Titanium carbide fiber

The formation of titanium carbide fibers by chemical vapor infiltration with titanium at 1200 C (Equation 9) can be carried out with short vapor grown carbon fibers. The flow rates of TiCU... 

In summary, continuous sapphire fibers are commercially available, and new YAG fibers are readily achieved with the Saphikon process, or the LHPG process (see Chapter 6), or else by the new containerless laser melt process (Chapter 4). Currently however, there is only one route known, i.e., HP-LCVD, that might eventually be capable of yielding continuous, single crystal fibers such as SiC or titanium carbide fibers. A single crystal SiC fiber by LCVD has... 

Polymeric titanate obtained by trans-esterification reaction of TIP with xylene diacetate were easily formed into fibers and films which were successfully converted to titanium carbide fibers and films (Thome, 1992). However, the products were carbon-deficient and described as TiC (jc = 0.4-0.6), and brittle. The preparation of TiC fibers from lignin-Ti02 hybrid (Hasegawa, 1998), ZrC fibers from phenolic rcsin-Zr02 hybrid (Hasegawa, 1999), B4C powders from the phenol-HsBOs hybrid (Hasegawa, 1999d) have been reported. 

Silicon carbide fibers have been used with aluminum, titanium, and coball-based superalloys for high-temperature structures and engine components. 

Recent research has explored a wide variety of filler-matrix combinations for ceramic composites. For example, scientists at the Japan Atomic Energy Research Institute have been studying a composite made of silicon carbide fibers embedded in a silicon carbide matrix for use in high-temperature applications, such as spacecraft components and nuclear fusion facilities. Other composites that have been tested include silicon nitride reinforcements embedded in silicon carbide matrix, carbon fibers in boron nitride matrix, silicon nitride in boron nitride, and silicon nitride in titanium nitride. Researchers are also testing other, less common filler and matrix materials in the development of new composites. These include titanium carbide (TiC), titanium boride (TiB2), chromium boride (CrB), zirconium oxide (Zr02), and lanthanum phosphate (LaP04). 

The multifilament fiber (10-20 xm diameter) as commercially produced consists of a mixture of /3-SiC, free carbon and SiOj. The properties of this fiber are summarized in Table 6.5. The properties of Nicalon start to degrade at temperatures above about 600°C because of the thermodynamic instability of composition and microstructure. A ceramic grade of Nicalon, called Hi Nicalon, having low oxygen content is also available Yet another version of a multifilament silicon carbide fiber is Tyranno, produced by Ube Industries, Japan. This is made by pyrolysis of poly (titano carbosilanes) and contains between 1.5 and 4wt% titanium. 

This process is carried out in Japan by Nippon Carbon Co. to make NICALON silicon carbide fibers, with high tensile strength and excellent temperature and oxidation resistance. It can also be used to generate coatings and solid objects. Modifications of the basic process include the addition of borosiloxanes as catalysts, and the incorporation of titanium, in the form of titanium alkoxides, to produce fibers containing titanium and oxygen as well as silicon and carbon. 

Adachi, S., Wada, T., Mihara, T., Miyamoto, Y., Koizumi, M., and O. Yamada, Fabrication of titanium carbide ceramics by high-pressure self-combustion sintering of titanium powder and carbon fiber. J. Am. Ceram. Soc., 72, 805 (1989). 

C-C/Cu-Clad-Mo Joints The microstructure of the composite/braze interface (Fig. I) reveals braze infiltration of the inter-fiber regions to several hundred micrometer distance in 5 min. This is consistent with the sessile-drop wettability test results [10] on Cu-Ti/porous C in which the sessile drop volume continuously decreased due to the reactive infiltration of open porosity in graphite, and sessile drops of high Ti content (e.g., Cu-28Ti) rapidly and completely disappeared into the graphite substrate. The reaction of carbon with Ti in the braze forms the wettable compound titanium carbide which facilitates self-infiltration and sound bonding. 

Eddy currents have also been u,scd to measure the volume fraction of titanium alloy reinforced with silicon carbide fibers [124], Beissner studied the effect of abnormal micro-structure on eddy current probe response, a change in response occurring due to the movement of fibers within rows leading to changes in volume fraction. 

