Showing papers on "Titanium published in 1983"

The interface zone of inorganic implants in vivo: Titanium implants in bone.

Abstract: The interface zone between titanium implants and bone is considered at the macroscopic, microscopic, and molecular levels. A high rate of successful dental implants of pure titanium is associated with a very close apposition of the bone to the titanium surface, called osseointegration. At the macroscopic level, osseointegration allows efficient stress transfer from the implant to the bone without abrasion or progressive movement that can take place if a fibrous layer intervenes. At the microscopic level, surface roughness and porosity provide interlocking of the implant and bone tissue which grows into direct contact with titanium. Sections studied in the electron microscope show that calcified tissue can be identified within 50 A of the implant surface. The interface zone includes a tightly adherent titanium oxide layer on the surface of the implant which may be similar to a ceramic material in relation to tissue response. The five year success rate of 90% in 2895 implants in clinical trials since 1965 is associated with the favorable behavior of bone tissue at the interface zone with pure titanium.

Electron microscopic analysis of the bone-titanium interface.

Abstract: Ten cylindrical implants, made of polycarbonate and covered with a 120-250-nm-thick layer of pure titanium, were implanted into each tibial metaphysis of five rabbits. Observation time was 12 weeks. The implants were surrounded by mature, living bone. No soft tissue intervened between bone and implant at any point. With TEM microscopy the titanium was shown to be bordered by a 20-nm-thick layer of proteoglycans, showing the characteristics of ground substance, and separating the collagen from the implant surface. Cells at the interface were likewise separated from the titanium by such a layer. Hydroxyapatite crystals were observed within the ground substance layer, occasionally seemingly in direct contact with the titanium. Normal mineralization was present 100-500 nm from the implant surface.While this study aims at defining interface anatomy, it also shows that macroscopi-cally smooth-surfaced titanium can readily heal into bone without a soft tissue envelope. This could be of help for materials' choice...

Process for the epoxidation of olefinic compounds

Abstract: A process for the epoxidation of olefinic compounds, consisting of reacting said compounds with hydrogen peroxide either introduced as such or produced by substances capable of generating it under the reaction conditions, in the presence of synthetic zeolites containing titanium atoms, of general formula: where x lies between 0.0001 and 0.04, and possibly in the presence of one or more solvents, operating at a temperature of between 0° and 150°C, and at a pressure of between 1 and 100 ata.

Structural properties of titanium dioxide films deposited in an rf glow discharge

Abstract: An rf glow discharge has been used to promote the reaction between titanium tetrachloride and oxygen in order to deposit thin films of titanium dioxide at low temperatures. Structural properties of the films have been studied as functions of deposition temperature (25 to 700 °C) and of substrate material (Si, sapphire, glass, NaCl, and Ti). Films deposited onto glass substrates were amorphous at temperatures less than 300 °C, anatase at 300 and 400 °C, a mixture of anatase and rutile at 500 °C, and only rutile at 600 °C and above. Films deposited on the other substrates showed similar behavior but the temperatures for specific crystalline forms differed for each substrate material. Deposition at low power densities and 400 °C resulted in large (∼5 μm) anatase crystallites in 1–2 μm films.

Nickel/titanium/vanadium shape memory alloy

Abstract: Nickel/titanium alloys having a nickel:titanium atomic ratio between about 1:02 and 1:13 and a vanadium content between about 4.6 and 25.0 atomic percent show constant stress versus strain behavior due to stress-induced martensite in the range from about 0° to 60° C.

Hydrogen separation using coated titanium alloys

Abstract: This invention relates to the separation of hydrogen from other fluids by contacting said fluids with a titanium alloy comprising about 13% by weight vanadium, about 11% by weight chromium, about 3% by weight aluminum, balance titanium, stabilized in the body centered cubic crystalline form, said alloy having at least one clean surface coated with a metal oralloy based on a member of the class consisting of palladium, nickel, cobalt, iron, vanadium, niobium or tantalum, and allowing hydrogen to permeate the coated alloy at a temperature between about 100° C. and about 500° C.

Aluminum production cell components

Abstract: An electrolytic aluminum-production cell component, comprising a preformed matrix based on at least one material from the group alumina, aluminum oxynitride, SiAlON, boron nitride, silicon carbide, silicon nitride, aluminum boride and carbides, carbonitrides, boronitrides and borocarbides of metals from Group IVb (titanium, zirconium and hafnium) Group Vb (vanadium, niobium and tantalum)17nd Group VIb (chromium, molybdenum and tungsten) having voids extending throughout its structure, the voids in the preformed matrix structure being filled or substantially filled with aluminum in intimate contact with the matrix.

