Lube-Tech PUBLISHED BY LUBE: THE EUROPEAN LUBRICANTS INDUSTRY MAGAZINE
No.110 page 1
Influence of polymeric friction modifiers in the lubrication of DLC contacts when used alone or in the presence of MoDTC
Croda’s polymeric friction modifiers (PFM) PerfadTM 3000,
Perfad 3006 and Perfad 3050 demonstrate unique frictional characteristics on steel-steel contacts and they also exhibit unique performance in DLC - steel contacts, helping to reduce friction and minimise wear.
It is very important to consider both friction and wear when conducting experiments, as low friction does not necessarily equate to low wear. Sometimes it can be observed that low friction is actually the direct result of high wear (as can be observed when using MoDTC), so additives which have the ability to reduce both friction and wear are highly desirable. Two pieces of work have been conducted to investigate the influence of friction modifiers on DLC lubricated surfaces, using a commercial moly-free 5W30 European Oil (ACEA C3) as a reference fluid: (1) Reciprocating sliding test – University of Leeds (2) Uni-directional sliding test – Croda.
Three different types of DLC coating have been investigated. Their approximate structure composition can be visualised in figure 1 and will be described in more detail.
Figure 2. Test arrangement for cast iron – a-C:H15 DLC plate flooded with lubricant
Figure 1. DLC triangle –
J.Robertson, Materials Science and Engineering, 2002 (129-281)
1.1 Friction as a Function of Time (5W30 ACEA C3 Oil) Polymeric friction modifiers have a positive influence in reducing friction in a sliding contact configuration of cast iron – aC:H15 DLC, when top-treated into the 5W30 ACEA C3 engine oil (figure 3). PFMs at a teat-rate of 0.5% resulted in a 5% reduction in friction, with 1% PFM contributing 20% reduction in friction.
LUBE MAGAZINE NO.139 JUNE 2017 33
1. Reciprocating Sliding Tests Work commissioned by Croda was undertaken at the University of Leeds, United Kingdom (Dr. Shahriar Kosarieh, Dr. Farnaz Motamen Salehi et al). The test arrangement was a reciprocating cast iron pin on a DLC plate. The coating was prepared by Oerlikon and was nominally a-C:H15 DLC coating applied to a HSS M2 grade steel plate. The pin was 20mm in length, 6 mm in diameter and had a 40mm radius curvature. The test was conducted at an oil temperature of 100ºC, reciprocating speed of 20mm/s and a frequency of 1 Hertz for 20 hours. A load of 390N was applied, giving an initial Hertzian pressure of 0.7GPa.
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72