document: The oxide thickness is calculated using the weight gain and surface area. Artificially changing the surface profile will modify the surface area and calculated oxide thickness. SEM images of samples removed after 111 days oxidation were used to define the change in surface profile length with variation in applied roughness. The profile lengths extracted from the images were then used to modify the length of the sample and therefore the surface area. Table 1 shows the original oxide thicknesses after 111 days oxidation, the modified oxide thicknesses based on the surface profile length and the percentage difference. Results show a maximum decrease in the oxide thickness of 4% when using a surface which accounts for roughness. Comparing the change in oxide thickness between different surface finishes indicates a variation of less than 1%. As such, the impact of the variation in the profile length on the calculated oxide thickness is considered to be insignificant. In addition, if the differences in weight gain were only due to differences in surface area, rougher samples would be expected to demonstrate thicker oxides at the earliest stages of oxidation.
extractive_keyphrases: images oxidation oxide oxides profile sample samples surface
abstractive_keyphrases: sem images surface area surface profile