Showing papers on "Titanium published in 1990"

Oxidation of an NiTi alloy

Abstract: In this study, the oxidation of the surface of a SO/50 (at.%) NiTi alloy was studied by XPS, AES and SEM. Samples of the NiTi alloy were oxidized at 23 °C and high temperatures at an oxygen pressure of 10-' Torr and in atmosphere. At 10 - ' Torr of 0 1 and 23°e, titanium was oxidized preferentially while nickel remained in the metallic form even after 40 min of exposure. At the same oxygen partial pressure and 400°C, a mixture ofTiO" . Ti 10 3 and Ti01 was formed, and nickel remained metallic. Eventually, after 40 min of 0 1 exposure, the whole surface was covered with a layer of TiO]. In atmosphere and at 23 °e, titanium again was oxidized preferentially, but NiO was detected on the surface after the first minute of air exposure, At a higher temperature of 450 °e. areas comprising a mixture of NiO and Ti01 , and areas consisting ofTiO] only were found. Below the top surface layer, a complete layer of TiO] was detected. Underneath the TiO] layer, a nickel-rich layer was present.

Titanium alloy blade coupler coated with nickel-chrome for ultrasonic scalpel

Abstract: Ultrasonic blade coupler comprising a blade element composed of a material selected from aluminum and titanium rendered sharpenable by a surface hardening treatment. The blade coupler exhibits improved acoustical properties with reduced energy consumption.

Some observations on the wetting and bonding of nitride ceramics

Abstract: Several series of experiments have been conducted to gain information about the wettability of AlN, BN, Si3N4 and two sialon ceramics by potential braze materials. It was possible to achieve wetting of all five ceramics using aluminium, copper-titanium alloys, and a Ag-28Cu-2Ti alloy. Wetting by aluminium and the Ag-28Cu-2Ti alloy was usually good. Both wetting and non-wetting alloys containing titanium reacted to form TiN and it is argued that the achievement of wettability is associated with a certain degree of hypostoichiometry. While aluminium should also have reacted, no clear evidence was obtained. In supplementary experiments it was found that bonds formed by brazing with aluminium at 1000 °C could have shear strengths as great as 60MPa. Although the experimental work was preliminary in nature, it suggested that good brazing systems could be developed.

Electrically programmable antifuse element incorporating a dielectric and amorphous silicon interlayer

Abstract: An electrically programmable antifuse element incorporates a composite interlayer of dielectric material and amorphous silicon interposed between two electrodes. The lower electrode may be formed from a refractory metal such as tungsten. Preferably, a thin layer of titanium is deposited over the tungsten layer and its surface is then oxidized to form a thin layer of titanium oxide which serves as the dielectric material of the composite dielectric/amorphous silicon interlayer. A layer of amorphous silicon is then deposited on top of the titanium oxide dielectric to complete the formation of the composite interlayer. A topmost layer of a refractory metal such as tungsten is then applied over the amorphous silicon to form the topmost electrode of the antifuse.

Oxide Adherence and Porcelain Bonding to Titanium and Ti-6A1-4V Alloy

Abstract: The bonding of an experimental low-fusing porcelain to titanium and Ti-6AI-4V was evaluated by an x-ray spectrometric technique that measures the area that remains covered with porcelain following a controlled deformation of the metallic substrate. Oxide adherence strength values for titanium and Ti- 6AI-4V oxidized at 750° and 1000°C were measured in tension with use of high-strength adhesives. The effect of further oxidation that would occur during porcelain firing was evaluated via simulated porcelain firings without actual porcelain application. Interface cross-sections of the titanium-porcelain and Ti-6AI-4V-porcelain bonds were examined in a scanning electron microscope (SEM). The porcelain was found to delaminate completely from the metal substrate, leaving less than 1% of the surface covered with porcelain. The oxide adherence of the specimens oxidized at 750°C was good, but those oxidized at 1000°C exhibited significantly lower oxide adherence (p = 0.001). The simulated porcelain-firing oxidation...

Biocompatible low modulus titanium alloy for medical implants

Abstract: A biocompatible titanium alloy with low elastic modulus containing titanium, about 10-20 wt. % or 35 to about 50 wt. % niobium and up to 20 wt. % zirconium useful for fabricating of orthopedic implants. This invention relates generally to high strength, biocompatible alloys suitable for use as a material for a medical prosthetic implant and, in particular, a titanium alloy which has a relatively low modulus of elasticity (e.g. closer to that of bone than other typically-used metal alloys) and does not include any elements which have been shown or suggested as having short term or long term potential adverse effect from a standpoint or biocompatibility.

