Cooling quenching

The yield strength and toughness of Dural differ enormously in these three conditions (slow-cooled, quenched, and quenched and aged) the last gives the highest yield and lowest toughness because the tiny particles obstruct dislocations very effectively. 

Secondary crystallization occurs most readily in polymers that have been quench-cooled. Quenched samples have low degrees of crystallinity and thus have relatively large volumes of amorphous material. A pre-requisite for secondary crystallization is that the amorphous regions must be in the rubbery amorphous state. Increased temperature accelerates the rate of secondary crystallization. The new volumes of crystallinity that form during secondary crystallization are generally quite small, amounting to less than 10% of the crystalline volume created during primary crystallization. 

Steel It has a higher C content (usually 0.5-1%) and is harder than soft bon. An important property of steel is that it may be hardened. If heated to bright redness (to obtain an austenitic alloy) and suddenly cooled quenched), by putting it in water, oil, etc, it becomes hard and brittle due to the formation of the very hard martensite. Brittleness can be removed by tempering (that is by a carefully heating for a short time at, say, 250-300°C) to release or dimmish the internal strains resulted from quenching. 

A solution of 50 g of isomyristicin (or analog) in 300 ml of dry acetone and 24 g of pyridine is cooled to 0° with vigorous stirring. Then add 54 g of cold tetranitromethane (slow), which will cause a slight temp rise of about 5° despite your external cooling. Quench this mixture, after stirring for a few more min, with 16.8 g in 300 ml of water. The stirring is continued until the... 

The Step 4 product (3.7 mmol) dissolved in 10 ml THF was treated with lithium aluminum hydride(5.8 mmol), then refluxed 8 hours. The mixture was cooled, quenched with saturated potassium sodium tartrate solution, filtered through Celite 545, and the filtrate concentrated. The residue was dissolved in 20 ml EtOAc, washed twice with 20 ml water, dried, reconcentrated, and the product isolated as a white foam. 

Multibed Converters with Direct Cooling (Quench Converters). In... 

A second phase will follow the cracking of these pyrolysis vapours, involving when needed, catalysts in classical cracking tubes in a way that will favour the formation of the desired products whenever possible. The final vapour obtained is generally rapidly cooled (quenched) at approximately 400°C, before being fractionated in a column where the components are separated and condensed in portions at convenient intervals. This... 

To a stirred suspension of potassium hydride (0.55 g, 1.38 mmol) in freshly distilled diglyme (2.0 ml), diethoxyacetonitrile [35] (0.129g, 1.0 mmol) and methyl isocyanoacetatc [36] (0.099 g, 1.0 mmol) in diglyme (1.5 ml) are added slowly with ice cooling under an argon atmosphere. The solution is heated at 70-80°C (5h), then cooled, quenched with saturated aqueous ammonium chloride, and extracted with dichloromethane (3 x 10ml) and ethyl acetate... 

The reactor had a safety relief valve whose disk would rupture when the pressure exceeded approximately 700 psi. Once the disk ruptures, the water would vaporize, and the reaction would be cooled (quenched) by the release of the latent heat of vaporization. 

This approach is suitable only if the reaction is sufficiently slow that the time elapsed during withdrawal and analysis of the sample is negligihle. Sometimes the sample is withdrawn and then quickly cooled ( quenched ). This slows the reaction (Section 16-8) so much that the desired concentration does not change significantly while the analysis is performed. 

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