Solution-precipitation process

There are indications that solution-precipitation processes are involved in the growth mechanisms in each case. 

The core and shell type of particulates are similar to one of the deposit morphologies formed on an Fe-Ni alloy from CO at temperatures above 500°C where the core consisted of a metal particle in the size range 0.09 to 0.2 pm, with a shell thickness typically of 0.04 jjm(23). The structure of the particles, i.e. a carbon layer on metal, is comparable to the laminar film on the metal, suggesting that the carbon in the shell has been precipitated. Free metal particles have not been observed on the iron foils that could serve as active centres for growth directly from the gas phase. Therefore, it must be concluded that a solution-precipitation process plays a part in determining the final morphology of the core / shell particles, but further details of the mechanism of growth cannot be established at present. 

The results of this in-situ SEM work suggest that solution-precipitation processes have some part in the development of four of the morphological types discussed, i.e. continuous laminar carbon films, mound growths, and two types of particulate material Although a small amount of filamentary carbon was observed, it does not appear to be a major characteristic of the Fe-CH4 reaction. 

In a solution/precipitation process developed by Roche [97] a carotenoid dispersion, prepared as described in Section Dl,. is treated for a short time with superheated steam and the resulting oil-water carotenoid mixture is stabilized by emulsification in an aqueous matrix solution the carotenoid precipitates from its initial solution in the oil phase in a finely divided amorphous form. 

In this section, I use IR spectroscopy to map two-dimensional water distributions as well as to consider its species in deformed granites. I especially focus on water distributions associated with solution-precipitation process of feldspar, and consider possible transport mechanisms of water. 

Rg.7 X-ray diffraction profiles of two MBBE-6 samples prepared by the melt-crystallization and solution-precipitation processes. The two diagrams became nearly identical for anneahng at a temperature 10 degrees below the melting point (379.8 K)... 

An important modification of the Raj and Chyung [80] model was made by Wakai [81], who assumed that the solution and precipitation took place at steps (kinks) formed at the grain boundaries. It was proposed that the solution-precipitation process involved the movement of these steps, and the strain rate was therefore related to the step velocity and density, with an expression analogous to Orowan s equation for dislocation movement ... 

A1(0H)3 decomposes at 300 °C to form y-AlOOH, which decomposes about 400 °C to form y -AkOs in the atmosphere. According to our previous results, y-AlOOH and y-AkOs were transformed into a-Ak03 above 400 °C by the capsule HIP. In addition, Mg(OH)2 did not melt at 500 °C in the HIP capsule. Therefore, in the mixture of hydroxides, Mg(OH)2 reacts with the intermediate compound between AlOOH or y-AkOs and a-Ak03. Generally, intermediate compound is very active because the atoms need rearrangement while the transformation occurs. The reaction between Mg(OH)2 and the intermediate compound would be very rapidly proceeded. This seems to be an example of Hedvall effect [7]. The water from the hydroxides would affect the formation of the intermediate phase [4] and the reaction of the intermediate phase and Mg(OH)2, based on the solution-precipitation process. 

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