Olefin polymerization catalyst and process for the polymerization of olefins

Abstract: In accordance with the present invention, there are provided olefin polymerization solid catalysts comprising [A] a solid titanium catalyst component containing titanium, magnesium and halogen as its essential ingredients, said catalyst component having supported thereon [B] a transition metal compound containing a ligand having a cycloalkadienyl skeleton and, if necessary, [C] an organoaluminum oxy-compound. In accordance with the invention, there are also provided olefin polymerization solid catalysts comprising [i] a solid containing a transition metal compound containing a ligand having a cycloalkadienyl skeleton, said solid having supported thereon [ii] a titanium catalyst component containing titanium, magnesium and halogen as its essential ingredients and, if necessary, [iii]an organoaluminum oxy-compound.

Thin film capacitor and manufacturing method thereof

Abstract: This film capacitors in accordance with the present invention include a silicon electrode (22), a first electrode layer (24) consisting of either one of titanium, titanium silicide, titanium nitride, tantalum, molybdenum, tungsten, tantalum silicide, molybdenum silicide, tungsten silicide, alloys thereof and compounds thereby, formed on the silicon electrode, a second electrode layer (25) formed on it consisting of platinum, palladium or rhodium, a dielectric layer (26) formed on it consisting of an oxide ferroelectric substance such as BaTiO₃ and a third electrode layer (27) formed on top of it. As the first electrode layer, use may also be made of rhenium oxide, osmium oxide, rhodium oxide or iridium oxide.

Aluminum bump, reworkable bump, and titanium nitride structure for tab bonding

Abstract: A semiconductor chip carrying integrated circuits has lead lines terminating in conductive terminal pads exposed to the exterior through openings in a passivation layer. The pads include pedestals or bumps extending up from them. Each of the pedestals includes a thin metallic adhesion layer deposited on the pad. A thick metallic layer of aluminum or an alloy of aluminum is deposited upon said thin metallic adhesion layer. The thick metallic layer includes at least one metal selected from the group consisting of aluminum, aluminum plus a small percentage of Cu, Ni, Si, or Fe. Several other alternative metals can be added to aluminum to form an alloy. The thick metallic layer forms the bulk of the height of the pedestal. An adhesion layer is deposited on the bump of aluminum composed of a thin film of titanium or chromium. A barrier layer is deposited on the adhesion layer composed of copper, nickel, platinum, palladium or cobalt. A noble metal consisting of gold, palladium, or platinum is deposited on the barrier layer. In a variation of the top surface, a thick cap of a reworkable bonding metal is deposited above the metallic bump as the top surface of said bump. The bump can be composed of a number of metals such as gold, copper, nickel and aluminum in this case with aluminum being preferred. In place of the adhesion and barrier metals one can employ a layer of titanium nitride deposited on said thick layer of metal.

The influence of small amounts of added elements on various anode performance characteristics for LaNi2.5Co2.5-based alloys

Abstract: The addition of small amounts of elements such as silicon, aluminium and titanium to LaNi2.5Co2.5 greatly influenced anode performance characteristics such as usable temperature range, capacity and its decay rate during repeated cycles, rate capability, low temperature dischargeability and self-discharge rate. The capacity decay was suppressed by the addition of silicon, but the rate capability decreased and the self-discharge rate increased. The alloy containing titanium exhibited a much longer cycle life, but much lower storage capacity and worse low temperature dischargeability. The addition of aluminium was very useful for improving the usable temperature range, cycle life and charge retention, and it did not cause too great a decrease in capacity and/or increase in overpotentials.

