Refractory metals ceramic material composite

Modem machining deals with an increasingly wide range of materials which includes, in addition to the traditional metals, high-chromium and nickel stainless steels, titanium, intermetallics, refractory metals, ceramics, glasses, fiber-reinforced composites, and many others. These materials have widely different properties. They react differently to machining and each presents a special machining problem. 

A more extensive comparison of many potential turbine blade materials is available (67). The refractory metals and a ceramic, sHicon nitride, provide a much higher value of 100 h stress—mpture life, normalised by density, than any of the cobalt- or nickel-base aHoys. Several intermetaHics and intermetaUic matrix composites, eg, aHoyed Nb Al and MoSi —SiC composites, also show very high creep resistance at 1100°C (68). Nevertheless, the superaHoys are expected to continue to dominate high temperature aHoy technology for some time. 

Stinton DP, Lowden RA, Besmann TM (1992) Fibre-reinforced tubular composites by chemical vapour infiltration. In Besmann TM, Gallois BM, Warren JW (eds) Chemical vapour deposition of refractory metals and ceramics II. Materials Research Society, Pittsburgh, PA, pp233-238... 

Figure D.l is reprinted from Journal de Physique IV, Vol. 5, L Vandenbulke and M Leparoux, Silicon and boron containing components by CVD and CVI for high temperature ceramic composites, C5-735-751,1995, with permission from EDP Science. Figure D.2 is reprinted from Materials Research Society, E M Golda and B Gallios, Chemical vapor deposition of multiphase boron-carbon-silicon ceramics, in T M Besmann, B M Gallois and J W Warren eds, Chemical vapor deposition of refractory metals and ceramics II, pp. 167-172, 1992, with permission from Materials Research Society.

Chem. Descrip. Boron nitride CAS 10043-11-5 EINECS/ELINCS 233-136-6 Uses Lubricant, filler for elec, insulating/thermally conductive materials, polymer matrixes, adhesives, pastes, potting compds., EP lubricants, refractories, refractory coatings, mold/die release, metal/ceramic and ceramic/matrix composites... 

Aluminum nitride may be used in composite structures containing aluminum for either structural or electronic applications, due to its attractive thermal, electronic, and mechanical properties [176-178]. AlN ceramics are also known to have a sufficiently high-temperature compatibility with refractory metals. Finally, AlN is an ecologically safe material. The structure of AlN as a ceramics layer of the multilayer Al/AlN composites has been investigated to only a limited degree [179]. 

Despite the wide availability of several comprehensive series in materials sciences and metallurgy, it is difficult to find grouped properties either on metals and alloys, traditional and advanced ceramics, refractories, polymers and elastomers, composites, minerals and rocks, soils, woods, cement, and building materials in a single-volume source book. 

The carbon-fiber/polymer composites reviewed in the previous section have excellent mechanical properties but limited temperature resistance. Maximum operating temperature is presently 370°C (Table 9.2). These composites cannot meet the increasingly exacting requirements of many aerospace applications which call for a material with low density, excellent thermal-shock resistance, high strength, and with temperature resistance as high or higher than that of refractory metals or ceramics. These requirements are met by the so-called carbon-carbon materials. 

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