Tribological behavior of polyamide 66/rice bran ceramics and polyamide 66/glass bead composites
Introduction
In recent years, development in the engineering of plastics has allowed thermoplastic resins to be used in parts of machine elements instead of metals. For use as triboelements, thermoplastic resins have often been combined with various fillers [1], [2], [3], [4], [5], [6], [7]. Solid lubricants, such as polytetrafluoroethylene, graphite, and molybdenum disulfide, bring low friction and either low wear due to the formation of lubricative transfer films [8], [9], or relatively high wear because of their removal [7], [10], [11], [12]. Fibrous fillers, such as carbon and glass fibers (GFs), can improve the mechanical properties and wear resistance of the matrix as a result of load support effects and high wear resistance of the fillers. Particulate fillers can also be useful for improving mechanical and tribological properties [13].
Rice bran ceramics (RBC), which is a hard porous carbon material, is made from rice bran [14]. RBC is manufactured by carbonizing a mixture of defatted rice bran and phenol resin in nitrogen gas at 900 °C. This ceramics material is composed of soft amorphous carbon corresponding to the defatted rice bran and hard glassy carbon corresponding to the phenol resin. RBC is a high-performance, multifunctional material offering high hardness (HV=4.4 GPa), high strength (σc=173 MPa), low density (ρ=1.26 Mg/m3), a porous structure, and low Young׳s modulus (E=11 GPa). Furthermore, RBC shows low friction and low wear under dry condition [15]. As a result, RBC particles are expected to find use as hybrid fillers that provide low friction and high wear resistance characteristics. In previous studies, thermoplastic resin/RBC composites were developed, and their friction and wear properties were experimentally ascertained [16], [17]. According to the study [16], five thermoplastic resins, namely, polyamide 66 (PA66), polyamide 11, polyoxymethylene, polybutylene terephthalate, and polypropylene, were used as matrix resins. Thermoplastic resin/RBC composites displayed lower friction and higher wear resistance compared with their pure resins. A PA66/RBC composite also showed superior tribological properties than a PA66/GF composite. The GF filler substantially improved the composite strength, although it did not improve the friction coefficient and wear. In another study [17], the effects of RBC particles on wear resistance of copper composites containing the particles were investigated. RBC particles improve the fracture toughness of the composite and reduce the friction coefficients, resulting in a mild wear mode. This indicates that RBC particles have great potential in industry as an anti-wear filler.
The tribological behaviors of glass-filled thermoplastic composites were reported [18]. Four forms of glass were used: GFs, hollow glass beads (GBs), solid GBs, and glass flakes. According to the results, the GF-filled composite and solid GB-filled composite showed the lowest wear, whereas the hollow GB-filled composite showed the highest wear.
Thus, it has been demonstrated that use of RBC particles or GBs as a filler improves the tribological properties, particularly the wear resistance, of thermoplastic resins. However, a comparison of RBC particles with GB fillers as low-friction and high-wear-resistant fillers has not been reported.
The present study investigated the fundamental tribological behavior of PA66 resin composites filled with either RBC particles or GBs at a wide range of normal loads and sliding velocities under dry condition. In addition, the utility of hard particulate fillers as low-friction and high-wear-resistant fillers is discussed.
Section snippets
Material preparation
The mean diameters of the RBC particles (Sanwa Yushi Co., Ltd., Japan) and GBs (Potters-Ballotini Co., Ltd., Japan) were 4.9 µm and 5.0 µm, respectively. The shape of the GBs was spherical, whereas that of the RBC particles was anisotropic, as shown in Fig. 1. The surfaces of the GBs were not treated with any coupling agent. The mechanical properties of both fillers are listed in Table 1. Each filler was compounded with pure PA66 by kneading at the same volume fraction of filler, i.e., 26 vol%.
Friction and wear properties of PA66/RBC and PA66/GB composites
Fig. 3 illustrates the typical variations in the friction coefficients plotted against the number of repeated passages. When the sliding velocity was 0.01 m/s and normal load was 1.96 N, the friction coefficients for pure PA66 increased gradually with more friction cycles and reached 0.50. Conversely, the PA66/RBC composite showed stable and low friction coefficient values. The friction coefficients for the PA66/GB composite showed middle values between those of the other materials. When the
Conclusions
- (1)
The values of friction coefficients for the PA66/RBC and PA66/GB composites were lower than those for pure PA66 at a sliding velocity of 0.01 m/s.
- (2)
High specific wear rates (>1×10−8 mm2/N) were observed for pure PA66 at low sliding velocities, which were unfavorable for use in a dry sliding bearing. In contrast, the wear rates of the PA66/RBC and PA66/GB composites were low (≤1×10−8 mm2/N), particularly at low sliding velocities.
- (3)
The use of RBC particles and GBs as hard particular fillers prevented
Acknowledgments
This work was supported by Japan Society for the Promotion of Science Grant-in-Aid for Scientific Research (No. 24360058). The authors would like to thank Tatsuhiro Urabe and Ryota Ifuku for their help in conducting the experiments.
References (22)
- et al.
Failure mechanisms in toughened epoxy resins―a review
Compos. Sci. Technol.
(1988) - et al.
Damping studies in fiber-reinforced composites―a review
Compos. Struct.
(1999) - et al.
Recent advances in polymer composites׳ tribology
Wear
(1995) - et al.
Effects of various fillers on the sliding wear of polymer composites
Compos. Sci. Technol.
(2005) Polymer-based bearing materials: the role of fillers and fiber reinforcement
Tribology
(1972)- et al.
Study of the friction and wear properties of MoS2-filled nylon 6
Wear
(1991) State-of-the-art of polymer tribology
Tribol. Int.
(1998)- et al.
Experimental study on microscopic wear mechanism of copper/carbon/rice bran ceramics composites
Wear
(2012) - et al.
The effect of fiber reinforcement on the friction and wear of polyamide 66 under dry rolling–sliding contact
Tribol. Int.
(1999) - et al.
Wear mechanisms in brittle solids
Acta Metall. Mater.
(1992)
Polymer materials and solid lubrication
J. Jpn. Soc. Tribol.
Cited by (23)
Evaluation of the polyamide's mechanical properties for varying infill percentage in FDM process
2022, Materials Today: ProceedingsCitation Excerpt :Automobile fields primary choice is PA 66 as an important member of the PA family [23], owing to higher stiffness and enhanced mechanical strength across various temperature levels, greater resistance to wear, excellent tribological properties, resistance against chemical hazards and self-lubrication. Therefore PA 66 is widely used in commercial applications and has its application in various sectors [24–25]. As per the literature survey being done, it is found that several researchers have studied and performed research on polymer materials with set of process parameters via FDM technique.
Mechanical and tribological characterization of lead calcium titanate borosilicate glass ceramic doped with ferric oxide
2018, Materials Today: ProceedingsSliding contact performance of injection moulded and selective laser sintered polyamide under dry and lubricated conditions
2023, Industrial Lubrication and TribologyEstimation of adhesive wear behavior of the glass fiber reinforced polyester composite materials using ANFIS model
2022, Journal of Elastomers and PlasticsAdditive Manufacturing of Polyamide 66: Effect of Process Parameters on Crystallinity and Mechanical Properties
2022, Journal of Materials Engineering and PerformanceInvestigation of adhesive wear properties of glass fiber reinforced polyester composites having different chemical compositions
2022, Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology