Showing papers on "Titanium published in 1968"

Band Structure and the Titanium LII, III X‐Ray Emission and Absorption Spectra from Pure Metal, Oxides, Nitride, Carbide, and Boride

Abstract: The titanium LII, III x‐ray emission and absorption spectra (λ∼27.5 A) from pure metal, oxides, nitride, carbide, and boride have been investigated using a plane‐crystal vacuum spectrometer with electron‐beam excitation and flow‐proportional counter detection. Emission spectra were studied over a wide range of accelerating voltages and takeoff angles, showing that satellite emission and self‐absorption effects can significantly distort the band shapes and energy positions of intensity maxima. A replica of the LII, III absorption spectrum can be constructed solely from emission spectra affiicted with widely different amounts of self‐absorption. The LII, III emission spectra from the oxides, nitride, and carbide exhibit an important crossover transition from the 2p level of the anion to the LII and LIII levels of titanium. Results indicate formation of a 3d band in titanium compounds which is only partially filled, giving rise to metallic conduction. X‐ray data is compared to density of states calculations ...

Crevice Corrosion of Titanium in Aqueous Salt Solutions

Abstract: Crevice corrosion of titanium in high temperature sodium chloride solutions was investigated. Corrosion occurred only in very restricted crevices and attack was greater the higher the salt concentration It was shown that crevice corrosion occurs because of the development of a low (~ 1) pH in the solution within the crevice and is not specific to chloride solutions. Crevice attack was demonstrated ion iodide, bromide and sulfate solutions. An electrochemical polarization technique was used to determine the effect of temperature and hydrogen and chloride ion concentrations on the corrosion of titanium and to determine the corrosion characteristics of several titanium alloys. Results indicate that titanium alloys containing sufficient molybdenum, nickel, or palladium are more resistant to nonoxidizing acid solutions than commercially pure titanium and, therefore, should be more resistant to crevice corrosion.

Amido-derivatives of metals and metalloids. Part VI. Reactions of titanium(IV), zirconium(IV), and hafnium(IV) amides with protic compounds

Abstract: The reactions of metal (Ti, Zr, or Hf) dialkylamides with acidic hydrocarbons (such as C5H6), hexamethyldisilazane, alcohols, and thiols are reported. In this way, numerous π-organometallic derivatives, such as CpTi(NMe2)3 and (π-C5H5)2Zr(NMe2)2, silylamides, alkoxides, and thiolates have been prepared. Noteworthy are (a) differences (possibly steric in origin), with regard to the number of groups displaced, between Ti amides and amides of either Zr or Hf, (b) the displacement order NR2 > SR > Cp ≫ OR, and (c) the monomeric nature of all the products. Reactions between decaborane and either Ti(NMe2)4 or Me3SnNMe2 afforded Ti(NMe2)4,2B10H14 and Me3SnNMe2,B10H14, which are probably best formulated as [Ti(NMe2)2]2+[B10H13,Me2NH]2– and [Me3Sn]+[B10H13,Me2NH]–, respectively.

The anisotropy of the thermal expansion of α‐titanium

Abstract: In order to resolve the discrepancy found in earlier work, the anisotropic thermal expansion of α-titanium has been determined by the X-ray method. If a small range of temperature is used the coefficient of expansion observed along the hexagonal axis (αc) is smaller than that in the basal plane (αa). The nature of the deviation of the α-titanium structure from ideal hexagonal close-packing and the room temperature elastic behaviour of the metal have been shown to be in agreement with the result that αc (5.6 × 10−6. °C−1) is smaller than αa (9.5 × 10−6. °C−1).

