Tendency To Coalesce Research Articles

Effects of polymer additives on pool boiling phenomena

The addition of small amount of soluble polymer makes the boiling behavior significantly different from that of pure water. The polymer additives reduce the tendency of coalescence between vapor bubbles. Consequently, they become smaller in size, larger in number, and tend to stay on the heating surface in a relatively orderly manner. No significant improvement in heat transfer rate caused by the polymer additives was observed in this work; the critical burn out heat flux was reduced slightly.

High fluence hydrogen implantation in copper: Blistering and grain boundary movement

Abstract Annealed polycrystalline copper samples are implanted with 325 keV H+ -ions at ambient temperature for total fluences of 2.2–8.4 × 1018 ions/cm2, and are examined using SEM and optical microscope. The critical fluence for blistering is about 5.2 × 1018 ions/cm2. The observations reported are (i) preferential decoration of grain boundaries with elongated blisters which have a tendency of interconnecting each other, (ii) irradiation induced grain boundary movement, (iii) onset of blistering only on few grains and tendency of coalescence, at the critical dose, (iv) spongy blister skins, and (v) simultaneous occurrence of blister exfoliation from the top and from the periphery. The observation (i) is attributed to preferential nucleation of gas bubbles along the grain boundaries and their successive coalescence; (ii) and (iii) are assigned to partial channelling; (iv) is understood to be a consequence of the growth and the coalescence of the bubbles within the skin: and (v) is considered to be the be...