High temperature soaking

Recent publications cite the reflow profile as the primary factor in mitigating voids for lead-free solder. The theory is that by using a high temperature soak in the reflow profile, the volatiles that create voids have an opportunity to burn off. If the volatiles do not escape before the... 

The soaking phase takes place in the rest of the reactor where the gas is at high temperatures. A portion of the carbon disappears by reactions with CO2 and steam. Some carbon, about 1—3 wt % of the oil feed, is present in the product gas. Natural gas feedstock produces only about 0.02 wt % of carbon. 

It is important to describe the preparation of these samples, which were annealed at high temperature in dry nitrogen gas and then rapidly quenched in liquid nitrogen. Because they were thereby rendered amorphous, there was no scattering due to the PTFE-like crystallinity that would complicate the data interpretation. Membranes were boiled in NiCL solutions and then soaked in H2O, D2O, and H2O/ D2O = 50 50 solutions. Due to the elimination of crystallinity from the melt-quench pretreatment, these samples were considerably hydrated at 41 vol %. 

A soaked powder may be easily distinguished from a non-soaked one. The latter retains a certain transparency while the former is dull, opaque (due to partial coagulation) and usually dark, of a grey-greenish colour, on account of the reactions undergone by the diphenylamine at a high temperature in the presence of water. 

Soaking at low temperatures without heating above 1000° F results in as much kerogen recovery as direct exposure to high temperatures. (Thirteen percent of the original carbon remains.)... 

To use, soak the exposed film in the prehardener for 10 minutes with moderate agitation. Then drain the film for a few seconds, immerse in water for 30 seconds, drain thoroughly, and immerse in the developer. In general, developers such as Kodak D-76 may be used up to 95F/35C. Above 95F/35C it may be better to use developers specifically formulated for tropical developing (Tropical Developers High-Temperature Processing up to 105F/40C, above). 

Catalyzed epoxy coatings lacked sufficient high-temperature resistance to soaked insulation for the long-term exposure. 

C. Soaking Phase. The soaking phase takes place in the rest of the reactor, where the gas is at high temperature. Minor changes in gas composition occur due to secondary reactions of methane and carbon. As the reaction rates are relatively low, the methane content is higher than would be expected from equilibrium. During the soaking phase, a portion of the carbon also disappears by reactions with CO2 and steam. However, some carbon is always present in the product gas from the reactor in a quantity equivalent to about 1-3% wt of the oil feed. Natural gas feedstock produces only a very small amount of residual carbon i.e., about 0.02% wt of the gas feedstock. 

Heat Treatment Temperature and Soak Time. A study of Mochida and Marsh (53) indicates, unlike classical kinetics, that time and temperature for mesophase formation are not interdependent. The reason for this is the controlling influence of viscosity (not found for reactions in the gas or solution phase). Maximum size of optical texture and coalescence results if the mesophase is formed under conditions which provide a minimum viscosity as quickly as possible. Probably, rate controlling processes for mesophase growth are not the dehydrogenated polymerization reactions. Therefore, the attainment, relatively quickly, of temperature of 400°C has provided the necessary size of molecule and consequently the resultant mesophase sbbws minimum viscosity because it is at a high temperature ( 400°C). Mesophase formed at lower (relative) temperatures can have a higher viscosity and coalescence behaviour can be restricted. 

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