Oxidation Effects on Porcelain-Titanium Interface Reactions and Bond Strength

Abstract: Titanium is strong, resists corrosion and has a low density and excellent biocompatibility. Conventional ceramic-metal restorations have been extensively used in dentistry because of their esthetic appearance and good mechanical properties. This study investigates oxidation effects on the porcelain-titanium interface reactions and bond strength. Pure titanium was treated in a porcelain furnace at temperatures of 600 to 1000°C under either vacuum or air. X-ray diffraction analysis of the surface of pure titanium revealed that the relative peak intensity of α-Ti decreased and that of TiO2 increased, with increasing firing temperature. The Vickers hardness number of titanium increased with temperature especially over 900°C, and was harder in air than in vacuum. The tension-shear bond strength of the porcelain-titanium system was the highest in the green stage and lowest after 900°C treatment. Metallographic microscopy of the porcelain-titanium interface revealed a thick band-like zone in the sample treated over 900°C. The excess thick layer of TiO2 apparently weakened the bond strength of porcelain-titanium. Unlike the conventional ceramic-gold alloy system the recommended degassing procedure was not suitable for porcelain-pure titanium restoration.

Nanocrystalline titanium-magnesium alloys through mechanical alloying

Abstract: The solid solubility of magnesium in titanium under equilibrium conditions is reported to be extremely small. Mechanical alloying of a mixture of titanium and magnesium powders resulted in the formation of nanocrystalline (10–15 nm in size) grains of Ti–Mg solid solution. This solid solution has a metastable fcc structure with a = 0.426 nm and contains about 3 wt.% (6 at.%) magnesium in it. It is suggested that the fcc structure has formed as a result of the heavy mechanical deformation of the hep structure introduced during milling. High temperature annealing of the metastable solid solution led to its decomposition forming the equilibrium phases, viz., elemental titanium and magnesium.

Manufacture of semiconductor device

Abstract: PURPOSE:To eliminate diffusion of a wiring metal and prevent junction leak by performing ion implantation of silicon or oxygen after performing heat treating of a high melting-point metal layer on the surface of a contact opening part. CONSTITUTION:After forming an insulation film 102 on a silicon substrate 103 and then a contact opening part, a high melting-point metal layer 101 is formed on an insulation film and the surface of the contact opening part. Titanium is sputtered here as a high melting-point metal. Then, performing heat treating using a high-speed heat treating furnace, etc., a titanium nitride 105 is formed on the contact opening part and a titanium silicide 106 is formed at the interface with the substrate. Furthermore, silicon or an oxygen 104 is ion-implanted to the surface of the titanium nitride 105. After that, a conductive wiring 107 is formed on the titanium nitride 105. It prevents wiring metal from being diffused even if heat is applied to at a post-process, etc., and leak current at junction from increasing.

Alkoxide-Hydroxide Route to Syntheltize BaTiO3-Based Powders

Abstract: When preparing homogeneous, fine barium titanate powders, the major difficulty is to avoid the spontaneous self-condensation between the Ti-OH groups. In the usual way of preparing fine barium titanate powders, chelating agents (citrate, oxalate) or simply unidentate ligands (alkoxy or carboxyl groups) are used to complex titanium atoms. Another way is to mix barium and titanium precursors in a strongly basic medium. The condensation between the Ti(OH)2-6Ba2+ species directly gives the perovskite compound. Using an alkoxide-hydroxide route, a homogeneous Ba-Ti solution was prepared that completely advanced by condensation between the Ti(OH)2-6Ba2+ species and led to a controlled-stoichiometry powder. Concerning pure barium titanate, dried powders exhibited the cubic perovskite structure, and a direct sintering at 1150°C, without calcination, led to highly dense BaTiO3 bodies with fine-grained uniform microstructure (1 μm) that exhibited a high permittivity value at room temperature (K= 5400). The alkoxide-hydroxide method was also used to prepare dense alkaline-earth perovskite ceramics with complex compositions.

Process and catalyst-inhibitor systems for preparing poly(ethylene terephthalate)

Abstract: Disclosed is a polymer and process for producing the polymer using a complex of titanium alkoxide with an alkali or alkaline earth metal salt.

Mechanically driven syntheses of carbides and silcides

Abstract: Most metal carbides or slicides may be synthesized at room temperature, by ball milling mixtures of elemental powders for some tens of hours with a vibratory mill. Both stable and metastable compounds containing a high density of defects can be obtained. In general, phases stable at low temperatures are synthesized. This observation allows us to confirm recent estimations for the maximum temperature (∼600 K) attained in these powders during mechanical alloying. Exceptions are found for some MSi2 suicides with M = titanium, iron or molybdenum for which both low- and high-temperature phases are formed.

