Titanium alloy valve

Figure 2.13 Schematic drawing of Roe s titanium-alloy valve glued to a 5 mm outer diameter sapphire tube.

The open end of the tube is sealed by means of a nonmagnetic titanium alloy valve (Figure 5). The numbered details are 1, valve body 2, valve stem drive handle 3, stem drive and packing gland ... 

As previously mentioned, the nickel—titanium alloys have been the most widely used shape memory alloys. This family of nickel—titanium alloys is known as Nitinol (Nickel Titanium Naval Ordnance Laboratory in honor of the place where this material behavior was first observed). Nitinol have been used for military, medical, safety, and robotics applications. Specific usages include hydraulic lines capable of F-14 fighter planes, medical tweezers, anchors for attaching tendons to bones, eyeglass frames, underwire brassieres, and antiscalding valves used in water faucets and shower heads (38,39). Nitinol can be used in robotics actuators and micromanipulators that simulate human muscle motion. The ability of Nitinol to exert a smooth, controlled force when activated is a mass advantage of this material family (5). 

Problem In 1965 some scientists produced a very special nickel-titanium alloy which can remember its programmed form. They called this kind of alloy memory metal and the special compound Nitinol , because it was discovered in the Nickel-Titanium Naval Ordonnance Laboratory. The memory metals are often used in engines, motors and other pieces of equipment, for which it is important to have a certain form at a certain temperature, e.g. for closing a valve. The conversion temperature of the Nitinol composition NqTq is approximately 50°C. Samples of such memory metals, like nitinol wires, can be obtained from Educational Innovations (teachersource.com). 

DLC deposited on stainless-steel and titanium alloys used for components of artificial heart valves has been found to be biologically and mechanically capable of improving their performance (McHargue, 1991). Devlin etal. (1997) showed improvements to carbon—carbon composite prostheses with DLC coating. 

Dion et al. (1993) evaluated the in vitro platelet retention of the new prosthetic heart valve that was designed by FII Company and Pr. Baudet, composed of Ti6A14V titanium alloy coated with DLC (obtained by CVD). The retention and adhesion of platelets was evaluated by analyzing radioactivity on the exposed wall of test or control tubes through which a blood cell suspension containing In-labelled platelets had circulated. Their results showed that on DLC/Ti6A14V, platelets adhered twice the amount that they did on the reference material (a silicone medical-grade elastomer the behaviour of which in contact with blood is the same as that observed with the National Institutes of Health-recommended polydimethyl siloxane) (Dion et al., 1993). 

Crucibles of titanium nitride and zirconium nitride are utilized for the melting of lanthanum alloys. ZrN, HfN and TaN are also used as electrodes in electronic valves. Niobium and zirconium nitrides could be used as superconductors due to their relatively high superconductor transition temperatures of 16.8 and 10 K respectively. 

The DSA-type anodes are inert , coated anodes made of a valve metal (titanium, niobium, or tantalum) base coated with an electrochemically active coating. The active coating is made either of noble metals or of mixed metal oxides. Noble metals in active coatings are usually platinum or platinum alloys. Mixed metal-oxide coatings contain active oxides and inert oxides the active components are usually ruthenium dioxide (R.UO2) and iridium dioxide (IrC>2) and the inert components are mostly titanium dioxide (TiC>2) and other oxides such as tantalum... 

Valve metal alloys and their anodic films are attractive materials for nanoelectronics [1,2]. Formation of Al-Ti alloys with an predefined titanium contamination and their porous anodizing gives the method of controlled modification of film structure and electrophysical properties [3]. In the present work, Al-W alloys fabrication and their anodizing have been investigated. The structure of fabricated films has been studied. 

The original saltwater condenser tube made of admiralty brass was found to be susceptible to erosion-corrosion at tube ends. Aluminum brass containing 2% aluminum was more resistant to erosion in saltwater. Inhibition with arsenic is necessary to prevent dezincification as in the case of admiralty brass. The stronger naval brass is selected as the tube material when admiralty brass mbes are used in condensers. Cast brass or bronze alloys for valves and fittings are usually Cu-Sn-Zn compositions, plus lead for machinability. Aluminum bronzes are often used as tube sheet and channel material for exchangers with admiralty brass or titanium tubes exposed to cooling water. 

Reasonably, the corrosion form is typical at relatively high velocities between the material surface and flie fluid, and it is particularly intensive in cases of two-phase or multiphase flow, i.e. hquid-gas and liquid-solid particle flow. Components often liable to erosion corrosion are propellers, pumps, turbine parts, valves, heat exchanger tubes, nozzles, bends, and equipment exposed to liquid sputter or jets. Most sensitive materials are those normally protected by corrosion products with inferior strength and adhesion to flie substrate, e.g. lead, copper and its alloys, steel, and under some conditions aluminium/aluminium alloys. Stainless steel, titanium... 

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