Evaporative coatings

Multiple-Effect Evaporators A number of approximate methods have been published for estimating performance and heating-surface requirements of a multiple-effect evaporator [Coates and Pressburg, Chem. Eng., 67(6), 157 (1960) Coates, Chem. Eng. Prog., 45, 25 (1949) and Ray and Carnahan, Trans. Am. Inst. Chem. Eng., 41, 253 (1945)]. However, because of the wide variety of methods of feeding and the added complication of feed heaters and condensate flash systems, the only certain way of determining performance is by detailed heat and material balances. Algebraic soluflons may be used, but if more than a few effects are involved, trial-and-error methods are usually quicker. These frequently involve trial-and-error within trial-and-error solutions. Usually, if condensate flash systems or feed heaters are involved, it is best to start at the first effect. The basic steps in the calculation are then as follows ... 

Fig. 6-4. Calculated curves showing relationship between intensity ratio and thickness for various values of exponent a. The abscissa scale is logarithmic. Circles = plated coatings squares = evaporated coatings. (Liebhafsky and Zemany, Anal. Chem., 28, 455.)...

The system is usually evacuated to a suitable characteristic pressure before the actual working process begins. This happens, for example, in plants tor evaporative coating, electron-beam welding, and crystal pulling in particle accelerators, mass spectrometers, electron microscopes and others. 

Evaporative coating, crystal pulling, mass spectrometers, tube production, electron microscopes, electron beam plants, and particle accelerators. 

J. Silver. Silver (mp 961 °C), has the highest electrical and thermal conductivity of any metal. It is used in making electrical contacts and in the construction of some laboratory ware. It is easily electrodeposited, and both chemical and evaporation coating with silver are possible. Silver is generally less resistant to attack by oxidizing agents than is platinum or gold. However, it is resistant to fused alkalies and fused alkali-peroxide mixtures. Therefore, it is used to make... 

In comparison, the measurements of Lukirskii (48) and lyesaar (49) are of the QDE of evaporated Csl coatings on flat substrates, and not on MCP s. These show the QDE peak associated with the strong absorption (4d - 4f transition) peak of Csl at about 100 eV. This agrees with the results obtained by measurement of the photoemission current from Csl evaporated coatings (50, 51). The high yields obtained on flat substrates will be reduced proportionally by the open area of the MCP unless a deflection grid is used. 

For all the sol-gel based optical-coatings we have already developed, the optical performances exceed 99% transmission and the laser damage thresholds ate over 16 J/cm at 1064nm - 3 ns and over 10 J/cm at 355 nm - 3ns. These laser damage threshold figures are much better than those corresponding to similar vacuum evaporated coatings. 

Temperature stability of an ingredient Process temperatures must be below the point where instability is realized. This could be the inlet temperature, which particles are exposed to momentarily upon each pass over the plate or the bed temperature. Bed temperatures for evaporative coating formulations are significantly lower than the inlet temperature, but may be the critical stability temperature consideration, since particles spend more time at that condition. 

Coating (immersion, electrolytic metal deposition, diffusion deposition, hot-dip metal coating, evaporation coating, and metal spray coating)... 

Evaporation coating involves the production of very pure, nonporous surface coatings by condensation of vacuum-evaporated metallic materials (physical vapor deposition). However, the extremely low coating thickness permits application of evaporation-coated parts in chemical engineering only in exceptional cases. 

Bohlmark J, Blomqvist H, Landalv L, Amerioun S, Ahlgren M (2011) Evaluation of arc evaporated coatings on rounded surfaces and sharp edges. Mater Sci Forum 681 145-150... 

IsA Copper (Evaporated) Coated onto Oven-Cured (380 c) PI-5878... 

The high speeds achieve similar good k values as in the falling-film evaporator. Coatings are rinsed off from the tube wall at the high-flow speeds. 

The authors hypothesized that the evaporated coatings were deposited with a sawtooth surface profile whose shape depended on the oblique angle of incidence. For 45° < 0 < 80,° it was felt that the long axes of the fluid lay parallel to the long axes of the sawtooth grooves. They also argued for 80° < 0 < 90° that the liquid crystal director was pointed into the teeth of sawtooth. Most of their data was obtained with SiO, but they stated that similar data was achieved with C and Au. 

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