Lightweight material

It also has lubricating properties similar to graphite. The hydrides are easily oxidized with considerable energy liberation, and have been studied for use as rocket fuels. Demand is increasing for boron filaments, a high-strength, lightweight material chiefly employed for advanced aerospace structures. 

Appllca.tlons. The principal appHcations of nickel-base superalloys are in gas turbines, where they are utilized as blades, disks, and sheet metal parts. Abcraft gas turbines utilized in both commercial and military service depend upon superalloys for parts exposed to peak metal temperatures in excess of 1000°C. Typical gas turbine engines produced in the United States in 1990 utilized nickel and cobalt-base superalloys for 46% of total engine weight (41). However, programs for future aerospace propulsion systems emphasize the need for lightweight materials having greater heat resistance. For such apphcations, intermetallics matrix composites and ceramic composites are expected to be needed. 

The original drive for the development of modem carbon fibers, in the late-1950s, was the demand for improved strong, stiff and lightweight materials for aerospace (and aeronautical) applications, particularly by the military in the West. The seminal work on carbon fibers in this period, at Union Carbide in the U.S.A., by Shindo, et al, in Japan and Watt, et al, in the U.K., is well-documented [4-7]. It is always worth pointing out, however, that the first carbon fibers, prepared from cotton and bamboo by Thomas Edison and patented in the U.S.A. in 1880, were used as filaments in incandescent lamps. 

Thermal oxidizers must be built to provide the residence time and temperatures to achieve the desired destruction efficiency (DE). As such, thermal oxidizers are comparatively larger than catalytic oxidizers since their residence time is two to four times greater. Historical designs of thermal oxidizers were comprised of carbon steel for the outer shell and castable refractory or brick as the thermal liner (a refractory is like a cement, which is put on the inside of the rector shell to act as a thermal insulation barrier). Modern units are designed and built using ceramic fiber insulation on the inside, which is a lightweight material, and has a relatively long life. Old refractory would tend to fail over a period of years by attrition of expansion and contraction. 

In the usual building and construction practice a structural sandwich construction is a special case of a laminate with flat, curved, or otherwise two thin facings. The facings are of relatively stiff, hard, dense, strong material that are bonded to a relatively thick core of a lightweight material that is considerably less dense, stiff, and strong than the facings. Structural sandwiches can be all plastics, all metals, or combination of plastic and metal, etc. 

This tells us that the best lightweight material to make our shaft is a material with a low density/(shear stress) / ratio. 

Composites fill many needs, especially the need for tough, lightweight materials used in cars and airplanes. Vehicles of the past have... 

Fan blade technology has advanced such that more efficient systems are now available in lightweight materials such as plastics. Due to this weight reduction as well as to the high strength associated with plastics and reinforced plastics, fan usage has been extended to larger diameter towers [3],... 

The extreme conditions of space demanded high-performance materials that could withstand them. And lifting large payloads off the launch pad would require conveyance vehicles constructed of lightweight materials. 

The mechanical foaming of PVC pastes has been carried out for some time on the basis of air or gas being whisked into specially formulated plastisols, which are cured using microwave or infrared ovens. The lightweight material is used for sound deadening or domestic applications. There has been a relationship established between the effects of residual emulsifier in the E-PVC resin grade and foaming behaviour (101). 

CBPC products do not have these drawbacks. The CBPC chemistry is not very sensitive to the waste components, and ash itself seems to participate in the setting reaction. The end product has low open porosity, yet is a lightweight material of high strength. 

The problem with post-consumer plastics is their immense variety and widespread application. One tonne of plastics can be converted into either 20000 two-litre drinks bottles or 120000 carrier bags Collecting, sorting, baling, and transporting such numbers of lightweight materials is a tremendous task, with typical cost levels as shown in Table 1.10. 

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