On the borothermic preparation of titanium, zirconium and hafnium diborides

Abstract: The formation of titanium, zirconium and hafnium diborides by reaction between metal dioxides and elemental boron in vacuum in the temperature range 1000 °–1750 °C has been investigated. It has been established that titanium diboride with a composition close to that of stoichiometric TiB2 is obtained after a heattreatment of the reactants at 1700 °C for I h; HfB2 is obtained after heat treatment at 1750 °C for 2 h. Experimental results show that higher temperatures are necessary for the preparation of stoichiometric ZrB2 by the borothermic method. The structure of HfB2, and its stability at boiling point and at room temperature in the presence of acids, mixtures of acids, mixtures of acids with oxidizing agents, and alkaline solutions has been studied.

Stress corrosion cracking of titanium alloys.

Abstract: The U.S. Bureau of Mines development of the Kroll process1 for the production of titanium metal resulted in the general availability of this material by the early 1950’s. Titanium was immediately hailed as the panacea for all structural applications demanding high strength and low density. Today, perhaps, this view could be regarded as somewhat overoptimistic. However, titanium alloys have been used successfully for a number of years in a wide range of industrial applications.

Dispersoid titanium and titanium-base alloys

Abstract: As a new article of manufacture a base metal of the group titanium and titanium base alloys containing a dispersoid of the group consisting of thorium, boron, rare earth elements having an atomic number of 57-71, and elements of groups IIIb and IIIc of the periodic table of elements, which are substantially insoluble in solid titanium but soluble in molten titanium, and combinations and compounds thereof, preferably in proportions of about 0.1 to 6 percent by weight of the total, and wherein said dispersoid is preferably dispersed in a particle size of several microns and under, said article being characterized by highelevated temperature creep strength.

Nuclear magnetic resonance and cryoscopic studies on some alkoxides of titanium, zirconium, and hafnium

Abstract: Cryoscopic and n.m.r. studies show that the ethoxide, n-propoxide, and n-butoxide of titanium are trimeric in solution over wide ranges of concentrations and temperature. Intramolecular exchange of terminal and bridging alkoxide groups is too rapid even at –90° to be resolved by n.m.r. at 60 Mc.sec. N.m.r. studies revealed reversible depolymerization of the trimers at high temperatures and low concentrations. Titanium isobutoxide and neopentoxide showed a concentration and temperature dependence of n.m.r. chemical shift due to the presence of monomers, dimers, and trimers. Zirconium and hafnium isopropoxides contain mixtures of trimers and tetramers, but the cryoscopically determined molecular weights are independent of concentration.

Mechanisms of Sensitization and Stablization of Incoloy Nickel-lron-Chromium Alloy 825

Abstract: Incoloy(1) nickel-iron-chromium Alloy 825 can become sensitive to intergranular attack by exposure to temperatures in the 1200–1400 F (649–760 C) range. Sensitivity to intergranular attack (as measured by the Huey test) can be correlated to the presence of a chromium-depleted area adjacent to the grain boundary. This area is caused by the cellular precipitation of chromium-rich M23C6 during sensitizing treatments. The chromium-depleted region is between the M23C6 cells, but because the carbides grow by boundary migration the depletion is not in the plane of the grain boundary. Incoloy Alloy 825 can be stablized against intergranular attack by eliminating the chromium-depleted area. The degree of stabiization is related to the amount of carbon remaining in solution after the stablizing treatment. The titanium content of the alloy helps to effect stabtization. Because it has a greater affinity for carbon than does chromium, the titanium reacts to form stable carbides and thus reduces chromium deple...

Fluocomplexes of titanium, silicon, tin and germanium, activated by tetravalent manganese

