Pitch-based carbon fibers

Electronic-Grade MMCs. Metal-matrix composites can be tailored to have optimal thermal and physical properties to meet requirements of electronic packaging systems, eg, cotes, substrates, carriers, and housings. A controUed thermal expansion space tmss, ie, one having a high precision dimensional tolerance in space environment, was developed from a carbon fiber (pitch-based)/Al composite. Continuous boron fiber-reinforced aluminum composites made by diffusion bonding have been used as heat sinks in chip carrier multilayer boards. 

Amoco Performance Products, Inc. 4500 McGinnis Ferry Road Alpharetta, GA 30202-3914, USA tel 1 770 772 8200 toll free 800 222 2448 fax 1 770 772 8753 carbon fibers (pitch based) 180... 

See carbon fibers, pitch-based carbon fibers, rayon-based carbon fibers... 

Carbon Fiber Pitch or PAN based Short fibers ... 

The torsional modulus is shown in Figure 20.22 and appears to be governed by the structure of the microsection increasing in the order— mesophase pitch based carbon fiber < rayon based carbon fiber < isotropic pitch based carbof fiber < PAN based carbon fiber. 

Note Such high values of Young s modulus can be achieved most readily in MESOPHASE PITCH BASED CARBON FIBERS (MPP based carbon fibers). 

MESOPHASE PITCH BASED CARBON FIBERS (MPP BASED CARBON FIBERS) are CARBON FIBERS obtained from MESOGENIC PITCH after it has been transformed into MESOPHASE PITCH (MPP) at least during the process of spinning, after the spun MESOPHASE PITCH fibers have been made non-fusible (stabilized) and carbonized. 

The rednction-adsorption capacity for Pt (IV) on activated carbon fibers obtained from viscose rayon, sisal, and pitch was stndied by Fu et al. by chemical analysis of the reaction solutions and XPS studies of the deposited platinum. The reduction-adsorption capacity increased with the time of activation of the carbon fiber and was the highest in the case of viscose-based carbon fibers. Viscose-based carbon fibers were capable of reducing appreciable amonnts of Pt (IV), even withont activation. The state of the platinum product depended on the reaction conditions. Under acidic reaction conditions, the deposited platinnm was mainly in the elemental state. However, under the alkaline conditions, the liquid-phase hydrolysis of Pt (IV) becomes significant, and most of the platinum deposited on the activated carbon fiber surface was present as PtO, which was not further reduced to the metallic... 

Producers of PAN-based carbon fiber include Toray, Toho Beslon, Mitsubishi Rayon, and Asahi Kasai Carbon in Japan Hercules, Amoco Performance Products, BASE Stmctural Materials, Eortafil (Akzo), and Mitsubishi Rayon in the United States and Akzo, Sigri, and Soficar in Europe. Primary suppHers of high performance pitch-based carbon fibers include Amoco Performance Products, Mitsubishi Kasai, and Tonen Corp. 

More than 95% of current carbon fiber production for advanced composite appHcations is based on the thermal conversion of polyacrylonitrile (PAN) or pitch precursors to carbon or graphite fibers. Generally, the conversion of PAN or pitch precursor to carbon fiber involves similar process steps fiber formation, ie, spinning, stabilization to thermoset the fiber, carbonization—graphitization, surface treatment, and sizing. Schematic process flow diagrams are shown in Eigure 4. However, specific process details differ. 

Fig. 4. Process flow diagrams for (a) PAN-based and (b) pitch-based carbon fiber processes.

Fig. 8. Comparison of electrical and thermal conductivity of PAN- and pitch-based carbon fiber to metals, where P = pitch, T = Thornel, and...

Fibers produced from pitch precursors can be manufactured by heat treating isotropic pitch at 400 to 450°C in an inert environment to transform it into a hquid crystalline state. The pitch is then spun into fibers and allowed to thermoset at 300°C for short periods of time. The fibers are subsequendy carbonized and graphitized at temperatures similar to those used in the manufacture of PAN-based fibers. The isotropic pitch precursor has not proved attractive to industry. However, a process based on anisotropic mesophase pitch (30), in which commercial pitch is spun and polymerized to form the mesophase, which is then melt spun, stabilized in air at about 300°C, carbonized at 1300°C, and graphitized at 3000°C, produces ultrahigh modulus (UHM) carbon fibers. In this process tension is not requited in the stabilization and graphitization stages. 

Pitch-based fibers generally have higher moduh but lower strengths than theh PAN-based counterparts. The specific properties of the various types of carbon fibers are compared in Figure 4. Pitch-based fibers also have higher electrical conductivity, which can be an important consideration in certain circumstances, for example, for use in electromagnetic inductance (EMI) shielding. 

Fig. 4. Methane delivery at 298 K for active pitch-based carbon fibers as a function of weight loss after activation in steam or COj [after 95].

Shin, S,. Jang, J., Yoon, S. H. and Mochida, I., A study on the effect of heat treatment on functional groups of pitch-based activated carbon fiber using FTIR, Carbon, 1997,35(12), 1739 1743. 

Alcaniz-Monge, J., Cazorla-Amoros, D., Linares-Solano, A., Yoshida, S. and Oya, A., Effect of the activating gas on tensile strength and pore structure of pitch-based carbon fibers. Carbon, 1994, 32(7), 1277 1283. 

Moehida, I., Kuroda, K., Miyamoto, S., Sotowa, C., Korai, Y., Kawano, S., Sakanishi, K., Yasutake, A. and Yoshikawa, M., Remarkable catalytic activity of calcined pitch-based activated carbon fiber for oxidative removal of SO2 as aqueous HjSO, Energy Fuels, 1997, 11(2), 272 276. 

Moehida, L, Kawano, S., Hironaka, M., Yatsunami, S., Korai, Y., Matsumura, Y. and Yoshikawa, M., Reduction of NO at very low concentration in air with NHj at room temperature over a series of calcined pitch-based active carbon fibers, Chem. Lett., 1995, (5), 385 386. 

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