Ferrocene Derivatives in Boundary Ferrocene Derivatives in Boundary LubricationLubrication

11:00 Plenary session

Chairman: prof. Joe Perez

Invited report

speaker

Hieronim Piotr Janecki

TU Radom - Poland

BALTTRIB' 200518 November 2005

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The aim andThe aim and subject of the project 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

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ExperimentalExperimental 1 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 0.025 mole/dm3 concentration in paraffin oil [[i]].

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ExperimentalExperimental 2 2

Model wear tests - Test ZA-2

Model wear tests

[[i]] G. Drechsler, H. Haupt: Schmierungstechnik 15 (1984), 6, S. 169-172

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]].

ZA – 2 Ball on cylinder configuration

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ExperimentalExperimental 3 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

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ExperimentalExperimental 4 4After 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

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Experimental 5Experimental 5

A wear scar of a*b 2.57 * 2.38 mm with wear volume VV = 0.7 * 10-3mm3

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

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Experimental 6Experimental 6

Load [N]

Wear V *10-3

[mm3]

(time1s)

(time3s)

10 0.24 0.2 0.07 30 0.7 0.20 0.127 50 1.3 0.19 0.128 70 2.20 0.183 0.123 90 2.40 0.177 0.122 110 2.60 0.186 0.127

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,

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Friction coefficient 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 7Experimental 7

Load [N]

(time1s)

10 0.2 30 0.20 50 0.19 70 0.183 90 0.177 110 0.186

Load [N]

Wear V *10-3

[mm3] (time1s) (time3s)

50 1.3 0.19 0.128 70 2.20 0.183 0.123

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Experimental 8Experimental 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.

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ExperimentalExperimental 9 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.

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ExperimentalExperimental 10 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]] H.P.Janecki, M.Janecka, H.G.Müller, U.Wendt: „Tribologia 4/1995 320-358,

m.p K

breakdown temp.

K

mass decrement

at breakdown

temp. 325 411 – 553 43.5%

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ExperimentalExperimental 11 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/dm3. 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.

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ExperimentalExperimental 12 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.

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ExperimentalExperimental 13 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).

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ExperimentalExperimental 14 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:

Element & Line

Weight Percent

Atomic Percent

*

Precisiony 3

SIGMA

K- RATIO**

S 9.21 16.73 0.10 0.0514 Fe 0.38 0.39 0.03 0.0046 Cu 90.41 82.88 0.35 0.8867

Table 3 EDS analysis results

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ExperimentalExperimental 15 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

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ExperimentalExperimental 16 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

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Summary 1Summary 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).

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Summary 2Summary 2Table 4 Percent share of sulphur and iron in 3SJ sulphide and on the surface

In compound On surface

C%S C%Fe C%S C%Fe

10.66 18.66 9.21 0.38%

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.

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Summary 3Summary 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.

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Summary 4Summary 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).

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Summary 5Summary 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]] H.P. Janecki, Ulrich Wendt „Instrumental Analysis in Tribology materials in preparing,

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Summary 6Summary 6 Table 5: Sequence of layers and their

thickness

Type of layer thickness of layer External adsorptive 0.0003 – 0.0005 µm

Oxide layer 0.01 – 0.1 µm Internal polished layer 0.1 µm

Considerable deformations

up to 2 µm

Average deformations up to 10 µm Slight deformations up to 50 µm

Core of the analysed material sample

1 m = 0.000001m = 10 4A ; 0.1m = 1000A, Electrons with the energy of ~ 25 keV penetrate the surface to the depth of ~ 1 – 1.5 m.