Carbides joining

Fig. 14.3 SEM on replica of welding sensitization of 304 stainless steel, a thin, feather-like carbides joined together, b detail of A...

Joining of C3 compounds was successfully demonstrated [11] using a cement of Ti carbide basis and hot pressing as method. Such operation can be done with certain geometries and at enormous cost and is only possible in high-tech applications such as in nuclear reactors. For less-demanding applications, gluing with polymer materials is an option. 

The basic building block of a silicon carbide crystal is the tetrahedron of four carbon atoms with a silicon atom in the center (Figure 1.4). There also exists a second type rotated 180° with respect to the first. The distance between the carbon and silicon atom is 1.89A and the distance between the carbon atoms is 3.08A [6]. SiC crystals are constructed with these units joining at the corners. 

A number of American companies became involved in restructuring. Union Carbide sold its Antwerp site to BP Chemicals Monsanto, its Seal Sands acrylonitrile unit to BASF Esso, its Stenungsund steam cracker to Statoil while Hercules joined up with Montedison to set up the Himont company, which accounted for 20 percent of the world polypropylene market. 

Polysulfone A number of adhesives have been found useful for joining polysufone to itself or to other materials. These include 3M Company s EC 880 solvent-base adhesive, EC 2216 room-temperaturecuring epoxy two-part paste, Bloomingdale Division, American Cyana-mid Company BR-92 modified epoxy with DICY curing agent, or curing agent "Z" (both spreadable pastes), vinyl-phenolics, epoxy-nylons, epoxies, polyimide, rubber-based adhesives, styrene polyesters, resorcinol-formaldehyde, polyurethanes, and cyanoacrylates. The EC 880, EC 2216, and the two BR-92 adhesives are recommended by the polysulfone manufacturer. Union Carbide (16) (17). 

Chin et al. [16] developed the chemical composition-process relationships in CVD-SiC from H2-CH3SiCl3. The phase relationships given in Fig. 10 indicate that the two parameters of supersaturation and temperature are joined by the mass transport requirements in terms of the rate of deposition of silicon carbide. In this case, the rate is also dependent on the hydrogen concentration as it is required in the reaction to form SiC and is the carrier gas for the reactants. At low hydrogen levels, pyrolytic carbon is formed. 

Karl Kordesch left Vienna in 1953, ostensibly on a vacation with his family and his two small children. After a somewhat surreptitious passage through the Soviet-controlled part of Lower Austria, he and his family eventually turned up in New Jersey with the US Signal Corps under the auspices of Project Paper Clip. Two years later he joined Union Carbide s research laboratory in Parma, Ohio, as a staff scientist working on batteries. At Union Carbide he eventually became a Corporate Research Fellow this meant, he recalled, complete freedom, including worldwide travel, and getting more money without the need to become a manager. Kordesch produced many patents and published lots of scientific papers. 

The reactions of acetylene which have been mentioned are analogous to those of the unsaturated hydrocarbons containing a double bond. Acetylene and other compounds which contain a carbon atom in combination with hydrogen and joined to a second atom in the manner which is represented by a triple bond, that is, those containing the group H —C =, show characteristic properties which serve to distinguish them from other substances. Such compounds are converted into metallic derivatives when they are treated with an ammoniacal solution of cuprous chloride or of silver chloride. If acetylene is passed into a solution of cuprous chloride in ammonia, a red precipitate is formed which has the composition C2CU2. This compound, which is a carbide of copper, is usually called copper acetylide. It explodes, when dry, if it is struck or is heated to 100°-120°. When treated with hydrochloric acid or with a solution of potassium cyanide, acetylene is formed. 

C. A. Lewinsohn, M. Singh, and C. H. Henager, Jr., Brazeless Approaches to Joining of Silicon Carbide-based Ceramics for High Temperature Applications, Ceram. Trans., 138,201 -12 (2003). 

C.A. Lewinsohn, R.H. Jones, T. Nozawa, M. Kotani, Y. Katoh, A. Kohyama, and M. Singh, Silicon Carbide Based Joining Materials for Fusion Energy and Other High-temperature Structural Applications, Ceram. Eng. Sci. Proc., 22, 621-25 (2001). 

M. Singh, A Reaction Forming Method for Joining of Silicon Carbide-based Ceramic, Scripta Mater., 37, 1 151-54 (1997). 

JOINING AND INTEGRATION OF ADVANCED CARBON-CARBON AND CARBON-SILICON CARBIDE COMPOSITES TO METALLIC SYSTEMS... 

Joining and integration of Carbon-Carbon and Carbon-Siiicon Carbide Composites... 

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