The increasing use of plastics with abrasive fillers and reinforcements created a demand for an even more abrasion resistant barrel than the standard iron/boron type. The use of glass fiber reinforced compounds for injection molding has been the single most important factor since a fabricator would be lucky if they could reach 6 months of continuous operation. This need has been successfully answered by the development of liner materials containing metallic carbides such as tungsten carbide and titanium carbide extending their life. 

The different types of boron nitride composites cited can be reinforced with fibrous materials such as titanium alloy fibers [287], Si/Zr oxynitride fibers [288], SiOg/TiOg/ZrOg fibers [289], and carbon fibers [290 to 292, 313] (see also Section 4.1.1.10.1, p. 58). BN-containing oxide and carbide ceramics are used to protect graphite from being attacked in metallurgical processes [293 to 295]. Porous ceramics and ceramic foams which can be infiltrated either with metals or lubricants may contain a-BN or are produced in boron nitride ceramic molds [296 to 299]. 

Tungsten-carbide cutting tools Titanium-nitride coatings on high-speed steel drill bits Silicon-carbide fibers and whiskers Boron-carbide abrasive blast nozzles... 

Until recently, the great majority of ceramic fibers were made from oxides such as alumina or mullite. But in the last few years, much woric has been done to develop practical processes for the production of other fiber materials, especially the refr actory carbides and nitrides. This work is beginning to bear results especially with silicon carbide fibers vt4iich have now reached full-scale production. Other materials such as silicon nitride, boron nitride, aluminum nitride, titanium carbide, hafriium carbide, and hafiiium nitride are at die development stage or in pre-production.l d... 

Metal-Ceramic Composites. Metals such as aluminum, titanium, copper and the intermetallic titanium aluminide, which are reinforced with silicon-carbide fibers or whiskers show an appreciable increase in mechanical properties particularly at elevated temperatures. These composites are being considered for advanced aerospace structures.1 1... 

Unlike ACs, carbide-derived carbons (CDCs) can be synthesized in such a way that they only exhibit extremely narrowly distributed micropores and no mesopores but, unlike OMCs, pores are not arranged in an ordered fashion. CDCs are most commonly produced by etching of carbide powders in dry chlorine gas at elevated temperatures (200-1200°C), but they can also be derived from monoliths, fibers, or thin films. The chlorine treatment followed by subsequent hydrogen annealing to remove residual chlorine compounds yields an SSA of typically between 1200 and 2000 va lg but activation may increase the SSA to values of up to 3200 m /g (cf Ref. 87 for a review). Recently, the CDI capacity of CDCs derived from titanium carbide (i.e., TiC-CDC) has been investigated, and a positive relation between capacity and the volume of pores smaller than 1 nm was suggested. This study suggests that the pore volume associated with ion accessible micropores is particularly attractive for CDI, and not, as it may be implied from the studies on OMC, the volume of mesopores. 

Preiss H., Berger L-M., Schultze D. Studies on the carbothermal preparation of titanium carbide fi-om different gel precursors. J. Eur. Ceram. Soc. 1999 19 195-206 Raman V., Paraschar V.K., Dhakate S.R. Synthesis ofsiUcon carbide whiskers from substituted silicon alkoxides and rayon fibers. J. Sol-Gel Sci. Technol. 2002 25 175-179... 

The nanorod represents an important building block for nanostructures. Nanorods would be useful as reinforcements in metal and ceramic matrix composites as well as ideal structures with which to pin vortices in high-temperature superconductors (119). Whiskers represent attractive reinforcing additives for metal and ceramic matrix compositions to impart more strength to the ceramic object. The superior performance of titanium carbide reinforcements is found in two different forms, discontinuous fiber and hollow microspheres, by controlled morphology carbide synthesis where titanium and carbon precursors combine in specially designed graphite... 

Metal-Matrix Composites. A metal-matrix composite (MMC) is comprised of a metal ahoy, less than 50% by volume that is reinforced by one or more constituents with a significantly higher elastic modulus. Reinforcement materials include carbides, oxides, graphite, borides, intermetahics or even polymeric products. These materials can be used in the form of whiskers, continuous or discontinuous fibers, or particles. Matrices can be made from metal ahoys of Mg, Al, Ti, Cu, Ni or Fe. In addition, intermetahic compounds such as titanium and nickel aluminides, Ti Al and Ni Al, respectively, are also used as a matrix material (58,59). P/M MMC can be formed by a variety of full-density hot consolidation processes, including hot pressing, hot isostatic pressing, extmsion, or forging. 

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