Effect of Fiber Shape on the Tribological, Mechanical, and Morphological Behaviors of Sisal Fiber-Reinforced Resin-Based Friction Materials: Helical, Undulated, and Straight Shapes.

Jian Zhuang,Qian Wu,Mingzhuo Guo,Siyang Wu,Jiale Zhao

doi:10.3390/ma14185410

Abstract

In this paper, we aim to evaluate the tribological, mechanical, and morphological performance of resin-based friction composites reinforced by sisal fibers with different shapes, namely helical, undulated, and straight shapes. The experimental results show that the shape of the sisal fibers exerts a significant effect on the impact property of the composite materials but no obvious influence on the density and hardness. The friction composite containing the helical-shaped sisal fibers exhibits the best overall tribological behaviors, with a relatively low fade (9.26%), high recovery (98.65%), and good wear resistance (2.061 × 10−7 cm3∙N−1∙m−1) compared with the other two composites containing undulated-shaped fibers and straight-shaped fibers. The impact fracture surfaces and worn surfaces of the composite materials were inspected by scanning electron microscopy, and we demonstrate that adding helical-shaped sisal fibers into the polymer composites provides an enhanced fiber–matrix interface adhesion condition and reduces the extent of fiber debonding and pullout, effectively facilitating the presence of more secondary plateaus on the friction surface, which are responsible for the enhanced tribological and mechanical properties. The outcome of this study reveals that sisal fibers with a helical shape could be a promising candidate as a reinforcement material for resin-based brake friction composite applications.

Highlights

Friction materials, as important parts of the brake system, are extensively used in the automotive, railway, air, and other similar transport fields [1,2]
As the above performance requirements cannot be satisfied by a single component, friction materials are usually manufactured as multi-component polymer composites, which contain at least 10 raw elements
The composites FMSF, FMUF, and FMHF exhibited roughly similar density values, almost all around 2.21 g/cm3, indicating that the sisal fiber shapes exerted no obvious effect on the density of the polymer composite systems

Summary

Introduction

As important parts of the brake system, are extensively used in the automotive, railway, air, and other similar transport fields [1,2]. As the above performance requirements cannot be satisfied by a single component, friction materials are usually manufactured as multi-component polymer composites, which contain at least 10 raw elements. According to their diverse functions in the friction materials, these raw elements are essentially divided into the following categories: reinforcement fibers, phenolic binders, friction modifiers (abrasives and lubricants), and particulate fillers (functional and inert) [6,7]. Metallic fibers (such as copper fiber and steel fiber) and synthetic fibers (such as aramid fiber and glass fiber) and their combinations were gradually applied in the friction material manufacturing industries [12,13,14] These metallic and synthetic fibers as non-biodegradable materials adversely affect the water and air environment during their use and disposal. Recent trends have demonstrated a need for environmental sustainability and natural fibers are gaining significance as reinforcement components in friction composite systems

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Conclusion