Elsevier

Wear

Volume 230, Issue 1, May 1999, Pages 35-38
Wear

Tribological properties of CeF3 nanoparticles as additives in lubricating oils

https://doi.org/10.1016/S0043-1648(99)00084-8Get rights and content

Abstract

This paper reports the synthesis of cerium trifluoride (CeF3) nanoparticles in the microemulsion of polybutanediimide (T154)/cyclohexane/water and their tribological properties as additives in lubricating oils. The results show that CeF3 nanoparticles are spherical and cylindrical in shape (size: 25 nm) and possess excellent extreme pressure and friction-reducing properties. The maximum nonseisure load (PB) is increased by 85.3%, and the decreasing percentage of friction coefficient is above 25% as compared with background oil (500SN base oil+4.6% T154+3% calcium alkylsulfonate (T101)+3% methyl-tricaprylamine chloride (aliquat336)). These may be caused by the formation of a transfer film in the contact surfaces. However, CeF3 nanoparticles cannot improve the anti-wear performance of lubricating oil effectively, and the reason may be that F ion generated by decomposing CeF3 corrodes the rubbing surfaces.

Introduction

Research on the rare earth halides as solid lubricants has been reported in recent years. Jost [1]has studied the tribological properties of LaF3 and reported that the anti-wear property of bonded coatings could be improved by two to four times. Sliney [2]has reported CeF3 and CeO2 as solid lubricants had good anti-wear and friction-reducing properties at high temperatures. Dumdum et al. [3]and Aldorf [4]have tested CeF3 particles as a grease additive. When CeF3 was dispersed in barium complex soap grease, the initial seizure load was higher than that when only MoS2 or graphite was added. Lian et al. [5]have proposed the mechanism of the synergism between CeF3 and zinc dialkyldithiophosphate (ZDDP) in lithium grease and believed that ZDDP could inhibit the decomposition of CeF3. However, the exploration of CeF3 nanoparticles as additives in oils has not been reported, until now.

The preparation and application of nanoparticles is a fast growing field in the world 6, 7, 8, because their special properties are different from their bulk, molecular or atomic. In this paper, we focus on the synthesis of CeF3 nanoparticles in a microemulsion and their tribological properties as additives in lubricating oils.

Section snippets

Synthesis of CeF3 nanoparticles

A microemulsion of polybutanediimide (T154)/cyclohexane/water is selected for the synthesis of the CeF3 nanoparticles. The ratio of T154/cyclohexane/water by weight is 1/200/8. The concentrations of Ce(NO3)3 solution and NH4F solution are 0.2000 and 0.6000 mol l−1, respectively. According to the ratio, T154, cyclohexane and Ce(NO3)3 are blended and stirred sharply to form microemulsion. Then, the NH4F solution which its volume is same as Ce(NO3)3 solution is gradually dropped into the

Nanoparticle size and shape

The color of CeF3 nanoparticles is white. Their average size is about 25 nm and their shapes are spherical and cylindrical as shown in Fig. 1.

Load carrying capacity

The effect of dispersants on load carrying capacity of CeF3 nanoparticles is shown in Fig. 2. It can be seen that the maximum nonseiure load (PB) in medium d is the largest among 500SN base oil, a, b, c and d under the same operating condition. This suggests that the synergism of methyl-tricaprylamine chloride (aliquat336) and calcium alkylsulfonate

Conclusions

As discussed above, the results can be summarized as follows.

The microemulsion of T154/cyclohexane/water can be used to generate monodispersive CeF3 nanoparticles. CeF3 nanoparticles possess excellent extreme pressure and friction reducing properties. By dispersing CeF3 nanoparticles in lubricating oils, the load carrying capacity and friction reducing property of oils can be improved significantly. PB value is increased by 85.3%, and the decreasing percentage of friction coefficient is above

References (8)

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