Surface recession amount

Analytical results for sulfate ions are for the net change in rainfall composition, after the rainfall flows over the surface of the exposed stone (Tables I and II). The net concentration, resulting from the interaction of rain with the stone surface, is calculated by subtracting the blank-sample concentration value from the value measured for the stone runoff. For very small rain amounts (typically 2 to 4 millimeters), blank volumes were too small to allow complete chemical analysis. Sulfate ion net concentration, in excess of that possible from sulfate loading, was calculated to identify the presence of soluble sulfate-containing minerals on the rock surface. Loss of rock mass, measured by the calcium concentration in the runoff, is expressed as surface recession, in micrometers of rock surface lost per rainstorm. The net calcium concentration in the runoff solution is converted to an equivalent volume of rock removed this result divided by the surface area of the exposed rock, yields a measurement of surface recession. ... 

Relation between environmental variables and surface recession. Carbonate-rock surface recession and the environmental variables measured in this program (i.e., rain amount, rain pH, hydrogen ion loading to the rock surface, and antecedent sulfur dioxide) exhibited a range of values at the North Carolina site during the last half of 1984. To examine qualitatively the relation between... 

The situation differs for large rain amounts. For large rain amounts, excess sulfate values for limestone exceed excess sulfate values for small rain amounts. Large-excess sulfate values for a large-rain-amount for limestone are associated with twice the surface recession of a marble sample for the same event. Some of this surface loss may be the result of the removal of a calcium sulfate mineral. 

Marble-surface recession at the North Carolina site was correlated with rainfall amount. The correlation coefficent was significant at greater than the 99-percent confidence level. Marble-surface recession also was correlated with hydrogen ion deposition to the rock. The linear relation between surface recession and hydrogen ion deposition was found to be ... 

Crevices, cavities, the inside of cracks, recessed parts of the surface, and especially the inside of capillaries are all more active for van der Waals adsorption than is a plane surface. The heats of adsorption will be higher on these active spots and, therefore, the first molecules to be adsorbed generally show a higher differential heat of adsorption. The heat of adsorption mostly tends to fall with increasing amount of adsorbed matter (see Sec. V,12). 

In the lubrication of ball bearings, oil is transported by surface creep from the grease supply to the raceway this creep is favored by the molecular heterogeneity of ordinary petroleum oils, whose more volatile components have lower surface tensions than the total oil mixture. If one imdertakes to lubricate with a radiation-resistant alkyl aromatic oil, however, the situation may be reversed, and the deliberate inclusion of a minor amount of an oil of lower surface tension is indicated. The recession phenomena reported for silicone liquids on a 400° surface remind us that at the high temperatures and temperature gradients existing in some military equipment oil films maybe expected... 

All the experimental evidence points to the conclusion that leveling takes place under conditions when the supply of the substance causing inhibition of the electrode process is under diffusion control. It was already clear to early investigators that the explanation should be sought in the local variations in the supply of the leveling agent over the surface profile. Peaks at the surface receive larger amounts of an additive than the recesses. This results in an increase in inhibition... 

Since the amount of Cr203 remains constant while the NiCr204 transforms into NiAl204 (cf. Figs 33.5(a), (c) and (d)), the Cr that is released by this transition is thought to diffuse from the oxide scale to the O/M interface. An enrichment of Cr was observed in the aUoy at the O/M interface after about 4 h of oxidation (cf. Refs. [3, 4]). This enrichment is mainly due to the recession of the O/M interface into the aUoy [3], but the diffusion of Cr from the oxide scale may have also contributed. Alternatively, as suggested in Ref. [15], the Cr may diffuse to the oxide surface where it subsequently evaporates as Cr203. 

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