Contribution of micropore destroying to adhesion and particle agglomeration

The contribution of adsorption in a contact zone to adhesion between two nonporous bodies is discussed in the framework of the theory of adsorption in micropores. A contact region is presented as a collection of slitlike micropores and a separation of bodies from a contact to infinity is considered as dismantling filled pores with a formation of two nonporous surfaces instead of each pore destroyed. The behavior pattern of adsorbate in the course of pore destroying depends on dimensions of liquid islands inside pores, temperature and adsorbate partial pressure. Due to overlapping of wall potentials, adsorption in a micropore at low pressures exceeds that on both separated surfaces. In this case, adsorbate evaporates from micropores during the separation and the energy of desorption contributes to the adhesion energy. The system consisting of carbon nanoparticles and trace amounts of polyaromatic compounds is discussed as an example of such behavior pattern. The random walk of nanoparticles in a gas phase or colloid particles in a solution may bring them together at a distance, which is equal to the separation between narrow micropore walls. One may see this phenomenon as vagabond micropore formations. Since a filling pressure for micropores is several orders of magnitude less than that for a nonporous surface, a micropore is not in equilibrium with the environment and, if there is an appropriate adsorbate, begins to adsorb at a low partial pressure, giving rise to concentrating contamination and a following particle aggregation.