Microstructure properties of particles reinforced polytetrafluoroethylene composite bearings after wear
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 ima...
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| Zitieren: | Microstructure properties of particles reinforced polytetrafluoroethylene composite bearings after wear / B.S. Ünlü, M. Uzkut, A.M. Pi̇nar, K. Özdi̇n // Фізико-хімічна механіка матеріалів. — 2015. — Т. 51, № 2. — С. 48-52. — Бібліогр.: 30 назв. — англ. |
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Ünlü, B.S. Uzkut, M. Pi̇nar, A.M. Özdi̇n, K. 2018-06-14T07:53:58Z 2018-06-14T07:53:58Z 2015 Microstructure properties of particles reinforced polytetrafluoroethylene composite bearings after wear / B.S. Ünlü, M. Uzkut, A.M. Pi̇nar, K. Özdi̇n // Фізико-хімічна механіка матеріалів. — 2015. — Т. 51, № 2. — С. 48-52. — Бібліогр.: 30 назв. — англ. 0430-6252 https://nasplib.isofts.kiev.ua/handle/123456789/134743 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. Вивчено спеціальні полімери підвищеної довговічності, які можуть забезпечити бажані властивості для буксових підшипників, зокрема, зносотривкість. За допомогою оптичної та електронної мікроскопії досліджено мікроструктурні властивості матеріалів на політетрафторетиленовій основі після зношування. Изучены специальные полимеры повышенной долговечности, которые могут обеспечить желаемые свойства для буксовых подшипников, в частности, износостойкость. С помощью оптической и электронной микроскопии исследованы микроструктурные свойства материалов на политетрафторэтиленовой основе после износа. Acknowledgement. I would like to thank Ersel Obuz for editing the language of the manuscript. en Фізико-механічний інститут ім. Г.В. Карпенка НАН України Фізико-хімічна механіка матеріалів Microstructure properties of particles reinforced polytetrafluoroethylene composite bearings after wear Мікроструктурні властивості наповнених композиційних підшипників на політетрафторетиленовій основі після зношування Микроструктурные свойства наполненных композиционных подшипников на политетрафторэтиленовой основе после износа Article published earlier |
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Microstructure properties of particles reinforced polytetrafluoroethylene composite bearings after wear |
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Microstructure properties of particles reinforced polytetrafluoroethylene composite bearings after wear Ünlü, B.S. Uzkut, M. Pi̇nar, A.M. Özdi̇n, K. |
| title_short |
Microstructure properties of particles reinforced polytetrafluoroethylene composite bearings after wear |
| title_full |
Microstructure properties of particles reinforced polytetrafluoroethylene composite bearings after wear |
| title_fullStr |
Microstructure properties of particles reinforced polytetrafluoroethylene composite bearings after wear |
| title_full_unstemmed |
Microstructure properties of particles reinforced polytetrafluoroethylene composite bearings after wear |
| title_sort |
microstructure properties of particles reinforced polytetrafluoroethylene composite bearings after wear |
| author |
Ünlü, B.S. Uzkut, M. Pi̇nar, A.M. Özdi̇n, K. |
| author_facet |
Ünlü, B.S. Uzkut, M. Pi̇nar, A.M. Özdi̇n, K. |
| publishDate |
2015 |
| language |
English |
| container_title |
Фізико-хімічна механіка матеріалів |
| publisher |
Фізико-механічний інститут ім. Г.В. Карпенка НАН України |
| format |
Article |
| title_alt |
Мікроструктурні властивості наповнених композиційних підшипників на політетрафторетиленовій основі після зношування Микроструктурные свойства наполненных композиционных подшипников на политетрафторэтиленовой основе после износа |
| description |
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.
Вивчено спеціальні полімери підвищеної довговічності, які можуть забезпечити бажані властивості для буксових підшипників, зокрема, зносотривкість. За допомогою оптичної та електронної мікроскопії досліджено мікроструктурні властивості матеріалів на політетрафторетиленовій основі після зношування.
