Niobium-titanium

Low Expansion Alloys. Binary Fe—Ni alloys as well as several alloys of the type Fe—Ni—X, where X = Cr or Co, are utilized for their low thermal expansion coefficients over a limited temperature range. Other elements also may be added to provide altered mechanical or physical properties. Common trade names include Invar (64%Fe—36%Ni), F.linvar (52%Fe—36%Ni—12%Cr) and super Invar (63%Fe—32%Ni—5%Co). These alloys, which have many commercial appHcations, are typically used at low (25—500°C) temperatures. Exceptions are automotive pistons and components of gas turbines. These alloys are useful to about 650°C while retaining low coefficients of thermal expansion. Alloys 903, 907, and 909, based on 42%Fe—38%Ni—13%Co and having varying amounts of niobium, titanium, and aluminum, are examples of such alloys (2). 

Special Alloys. AHoys of tin with the rater metals, such as niobium, titanium, and 2kconium, have been developed. The single-phase alloy Nb Sn [12035-04-0] has the highest transition temperature of any known superconductor (18 K) and appears to keep its superconductivity in magnetic... 

The alloy niobium titanium (NbTi) and the intermetaUic compound of niobium and tin (Nb.3 Sn) are the most technologically advanced LTS materials presently available. Even though NbTi has a lower critical field and critical current density, it is often selected because its metallurgical properties favor convenient wire fabrication. In contrast, Nb.3Sn is a veiy brittle material and requires wire fabrication under very well-defined temperature conditions. 

Niobium-Titanium Nb-8Ti exhibits unusual behaviour although the... 

The most important tin mineral is cassiterite (Sn02). Theoretically, the tin content of cassiterite is 78%. However, in the majority of cases, cassiterite contains impurities and the tin content may vary from 65% to 78%. The major impurities of cassiterite include tantalum, niobium, titanium and other elements, usually in the form of solid solutions. The impurities in the cassiterite often have a pronounced effect on flotation properties of cassiterite. 

Chromium iron manganese brown spinel, formula and DCMA number, 7 348t Chromium iron nickel black spinel, formula and DCMA number, 7 348t Chromium isotopes, 6 476 Chromium magnesium oxide, 5 583 Chromium manganese zinc brown spinel, formula and DCMA number, 7 348t Chromium-nickel alloys, 77 100-101 Chromium-nickel-iron alloys, 17 102-103 Chromium-nickel stainless steels, 15 563 Chromium niobium titanium buff rutile, formula and DCMA number, 7 347t Chromium(III) nitrate, 6 533 Chromium nitride, 4 668... 

Nickel niobium titanium yellow rutile, formula and DCMA number,... 

Nickel antimony titanium yellow Nickel niobium titanium yellow Nickel tungsten titanium yellow Chrome antimony titanium yellow Chrome niobium titanium yellow Chrome tungsten titanium yellow Manganese antimony titanium brown Manganese niobium titanium brown Manganese chrome antimony brown... 

Ceramic materials cost less, currently at 10 a pound versus 70 a pound for niobium-titanium. 

Cutaway view of the rotor of a superconducting generator. While the operating principle is the same as that of a conventional, rotating generator, the rotor is different. It is hollow and vacuum-enclosed, and instead of copper conductors, it contains a niobium-titanium Superconducting field winding held in place by radial slots. 

I do think it ll be revived in the U.S. I feel we could start up again tomorrow and build those machines, without waiting for the ceramics. Niobium-titanium is good, but you also have niobium-tin, with the advantage that it ll withstand twice the field of niobium-titanium and you get pretty good current density. 

The magnets do require expensive helium refrigeration systems to cool the niobium-titanium coils to superconducting temperatures. Thus, a liquid nitrogen system should be less expensive, simpler to operate, and more reliable. But some scientists are dubious. Said John Hulm ... 

---