Influence of a Diamond-Like Carbon-Coated Mechanical Part on the Operation of an Orbital Hydraulic Motor in Water

Ervin Strmčnik,Mitjan Kalin,Franc Majdič

doi:10.3390/met9040466

Abstract

The increasing focus on reducing the environmental impact of hydraulic applications has driven efforts to apply new surface-engineering technologies and replace classic lubricants with alternative solutions. In particular, water has gained increasing attention in recent years. However, water has very poor lubrication properties and, especially in combination with steel/steel contact, it leads to severe tribological behavior. A literature review and preliminary research showed that appropriate surface engineering regarding diamond-like carbon (DLC) coatings represents a promising solution to overcome the limitation of steel/steel contacts in water. Basic tribological ball-on-disc tests were performed. The result of the tribological investigation showed that there was very low friction and wear in the steel/DLC contact in water. This was our motivation for using DLC coating in a real hydraulic application. The DLC was deployed on the floating outer ring, so steel/DLC contacts between the floating outer ring and three other important parts were created. It was proven that the poor lubrication properties of the water were overcome with appropriate surface engineering. In such a case, the hydraulic motor operated satisfactorily when the water was applied as a working fluid.

Highlights

The growing levels of environmental awareness and the need for sustainable use [1] have encouraged scientists and engineers to focus more on improving the efficiency of technical solutions in recent years
In the first part is the total efficiency of the original hydraulic motor when it was tested in oil
The results represent reference values, and these values were later compared to the values of the total efficiency of the hydraulic motor when it was operated under different conditions in terms of contacts and fluids

Summary

Introduction

The growing levels of environmental awareness and the need for sustainable use [1] have encouraged scientists and engineers to focus more on improving the efficiency of technical solutions in recent years. The total efficiency is very much related to mechanical [10] and volumetric losses. Due to the moving parts in the machines, there are always contacts being formed that are very much related to tribological issues. Tribological conditions are more severe when water is used instead of oil [14]. Water has a lower viscosity and poorer lubrication properties [18,19]. These limitations can be overcome with an appropriate surface-engineering approach. Diamond-like carbon (DLC) is one of the possible solutions for improving tribological conditions in contacts [20,21,22]

Methods

Results

Discussion

Conclusion