Abstract
Lubricated reciprocating tests were conducted on an SRV tester to investigate effects of stroke and frequency on frictional and wear properties of flaky graphite cast iron used for marine cylinder liner by varying frequency and stroke under a given sliding velocity in boundary and mixed lubrication regime. It was clarified that changes in coefficient of friction were significantly dependent on stroke and frequency: in boundary lubrication, coefficient of friction at steady state showed a lower value at a combination of lower frequency and therefore larger stroke. In mixed lubrication, however, a combination of lower frequency and larger stroke produced a higher friction. In boundary lubrication where no run-in process was observed, higher frequency contributed to producing rougher surfaces resulting in higher friction. In mixed lubrication bordering on boundary lubrication higher frequency promoted run-in, enhancing film formation and lowering friction. Effects of frequency and stroke also reflected on wear, changes in separation voltage between a disk and a ball specimen, which were in accordance with changes in friction.
Highlights
Marine cylinder liner materials are investigated in terms of microstructure, surface topography, lubricity etc. to perform minimum friction and wear to meet increasing demands on reducing pollution and fuel costs [1,2,3,4,5]
Effects of stroke and frequency on reciprocating friction and wear of cylinder liner with different surface finish were studied by varying frequency and stroke under a given sliding velocity in boundary and mixed lubrication
The main results from this study are as follows: 1. There were two regimes in boundary lubrication depending on promotion of run-in
Summary
Marine cylinder liner materials are investigated in terms of microstructure, surface topography, lubricity etc. to perform minimum friction and wear to meet increasing demands on reducing pollution and fuel costs [1,2,3,4,5]. Many of investigations were conducted under reciprocating sliding because of their applications. It is quite often, that experimental backdrops of selecting specific frequency and stroke are left unclear. In reciprocating contacts which are subjected to non-steady sliding velocity, changes in frequency and stroke under a given sliding velocity should have different respective effects on oxide film and oil film formation. It is pointed out that oil film thickness at an acceleration and deceleration stage during one stroke were different from each other [7,8],demanding the need for newly building up EHL (Elastohydrodynamic Lubrication) theory as the present EHL theory is based on steady sliding velocity
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