Изучены специальные полимеры повышенной долговечности, которые могут обеспечить желаемые свойства для буксовых подшипников, в частности, износостойкость. С помощью оптической и электронной микроскопии исследованы микроструктурные свойства материалов на политетрафторэтиленовой основе после износа.
|
| issn |
0430-6252 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/134743 |
| citation_txt |
Microstructure properties of particles reinforced polytetrafluoroethylene composite bearings after wear / B.S. Ünlü, M. Uzkut, A.M. Pi̇nar, K. Özdi̇n // Фізико-хімічна механіка матеріалів. — 2015. — Т. 51, № 2. — С. 48-52. — Бібліогр.: 30 назв. — англ. |
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48
Ô³çèêî-õ³ì³÷íà ìåõàí³êà ìàòåð³àë³â. – 2015. – ¹ 2. – Physicochemical Mechanics of Materials
MICROSTRUCTURE PROPERTIES OF PARTICLES REINFORCED
POLYTETRAFLUOROETHYLENE COMPOSITE BEARINGS
AFTER WEAR
B. S. ÜNLÜ 1, M. UZKUT 2, A. M. PİNAR 1, 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
49
Experimental studies. Preparation of experimental materials. In this study, the
pure PTFE, C-PTFE, B-PTFE and G-PTFE particle reinforced materials have been
used as journal bearing and SAE 1050 material as a shaft. The chemical compositions
of the journal material used in the experiments are (%): 0.51 C; 0.3 Si; 0.7 Mn; 0.04 P;
0.05 S; balance Fe. Dimensions of bearing specimens were as follows: inner diameter
(d = 10+0.05 mm), width (B = 10 mm), outer diameter (D = 15 mm).
The specimens have been worn and friction coefficients have been measured on
radial journal bearing wear test rig in dry conditions as described by Atik et al. [18] and
Ünlü and Atik [19]. The wear losses have been measured in dry conditions with 20 N
loads, 250 rpm (v = 0.130 m/s) and every 30 min for 2.5 h (1177.5 m sliding distance).
The specimens were cleaned by acetone. The microstructures of the specimens wear
surfaces have been photographed using the optical microscope (Hund Wetzlar
CCD-290) and scanning electron microscope (Jeol JSM-6060).
Radial journal bearing wear test rig. Bearings materials in journal bearings are
generally selected from materials which have lower wear strength than the shaft mate-
rial, thereby lowering the shaft wearing significantly. For this reason, journal bearing
wear test apparatus are designed to examine the wear of bearing materials. In this
study, a special bearing wear test apparatus has been designed to examine the wearing
of the bearing material and the shaft together. Therefore, it is possible to investigate
different bearing and shaft materials and also the effects of heat treatments on these
materials. Such a mechanism provides wear of bearings rather than using standard
methods as this is a more appropriate direction [18]. The system is formed by a weight
applied by a rigid bar, a steel bar connected to the bearing from a distance and a com-
parator. Friction coefficient is determined from the friction force formed along the rota-
ting direction of the bearing and the movement of the steel bar connected to the bearing
[19]. Radial wear test rig is illustrated in Fig. 1.
Fig. 1. Radial journal bearing wear test rig: 1 – comparator; 2 – rigid bar;
3 – load contact point (rolling bearing); 4 – journal sample;
5 – journal bearing samples; 6 – plate bar; 7 – motor; 8 – loads.
Results and discussion. Hardness values, surface roughness, friction coefficient,
bearing temperature, bearing weight loss, and bearing wear rate of PTFE bearings were
determined in our previous study [20]. These values are as follows hardness – 51; 61;
65 and 54 Share-D for PTFE, C-PTFE, B-PTFE and G-PTFE, respectively. Surface
roughness values are 1.59; 0.71; 1.1 and 3.95 µm for PTFE, C-PTFE, B-PTFE and
G-PTFE, respectively, before wear. Surface roughness values are 2.26, 0.78, 0.92 and
3.52 µm for PTFE, C-PTFE, B-PTFE and G-PTFE respectively after wear. Friction
coefficients were obtained between 0.2 and 0.3, bearing temperatures were measured
between 36 and 37 °C in all journal bearings. Bearing wear rate of pure bearing is
(mm3/Nm): 7.2⋅10–6; 4.7⋅10–6; 8.5⋅10–6, and 2.86⋅10–6 for PTFE, C-PTFE, B-PTFE and
G-PTFE, respectively [20].
