London-van der Waals Force
Hamaker Constants for Dissimilar Materials
For two dissimilar materials, the Hamaker constant may be
estimated in term of Haymaker constant of each material. That is
![](formulas1/image120.gif) |
(7) |
or alternatively
![](formulas1/image122.gif) |
(8) |
For contact of two dissimilar materials in the presence of a third media,
![](formulas1/image124.gif) |
(9) |
From Equation (8) it follows that
![](formulas1/image126.gif) |
(10) |
or
![](formulas1/image128.gif) |
(11) |
Lifshitz developed the macroscopic theory relating the Hamaker
constant to dielectric constants of the materials. Accordingly,
![](formulas1/image130.gif) |
(12) |
Values of are
given in Tables 3 and 4 for a number of materials. (Note that
.) |