Ferrocene Derivatives in Boundary Lubrication 11:00 Plenary session Chairman: prof. Joe Perez Invited report speaker Hieronim Piotr Janecki TU Radom - Poland BALTTRIB' November 2005

on line2 The aim and subject of the project The subject of this report are selected results from the studies on the evaluation of the effect of some paraffin oil based liquid lubricants modified with ferrocene derivatives upon friction surface modification. The aim and subject

on line3 Experimental 1 Lubricating agents Lubricating agent [[i]] H.P. Janecki: Tribologia 1/99, (163), 21-40, The lubricating agent was a solution of 1,1 ' - diethyl-2-thia[3]ferrocenophane sulphide (3SJ) of mole/dm 3 concentration in paraffin oil [[i]].[i]

on line4 Experimental 2 Model wear tests - Test ZA-2 Model wear tests [[i]] G. Drechsler, H. Haupt: Schmierungstechnik 15 (1984), 6, S The tests were performed using Tribometer ZA-2 (Ball on cylinder) designed by Drechsler et al. specifically for the study of additives and lubricants [[i]].[i] ZA – 2 Ball on cylinder configuration

on line5 Experimental 3 Model friction investigations have been carried out to study the ball-on-cylinder configuration (see below) made from steel 100Cr6 inside a thermostat chamber where the temperature was kept at 303 K for the duration of the experiment. Cylinder diameter d = 50 mm, cylinder length l = 40 mm, hardness Hrz = 63(Rockwell), speed range 200 rpm, ball diameter 1/2". Model wear tests

on line6 Experimental 4 After the tests had been completed, the surfaces of the balls were analysed using an optical microscope and Elektronmicroscope. Model wear tests Fig.1 example of measured wear scars a b

on line7 Experimental 5 A wear scar of a*b 2.57 * 2.38 mm with wear volume V V = 0.7 * mm 3 was recorded for a steel 100Cr6 kinematics pair at the load of 31 N. Selected measurement results obtained for a solution of 3SJ sulphide have been given in Table 1: look the Table The 3SJ sulphide exhibited the highest reactivity towards the surface tested Wear scar and wear scar diameter

on line8 Experimental 6 Table 1 Selected results of wear measurements carried out using Tribometer ZA-2 Keeping in mind the division of friction conditions depending on the friction coefficient determined [[i]], it becomes clear that the experiments were carried out under boundary friction conditions. [[i]] F.P.Bowden,D.Tabor:"Wprowadzenie do Trybologii" WNT W-wa 1980,[i]

on line9 Friction coefficient  The third column in Table 1, which illustrates a change in friction coefficient within the first second of tribometer ZA- 2 operation, seems to be interesting in the light of theoretical considerations. It should be noted that starting from a load of 50 N the system moves within the first second of operation beyond the boundary friction area towards dry friction > 0.15, but within the third second it returns to the boundary friction area. Experimental 7

on line10 Experimental 8 And so we are back with the motto of this project "the first seconds and minutes of the friction pair's motion are the most important ones". Figs 2 – 3 illustrate the surfaces examined. It can be clearly seen that the reaction layers are non-uniformly arranged on the surfaces of the balls tested. Wear scar SEM image after ZA-2 test, N = 50N,  = 0.096, t=3min Wear scar SEM image after ZA- 2 test, N = 50N,  = 0.096, t=3min, wear scar center Fig 2.

on line11 Experimental 9 Currently available results of investigations of sulphur ferrocene derivatives indicate a possibility to generate mixed organic-inorganic layers on friction surfaces. The final results of the analysis are shown in Fig. 3, where a wear scar with traces of reaction products on the surface is clearly visible, cf.:. Enlarged SEM image of wear scar after ZA-2 test, N = 50N, = 0.096, t=3min, reaction products are visible along friction path Results of steel 100Cr6 surface analysis obtained using an EDS analyser right side Fig 3.

on line12 Experimental 10 Earlier studies carried out using the "hot-wire" method indicated that 3SJ - 1,1'diethyl-2-thia[3]ferrocenophane was the most reactive compound in the conditions under which tribological experiments and model thermal tests were performed[[i]].Differential thermal analysis (DTA) measurements as a standard method of determining the transformation temperatures of materials have been done. The thermal 3SJ characteristics has been presented in Table 2: Characteristic thermal properties determined using the derivatographic method (DTA)[i] [[i]] H.P.Janecki, M.Janecka, H.G.Müller, U.Wendt: „Tribologia 4/ ,

on line13 Experimental 11 After differential thermal analysis (DTA) measurements Model investigations in static thermal conditions have so far been carried out in paraffin oil solutions. For this model study 3SJ solution in paraffin oil was used. The concentration of the 3SJ compound was 0,25 mole/dm 3. The samples used were (1) a bronze B1010 plate and (2) a polished copper plate. They were immersed in an oil solution and heated in a drying chamber at 411K for 3 hours. The surfaces of the samples after static-thermal tests were studied with the naked eye and with the help of a magnifying glass.

