Wear Behavior of CuSn Coated Piston Ring Sliding against Nodular Cast Iron Cylinder Liner under Heavy-Duty Conditions

Wenhua Li,Ruoxuan Huang,Baihong Yu,Fengming Du,Yan Shen,Yutao Lv

doi:10.3390/met9020139

Abstract

In order to investigate the friction and wear behavior between the nodular cast iron cylinder liner (Fe) and CuSn coated piston ring under heavy-duty conditions, piston rings with chromium(Cr) coating and CuSn-Cr coating were tested using the piston ring reciprocating liner test rig at the simulated working conditions of 56 MPa, 200 r/min, 190 °C. Compared with the Cr/Fe pair, the CuSn coating consumption of the CuSn-Cr/Fe pair made friction coefficient and cylinder wear loss decrease by 2.8% and 51.5%, respectively. Different size Sn patches worn from the CuSn coated piston ring were embedded into the cylinder liner surface based on the surface topography. This process was shown to reduce the surface roughness of a cylinder liner and form flatter plateau structures. Chemical elements analysis indicated that plateau structures on the cylinder liner surface matched with CuSn-Cr coated ring are helpful to promote the tribo-chemical reaction and generate the reactive products to protect the mutually contacted asperities.

Highlights

Piston ring and cylinder liner (PRCL) is one of the most important mating pairs in a diesel engine
Extreme pressure additives, such as zinc dialkyl dithiophosphates (ZDDP), will react with the micro-asperities to form a tribo-chemical film under the boundary lubrication [4,5,6]
Cr particles had peeled off from the piston ring, we found no evidence of contamination of the cylinder liner

Summary

Introduction

Piston ring and cylinder liner (PRCL) is one of the most important mating pairs in a diesel engine. Its tribological performance plays an important role in the normal operation of a diesel engine. Under normal circumstances, when the sliding velocity of the piston ring decreases in the vicinity of the top dead center, combustible gas will exert a high temperature and high pressure on the PRCL interface. The lubrication state of the PRCL will convert the hydrodynamic lubrication to the boundary lubrication. Extreme pressure additives, such as zinc dialkyl dithiophosphates (ZDDP), will react with the micro-asperities to form a tribo-chemical film under the boundary lubrication [4,5,6]

Methods

Results

Conclusion