD for use in infrared emitters

Description: The authors have prepared InAsSb/InGaAs strained-layer superlattices (SLSs) using metal-organic chemical vapor deposition (MOCVD). X-ray diffraction was used to determine lattice matching as well as composition and structure of the SLS`s. The presence of an InGaAsSb interface layer was indicated by x-ray diffraction for samples grown under non-optimized conditions. Interfacial layers were also identified with transmission electron microscopy (TEM). Two types of interfaces were observed by TEM. The different contrasts observed by TEM could be due to a difference in composition at the interfaces. The width of the x-ray peaks can be explained by a variation of the layer thickness.
Date: February 1, 1995
Creator: Biefeld, R.M.; Follstaedt, D.M.; Kurtz, S.R. & Baucom, K.C.
Partner: UNT Libraries Government Documents Department

Phase stability in Ga{sub x}In{sub 1{minus}x}As{sub y}Sb{sub 1{minus}y}/GaSb heterostructures

Description: The crystallographic and microstructural characteristics of liquid phase epitaxy lattice-matched In{sub x}Ga{sub (1{minus}x)}As{sub y}Sb{sub (1{minus}y)}/GaSb (100) heterostructures is presented. Using both transmission electron microscopy and high resolution X-ray diffraction, a variety of diffusional based phase transformations in the epitaxial films are observed, including: spinodal decomposition, compositional modulations of the order of 30 nm, and weak long range ordering. These results are interpreted in terms of the possible influence of substrate surface structure on the phase stability of epitaxial layers.
Date: October 1, 1998
Creator: Chen, Y.C.; Bucklen, V.; Rajan, K.; Freeman, M.; Cardines, R.P. Jr.; Nichols, G. et al.
Partner: UNT Libraries Government Documents Department

Novel materials and device design by metal-organic chemical vapor deposition for use in infrared emitters

Description: The authors have grown AlSb and AlAs{sub x}Sb{sub 1{minus}x} epitaxial layers by metal-organic chemical vapor deposition(MOCVD) using trimethylamine or ethyldimethylamine alane, triethylantimony and arsine. These layers were successfully doped p- or n-type using diethylzinc or tetraethyltin, respectively. They examined the growth of AlAs{sub x}Sb{sub 1{minus}x} using temperatures of 500 to 600 C, pressures of 65 to 630 torr, V/III ratios of 1--17, and growth rates of 0.3 to 2.7 {micro}m/hour in a horizontal quartz reactor. They have also grown gain-guided, injection lasers using AlAsSb for optical confinement and a strained InAsSb/InAs multi-quantum well active region using MOCVD. The semi-metal properties of a p-GaAsSb/n-InAs heterojunction were utilized as a source for injection of electrons into the active region of the laser. In pulsed mode, the laser operated up to 210 K with an emission wavelength of 3.8--3.9 {micro}m. The dependence of active region composition on wavelength was determined. They also report on the 2-color emission of a light-emitting diode with two different active regions to demonstrate multi-stage operation of these devices.
Date: December 1, 1996
Creator: Biefeld, R. M.; Kurtz, S. R. & Allerman, A. A.
Partner: UNT Libraries Government Documents Department

Microstructural stability in LPE Ga{sub x}In{sub (1{minus}x)}As{sub y}Sb{sub (1{minus}y)}/GaSb heterostructures

Description: The morphological and structural characteristics associated with the growth of lattice matched In{sub x}Ga{sub (1{minus}x)}As{sub y}Sb{sub (1{minus}y)}/GaSb (100) heterostructures is presented. The experiments focused on studying the effect of growth on vicinal surfaces tilted from the exact (100) orientation as well as variations in epilayer chemistry. It was found that variations in these process parameters had very strong effects on both the nucleation characteristics of the epilayer and the atomistic scale homogeneity of the alloy. The <100> and <110> variants in compositional modulation/phase separation were detected, as well as the evolution of weak (110) ordering. These results are discussed in the context of other studies on phase stability in III-V epitaxial structures, especially in terms of surface reconstruction and kinetic effects near conditions of spinodal decomposition.
Date: June 1, 1998
Creator: Chen, C.Y.; Bucklen, V.; Rajan, K.; Freeman, M. & Cardines, R.P.
Partner: UNT Libraries Government Documents Department

InAsSb-based mid-infrared lasers (3.5--3.9 {micro}m) and light-emitting diodes with AlAsSb claddings and semi-metal electron injection grown by metal-organic chemical vapor deposition

Description: Mid-infrared (3--5 {micro}m) lasers and LED`s are being developed for use in chemical sensor systems. As-rich, InAsSb heterostructures display unique electronic properties that are beneficial to the performance of these midwave infrared emitters. The metal-organic chemical vapor deposition (MOCVD) growth of AlAs{sub 1{minus}x}Sb{sub x} cladding layers and InAsSb/InAsP superlattice active regions are described. A regrowth technique has been used to fabricate gain-guided, injection lasers using undoped (p-type) AlAs{sub 0.16}Sb{sub 0.84} for optical confinement. In device studies, the authors demonstrate lasers and LEDs utilizing the semi-metal properties of a p-GaAsSb/n-InAs heterojunction as a source for injection of electrons into the active region of emitters. This avoids the difficulties associated with n-type doping of AlAsSb cladding layers required for conventional p-n junction lasers and also provides a means for construction of active regions with multiple gain stages. Gain guided injected lasers employing a strained InAsSb/InAs multi-quantum well active region operated up to 210 K in pulsed mode, with an emission wavelength of 3.8--3.9 {micro}m. A characteristic temperature of 40 K was observed to 140 K and 29 K from 140 K to 210 K. An optically pumped laser with an InAsSb/InAsP superlattice active region is also described. The maximum operating temperature of this 3.7 {micro}m laser was 240 K.
Date: October 1997
Creator: Allerman, A. A.; Biefeld, R. M. & Kurtz, S. R.
Partner: UNT Libraries Government Documents Department

