Solid lubricants/tribological additives

Solid Lubricants/Tribological Additives 375 Comparison of Various Solid Lubricant Powders... 

Solid Lubricants/Tribological Additives 393 Table 19.7 Various applications of M0S2, Graphite, PTFE and BN in different polymers. 

Surface Property Modifiers with further division into a) solid lubricants/tribological additives that include molybdenite, graphite, PTFE and boron nitride and b) antiblocking fillers such as silica. Chapter 19. 

Soft metals such as indium, tin and bismuth are good solid lubricants, but they cannot be used as a lubricating oil additive because of their poor dispersibility in oils. However, their nanoparticles prepared by the direct solution-dispersing method have been found to have better oil solubility and can be directly used as lubricating additives. Their tribological properties have been evaluated on a four-ball tester and the results are presented as follows. 

Just like other lamellar solids, boric acid is also self-lubricating. Its lubrication mechanism is similar to that of the other solid lubricants. It can be manufactured as very fine nanopowders. Because of their light weight, these nano-powders can easily be dispersed in oils and used as colloidal anti-friction and -wear additives. Tribological studies have confirmed that they have very high capacity to reduce friction and wear. TOF-SIMS and XPS studies... 

The two most often used fillers in thermoplastics are PTFE and PDMS or silicone. The respective functions of the two materials are quite different. PTFE is almost the wonder additive for tribological applications, whether in a solid polymer or liquid lubricant. The mechaiucal properties of PTFE hold over a range of -260°C to 260°C with a melt temperature of 321°C. It is chanicaUy inert and hydrophobic. The effect of PTFE as a solid lubricant can be understood from its performance as a homopolymer. As a homopolymer, PTFE has the lowest coefficient of friction of all polymeric materials sliding against metal surfaces. This is due to the lack of bulky side groups on the molecular chain and the formation of a low friction transfer film on the opposing counterface. However, due to the poor mechanical properties, PTFE alone also... 

If the circumstances require the use of a pre-applied solid film, then in addition to the tribological properties of the film (x,.e. its intrinsic friction and wear and its interaction with the countersurface against which it rubs) the adhesion of the film to the substrate surface comes into consideration. An important aspect of practical lubrication... 

Several types of nanoparticles can be envisaged as lubricant additives. The chapters of this book describe different possible nanolubricants nested nanoparticles (fuUerenes, onions and nanotubes) made on metal dichalcogenides or carbon, reverse overbased micelles, metallic nanoparticles and boron-based nanolubricants. In some cases, the authors chose to study these particles because their structure is close to well-known lamellar structures in tribology (for example inorganic fuUerenes of M0S2). However, dispersion of nanoparticles in oil is not always simple. Thus, in a first part, some rules will be shown about the dispersion of solid nanoparticles in a liquid. 

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