Niobium carbonitride

Niobium carbonitride has comparable properties to NbN, including a relatively high critical temperature [165]. The material has been prepared by the CVD of a mixture of bis(toluene) niobium (21) and hydrazine, NH2-NH2 [254]. 

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Pike, G., Pierson, H. O., Mullendore, A., and Schirber, J., Superconducting Thin Film Niobium Carbonitrides on Carbon Fibers, / / . Polymer Symp., No. 29, pp. 71-81, John Wiley Sons, New York (1976)... 

Brennfleck, K., Dietrich, M., Fitzer, E., andKehr, D., Chemical Vapor Deposition of Superconducting Niobium Carbonitride Films on Carbon Fibers, Eroc. 7th Int. Conf. on CVD, (T. Sedgwick andH. Lydtin, eds.), pp. 300-314, Electrochem Soc., Pennington, NJ 08534 (1979)... 

Table 11.3 presents the results of an equilibrium calculation relating to the precipitation of a number of phases, including the niobium carbonitride phases, from dilute solution in an austenitic steel at 1223 K. The calculation shows that at this temperature, the Nb (N, C) phase itself is stable, together with AIN, BN and MnS as other precipitated phases. By carrying out a series of such calculations for a number of temperatures for the given steel, the changes in the amounts of the precipitated phases can be determined, as well as the composition of the carbonitride phase. This is illustrated for the present steel in Fig. 11.1. 

Table 11.3 Calculation equilibrium in the Fe-B-C-Mn-N-Al-O-Nb system at 1223 K, including the niobium carbonitride phase...

K. Brennfleck, E. Fitzer, SiC-Coatings as Protective Layers for Carbon Fibers and Adhesion Promoters for Superconducting Niobium Carbonitride, Proc. 4th Eur. Conf. on CVD, Phillips Center for Manufacturing Technoloy, Eindhoven, The Netherlands, 1983, pp. 370-75. 

Sha] Sharma, R.C., Lakshmanan, V.K., Kirkaldy, J.S., Solubility ofNiobium Carbide and Niobium Carbonitride in Alloyed Austenite and Ferrite , Metall Trans. A, 15A, 545-553 (1984) (Phase Relations, Experimental, 27)... 

Zaj] Zajac, S., Jansson, B., Thermodynamics of the Fe-Nb-C-N System and the Solubility of Niobium Carbonitrides in Austenite , Metall. Mater. Trans. B, 29B, 163-176 (1998) (Calculation, Phase Relations, Thermodyn., 33)... 

Nam KD, Ishihara A, Matsuzawa K, Mitsushima S, Matsumoto M, Imai H, Ota K (2010) Partially oxidized niobium carbonitride as non-platinum cathode for PEFC. Electrochim Acta 55 7290-7297... 

P. Rios, Expression for solubility product of niobium carbonitride in austenite,... 

Nitrogen and carbon are the most potent solutes to obtain high strength in refractory metals (55). Particulady effective ate carbides and carbonitrides of hafnium in tungsten, niobium, and tantalum alloys, and carbides of titanium and zirconium in molybdenum alloys. 

Zirconium and niobium polymers were prepared by fairly similar routes, the ammonolysis of the tetrakis-dialkylamines [88] or the chlorides [89,90] in liquid ammonia. After pyrolysis, nitrides or carbonitrides were obtained in high ceramic yields. 

Kim H S, Bugli G, Djega-Mariadassou G (1999) Preparation and characterization of niobium carbide and carbonitride. J Solid-State Chem 142 100-107... 

Niobium is used to combine with carbon and nitrogen, thus reducing the formation of chromium carbonitrides. This reduces the possibility of intergranular corrosion when stainless is welded or heat-treated. Niobium also contributes to age hardening in some precipitation-hardening stainless grades. 

Titanium can serve a similar purpose as niobium relative to carbonitride stabilization. Titanium is added to some precipitation-hardening stainless steels (e.g., S46500) as an age-hardening agent. 

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