Tribological significance

Gao, F., Kotvis, P.V., Stacchiola, D., Tysoe, W.T. Reaction of tributyl phosphate with oxidized iron surface chemistry and tribological significance. Tribol. Lett. 18, 377-384 (2005). doi 10.1007/sl 1249-004-2768-1... 

The present book is written by authors whose backgrounds are mainly in mechan ical engineering. They present individual contributions to the development of microscopic tribology, with significant effort being made to form a bridge between fundamental studies and applications. 

Investigations in the past also emphasized the effect of various additives of the slurry on the tribology during CMP [18,19]. It was observed that the presence of a flocculent reduces the surface frictional force (see Fig. 4.9a). Also, the ionic strength of the slurry has a significant impact on the frictional force (shown in Fig. 4.9b). It can be noted from these data that the friction at the surface depends significantly on the chemical interaction at the interface, besides the mechanical aspects. 

Another type of surface-treated pads is the low-shear surface-engineered pads. When used in copper CMP, the pads exhibited vastly improved tribological performance in comparison to the untreated pads. More specifically, these pads gave a much lower COF over a larger range of Sommerfeld numbers compared to untreated pads. The reduction in shear-induced stress and its accumulation within the copper films can significantly... 

The desorption process for a polymer is usually much slower than that for a small molecule. As shown in Fig. 13.16, the polymer molecule may be in equilibrium between fully desorbed and fully adsorbed via a zipper process. Under tribological conditions, the absorbed polymer will lubricate the surface and therefore prevent material removal under the applied shear. This will take place until polishing conditions surpass the engineered threshold shear force. At low shear force, the removal rate (RR) will be minimal. As the threshold is obtained, the RR response will significantly increase and follow a typical pressure-velocity PV) response as further force is applied. 

Among the various compounds of carbon, the carbides of different elements have a special significance from the tribological point of view. Many of these materials, for instance WC, SiC, and TiC, are mechanically hard and have found use in the tribological industry. The carbonitride (or what can also be called the carbide of nitrogen) is an important constituent of this class of materials. In the last decade or so, the theoretical prediction of crystalline carbonitride phases that could be harder than diamond has generated much interest in the synthesis of this material. 

The theoretical studies undertaken over the last decade have led to significant breakthroughs in our understanding of tribology. However, much work remains to be done. In concluding, we would like to emphasize some of the important lessons learned, unresolved problems, and directions for future studies. 

---