Cracks, formation

A common experimental method for creating a region of spall is through the flat impact of plates of material. Such impact leads to a process of planar spall in which an interior planar region of material is carried into tension and failure occurs through a process of crack formation or hole cavitation. Much... 

If the technical regulations are adhered to for constructional steels in neutral waters, there are no conditions for H-induced corrosion. On the other hand, hardened and high-strength materials with hardnesses above HV 350 are very susceptible [60,82,92], since anodic polarization encourages crack formation in saline media and anodic pitting occurs with acid products of hydrolysis [93]. 

T. Tsukada, K. Kakinoki, M. Hozawa, N. Imaishi, K. Shimamura, T. Fukuda. Numerical and experimental studies on crack formation in LiNb03 single crystal. J Cryst Growth 750 543, 1997. 

Sprung, m. crack, chink, fissure (of strata) fault jump, spring, bounce, ieap (in a curve) break, discontinuity (in spectra) transition (of waves) hop. -bildung,/. crack formation, fissuring. -feder, /. (eiastic) spring. 

Controlled removal of the template is especially important when zeolite based membranes are involved consisting of a continuous MFI layer on a ceramic or sintered metal support (ref. 14). In these novel composite ceramic membranes the formation of cracks during template removal would be detrimental. The unique properties (ref. 14) of metal-supported MFl-layer membranes prove that indeed crack formation can be essentially prevented. 

The constant applied load is only 20 mN so there were no crack formations occurring during the friction tests of all the samples though there is penetration depth on the sample surface. The friction coefficient reflects the surface feature of H DLC samples. Figure 37 shows the friction coefficient of all samples. Sample 2 has the lowest friction coefficient compared to other samples which have the friction coefficient in a range of 0.049-0.065. 

Daccord, G., Lemanczyk, R., and Vercaemer, C. "Gelled Hydrocarbon Mixtures and Their Use in Hydraulic Crack Formation in Underground Formations," German Patent 3,247,758(1983), Chemical Abstracts 99(12) 90859h(1983). 

Poor adhesion of membrane to metal is the leading cause of failure in solid-state potentiometric sensors [116], For glass membranes, the mismatch of thermal coefficients of expansion between thin glass membrane and metal (mostly Pt) has been attributed to premature failure due to hairline crack formations in the glass layer [60], For polymer-based membranes, water vapor penetration was reported to compromise the membrane-metal interface, therefore affecting the sensor s performance. 

The slurry process has been enhanced with vacuum to fabricate planar SOFCs [78], This method is of low cost and thus has been widely used to develop low-cost SOFCs. However, together with other liquid precursor methods such as sol-gel and spray pyrolysis, it is time, labor, and energy intensive because the coating-drying-sintering has to be repeated in order to avoid cracking formation. 

Fig. 6.11 Optical microscopy of the surface lary forces during drying of propanol [Lei 9]. of a 25 pm thick micro PS layer on the Si sub- (c) SEM micrograph of a disintegrated micro strate, showing (a) crack formation in the wet PS film formed at high current density...

Hillerborg, A., Modeer, M. and Petersson, P.E. (1976). Analysis of crack formation and crack growth in concrete by means of fracture mechanics and finite elements. Cement Concrete Res. 6, 773-782. 

Intuitively, it seems likely that a decrease in crosslink density on exposure would promote coating erosion. In clearcoats, on the other hand, the most serious appearance problem is crack formation. 

Apparently two opposing effects play a part On the one hand the glass fibres take over a part of the stress, thus partially releasing the stress on the polymer. On the other hand, fibres cause, in particular at their ends, stress concentrations, which can initiate crack formation. 

The theory of Evans includes lateral crack formation and leads to an expression for the volume lost from the surface material per volume of the impacting particle, S, as follows ... 

Refs 1)R.J.Heredia, "Significance of Cracks in HE Shell and Effect of Interior Coating on Crack Formation, PATR2269 (1956) 2) Armour Research Foundation Rept No 5 (Final Rept), "industrial Engineering Study on the Determination of Additives to Eliminate Cracking of Cast Explosives Chicago, 111, Sept 8, 1958 3)D.H.Johnson, "Study of Crack... 

Since the strain arising from an ideal sharp indenter cannot be wholly elastic (as is the case with a blunt indenter), a number of new specific features of failure of a particular material may arise, especially in the early stages of crack formation under the influence of surface penetration at low loads. It is reasonable to suppose at the same time that as the crack region extends widely below the contact zone, the influence of indenter geometry should become significant. 

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