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Ô³çèêî-õ³ì³÷íà ìåõàí³êà ìàòåð³àë³â. – 2015. – ¹ 2. – Physicochemical Mechanics of Materials

MICROSTRUCTURE PROPERTIES OF PARTICLES REINFORCED
POLYTETRAFLUOROETHYLENE COMPOSITE BEARINGS
AFTER WEAR

1
2
1
B. S. ÜNLÜ , M. UZKUT , A. M. PİNAR , K. ÖZDİN 3
1
Celal Bayar University, Faculty of Technology, Department of Mechanical and Manufacturing
Engineering, Turgutlu, Manisa, Turkey;
2
Celal Bayar University, Vocational High School, Department of Machinery, Turgutlu, Manisa, Turkey;
3
Hitit University, Engineering Faculty, Department of Mechanical Engineering, Çorum, Turkey
High-performance engineering polymers that ensure the desired properties for journal
bearings and give good wear results are investigated. In this study, microstructure
properties of polymer-based particle reinforced PTFE composite bearings have been
determined by optical and SEM wear surface images.
Keywords: wear, microstructure, polytetrafluoroethylene composite, bearing.
For the past few decades, polymeric materials have been widely used in industry.
Some of these materials are thermoplastics (polypropylene (PP), polyethylene (PE),
polyoxymethylene (POM), polytetrafluoroethylene (PTFE) and polyamide (PA) etc.).
The main advantage of these polymers is high wear and corrosion resistance. These
materials (PTFE) are especially used due to their good tribological properties and solid
lubricant properties in the food industry and due to their good performance in non-
lubricated dry conditions in journal bearings. PE has low density, high elasticity, and
strength. PA, POM and PTFE have good sliding and wear properties at low frictions.
Polyoxymethylene is a material which is generally used in engineering applications and
is highly self-lubricating [1–7].
PTFE bearings are frequently used in various machines due to their low friction
coefficients in boundary lubrication conditions. The major problems in designing
polymer bearings are selecting optimal dimensions and material type for a long life and
obtaining lower friction and wear losses. Tribological properties of polymer radial
bearings are affected by the adhesion on the surfaces of steel-polymer, cohesive cha-
racteristics of the polymers used and thermal effects in the friction area at high p–v
(pressure.velocity) values [8–10]. These (p.v) value are not valid for polymeric mate-
rials. Velocity is affected by applied pressure in these materials [11, 12]. Even though
some filler materials are added to the polymers, their effects on tribological properties
are not clearly known. There are different opinions in literature on how fillers affect the
polymer wear. These filler materials decrease wear by modifying the opposite surface
and supporting the load. This increasing effect on wear is due to increased adhesion.
They also reduce wear of the PTFE composites and can induce abrasive wear of the
counterface [13–15]. If polymeric materials are worn in abrasive conditions, wear rate
decreases with an increase in grit grade number [16].
Polymer-based PTFE materials can be used as journal bearings at low speeds [17].
The objective of this study is to determine the wear surface properties of the pure PTFE,
35% Graphite (C-PTFE), 60% CuSn10 (B-PTFE), and 25% glass-fiber (G-PTFE)
particle reinforced PTFE journal bearings at low speeds (v = 0.13 m/s).

Corresponding author: A. M. PİNAR, e-mail: ahmet.pinar@cbu.edu.tr
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