Gas Chromatography-Mass Spectroscopy Study of tert-Butylarsine Stability and Purification

Description: TBA (tert-butylarsine, H{sub 2}AsC(CH{sub 3}){sub 3}) has been demonstrated to be an effective arsenic precursor for the deposition of compound semiconductors such as GaAs by MOCVD (metal organic chemical vapor deposition). TBA is used as a liquid (bubbler) source in MOCVD and is a less toxic alternative to the more commonly used gaseous arsine (AsH{sub 3}). Materials and device performance using TBA have in many cases equaled or surpassed those using arsine. This includes the first observation of fractional quantum Hall behavior in a two dimensional electron gas structure grown by MOCVD. Despite the beneficial characteristics, the use of TBA in our laboratories has revealed some inconsistent behavior. Small pressure rises have been observed in the TBA bubbler sources when left unused over a period of many days. Measurements of the TBA partial pressure using UV absorption revealed that new absorption peaks could be observed after storage. The features of the absorption profile were insufficient to ascribe to a specific chemical species. Attempts to remove the gaseous impurities with liquid nitrogen freeze-pump-thaw techniques had limited success. Unfortunately, there is no published information on the room temperature decomposition of TBA. In this paper, we present a series of GCMS (gas chromatography-mass spectroscopy) analyses designed to determine the stability of TBA and identify its decomposition products in storage containers. The GCMS is also used to evaluate several methods for in-situ purification of TBA.
Date: July 20, 1999
Creator: Bartram, M.E.; Breiland, W.G.; Bruskas, L.A. & Killeen, K.P.
Partner: UNT Libraries Government Documents Department

Gallium arsenide photocathode for the free electron laser

Description: The efforts of the FEL source have been concentrated on cesiated GaAs(100) wafers. These crystals have shown photoyield of <.1 to 9% quantum efficiency with the cesium and oxygen treatment. The work function and coverage curves exhibit the same properties as measured in the literature. The use of Auger Electron Spectroscopy and X-ray Photoelectron Spectroscopy have been instrumental in determining the surface cleanliness and the surface oxidation states. The sputtered surfaces have been investigated as a function of rare gas mass and sputter ion voltage, giving similar results to earlier literature values. Temperature annealing appears to be critical after sputter cleaning in achieving any significant photoyield. Contacts of Ag-Mn and Ni-Si have been deposited, heated, and analyzed using Auger Depth Profiling techniques. 16 refs., 9 figs.
Date: January 1, 1985
Creator: Stotlar, S.C.; Springer, R.W.; Sherwood, B. & Cordi, R.
Partner: UNT Libraries Government Documents Department

Polarization Possibilities of Small Spin-Orbit Interaction in Strained-Superlattice Photocathodes

Description: Strained-superlattice photocathodes based on InGaP/GaAs were investigated. The photocathode performance is found highly dependent on the superlattice parameters. The electron confinement energy in superlattice appears important. The strained-superlattice structure based on GaAsP/GaAs, with a maximum polarization as high as 90% and more than 1% quantum efficiency, is presently the prime candidate for the ILC polarized electron photocathodes. A recent systematic study shows, however, that the peak polarization seems saturated even though the heavy-hole (HH) and light-hole (LH) band splitting is increased significantly, indicating that there is a material specific spin relaxation mechanism. It is widely accepted that the D'yakonov-Perel mechanism is the dominant spin relaxation mechanism in the III-V compound superlattice structures with a low p-doping ({le} 10{sup 17} cm{sup -3}), and that the spin relaxation may be reduced by choosing a material with a smaller spin-orbit interaction. As the spin-orbit interaction in phosphides is much smaller than in arsenides, strained-superlattice structure based on InGaP/GaAs were investigated. The computer code SPECCODE developed by Subashiev and Gerchikov has been used for calculating the band structures in superlattice.
Date: August 25, 2010
Partner: UNT Libraries Government Documents Department

Uniform Aqueous Corrosion of Aluminum--Effects of Various Ions

Description: The most important variable in water quality on the uniform corrosion of Al was the pH. Solutions of distilled water containing phosphate ions and citrate ions were the only media which showed a definite specific ion effect. Phosphate inhibited the corrosion and citrate increased it. Oxalate ions appeared to increase corrosion, but the effect is not definitely demonstrated by the data. Corrosion was dependent only on pH in tap water, reactor process water, distilled water, and distilled water containing up to 100 ppm of chloride, nitrate, sulfate, bicarbonate, hydrogen peroxide, acetate, arsenate, silicate, dichromate, molybdate, and mixtures of these ions. Solutions of up to 10,000 ppm chloride in distilled water showed no specific ion effect upon uniform Al corrosion. The effects of 0 to 10 ppm of dichromate and phosphate ions were investigated over the range pH 4 to pH 7. Phosphate at 10 ppm inhibited corrosion in solutions containing up to 2 ppm of dichromate, but at 10 ppm dichromate the phosphate does not appear to inhibit corrosion. Also at 10 ppm dichromate, the effect of pH is diminished over the range pH 4 to pH 7. Corrosion rates varied with the flow rates of the test solutions at low flow rates, and were lowest at the lowest flow rates. This effect was attributed to the buildup of aluminate ion conconcentration in the lower flow systems. Short term corrosion tests at 92 deg C revealed major specific ion effects. Minor effects were lost in experimental uncertainties. The inhibiting effect of phosphate under these conditions has been shown to exist over longer exposures at higher temperatures. (auth)
Date: June 10, 1957
Creator: Troutner, V. H.
Partner: UNT Libraries Government Documents Department