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Langmuir—Blodgett (LB) films of 22-tricosenoic acid and of 22-tricosenoic acid polymerised in the presence of an electron beam, and in situ composite LB films of 22-tricosenoic acid/CdS were prepared. The friction and wear behaviour of the LB films were investigated with a ball-on-block one-way reciprocating friction tester. The structures and morphologies of the LB films were analysed and observed using atomic force microscopy. The wear resistance of the LB films was increased after polymerisation of the acid, and the composite LB film of 22-tricosenoic acid/CdS showed better wear resistance because the inorganic nanocores of CdS acted to resist wear and to carry load. The LB film of the acid experienced structural changes during the friction process.

An N-modified nano / micrometre borate (MNMB) as an oil additive was synthesised by an ultrasonic dispersion and emulsion reaction in the microemulsion phase. The particles of the MNMB additive were between 20 and 500 nm in diameter. The tribological properties of the MNMB as an oil additive were investigated using a four-ball tester. The results reveal that the MNMB possesses good tribological properties. When the boron concentration is 0. 05 wt. %, the wear-scar diameter is smallest and the seizure load is highest. The antiwear and extreme-pressure properties of the MNMB were best at a viscosity of 65. 3 mms2. Small-area X-ray photoelectron spectroscopy (XPS) and electron probe microanalysis (EPMA) indicate that the MNMB additive can form a tribological mixed reaction film containing C, O, B, N, and Na on a rubbing surface. The elemental boron exists in four different chemical states, but is mainly present in the form of BN on the rubbing surface.

An amine salt of an alkoxylphosphate (a P- and N-containing organic compound, PN) was synthesised. Its extreme-pressure, antiwear, and friction-reducing properties were evaluated as an additive in liquid paraffin and a mineral oil. Tests were performed on a four-ball friction and wear tester with an AISI 52100 steel ball self-mated pair and the results were compared with those of sulphurised olefin (SO), zinc di-n-butyldithio-phosphate (ZDDP), and dibutylphosphite (DBP). The morphologies of the worn steel surfaces were observed using a scanning electron microscope, while the binding energies of some typical elements on the worn surfaces were determined using X-ray photoelectron spectroscopy. The additives were found to increase the load-carrying capacity and to reduce wear and friction coefficient considerably. PN as an additive exhibits better load-carrying, antiwear, and friction-reducing properties than SO, ZDDP, and DBP under the same test conditions.

The interaction of zinc dialkyldithiophosphate (ZDDP) with cerium fluoride and cerium dioxide in lithium grease has been studied for friction, wear, and EP characteristics on a four-ball and SRV tester. The combination of ZDDP and cerium trifluo-ride has been shown to be beneficial in reducing wear, especially over a long period of friction and with increasing EP load. The test results show that adding cerium dioxide to lithium grease does not improve the antiwear and friction performance of the paste. The analytical results of X-ray photoelectron spectrum (ESCA, XPS) reveal that ZDDP inhibits the decomposition of cerium fluoride and improves its film-forming property. The wear scar reaches a minimum at an atomic concentration ratio of 3P:2Zn:1S:25F, and an atomic concentration ratio of 2S:2P:1Zn:4F gives the highest EP load. The scratch test results show that combining ZDDP with cerium trifluoride improves the tenacity of the surface film. The stabilisation of cerium trifluoride by ZDDP is proposed.

In this paper, an organic compound containing a nitrogen element, Schiff base, is synthesised, and its tribological characteristics are evaluated by four-ball and Timken machines. Schiff base possesses friction-reducing and antiwear properties, especially under low load. Results from X-ray photoelectron spectroscopy (XPS) reveal that the binding energy of N1s increases in the boundary film. Differential thermal analyses (DTA) indicate that Schiff base reacts with iron powder, forming complex compounds through hydroxy and azomethine. An action mechanism, with surface-complex compound films being formed on the surface, is proposed.

Three new oil-soluble alkylthiomethylbenzotriazoles were synthesised with the reaction of 1-chloromethylbenzotriazole and sodium alkyl mercaptan in iso-propanol at room temperature for 12 h. Their load-carrying capacity and friction and wear properties when added to liquid paraffin were then evaluated using a Seta-shell four-ball machine. Their thermal stability in static air was examined by DSC analysis, and their friction reduction and antiwear mechanisms were investigated using XPS and AES analysis.

The antiwear (AW) and extreme pressure (EP) properties of chlorine, sulphur, phosphorus-containing organic compounds and zinc dialkyldithiophosphate (ZDDP) oil additives are affected greatly by their reactive ability to the metal surface, as well as by the chemical composition, chemical state, physical and mechanical properties of the protective films formed. Over four decades, research has taken place on boundary lubrication, and a much better understanding of the AW and EP action mechanism of one additive by itself in base oil has been obtained, and much more knowledge on the relationship between wear and decomposition of additives, adsorption and reaction of the additive or its decomposed products with metal, has been gained. A series of analytical methods and a great number of modern surface analytical tools have been set up and used for research in this area. The problems and some suggestions for the future study on boundary lubrication of oil additive are proposed.

This paper reports a study on the effects of concentration and the molecular structure of amines on the antiwear properties of TBP, TCP and TBPi, evaluated with a four-ball machine. It was found that amines reduce the antiwear properties of P-containing additives in the order primary>secondary>tertiary amine, and a critical amine concentration exists at which P-containing additives lose their antiwear properties. XPS analysis indicated that the competitive adsorption of amines onto the rubbed surface causes a reduction of the antiwear properties of P-containing additives.

Six organic borates of different molecular chain length were synthesised, and the friction and wear properties of these borates as oil additives were evaluated using a Timken Tester. X-ray photoelectron Spectroscopy (XPS) was used to study the surface composition and valence state of boron on the rubbed surfaces. It was found that the antiwear and friction reduction effects of the borates are significantly influenced by the molecular chain length. The longer the chain length, the lower the friction coefficient and wear, and the higher the failure load. XPS analyses of rubbed surfaces revealed that the binding energy of BIS increased after rubbing, but no pure B(OH)3 and B2O3 was generated. the load-carrying capacity and the antiwear effect are probably related to the ratio of numbers of carbon atoms to numbers of boron atoms on the rubbed surfaces.