Titanium α- nitrogen solid solution formed by high temperature nitriding: diffusion of nitrogen, hardness, and crystallographic parameters

Abstract: The nitriding of titanium by nitrogen has been carried out at 1350 °C and 1450 °C, and the nitrogen concentrations at different levels in the α-phase layer determined by direct analysis, using the14N(d,α)12C nuclear reaction. The concentrations at the α/e interface agree with the published phase diagram, but a significant deviation is observed at the α/β interface. The diffusion coefficients were calculated from the experimentally obtained profiles and were found to agree well with those calculated using a simple model describing the nitriding reaction. The crystallographic parameters of the hcp titanium α-nitrogen solid solutions were determined and showed evidence of a cooperative effect in the deformation of the crystallographic interstices. Vickers microhardness was measured with a 100 g load for nitrogen concentrations above 10 at. pct.

Wettability and contact interaction of gallium-containing melts with non-metallic solids

Abstract: The wettability of sapphire, quartz and graphite by gallium, gallium-based binary alloys with indium, tin, copper, silver, nickel, manganese, chromium, vanadium and titanium and by ternary Cu-Ga-Ti, Cu-Ga-Cr and Cu-Ga-Mn alloys has been studied by sessile drop, plate weight and meniscus form methods. The character and intensity of contact reactions and the composition of transition layers at the solid—melt boundary have been investigated by X-ray analysis and profilographic measurements and the correlation between the wettability and the contact reaction intensity has been established. The condition for high wettability of non-metallic solids by multicomponent melts is shown to be a combination of high affinity of a component for solid phase atoms with high thermodynamical activity of this component in the melt.

An application of pure titanium to the metal porcelain system.

Abstract: The purpose of this study is to investigate the feasibility of pure titanium to the metal-porcelain system.Since thermal expansion coefficient of pure titanium was 9.41×10-6/°C (100-400°C) and was considerably smaller than those of the conventional alloys for porcelain, a porcelain having the thermal expansion coefficient of 8.5-8.9×10-6/°C was experimentally prepared.The bonding strengths of pure titanium to newly prepared porcelains were more than 160kg/cm2, which is close to those between conventional metals and “Vita” porcelains.Pure titanium has the intermediate mechanical properties between gold and nickel-chromium alloys and higher sag resistance than these alloys.

Oxidation of silicide thin films: TiSi2

Abstract: The oxidation of TiSi2 thin films on polysilicon illustrates extreme examples of behavior. At 700 °C in wet O2, one observes the formation of titanium oxide and the simultaneous rejection of silicon towards greater depths, away from the oxidized surface layer. At 1100 °C with the same type of sample, one observes the growth of a metal‐free layer of SiO2, the formation of which required not only the use of the whole available polysilicon, but the reduction of the initial disilicide to a lower silicide, mostly TiSi. These observations are discussed in terms of previous results obtained either with TiSi2 or with other silicides, and in terms of what is known about the thermodynamics of the system titanium oxide‐silicon oxide.

Nickel/titanium/copper shape memory alloy

Abstract: Nickel/titanium alloys containing less than a stoichiometric quantity of titanium, which have a high austenitic yield strength and are capable of developing the property of shape memory at a temperature above 0° C., may be stabilized by the addition of from 7.5 to 14 atomic percent copper. These stabilized alloys also possess improved workability and machinability.

Infrared and X-ray diffraction investigations of vanadium–titanium oxides for the oxidation of alcohol

Abstract: Vanadium oxide supported on titania has been studied by infrared spectra and X-ray diffraction for qualitative and quantitative analysis, together with the rate of oxidation of alcohol and reduction of oxide. The rate of ethanol formation passes through a maximum at V–Ti-11 (11 wt% V2O5) in the presence or absence of oxygen gas. At low surface concentrations of vanadium oxide below V–Ti-11 a new vanadate phase is observed in the i.r. spectra. The active oxygen species correspond to amorphous or two-dimensional vanadium oxide in the catalyst. It is concluded that the catalytic activity of V–Ti oxides originates mainly from the presence of such species.

Electrode with electrocatalytic surface

Abstract: An electrode for use in electrolytic processes comprises a base of film-forming metal such as titanium with an operative outer electrocatalytic surface which is an integral surface film of a compound of the titanium base, usually the oxide, incorporating a platinum-group metal electrocatalyst, preferably iridium, rhodium, palladium and/or ruthenium as metal or oxide. The surface film is formed by the application of a dilute solution of a thermodecomposable iridium, rhodium and/or ruthenium compound containing an agent such as HCl which attacks the titanium base and converts metal from the base into ions which are converted to the compound in a subsequent heating step. The concentrations of this agent and of the thermodecomposable compound and the number of applied layers are such that during heating the electrocatalyst formed from the decomposed compound is incorporated fully in the surface film formed from the base. The base is usually in sheet form, but may also be a powder.