Enhanced DLC wear performance by the presence of lubricant additives

Romina Paula De Castro Costa,Vladimir Jesus Trava-Airoldi,Deiler Antônio Lima Oliveira,Fernanda Roberta Marcian

doi:10.1590/s1516-14392011005000023

Romina Paula De Castro Costa, Vladimir Jesus Trava-Airoldi + Show 2 more

Open Access

https://doi.org/10.1590/s1516-14392011005000023

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Abstract

Lubricant additives play significant role for reducing friction and wear of mechanical elements. The additives presented in 5W30 oil were developed for metal surfaces. However, they have been used in engine pieces covered with DLC coatings because they also offer the potential to reduce friction losses and wear in automotive applications. The friction and wear tests were carried out by using a UMT-CETR ball-on-disk tribometer in rotational mode under 5W30 synthetic oil at 100 °C. The X-ray photoelectron spectroscopy (XPS) showed the presence of Mo and S in the wear tracks. These elements are from decomposition of ZDDP and MoDTC additives producing MoS2 in DLC surface, which offers enhanced durability by low wear rate.

Highlights

The demand for more compact, efficient and powerful engines has stimulated the undergoing of studies for improvement these technological aspects
This study focuses on the combined effects of material pair and the nature of the lubricant additives
The 316L/DLC pair in air condition presented a friction coefficient around 0.18, while the wear rate decreased 20% compared to DLC/DLC pair in the same condition

Summary

Introduction

The demand for more compact, efficient and powerful engines has stimulated the undergoing of studies for improvement these technological aspects. Becker (2004) showed that inside the internal combustion engines, 15% of the total fuel energy is mechanically lost as friction[1]. Podgornik et al (2003) and Taylor (1998) conducted studies to investigate feasible alternatives towards the enhancement of engine efficiency, such as coatings in certain components, in attempt to minimize friction and wear[2,3]. According to Podgornik (2001) the coatings must have high levels of hardness, wear resistant surfaces, good frictional properties, and maintenance of mechanical resistance[4]. Some authors[3,4,8] mention several studies using DLC coatings in internal combustion engine components because of their excellent tribological behavior in severe environments. DLC has been mentioned as an applicable coating in valve lifters, obtaining good results for friction and wear[9,10]

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