High-temp ceramic prepreg hot stuff
A reasonably-priced industrial grade ceramic prepreg with high-temperature capabilities that will not fail catastrophically has long been a kind of holy grail of the materials world. Not so anymore. Hexcel Composites has just introduced a proprietary ceramic prepreg reinforced with continuous aluminosilicate fibers with the tradename HexceramiTM. The material is structurally stable up to 1,600F (871C) and is priced lower than higher-temp materials going into aerospace applications. "The fracture properties are such that you can actually hammer a nail through this material with no catastrophic failure," says Ceramics Engineer Kevin McViker. The material, which is currently being considered for industrial applications, may be appropriate for many high-temperature parts and components.
Product Code 4465
Low-flow carbon fiber prepreg a tough cookie
Aldila Materials' 949 carbon fiber prepreg is a hot-melt-impregnated, 250F curable epoxy resin reinforced with unidirectional, lower-cost, standard modulus carbon fibers. Flexural modulus of this tough cookie of a material is 17 Msi (at 77F). The versatile material, which has a 165F service capability, is ideal for the sports, industrial, aerospace, and automotive industries, say company representatives.
Aldila Materials Technology Corp.:
Product Code 4467
Conductive elastomers take market by storm
"It's not totally new, but it's one of the hottest areas in EMI shielding today," says Joseph Butler, marketing manager at Chomerics, a producer of gasket materials of all types. The beauty of Chomerics' Cho-Form« EMI gasketing technology is that it can economically be applied to a variety of housing substrate materials and geometries via an automated dispensing system. The base material, a silicone resin, comes with conductive silver-plated copper or nickel/graphite particles. It has exceptional shielding characteristics(>75 dB, 200 MHz to 10 GHz) and can also provide an environmental, dust, or pressure seal. Applications include cell phones, satellites, TV set-top devices, and PC cards. Unfortunately, the tiny bead (0.034 inch high 3 0.040 inch wide) precludes its use in large-size industrial enclosures. Maximum flange width, says Butler, is about 0.1 cm.
Product Code 4469
Carbon/carbon composite ups wafer yields
Graphite has long been the conventional material of choice for CZ (Czochralski) furnace components. But SEMICARB«, a carbon matrix reinforced with carbon fibers produced by chemical vapor infiltration, has been shown to increase silicon wafer yields up to 7%. "The composite is particularly effective in the production of components for the 300-mm wafer process," says Robert Metter of SGL Carbon Composites-Hitco. In addition, the thermal characteristics (between 8-28 W/m deg K) of the material result in a 10% reduction in furnace energy use and lower cycle cool-down times by about 50%.
SGL Carbon Composites:
Product Code 4466
Extremely high-modulus SMC
Bill Childs, technical director at Quantum Composites, dares engineers to take a panel of the company's new QC 8800 composite material and bend it in half. The material, which is a fiberglass-reinforced sheet molding compound (SMC) has "unusually high mechanical strength and incredible abuse resistance," says Childs. "You can bend it in half and it won't crack." He's not kidding. Many reinforced SMCs suffer from brittleness and no real impact resistance, but QC 8800 has a flexural modulus of 3 Msi and a tensile strength of 50 Ksi. According to Childs, current applications for this novel material run the gamut from artificial limbs to auto skid plates to electrical components.
Product Code 4464