Jun Zhong Jun Zhong Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.72512

#### **Abstract**

In this chapter, to assist the design of aluminum processing, density functional theory is utilized to depict optimal adsorption geometries on an Al (111) surface for two commonly used boundary-layer lubricant additives: vinyl-phosphonic and acetic acids, i.e., tri-bridged, bi-bridged, and uni-dentate coordinations of these adsorbates are examined to determine the optimal binding sites on the surface. During these static analyses, charge density of states for molecular oxygen ions reacting with Al ions in the surface is applied to revealing the evolution essentials of molecular binding strength on surface. In addition, ab-initio molecular dynamics based upon density functional theory is employed to probe dynamic decomposition pathways on the Al (111) surface for two other important boundary-layer lubricant additives: butanoic acid and butanol alcohol. These decomposition pathways may occur upon molecular collisions with the surface, leading to formation of molecular pieces adhering on surface. Simulations are found to be in qualitative accord with existing experimental observations.

**Keywords:** density functional theory, ab-initio molecular dynamics, vinyl-phosphonic acid, acetic acid, butanoic acid, butanol alcohol, Al (111) surface
