Trace Amounts Of Ti Research Articles

Abrasion Wear Resistance of Ni - Mo Alloyed High-Chromium Cast Iron

The paper presents the results of research on the high-chromium cast irons of chemical composition (in wt. %) 2-4 C, 21-22 Cr, 1-2 Mo, 5-6 Ni, 1 Mn with the trace amount of Ti and. The cast irons were examined in the as-cast state and after heat treatment which comprised the austenitizing at temperature of 900°C for 1 hour and cooling to room temperature in air, followed by tempering at 450 or 600°C for 6 hours and cooling in air. The abrasion resistance of cast irons was evaluated using the pin-on-disk method under the dry abrasion conditions. Tests showed the as-cast chromium cast irons with mostly austenitic matrix have proven the higher abrasion resistance than those after destabilization treatment and tempering.

Laser-Induced Breakdown Spectroscopy for the Rapid Characterization of Lead-Free Gunshot Residues.

This study investigated the use of laser-induced breakdown spectroscopy (LIBS) and scanning electron microscopy energy dispersive X-ray spectroscopy (SEM-EDX) as means of characterizing gunshot residue (GSR) originating from commercially available lead-free rounds. Data from two experiments are presented in this work. One experiment focused on identifying prominent analytical markers present in lead-free GSR by LIBS while the other applied SEM-EDX to determine the degree of evidence preservation after LIBS analysis. Samples of GSR were collected via tape-lift method from the hands of volunteer shooters and instrumental analyses were conducted in triplicate. As a result, the lead-free ammunition analyzed in this work generated GSRs comprising primarily Ba, Al, Si, and/or K. Trace amounts of Ti, Fe, and S were also apparent in some compositions. Through SEM-EDX analysis, a spheroidal geometry consistent with traditional lead-containing GSR was observed. Additionally, it was determined that evidence is preserved after LIBS analysis which supports the implementation of LIBS as a rapid preliminary screening method followed by confirmatory testing via SEM-EDX on the preserved evidence.

Suppressing Al2O3 nanoparticle coarsening and Cu nanograin growth of milled nanostructured Cu-5vol.%Al2O3 composite powder particles by doping with Ti

Both the coarsening of Al2O3 nanoparticles and the growth of Cu nanograins of mechanically milled nanostructured Cu-5vol.%Al2O3 composites with, and without, trace amounts of Ti during annealing at 973K for 1h were investigated. It was found that doping with a small amount of Ti (e.g. 0.2wt%) in a nanostructured Cu-5vol.%Al2O3 composite effectively suppressed the coarsening of Al2O3 nanoparticles during exposure at this temperature. Further, the Ti addition also prevented the concomitant abnormal growth of the copper grains normally caused by the coarsening of the Al2O3 nanoparticles. Energy dispersive X-ray spectroscopy analysis of the Al2O3 nanoparticles in the annealed Cu-5vol.%Al2O3-0.2wt%Ti sample suggested that the Ti atoms either diffused into the Al2O3 nanoparticles or segregated to the Cu/Al2O3 interfaces to form Ti-doped Al2O3 nanoparticles, which was more stable than Ti-free Al2O3 nanoparticles during annealing at high homologous temperatures.

Enhancing B removal from Si with small amounts of Ti in electromagnetic solidification refining with Al–Si alloy

Small amounts of Ti (<2037 ppma) were employed as an additive to enhance B removal from Si in electromagnetic solidification refining with an Al–Si alloy. The B removal process was investigated by varying the initial concentration of Ti, the cooling rate, and the liquidus temperature of the Al–Si alloy. Experimental results show that the small amounts of Ti were primarily responsible for enhancing B removal. This B removal process was more efficient at lower cooling rates combined with the use of Al–Si alloy solvents having lower liquidus temperatures. With the addition of 2037 ppma Ti, the residual B in the refined Si could be controlled to 1.2 ppma, which meets the requirements for manufacturing solar cells. The added Ti could be simultaneously removed because of its extremely low segregation coefficient between solid Si and liquid Al–Si alloy. Although trace amounts of Ti and Al were present in the refined Si, they are expected to be removed in the next processing step, which is directional solidification in vacuum. Finally, the mechanism of this B removal process is discussed.

Chemical composition of coexisting columbite-group minerals and cassiterite from the Black Mountain pegmatite, Maine

Detailed examination of hand samples and backscatter electron images of Nb-,Ta-,Sn-oxide minerals from the Black Mountain pegmatite has revealed the presence of discrete crystals, as well as cassiterite-hosted micrograins of columbite-group minerals (CGM). Micrograins and discrete grains of CGM show a wide range of Mn/(Mn + Fe) values, but only the micrograins have limited Ta/(Ta + Nb) values. Trace amounts of Ti, Sc, Fe3+ and Sn are common in both generations of CGM, but their total rarely exceeds 1.0 oxide wt%. The chemistry of the host cassiterite is relatively homogeneous and pure; the total concentration of FeO, MnO, Nb2O5, Ta2O5 and TiO2 rarely exceeds 2.0 wt%. While discrete CGM grains show weak progressive zonation and minor replacement, micrograins display complex oscillatory zonation, resorption and/or replacement textures. Textural evidence suggests that the micrograins crystallized after the formation of discrete grains of columbite and cassiterite. On the whole, both discrete crystals and micrograins of CGM show increasing Mn/(Mn + Fe) with fractionation as commonly observed in F-enriched granitic pegmatites. Micrograins of CGM typically show higher Ta/(Ta + Nb) values compared to their discrete crystal counterparts. Textural characteristics of CGM micrograins are inconsistent with an origin by exsolution, and instead, indicate primary precipitation.

