Shatter cracks

Short, discontinnons internal fissnres in wrought metals attributed to stresses produced by localized transformation and decreased solubility of hydrogen during cooling after hot working. In a fracture surface, flakes appear as bright silvery areas on an etched surface, they appear as short, discontinuous cracks. Also called shatter cracks or snowflakes. 

In certain diseases, such as osteomalacia, syphilis, and osteomyeHtis, bones break spontaneously and without a trauma. The severity of the fracture usually depends on the force that caused the fracture. If a bone s breaking point was exceeded only slightly, then the bone may crack rather than break all the way through. If the force is extreme, such as in an automobile collision or a gunshot, the bone may shatter. An open or compound fracture is particularly serious because infection is possible in both the wound and the bone. A serious bone infection can result in amputation. 

The first serious notice of C4 hydrocarbons came with the development of refinery cracking processes. When catalytic cracking became popular, refiners were faced with disposing of a couple of thousand barrels per day of a stream containing butane, butylenes, and small amounts of butadiene. Their first thought was to burn it all as refinery fuel, but then they developed the alkylation process. With that, they could undo some of the molecule shatter that took place in the crackers and reassemble some of the smaller pieces as alkylate, a high-octane gasolinerblending component. 

Toughness. An abrasive s toughness is often measured and expressed as the degree of friability, the ability of an abrasive grit to withstand impact without cracking, spalling, or shattering. 

Samples are mechanically brittle at sufficiently low temperatures, normally below the T . They also are seen to be brittle at very short times. Thus, a short sharp impact can shatter a material at room temperature if it is naturally below its Tg or if the material has been frozen. Materials that are rubbery at room temperature can be sufficiently brittle at low temperatures to fail catastrophically. In the space shuttle Challenger, an explosion was caused by uncombusted fuel escaping when a rubber O-ring was rendered brittle by low-temperature weather. The key in all of these examples is the speed of molecular motion. For energy to be dissipated, a stress can cause a local increase in molecular motion. If that route is denied by time constraints (e.g., a fast shock) or temperature control (molecular immobility), then a crack is the only way energy can leak out. Cold toffee... 

Occasionally a crack will develop in an apparatus because of mechanical shock or internal strains which were not completely removed by annealing. Providing the glass is not shattered or the part is not under a large, externally produced strain, the crack may be healed by gentle heating. The area around the crack is first slowly heated, and then the soft flame (somewhat hotter than an annealing... 

When a glass cracks, it shatters. When a crystal cracks, it cleaves along a flat plane. Explain why. 

The matching of expansion behavior is of the utmost importance to manufacturers of, for example, multi-layer capacitors, porcelain enameled cast iron sinks, fiber reinforced composites, light bulbs, etc. In all cases, various materials in rigid contact must have their expansion characteristics carefully matched. Inattention to this runs the risk of cracking and shattering of a light bulb at its seal to aluminum, delamination of metallic conductive leads from the ceramic substrate in a hybrid circuit, etc. By changing the composition of a constituent material, its... 

Since the surface strains are largely compressive in nature, the tendency to the development of cracking in the surface should be small. However, some surface cracking or shattering does occur in materials which are brittle in bulk, particularly if they cleave easily. The final surface may then be composed, in part or in whole, of systems of cleavage facets (15, 33). This phenomenon has been observed in a number of ionic crystals, such as rock salt and fluorspar, but not so far in metals. 

Epoxy systems with flexibihsers and properly-selected fillers exhibit high resistance to rapid changes in temperature and do not show signs of cracking or shattering. Rigid epoxy systems can cause severe problems. Better formulated systems can withstand repeated thermal shock cycles from 180°C to -75°C without failure. 

The failure of PC in compression was violent. Compression cylinders would shatter violently and the remaining core of the cylinders had either a cone shape or a near vertical failure surface. Flexural beam specimens also failed in a violent manner as a tensile crack developed in the zone of maximum moment near mid-depth. The specimens were broken into almost two identical pieces and the failure surface was near vertical. The tensile bond strength between the PC overlays and the portland cement concrete substrate was found to be strongly dependent on the type of resin used. In overlay or repair applications, it is usually desirable to have tensile bond failures occurring in the portland cement concrete substrate rather than at the interface between the two materials. 

Ecdel [Eastman], TM for an elastomer which imparts excellent low-temperature resistance that significantly reduces product loss due to flex cracking and shattering during cold weather distribution. 

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