Improving the Tribological Properties of Technical Polymers with Metal Sulphide Compounds

Andreas Hausberger,Florian Grün,Lars Hensgen,Clemens Kappl,Tanja Stiller

doi:10.3390/lubricants9090091

Abstract

Technical thermoplastic materials (e.g., PEEK, PPA and POM) are widely used for tribological applications combined with different filler systems (e.g., glass- or carbon fibres) because of their excellent mechanical properties. The friction and wear behaviour of thermoplastics can be specifically improved by solid lubrication systems such as graphite, PTFE and MoS2. Besides these systems, others such as WoS2 and MnS are becoming scientifically interesting. This work investigates the influence of different solid lubricants—alternative metal sulphides and polymer-based—in combination with different glass fibre contents on the tribological behaviour of unfilled PEEK and glass fibre-filled PPA. For this purpose, compounds were produced and injection-moulded into tribological test specimens that were subsequently tested. It is particularly evident for both matrix materials that the solid lubricant SLS 22 shows a 25% wear rate reduction when compared to MoS2 and, in addition, the proportion of fibre content in PPA shows an additional wear rate reduction by a factor of 10. The friction level could be kept at a similar level compared to the usually utilised solid lubricants. The investigations showed the potential use of metal sulphide filler systems in high-performance thermoplastic with enhanced tribological properties as alternatives to the well-established solid lubricants.

Highlights

The friction level could be kept at a similar level compared to the usually utilised solid lubricants
The investigations showed the potential use of metal sulphide filler systems in high-performance thermoplastic with enhanced tribological properties as alternatives to the well-established solid lubricants
For moving parts in furniture or bearings made of polymers, high friction is undesired, whereas, for instance, in emergency brake cases high friction is absolutely required [1,2,3,4]

Summary

Introduction

In the private sector as well as in industry, friction can be either a pleasant or an unwelcome factor. For moving parts in furniture or bearings made of polymers, high friction is undesired, whereas, for instance, in emergency brake cases high friction is absolutely required [1,2,3,4]. An undesired friction level for a certain application can cause high energy consumption as, for example, in requiring cooling systems due to the generated frictional heat. Further problems can occur in the case where high friction causes high wear, resulting in unavoidable maintenances to replace components [1,2,3]. An optimized material selection for a specific tribological application will result in a product with better performance and a longer lifetime

Objectives

Methods

Conclusion