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A sedimentation column device is described and tested for determining the effect of surfactants on the static stability of coal-oil mixtures (COM). The sedimentation ratio (bottom-sampled wt % coal in treated slurry/untreated slurry after 24 h settling) was found to be an effective screening parameter for the effectiveness of commercial surfactants on COM stability. From the settling behavior of 25 wt % coal slurries, determined with a sedimentation balance, a compressive settling (subsidence) model was found to be appropriate. This led to an interpretation of COM stability in terms of network stability rather than classical isolated colloidal particle stability. The effects of water and surfactant structure were assessed and led to identification of the most effective classes of surfactants and interpretation of COM stability at the macroscopic, microscopic, and molecular levels.

A new method for the reactive ion etching of a transparent conducting indium‐tin oxide (ITO) film has been investigated. With a gas mixture consisting of acetone, argon, and oxygen, high etch rate selectivities of ITO to a number of underlying materials were achieved. A useful variation on the etch process employs hydrogen chloride in a first etch step followed by the acetone‐based etch. Acetone is a source of reactive organic radicals in the plasma discharge that etch ITO films by forming volatile organometallic compounds. Selective chemical vapor deposition of carbon films on surfaces that do not etch can occur using this chemistry, but with sufficient oxygen in the plasma this is eliminated. An analysis of the plasma etch chemistry based on plasma emission spectroscopy is also presented.

Platinum etching characteristics in aqua regia have been studied. It was found that prior exposure to an oxygen plasma inhibits the dissolution of platinum in aqua regia. Oxygen, far more abundant in the exposed platinum than in the unexposed platinum, plays a key role in forming an inhibition layer, such as PtO2, which prevents chlorine ion attack. This inhibition layer appears to retard platinum etching effectively in chlorine-based etch solutions. The layer has been observed to form at a fast rate, and it is insensitive to the oxygen partial pressure in the plasma chamber. The insoluble characteristics of both the inhibited platinum and the platinum silicide in aqua regia make it feasible to form an unframed contact interconnection for applications of very large scale integration.