Visible-light-driven TiO 2 catalysts doped with low-concentration nitrogen species

Visible-light-driven nitrogen-doped TiO 2 was synthesized using a novel nitrogen-ion donor of hydrazine hydrate. Low-concentration (∼0.2 at%) nitrogen species and Ti 3+ were detected in the TiO 2-based photocatalyst by X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) spectroscopy. The trace amount of Ti–N would contribute to the minor band-gap narrowing of about 0.02 eV. Those nitrogen-containing species, especially the NO 2 2− species, form surface states, which make the catalysts possible to degrade 4-chlorophenol (4-CP) under visible irradiation ( λ>400 nm). Moreover, Ti 3+ species induce oxygen vacancy states between the valence and the conduction bands, which would also contribute to the visible response. The photocatalytic activity of the nitrogen-doped TiO 2 catalyst was thought to be the synergistic effect of nitrogen and Ti 3+ species. The catalysts showed higher photocatalytic activity for degradation of 4-CP than pure TiO 2 under not only visible but also UV irradiation. The visible response and the higher UV activity of the nitrogen-doped TiO 2 make it possible to utilize solar energy efficiently to execute photocatalysis processes.

Optimization of plasma uniformity in laser-irradiated underdense targets

We used the Hyades [1] and Helios [2] radiation-hydrodynamic simulation tools, and the Cretin atomic kinetics code [3] to model low-density SiO 2 aerogel carriers doped with trace amounts of Ti and subjected to high-energy pulsed laser irradiation. Underdense targets are expected to respond to laser irradiation more uniformly as compared with solid targets, and therefore provide a better platform upon which to perform measurements of the properties of warm dense matter. We report modeling results for several cases of interest, with laser intensities in the range of 5 × 10 12 -6 x 10 13 W/cm 2 , SiO 2 densities in the range of 2-8 mg/cm 3 and Ti doping in the range of 0-6%. Recommendations are given for the conditions under which relatively uniform temperature and density can be obtained.

Solution Properties of Aluminum and Titanium Complexes with o -Chlorophenylfluorone and Competition Coordination for Selective Determination of Trace Amounts of Titanium

The competition coordination for selective determination (CCSD) is described and the complexations of Ti(IV) and Al(III) with o-chlorophenylfluorone (o-CPF) is studied at pH 4.5 in presence of Triton X-100. The determination of equilibrium constants of the complexes was made by the spectral correction technique in place of ordinary spectrophotometry. The complexes are formed as [Al(o-CPF)3]3− and [Ti(o-CPF)3]2− and their stepwise and cumulative stability constants are calculated. Trace amounts of Ti can substitute Al from its o-CPF complex and the competition coordination has been used in the quantitative determination of Ti in water samples with satisfactory results.

Silicide engineering: influence of alloying elements on CoSi2 nucleation

ABSTRACTEvidence is presented that the nucleation of CoSi2 can be influenced by the presence of small amounts of other elements. The presence of trace amounts of Ti in the CoSi (originating from either a Ti capping layer or interlayer) causes an increase in the CoSi2 nucleation temperature. Moreover, the presence of Ti in the CoSi induces a preferential orientation of the CoSi2 : for an increasing amount of Ti, we observed a transition from polycrystalline CoSi2 over preferential (220) orientation towards epitaxial (400) CoSi2. We observed similar effects for other elements (e.g. Ta, W, C, Mo, Cr). We were able to explain these findings based on the heterogeneous nucleation of CoSi2.

Spectrochemical Analysis for Trace Amounts of Ti, B, Zr, and Be in 7075 Aluminum Alloy

The general alloy analysis technique has proven to be very useful in our laboratory. By using a modification of this technique a special analytical problem was solved and is reported here. This problem came about through the metallurgical studies in the Air Force Materials Laboratory on the effect of trace level additions of titanium, boron, zirconium, and beryllium on grain refining and other metallurgical properties for 7075 aluminum alloys. For these studies, it was necessary to determine the concentration level in the base material as well as the concentration after the additions. A point-to-plane technique could have been used but standards were not readily available for concentration levels of interest. Normal solution techniques such as the rotating disk will not provide adequate limits of detection for these low levels. In order to provide greater line intensities for the trace elements it was necessary to change the general alloy technique by increasing the carrier gas flow, current, and the concentration level of the analytical solution. Table I gives the operational parameters used. Synthetic standards were prepared containing the proper amounts of aluminum, zinc, magnesium, and copper for the alloy and using a blank plus increasing increments of the elements of interest. With the blank as the low standard, the following concentration ranges were covered: titanium 10–1010 ppm; boron 6-206 ppm; zirconium 15–1015 ppm; and beryllium 5–95 ppm. Both standards and samples were made up to contain 10 mg/ml of the alloy, 15 mg/ml of sodium chloride, and 0.02 mg/ml of indium, the internal standard. The analytical lines that were used are given in Table II. Duplicate determinations of standards and samples were made on each plate and analytical curves were prepared after correcting for the blank and where necessary the background.