Table 9. Correlation of Electrical Properties of Coatings with Performance 



Electrical 

 Property" 



Correlation Coefficient Between Electrical Properties 

 and Atmospheric Performance* 



Unscribed Panels 



Scribed Panels 



6 Hours 



10 Days 



400 Days 



6 Hours 



10 Days 



400 Days 



LogRoc 

 Log(Ri/R)^ 



Log (R/R)^^ 



C 



Log C/C| 



All Listed 

 Properties'^ 



+0.01 

 -0.27 

 +0.38 

 -0.27 



0.75 



-0.08 

 -0.31 

 +0.03 

 -0.24 

 +0.16 

 -0.12 



0.76 



-0.29 

 +0.01 

 -0.09 

 -0.05 

 +0.25 

 +0.02 



0.76 



-0.27 

 +0.12 

 +0.59 

 +0.01 



0.80 



-0.19 

 -0.16 

 -0.18 

 -0.05 

 +0.59 

 +0.14 



0.80 



-0.42 

 +0.14 

 -0.23 

 +0.09 

 +0.47 

 +0.10 



0.88 



As listed in Table 2. 



' Protection ranking of coating systems on unscribed or scribed panels as determined 

 at Kwajalein, M. I., and listed in Table 5. 



Absolute value of the square root of R for the best linear equation involving all 

 the independent variables (electrical properties) for which values are listed above. 



For each coating system, the electrical properties listed (that is, the 

 DC and AC resistances, the capacitance, and the changes in these values during 

 the immersion periods indicated) were compared to the performance under 

 atmospheric exposure. The correlation coefficients were determined for 

 exposure periods of 1/4 day, 10 days, and 400 days. 



For some of the electrical properties, significant correlations were 

 obtained. Thus, for example, the greater the change in AC resistance, the 

 lower is the quality of the coating as based on atmospheric field exposure 

 results with unscribed panels. For these changes in AC resistance after 1/4 day 

 or 10 days of immersion, this correlation is significant, but it becomes less 

 significant after 400 days of exposure. 



43 