On the evaluation of stability of rare earth oxides as face coats for investment casting of titanium

Abstract: Attempts have been made to evaluate the thermal stability of rare earth oxide face coats against liquid titanium. Determination of microhardness profiles and concentration profiles of oxygen and metallic constituents of oxide in investment cast titanium rods has allowed grActation of relative stability of rare earth oxides. The relative stability of evaluated oxides in the order of increasing stability follows the sequence CeO2 — ZrO2 — Gd2O3 — didymium oxide — Sm2O3 —Nd2O3 — Y2O3. The grading does not follow the free energy data of the formation of these oxides. A better correlation with the experimental observations is obtained when the solubility of the metallic species in titanium is also taken into consideration.

Formation of titanium nitride on semiconductor wafer by reaction of titanium with nitrogen-bearing gas in an integrated processing system

Abstract: A process is disclosed for forming a layer of titanium nitride on a semiconductor wafer which comprises forming a titanium layer on the wafer in a vacuum deposition chamber in the substantial absence of oxygen-bearing gases; transferring the titanium coated wafer to a sealed annealing chamber without substantially exposing the newly formed titanium layer to oxygen-bearing gases; annealing the titanium-coated semiconductor wafer in a nitrogen-bearing atmosphere in the sealed annealing chamber, and in the substantial absence of oxygen-bearing gases, at an annealing temperature of from 400° C. up to below about 650° C. to form a titanium nitride compound on the wafer; and further annealing the wafer at a temperature of from about 800° C. to about 900° C. to form a stable phase of stoichiometric titanium nitride (TiN) on the wafer. The resulting layer of titanium nitride may be patterned to form local interconnects on the wafer, as well as to provide barrier portions between underlying titanium silicide and metal contacts such as aluminum. In a preferred embodiment, the initial annealing temperature ranges from about 400° C. up to below about 600° C. whereby substantially all of the titanium will react with the nitrogen to form titanium nitride on the wafer.

A chemical method for tin disulphide thin film deposition

Abstract: Thin films of tin disulphide (SnS2) have been chemically deposited for the first time from an acidic bath, using sodium thiosulphate (Na2S2O3) as a sulphur source, onto glass, tin oxide-coated glass and titanium substrates. Their electrical, optical and photoelectrochemical properties have been studied. The chemically deposited SnS2 films are n-type semiconductors and the optical band gap is 2.35 eV. The room temperature resistivity is of the order of 103-104 Omega cm. As-deposited SnS2 films showed photovoltaic activity.

Structural Investigations of Prehydrolyzed Precursors Used in the Sol‐Gel Processing of Lead Titanate

Abstract: A variety of titanate gels were prepared from lead acetate and titanium isopropoxide in methoxyethanol. In the presented study {sup 1}H and {sup 13}C Fourier transform-nuclear magnetic resonance and mass spectroscopic techniques were used to identify the structure of the lead and titanium precursors formed from lead acetate and titanium isopropoxide, respectively, when refluxed in methoxyethanol. The lead and titanium precursors were determined to be Pb (OOCCH{sub 3}) (OC{sub 2}H{sub 4}OCH{sub 3}). xH{sub 2}O, where x {lt} 0.5, and Ti{sub 2}(OC{sub 2}H{sub 4}OCH{sub 3}){sub 8}, respectively. Similar spectroscopic procedures were applied to identify the lead titanium complex formed from the reaction between lead and titanium precursors.

Dissolved titanium in the open ocean

Abstract: VERY little is known about the marine geochemistry of dissolved titanium, mainly because of the difficulties involved in the analysis of this highly refractory element at the extremely low levels present in sea water. Recent advances in analytical instrumentation using inductively coupled plasma mass spectrometry have lowered trace-element detection limits (particularly for refractory metals) to levels that occur naturally1,2. Titanium is relatively abundant in the Earth's crust (0.57% by weight3), yet its concentration in sea water is extremely low. Here we present measurements of titanium profiles in the open ocean. Dissolved titanium is found to be a reactive short-residence-time element, with a unique and highly non-uniform spatial distribution. Dissolved titanium is depleted in surface waters and enriched in deep waters, with a range of more than two orders of magnitude, and there are several indications that it is scavenged (removed by biotic or abiotic processes). This unusual oceanic distribution makes titanium potentially useful as a new tracer of chemical transport processes in deep waters.

Degradation of organic chemicals with titanium ceramic membranes

Abstract: Complex organic molecules, such as polychlorinated biphenyls can be degraded on porous titanium ceramic membranes by photocatalysis under ultraviolet light.