Rates of moisture absorption by the coatings of three types and three brands of modified 18-8 austenitic electrodes were determined at temperatures of 75, 85 and 100°F and relative humidities of approximately 50, 70, 82 and 96%. The rates of absorption varied with the different brands, the most pronounced variations taking place at the higher humidities. Temperature was found to be very effective in influencing the rate at which moisture is picked up by the coatings, but the total amount absorbed at equilibrium was found to be determined by relative humidity, at least for the range of temperatures used in this investigation. Some of the absorption data were plotted in logarithmic graphs and the empirical equation for the straight portion of the curves and the values of the constants were determined.
Moisture-loss determinations on these same coatings were made at 250, 350, 450, 550 and 650°F. The initial moisture contents of the coatings were between 3.00 and 4.00%. Two brands of the EL307 type lost their moisture quite rapidly at temperatures below 350°F, whereas the third brand required a temperature of approximately 400°F to bring the moisture content below 1.00%. Two brands of types ET307 and ET308-Mo required a temperature of only 250°F for 30 min to bring the moisture below 1.00%, whereas the third brand required a temperature of approximately 300°F to reduce it below 1.00%.
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| Number of Pages : | 24 |
| Published : | 1955 |
