Relationship Between Roughness and Oleophilicity

Furthermore, the PSDs also reveal that the surface roughness depends on the scan area or spatial frequency range For example, in the high spatial frequency range (f 1 pm sample 1 exhibits higher PSD values than sample 2. This changes for spatial frequency between 0.01 pm and 0.4 pm, and sample 1 is smoother than sample 2. The same behavior can be observed for the samples 4 and 5. 

Kj values (Table 7.1) were calculated from the PSD functions for four different spatial frequency decades between 0.01 pm and 100 pm. The samples 4 and 5 exhibit the highest wetting parameter in this sample series, and hence for both samples the best wettability, i.e. the lowest CA, is expected. 

Samples 1x1 pm 10X10 pm 50X50 pm 360x270 pm 140x105 pm 35X26 pm b 

Our wetting analysis methodology was optimized for the wetting system metal surface - oil drop - air . Simultaneously, the influences of the system temperature and surface condition on the wettability were investigated. The results show that the CA behavior clearly depends on these environmental conditions. 

In conclusion, our investigations of rough stainless steel surfaces revealed that the surface roughness clearly influences the oleophilicity. This means there is a correlation between the roughness and wetting properties. 

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Before starting the investigation regarding the relationship between roughness and oleophilicity, it was necessary to perform some preliminary investigation on the new wetting system metal surface - oil drop - air The influence of the temperature on the wettability as well as the effect of a pre-wetted, or oily, surface was examined. 

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