Zefu Zhang

The effect of LaF3 nanocluster modified with succinimide on the lubricating performance of liquid paraffin for steel-on-steel system

Abstract LaF 3 nanocluster modified with succinimide was prepared. The effect of the modified LaF 3 nanocluster on the lubricating performance of liquid paraffin for steel-on-steel sliding system was investigated on a four-ball machine. The morphology of LaF 3 and its lubricating mechanisms as additive in liquid paraffin were studied by means of transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). It was found that LaF 3 nanocluster modified with succinimide as an additive in liquid paraffin increased the load-carrying capacity and had good antiwear and friction-reduction behaviour. The XPS analysis of the worn steel surfaces indicated that a boundary lubricating film consisting of physically adsorbing film (succinimide) and tribochemically reacting film (lanthanum oxide and ferrous fluoride) was generated during the friction process. This contributed to improving the lubricating performance of liquid paraffin.

Study on lubricating mechanisms of La(OH)3 nanocluster modified by compound containing nitrogen in liquid paraffin

Abstract In this paper, the tribological properties of La(OH) 3 nanocluster modified by compound containing nitrogen as additive in liquid paraffin were investigated using four-ball machine. The results show that La(OH) 3 nanocluster modified by compound containing nitrogen as additive in liquid paraffin has high load-carrying capacity, good antiwear and friction reduction properties. The lubricating mechanisms were studied by using EPM-810Q model electron probe microanalyzer (EPMA) and PHI-5702 multi-technique surface X-ray photoelectron spectrometer (XPS). The results show that the boundary film on the worn surface is made of physically adsorbing film (N-containing organic compound) and tribochemical reaction film (lanthanum oxide). The physically adsorbing film and tribochemical reaction film formed during friction contributed to good tribological properties of La(OH) 3 nanocluster modified by compound containing nitrogen as additive in liquid paraffin.

The tribological behaviors of 2-mercaptobenzoxazole derivatives as additives in liquid paraffin

Abstract Some potentially active heterocyclic compounds including 2-(di- n -octylaminomethyl) thiobenzoxazole were synthesized. The friction and wear behaviors of these potentially active heterocyclic compounds as additives in liquid paraffin were investigated on a four-ball machine. The tribochemical interaction between the additive and the counterface metal was explored with X-ray photoelectron spectroscopy. It was found that 2-(di- n -octylaminomethyl)-thiobenzoxazole was effective in reducing wear as a potential novel additive in liquid paraffin.

Study on tribological properties of the complex of rare earth dialkyldithiocarbamate and phenanthroline in lubricating grease

Abstract Three complexes of rare earth dialkyldithiocarbamate (DTC) and phenanthroline (Phen) were synthesized. Their tribological properties as additives in lithium grease were evaluated using a four-ball machine and a SRV machine. As a comparison, the tribological properties of molybdenum dialkyldithiocarbamate (MoDTC) as an additive in lithium grease were also investigated. The thermal stabilities of rare earth complexes were also investigated with a thermal gravity analyzer. The results indicate that these rare earth complexes possess excellent load-carrying capacity, antiwear and friction reduction properties, and high thermal stability. Their extreme pressure properties are superior to that of MoDTC. At lower concentration and lower load, the antiwear properties of lanthanum and neodymium complexes are superior to those of MoDTC. At lower concentration and higher load, the antiwear properties of the these rare earth complexes are inferior to those of MoDTC. But the wear increases, as the increase of concentration of rare earth complex. The results of Auger electron spectroscopy and X-ray photoelectron spectroscopy analyses indicate that these rare earth complexes as additives in lithium grease can form a protective film containing rare earth oxide, sulfate and an organic compound containing sulphur and nitrogen on a rubbed surface. Especially, the lubricating film rich in rare earth and sulphur contributed largely to the excellent tribological properties of EDTC. Ln. Phen.

Friction and wear behaviors of the complexes of rare earth hexadecylate as grease additive

Four complexes of rare earth hexadecylates (La, Pr, Sm, Gd) and copper hexadecylate were synthesized. Their tribological properties as additives in lithium grease were evaluated using a four-ball machine and a ring-block tester. The results indicated that these rare earth hexadecylates possessed antiwear and friction reduction properties in lithium grease. Their antiwear and friction reduction properties in lithium grease were better than that of copper hexadecylate. The lubricating mechanisms of the complexes as lithium grease additive were investigated using X-ray photoelectron spectroscopy (XPS). The results showed that tribochemical reaction happened during rubbing. The products of the tribochemical reaction were beneficial for improving the friction and wear behaviors of the lithium grease.

