Other Whisker Materials

Silicon-carbide whiskers comprise die bulk of all ceramic whiskers. Other whisker materials are produced on an experimental basis and include  

Parche, M. C., Facts About Silicon Caibide, The Carborundum Co., Niagara Falls, NY (1961) 

EtUnayer, P., and Lengauer, W., Nitrides, in Ullmann s Encyclopedia of Industrial Chemistry, 5th. Ed. VCH (1985) 

Johnson, D. W., Jr., Powder Preparation, Ceramics, iaAdvance in Powder Technology, (G. Y. Chin, ed.), American Society for Metals (1981) 

Biswas, D. R., Development of Novel Ceramic Processing, J. Materials Sci., 24 3791-98 (1989) 

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Results on other composite materials are similar to those obtained by Morrell and Ashbee.56 Creep asymmetry has been demonstrated for two grades of siliconized silicon carbide,35,60,61 SiC whisker-reinforced silicon nitride,53 HIPed silicon nitride,29 and vitreous-bonded aluminum oxide.29 Again, stresses required to achieve the same creep rate were at least a factor of two greater in compression than in tension. In two grades of siliconized silicon carbide,35,58-61 the stress exponent changed from 4 at creep rates below... 

Since the early 2000s, plant-derived biobased fibrous fillers have been frequently used for the reinforcement of PLA-based materials. A well known and frequently used plant-derived fibrous filler is kenaf. Like the case of pollen as an additive, the wettability between PLLA and kenaf should be improved by the addition of a compatibilizer. Other fibrous materials are cellulose fibrous materials or fibres [383,384], cellulose whiskers [385], recycled cellulose fibre [386], cotton fibre [387], sugar beet pulp [388], flax [389], bamboo fibre [390], kenaf [391-393], papyrus [394], hemp fibre [395], cuphea and lesquerella [396], ramie [397], rice straw fibre [398], red algae fibre [399], miscanthus fibre [400], abaca fibre [401], milkweed [402], wood fibre [403] and recycled newspaper fibre [404], Poly(L-lactic acid) fibre can also be used to reinforce soft plastics such as PCL [405],... 

A carbon whisker pretreated by hot aqueous HNO turned out to be the most active carbon cathode for hydroxylation of benzene to phenol and HQ among other carbon materials [146b]. 

Calcium carbonate whiskers are produced with calcite, marble, or limestone as raw materials, and the process is simple. Compared with other whiskers obtained from more complex and high-temperature processes, calcium carbonate whiskers have lower cost and more significant economic value, leading to their large-scale use for industrial and consumer products. In addition, calcium carbonate whiskers are nontoxic and biodegradable in an acidic environment thus environmental pollution and any unfavorable effects on humans are low as well. ... 

Man-made fibers ean be amorphous, polycrystalline, or ciystalline. The amorphous fibers inelude the man-made vitreous fibers typified by the insulation wools, which form the bulk of man-made inorganic fibers. Polycrystalline fibers include continuous carbon fibers used in composite material and specialty fibers such as Saffil. Crystalline man-made fibers include ceramic whiskers, such as silicon carbide and silicon nitride, which are used in reinforce metals and other composite materials. 

Fibrous Composites. These composites consist of fibers in a matrix. The fibers may be short or discontinuous and randomly arranged continuous filaments arranged parallel to each other in the form of woven rovings (coUections of bundles of continuous filaments) or braided (8). In the case of chopped strand mat the random arrangement is planar. In whisker (needle-shaped crystals or filaments of carbon and ceramics) reinforced materials the arrangement is usually three-dimensional and the resulting composites are macroscopically homogeneous. 

For the remainder of this book, fiber-reinforced composite laminates will be emphasized. The fibers are long and continuous as opposed to whiskers. The concepts developed herein are applicable mainly to fiber-reinforced composite laminates, but are also valid for other laminates and whisker composites with some fairly obvious modifications. That is, fiber-reinforced composite laminates are used as a uniform example throughout this book, but concepts used to analyze their behavior are often applicable to other forms of composite materials. In many Instances, the applicability will be made clear as an example complementary to the principal example of fiber-reinforced composite laminates. 

By this time the industry required a more inclusive term to describe RPs, so composite was added. Thus the name in the plastics industry became Reinforced Plastic Composites. More recently they became known only as Composites. However composites identify many other combinations of basic materials (Table 6-18). The fiber reinforcements included higher modulus glasses, carbon, graphite, boron, aramid (strongest fiber in the world, five times as strong as steel on an equal-weight basis), whiskers, and others (Table 6-20 and Figs. 6-13 and 6-14). In... 

Other ceramic cutting-tool materials include alumina, Si-Al-0-N, alumina-carbide composites and, more recently, a composite of silicon nitride reinforced with silicon carbide whiskers. This last material can be produced by chemical-vapor infiltration (CVI) and has high strength and toughness as shown in Table 18.3.Cl... 

Fig. I.IB illustrates fibers typical of commercial asbestos, while Fig. l.ll shows Fiberglas and Fig. I.IJ silicon carbide whiskers. Some of the fibers in these examples are bent, occasionally through 180°, indicating considerable flexibility. Whiskers of other compounds can also bend but the tensile strength of these materials is their most remarkable feature. The measured values (Table 1.2) are at least ten times higher than those observed for the same compounds in bulk or in another morphology (Walker and Zoltai, 1979). The numerous investigations into the causes of this unique response have produced several hypotheses.

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