Study of mechanism which causes film formation on mercury surfaces

The mechanism by which small quantities of dissolved tin, sodium, and lithium lower the rate of evaporation of mercury in vacuum is determined. An apparatus was built in which dilute amalgams could be prepared and studied in an oxygen-free environment before being exposed to oxygen under controlled conditions. The apparatus was able to maintain a pressure of less than 1.3 x 0.000001 N/sqm (10 to the minus 8th power torr) of gases and vapors other than mercury and less than 1.3 x 10 to the minus 8th N/sq m (10 to the minus 10th power torr) partial pressure of oxygen; also, it provided for mechanical sweeping of the liquid metal surfaces in the vacuum environment. The rates of evaporation of pure mercury and of dilute amalgams of tin (52 ppm), sodium (229 ppm), and lithium (165 ppm) were determined at temperature between 25 and 55 C both before and after 70 minute exposures to an approximately 270 N/sq m (2 torr) pressure of oxygen. The rates of evaporation of the pure mercury and the amalgams as first prepared were similar but the rates for the amalgams were reduced by at least 80% at 25 C as a result of the exposure to oxygen. The effect of the oxygen treatment could be completely removed by sweeping the amalgam surfaces. It was concluded that the reduced rates of evaporation resulted from the formation of transparent, insoluble, oxide films on the amalgam surfaces

Measurement of contact angles and evaluation of surface coatings

Stable surface treatments for 301 stainless steel, copper, and aluminum alloy contact with liquid

Guidelines for identification of concrete in a materials property database

Guidelines for the identification of concrete in a materials property database are presented to address the complex problem of distinguishing one concrete from another. These guidelines are based on a logical scheme for systematically organizing and subdividing data and information about concrete and its constituents; they reflect consensus recommendations for a multilevel material description and designation system. Aspects of the guidelines include a classification system used to establish a series of primary identifiers, methods for reporting constituent information and mixture proportions, fields describing the source of the concrete and its processing history, and recommendations for reporting baseline or reference properties

HYDRATION OF TRICALCIUM ALUMINATE AND TETRACALCIUM ALUMINOFERRITE IN THE PRESENCE OF CALCIUM SULFATE

It is the purpose of this report to summarize the state of knowledge regarding the hydration of C//3A and C//4AF in the presence of calcium sulfate at ordinary temperatures. These interstitial phases in combination with calcium sulfate may comprise up to 20 percent of portland cement and their hydration reactions affect rheological properties, early strength gain characteristics, and durability. Within limitations, reported results are related to the hydration of the interstitial phases in portland cement. Although C//3A and C//4AF are used as models for the interstitial phases in portland cement, two factors may lead to differences in the hydration behavior of the pure phases and the interstitial phases in cement paste. First, in the manufacture of cement, extensive substitution may occur resulting in the formation of anhydrous aluminate and ferrite solid solutions of variable composition. Second, the interstitial phases in commercial cements hydrate in the presence of other phases. These factors may result in significant variations in the rates, and possibly, in the mechanisms of interstitial phase hydration in commercial cements