reactions, including oxidation of the lubricant and the contacting surfaces. The lubricant also degrades and polymerization occurs, among other reactions []. The boundary lubrication films function through several mechanisms as explained by Hsu and Gates []. These include sacrificial layer, low-shear interfacial layer, FM, shear resistance and load bearing solids. Lubricant base oils are hydrocarbons and equally undergo several chemical reactions like oxidation, thermal decomposition and polymerization. Since hydrocarbons oxidize through the free radical mechanism, iron, like other metals, decomposes hydrocarbons. The boundary lubrication films adsorbed to the metallic surfaces in contact are formed when hydrocarbons react with oxygen. These chemical reactions produce polar species like carboxylic acids. The polar species can adsorb to the metal surface, react with the metal and form metal complexes []. The chemical reactions induced by relative motion in a loaded contact are studied in Tribochemistry. The chemical reactions in the boundary lubricated contact follow the pathway that produce hard, durable, load carrying components, as well as soft polymeric components. The components of the boundary lubrication film can be formed by decomposition, reactions between the lubricant additives, base oil and the contacting surface elements. As temperature is related to frictional transition and adsorption film formation, the operating temperature in the contact enables the beneficial reactions or otherwise []. The appropriate temperature makes the rate of the beneficial reaction products formation to be more than the rate of desorption or film removal by rubbing. These special chemical reactions in the sliding contact may be reinforced by wear debris. It is possible to have a self-repair mechanism under boundary lubricated sliding. This depends on the contact conditions, the active chemical elements and the environment surrounding the contact area []. Tribotest Methods in Boundary Lubrication Tribotesting can be done in many ways. The configuration one selects would be such that imitates the machinery or tribosystem contact being investigated. Some tribotest contact configurations are ball-on-disc with slide and roll combination as used in a minitraction machine (MTM) tribometer [], flat-on-flat reciprocating sliding, ball-on-ring, ball-on-flat
reactions, including oxidation of the lubricant and the contacting surfaces. The lubricant also degrades and polymerization occurs, among other reactions []. The boundary lubrication films function through several mechanisms as explained by Hsu and Gates []. These include sacrificial layer, low-shear interfacial layer, FM, shear resistance and load bearing solids. Lubricant base oils are hydrocarbons and equally undergo several chemical reactions like oxidation, thermal decomposition and polymerization. Since hydrocarbons oxidize through the free radical mechanism, iron, like other metals, decomposes hydrocarbons. The boundary lubrication films adsorbed to the metallic surfaces in contact are formed when hydrocarbons react with oxygen. These chemical reactions produce polar species like carboxylic acids. The polar species can adsorb to the metal surface, react with the metal and form metal complexes []. The chemical reactions induced by relative motion in a loaded contact are studied in Tribochemistry. The chemical reactions in the boundary lubricated contact follow the pathway that produce hard, durable, load carrying components, as well as soft polymeric components. The components of the boundary lubrication film can be formed by decomposition, reactions between the lubricant additives, base oil and the contacting surface elements. As temperature is related to frictional transition and adsorption film formation, the operating temperature in the contact enables the beneficial reactions or otherwise []. The appropriate temperature makes the rate of the beneficial reaction products formation to be more than the rate of desorption or film removal by rubbing. These special chemical reactions in the sliding contact may be reinforced by wear debris. It is possible to have a self-repair mechanism under boundary lubricated sliding. This depends on the contact conditions, the active chemical elements and the environment surrounding the contact area []. Tribotest Methods in Boundary Lubrication Tribotesting can be done in many ways. The configuration one selects would be such that imitates the machinery or tribosystem contact being investigated. Some tribotest contact configurations are ball-on-disc with slide and roll combination as used in a minitraction machine (MTM) tribometer [], flat-on-flat reciprocating sliding, ball-on-ring, ball-on-flat