Abstract: ACTIVATED FLUOCOMPLEXES OF THE TYPE M2XF6:MN, WHERE X REPRESENTS SILICON, TITANIUM OR TIN OR MIXTURES OF THESE ELEMENTS WITH EACH OTHER OR WITH GERMANIUM, M REPRESENTS A OMONVALENT CATION AND MN IS TETRAVELENT, ARE YELLOWISH, CRYSTALLINE PHOSPHORS EXCITED BY U.V. AND VISIBLE RADIATION TO FLUORSECE STONGLY IN THE RED. K2TIF6:MN IS TYPICAL. IT RESPONDS STRONGLY TO EXCITATION BY RADIATION OF 3150, 3650 AND 4550 A.U. WAVELENGTHS. ITS PRINCIPAL EMISSION PEAK IS AT 6320 A.U., WITH SECONDARY PEAKS AT 6140 AND 6360 A.U. THE PHOSPHORS MAY BE PREPARED BY MIXING, IN SOLUTION, MNF6=H2XF6 AND THE FLUORIDE OF THE DESIRED CATION (S), AND CRYSTALLIZING OUT THE PHOSPHOR PRODUCT.

Distribution in depth of the primary X-ray emission in anticathodes of titanium and lead

Abstract: The ionization distribution in depth has been determined experimentally for two elements, lead and titanium, at various incident electron energies, by the sandwich tracer technique previously used by Castaing and Descamps. The experimental curves of the ionization distribution in depth at 29 kv for lead and titanium are compared with curves calculated from the distribution in depth and energy of the incident electrons computed by Bishop. Agreement between the experimental and theoretical results is good. The surface ionization straightphi0, which is mainly due to backscattering of the electrons, has been determined at various accelerating voltages for titanium, nickel and lead. straightphi0 is a function of the atomic number of the anticathode and of the accelerating voltage. Good agreement is obtained between the experimental values and values calculated by Duncumb and Melford. The x-ray absorption correction curves f(×) for titanium and lead have been computed from the experimental curves of the distribution in depth of the characteristic emission. These are compared with the curves predicted by the `Philibert correction'.

Präparation und Supraleitungseigenschaften von Niobnitrid sowie Niobnitrid mit Titan-, Zirkon- und Tantalzusatz

Abstract: A description of preparation for samples of niobium nitride without and with admixtures of titanium, zirconium and tantalum by diffusion of nitrogen under pressure into niobium wires without and with admixtures of titanium, zirconium and tantalum respectively, is given. For samples of pure niobium nitride with different compositions the influence of the nitrogen content on the transition temperature to superconductivity has been investigated with the result of a transition temperature not exceeding 16.5 °K even for the stoichiometric composition NbN. This is in contrary to other authors. For diffusion wires of the systems (Nb-Ti)N x , (Nb-Zr)N x and (Nb-Ta)N x the critical temperature, lattice parameter and nitrogen content as a function of the admixture of titanium, zirconium and tantalum respectively, are given. For the first time the magnetisation curve of niobium nitride has been measured showing the behaviour of type II superconductors. Concerning the kinetics of formation of niobium nitride by diffusion the nitrogen content is increasing for constant nitrogen pressure with raising temperature of diffusion, but is decreasing in the high temperature region.

Fracture of titanium-hydrogen alloys

Abstract: Tensile tests on coarse-grained (~0.3 mm) commercially-pure titanium containing 0, 30, 50, 85, 250 and 525 p.p.m. of hydrogen have been carried out. The tests were performed at −196 °, −78 °, 20 °, 150 ° and 300 °C at a strain rate of ~1.0 × 10 −3 sec −1 . The hydrogen embrittlement of the titanium, measured in terms of a reduction in both fracture stress and elongation to fracture, was enhanced by increasing hydrogen content and decreasing test temperature. This mechanical behaviour has been correlated to the influence of precipitate morphology and test temperature on the introduction of cracks into the titanium matrix by failure associated with the hydride precipitates.

Platinum thin-film metallization method

Abstract: Platinum thin-film metallization is selectively etched with aqua regia, using a chromium or titanium film as an etch-resistant mask. In a specific embodiment, an integrated circuit structure is metallized with successive layers of titanium, platinum, gold and a metal selected from molybdenum, tungsten, rhenium and corrosion-resistant alloys thereof. The system is particularly suited for the formation of insulated ''''cross-over'''' metallization, or multi-level interconnecting metallization.