Elevated-temperature strength

Mechanical Properties and Stability at Elevated Temperature. One increasingly important characteristic of carbon fibers is their excellent performance at elevated temperatures. Strength tested in an inert environment remains constant or slightly increases to temperatures exceeding 2500°C. Amoco s high modulus pitch carbon fiber P-50 maintains approximately 80% of room temperature modulus at temperatures up to 1500°C, then decreases more rapidly to 30% at 2800°C (64). The rapid decrease in modulus is a result of increased atomic mobiHty, increa sing fiber plasticity. 

The ferritic steel 430S17 has enhanced oxidation resistance and finds some applications in sheet form, but its strength at elevated temperature is low. The higher chromium (20-30%) ferritic types show excellent oxidation resistance, but have poor elevated-temperature strength and, being difficult to produce and fabricate, are not used in large quantity. Cast versions of 27-30% Cr are quite widely used, especially where oxidation resistance, coupled with abrasion resistance, is required when high carbon contents are utilised. Such alloys are brittle. 

Metal Metal, ceramic, carbon, glass fibers Elevated temperature strength Electrical resistance Thermal stability... 

Ceramic Metallic and ceramic particles and fibers Elevated temperature strength Chemical resistance Thermal resistance... 

Thermosets, beads, flakes, ceramic particles, Elevated temperature strength... 

T6 145 240 5 Pressure-tight castings, good elevated temperature strength, weldable... 

Chrome-moly steels have % to 9% chromium and either % or 1% molybdenum. Chromium increases scaling resistance and molybdenum improves or provides elevated temperature strength. Carbon content is kept low to maintain weldability. Chrome-moly steels are widely used for piping and pressure vessels operating up to 1000°F in environments such as steam or hydrogen and are available in many product forms. The two most popular alloys are 1 chrome- moly and 2 chrome-1 moly. 

Modified coppers are commercially pure coppers with very small amounts of alloying elements for improvement in properties such as machinability or elevated temperature strength while maintaining high electrical conductivity. 

Most of these are carbon-manganese-molybdenum alloys with small additions of chromium and/or nickel plus vanadium or niobium. Vanadium or niobium acts as a carbide stabilizer and grain refiner, improving both elevated temperature strength and notch ductility. An exception is Fortiweld (MOBO 45 is the same steel), which is a boron-treated 1/2% molybdenum steel. This alloy is the cheapest of the group, but has hardly been used for reactors in the U.K., possible because its impact properties in thick sections are not so attractive as alternative steels. 

With respect to elevated-temperature strength, the 30 mol% particulate composite is better than the platelet counterpart. In contrast, with regard to fracture toughness and SCG... 

Adhesive lap shear strengths of the ATS-modified LARC-13/titanium bonds tested at ambient and elevated temperatures are presented in Table 5. As was found in previous studies (Table 1), toughness has been achieved at a sacrifice to the elevated temperature strengths of the adhesives containing individual elastomers ATSj q to... 

Elevated temperature strength, chemical resistance, thermal resistance, etc. 

It has been our practice to preload the tensile specimens at a crosshead speed of 0.00004 cm/s to a 455-kg (1000 lbs) load to allow the copper collets to deform around the root radius of the buttonhead. After seating for 5 minutes the specimen is loaded to failure using a crosshead speed of 0.004 cm/s. For elevated temperature strength measurements the heated furnace is placed around the preloaded specimen, which is allowed to reach the test temperature ( 15 minute soak time), and then fast-loaded to failure. During the initial testing at 1400°C the first three PY6 specimens failed under preload (455 kg -140 MPa) during the 15-minute soak time. To prevent premature... 

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