on line14 Experimental 12 After thermal tests the sample surfaces did not change, except for sample 1, which was covered with a grey opalescent bloom of reaction products of the 3SJ solution. The samples were then analysed by SEM/EDS. Two parallel tests were performed. Samples 1 and 2 were studied immediately after their removal from oil solutions. The surfaces of samples 3 and 4 were washed with acetone and dried before the analysis.

on line15 Experimental 13 An instrumental analysis was performed for selected elements of kinematic pairs and representative samples. The samples analysed were: -1- polished copper plate surface, -2- polished bronze B1010 plate surface, -3- polished copper plate surface (washed with acetone), -4- polished bronze B1010 plate surface (washed with acetone).

on line16 Experimental 14 Figs 4 and 5 show surface analysis results obtained using SEM/EDS analysis methods. A review of the results points to the occurrence of interesting interactions between the surfaces of the samples tested and the solution of 3SJ in paraffin oil. This is particularly apparent in the case of sample 1. Sample 1 analysis results are presented in Table 3: Table 3 EDS analysis results

on line17 Experimental 15 The 3SJ compound - 1,1'diethyl-2-thia[3]ferrocenophane also reacts intensively with the surface of the copper sample (Sample 1). The shares of sulphur and iron in the grey opalescent reaction layer reach 9.21% and 0.38%, respectively. The image of a polished copper plate surface obtained using an electron microscope is shown in Fig. 4.: test in the solution of 3SJ sulphide in paraffin oil at 411K for 3 hours The results of the EDS analysis of copper surface shown in Fig. 4 left side Fig 4 Back to summary

on line18 Experimental 16 The bronze B1010 surface after friction was studied by means of scanning electron microscopy and Auger electron spectroscopy. The investigation results are shown in Fig 5 SEM image of bronze B1010 surface tested in the solution of 3SJ sulphide in paraffin oil left side AES analysis results right side Fig5 distribution of ferrocene iron on the B1010 surface in the middle

on line19 Summary 1 The results of model friction and thermal tests lead to the conclusion that in the conditions studied there was a reaction between the sulphide tested and the surface See Table 4 on Next slide If there had been unreacted sulphide (C5H4)2Fe(CHC2H5)2S 1,1'diethyl-2- thia[3]ferrocenophane left on the surface, the share of sulphur and iron would have been 10.66% and 18.66%, respectively (see Table 4).

on line20 Summary 2 Table 4 Percent share of sulphur and iron in 3SJ sulphide and on the surface Because C% S equals 9.21% < 10.66% and C% Fe equals 0.38% < 18.66%, it can be therefore concluded that a reaction layers contain less sulphur and iron than the 3SJ compound forms on the surface of the plate tested.

on line21 Summary 3 Under the experimental conditions no significant sulphur and ferrocene iron peaks were observed on the surfaces of samples 3 and 4 washed thoroughly with acetone. Hence, the interactions observed under the experimental conditions do not lead to the formation of stable layers combined with the surface being studied. Additional friction tests on bronze B1010 samples were carried out using ZA-2 and their surfaces were analysed by AES. Some of the analysis results have been given on Fig 4.Fig 4

on line22 Summary 4 The above results confirm the previously observed tendency of ferrocene sulphur derivatives to form reaction layers on the surfaces of analysed samples. On the basis of tribological and chemical research there has been suggested the mechanism of changes in ferrocene sulphur derivatives [12], which consists in physical adsorption, followed by the reaction of sulphur with surface metal as well as with iron from a ferrocene derivative, and then the migration of reaction products on the surface (also into the layer).

on line23 Summary 5 It follows from the percentage share of sulphur and iron in ferrocene derivatives as well as from spectroscopic analysis of the derivatives that the reaction layer formed on the surface may be a mixture of copper sulphides, ferrocene iron and unreacted molecules of the compound studied. The basic analytical research presented in [[i]] indicates that the surface layer being discussed and analysed may be described as shown in Table 5:[i] [[i]] H.P. Janecki, Ulrich Wendt „Instrumental Analysis in Tribology materials in preparing,

on line24 Summary 6 Table 5: Sequence of layers and their thickness 1  m = m = 10 4 A ; 0.1  m = 1000A, Electrons with the energy of ~ 25 keV penetrate the surface to the depth of ~ 1 – 1.5  m.