Synthesis, structure and spectroscopic properties of dimethylammonium lanthanide tetrakis(N, N-dimethyldithiocarbamate)

Trivalent lanthanide complexes of the type [Ln(me 2 Dtc) 4 ]H 2 NMe 2 (Ln=La, Pr-Nd, Sm-Ho; Me 2 Dtc= N , N -dimethyldithiocarbamate) have been prepared and characterized by means of elemental analyses, IR spectra, electronic spectra, 1 H NMR spectra and conductivity measurements. The X-ray crystal and molecular structure of the neodymium complex has been determined from diffractometer data. There are two independent [Nd(Me 2 Dtc) 4 ]H 2 NMe 2 monomers in each unit cell; the metal coordination number is 8. Spectroscopic properties of the complexes are discussed.

A NOVEL SYNTHESIS OF HEXASUBSTITUTED CYCLOTRIPHOSPHAZENES

ABSTRACT Hexaaryloxyphosphazenes [N3P3(O-C6H4-R)6] (R=H, CH3, OCH3, C(CH3)3, CHO, COCH3, COOR, C6H5, NO2, F, etc) were readily obtained with ca 70% isolated yield in refluxing acetonitrile in the presence of anhydrous potassium phosphate. All compounds were characterized by means of elemental analysis, 1H-NMR, 31P-NMR spectroscopy.

Tribological properties and lubricating mechanisms of the rare earth complex as a grease additive

One N-salicylidene derivative of malonic dihydrazide (Schiff base) and its complexes of lanthanum and copper were synthesized. Their tribological properties as additives in lithium grease were evaluated using a four-ball machine. The results indicate that these compounds possess good load-carrying capacity, friction reduction, and anti-wear properties. In particular, the complex of lanthanum has excellent load-carrying capacity, similar to those of zinc dialkyldithiophosphate and molybdenum dialkyldithiocarbamate, and exhibits good anti-wear property. The thermal stability of these compounds were investigated with a thermal gravity analyzer. The lubricating mechanism of these compounds as additives in lithium grease was investigated with analytical tools such as an electron probe micro-analyzer and an Auger electron spectroscope.

Dithiocarramate Complexes of Trivalent Lanthanides and X-Ray Crystal Structutris(N,N-Dhsopropyldithiocakhamato)(1,10-Phenanthroline)Neodymium(III)

Abstract A series of lanthanide complexes of the general formula. [Ln(i-Pr2dtc)3 (phen)] (Ln = La, Pr, Nd, Sm-Lu. Y; i-Pr2dtc = N, N-diisopropyldithiocarbamate: phen = 1,10-phenanthroline), have been prepared and characterired by nicans of chemical analyses. IR spectra, electronic spectra. H NMR spectra and conductivity measurements. The X-ray crystal and molecular structure of [Nd(i-Pr2dtc)3(phen)] has been determined by diffractometer data. The central Nd(III) atom is octa-coordinated and is in a distorted dodecahedral geometry. being coordinated through six sulphur atoms of three bidentate dithiocarbamates and through two nitrogen atonis of a phen ligand. Spectroscopic properties of all complexes are discussed.

Tribological properties of aluminum-on-steel system under the lubrication of grease containing a complex of lanthanum N-salicylidene derivative of malonic dihydrazide

Abstract A complex of lanthanum and N -salicylidene derivative of malonic dihydrazide (Schiff base) was synthesized, and its tribological properties as additive in lithium grease were evaluated using a block-on-ring wear tester with a SAE52100 steel ring against an Al 2024 block. The protective film formed on the rubbed surface of aluminum was investigated by SEM, XPS and AES. Friction and wear tests reveal that this rare earth complex possesses an excellent load-carrying capacity and a very good antiwear ability for aluminum. The results of AES and XPS analyses illustrate that the prepared Schiff base La complex as additive in lithium grease forms a protective film containing lanthanum oxide and organic compound containing carbon and nitrogen on the rubbed surface of aluminum.