Maximum Substrate Temperature Research Articles

Formation region of amorphous thin CoZr and CuZr films prepared by cocondensation on hot substrates

The glass formation ranges of thin CoZr and CuZr films condensed on cold and hot substrates (10–800 K) are experimentally determined by X-ray diffraction. The maximum substrate temperatures allowed to condense amorphous films are only slightly below the crystallization temperatures of the amorphous phases. These experimental results are compared with predictions of the glass formation ranges from thermodynamic calculations and instability models. At low substrate temperatures, where no phase separation is possible due to kinetic restrictions, the amorphous phase is favoured in the range between theTo lines which are the stability limits of the extended solid solutions on both sides of a metastable binary phase diagram. For high substrate temperatures, where at least one species of the binary alloy is able to move, the amorphous state can be described to be in a metastable equilibrium with the extended solid solutions neglecting the intermetallic compounds. Therefore, the single-phase amorphous state is restricted to the range between theTml lines which are the metastable liquidus temperatures.

Self-annealing of rapidly solidified deposit layers of FeCSi alloys by flame spraying

Abstract Two FeCSi alloys containing 2.20 and 4.16wt.% C are incrementally deposited on a steel substrate by flame spraying. The substrate temperature gradually increases during spraying. The maximum temperature is in the range of about 330 to 670 K depending on the cooling conditions. The cooling rate of the flattened metal droplets during solidification is almost independent of the substrate temperature. As the maximum substrate temperature rises, metastable austenite and a metastable h.c.p. ϵ phase formed on rapid solidification start to decompose during spraying. The cooling rate, the cause of the self-annealing, the decomposition of the metastable phases and the hardness of the deposit layer are examined.

Very high rate reactive sputtering of TiN, ZrN and HfN

The reactive sputtering rate for the group IVb nitrides approaches the sputtering rate for the metal provided that there is precise control of the process parameters. For TiN the reactive sputtering rate is 100% of the metal rate whereas for ZrN and HfN the rate is 95% of the metal rate. Compared with chemical vapor deposition and other physical vapor deposition processes, reactive sputtering of these compounds is a low temperature process. The maximum recordable substrate temperature immediately after deposition was 315 °C. The hardness of the TiN and ZrN coatings is greater than the bulk value, and the adhesion of these coatings to M2 steel is excellent. Cutting tool tests showed that TiN coatings reactively sputtered at a high rate are very effective in enhancing tool life.

High-performance heat sinking for VLSI

The problem of achieving compact, high-performance forced liquid cooling of planar integrated circuits has been investigated. The convective heat-transfer coefficient h between the substrate and the coolant was found to be the primary impediment to achieving low thermal resistance. For laminar flow in confined channels, h scales inversely with channel width, making microscopic channels desirable. The coolant viscosity determines the minimum practical channel width. The use of high-aspect ratio channels to increase surface area will, to an extent, further reduce thermal resistance. Based on these considerations, a new, very compact, water-cooled integral heat sink for silicon integrated circuits has been designed and tested. At a power density of 790 W/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , a maximum substrate temperature rise of 71°C above the input water temperature was measured, in good agreement with theory. By allowing such high power densities, the heat sink may greatly enhance the feasibility of ultrahigh-speed VLSI circuits.

Upper Lethal Temperatures in Relation to Osmotic Stress in the Ribbed Mussel Modiolus demissus

Upper lethal temperatures for the ribbed mussel Modiolus demissus (Dillwyn) were determined for thermal acclimations of 15.0, 20.0, and 25.0 C and osmotic acclimations at 5, 15, and 28‰ S, which yielded nine combinations. These upper lethal temperatures for 1440 min exposure ranged from 38.42 to 40.18 C, generally paralleling increases in thermal acclimation. The upper lethal temperature within any thermal acclimation decreased as the salinity of the bioassay departed from the appropriate level of osmotic acclimation. Depression of the upper lethal temperature was more pronounced in the test medium of 5‰ S. The shift from osmoconformity to osmoregulation, which occurs in this species when the ambient salinity is reduced to 350 mosmols (approximately 10‰ S) apparently extends the metabolic load or stress relative to that induced by similar temperatures in higher levels of salinity. Order of death in any bioassay was independent of size expressed as length, and specific sex.The upper lethal temperatures are higher than the mean temperature of the substrate of the collecting site during the warmest period of the summer, but are approximately the same as the maximum substrate temperature during that period. Survival of ribbed mussels in such potentially lethal conditions is explained by the shorter intermittent natural exposures than those employed in the bioassays.