Mechanical properties crack growth

Sintered sihcon carbide retains its strength at elevated temperatures and shows excellent time-dependent properties such as creep and slow crack growth resistance. Reaction-bonded SiC, because of the presence of free sihcon in its microstmcture, exhibits slightly inferior elevated temperature properties as compared to sintered sihcon carbide. Table 2 (11,43) and Table 3 (44) show selected mechanical properties of sihcon carbide at room and elevated temperatures. 

While lead of purity in excess of 99.99% is commercially available, it is very rarely used owing to its susceptibility to grain growth and fatigue failure by intercrystalline cracking, and indifferent mechanical properties. Because of its generally superior corrosion resistance, pure lead to BS 334 1982 type A, shown in Table4.13, is occasionally used in chemical plant, but only if there is no suitable alternative. 

The local dissolution rate, passivation rate, film thickness and mechanical properties of the oxide are obviously important factors when crack initiation is generated by localised plastic deformation. Film-induced cleavage may or may not be an important contributor to the growth of the crack but the nature of the passive film is certain to be of some importance. The increased corrosion resistance of the passive films formed on ferritic stainless steels caused by increasing the chromium content in the alloy arises because there is an increased enhancement of chromium in the film and the... 

Fluoroelastomers Novikova et al. [32] reported unproved physico-mechanical properties of fluoro mbbers by reinforcement with chopped polyamide fibers. Other fiber reinforcements are covered by Grinblat et al. [33]. Watson and Francis [34] described the use of aramid (Kevlar) as short fiber reinforcement for vulcanized fluoroelastomer along with polychloroprene mbber and a co-polyester TPE in terms of improvement in the wear properties of the composites. Rubber diaphragms, made up of fluorosilicone mbbers, can be reinforced using aramid fiber in order to impart better mechanical properties to the composite, though surface modification of the fiber is needed to improve the adhesion between fluorosUicone mbber and the fiber [35]. Bhattacharya et al. [36] studied the crack growth resistance of fluoroelastomer vulcanizates filled with Kevlar fiber. 

Ceramic-matrix fiber composites, 26 775 Ceramics mechanical properties, 5 613-638 cyclic fatigue, 5 633-634 elastic behavior, 5 613-615 fracture analysis, 5 634-635 fracture toughness, 5 619-623 hardness, 5 626-628 impact and erosion, 5 630 plasticity, 5 623-626 strength, 5 615-619 subcritical crack growth, 5 628—630 thermal stress and thermal shock, 5 632-633... 

Ohji T (1994) Tensile Creep Rupture And Subcritical Crack Growth of Silicon Nitride. In Hoffmann MJ, Petzow G (eds) Tailoring of Mechanical Properties of Si3N4 Ceramics. Kluwer Academic Publishers, Netherlands, p 339... 

Abstract The fracture properties and microdeformation behaviour and their correlation with structure in commercial bulk polyolefins are reviewed. Emphasis is on crack-tip deformation mechanisms and on regimes of direct practical interest, namely slow crack growth in polyethylene and high-speed ductile-brittle transitions in isotactic polypropylene. Recent fracture studies of reaction-bonded interfaces are also briefly considered, these representing promising model systems for the investigation of the relationship between the fundamental mechanisms of crack-tip deformation and fracture and molecular structure. 

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