After wear tests, the roughness of pure and C-PTFE bearings have increased, but
roughness values of B-PTFE and G-PTFE bearings decreased. Similarity between the
friction coefficient and bearing temperature of pure and filled PTFE bearings is the
50
result of PTFE coating on the filled materials surface and thus forcing this bearing to
act as pure PTFE bearing. Wear resistance of particle filled PTFE bearings increased
about 2…3 times because of particle reinforcement. Graphite, bronze, and glass rein-
forcement grains and wear surfaces were shown in the microstructure. These results are
supported by wear surface optical and SEM images (Figs. 2, 3). In this study, few ad-
hesive wear occurred for particle filled bearings, due to better wear resistance signifi-
cance of bronze, glass, and graphite solid lubrication property (Figs. 2, 3b–d), corres-
ponding properties for pure PTFE bearing (Figs. 2, 3a). In our previous studies [21,
22], we examined polymer based PE, PA, POM, pure PTFE, graphite, bronze and
glass-fiber reinforced PTFE, pure Bakelite and bronze and ferrous reinforced Bakelite
bearings [21]. We reported that particle reinforcement increased the wear resistance of
polymer bearings.
Fig. 2. Microstructure of wear surface:
a – PTFE; b – C-PTFE; c – B-PTFE;
d – G-PTFE. ×100.
Authors [23, 24] have investigated wear properties of PTFE composites. They
observed the less abrasive and adhesive wear in particle reinforced PTFE composites.
They reported that some materials, such as graphite and bronze powder as fillers could
effectively increase the wear life of PTFE-based composites. Also, graphite was a
potential of lubricants, which could also form a transfer film on the sliding surface. The
PTFE-filled composites showed much smoother surfaces than the same composites
filled with graphite.
Fig. 3. SEM Microstructure of wear surface:
a – PTFE; b – C-PTFE;
c – B-PTFE; d – G-PTFE.
Xiang et al. [25] have investigated friction and wear properties of PTFE compo-
sites. They reported that PTFE fabric composite exhibits a very low coefficient of fric-
tion, high wear resistance and less wear as compared to C86300 composite under simi-
lar testing conditions due to the solid lubricant structures of the two PTFE composites.
51
Khoddamzadeha et al. [26] have investigated bronze, carbon fiber and graphite
reinforced PTFE composites for sliding bearing applications. They found that these
fillers significantly improve the hardness and the wear resistance of PTFE. The hard-
ness of the PTFE composite is affected by the content level of the fillers and the fillers
hardness as well. They say: “The wear behavior of PTFE composites is a complex
phenomenon, which depends on the nature of the fillers, the content level of the fillers
present, and their morphology. The PTFE composites have friction coefficients similar
to pure PTFE. This may be attributed to the presence of a thin transfer film of PTFE on
the counter surface that enables the PTFE composites to maintain almost the same
frictional properties as pure PTFE”. They also observed that the adhesive wear of the
reinforced PTFE composites are less than that of pure PTFE.
Khan et al. [27] wrote that the physical and tribological properties were improved
by the use of PTFE micropowder in ethylene–propylene–diene–rubber (EPDM). They
observed agglomerated particles having a particle size even less than 0.5 mm in
microstructure.
Authors [28–30] have investigated carbon nanoparticle reinforced, carbon fibers
reinforced, and PA6 filled PTFE composites respectively. They reported that these
reinforcement materials decrease adhesive wear and improve wear resistance in PTFE
materials. In our study, we obtained similar adhesive wear surfaces in PTFE bearings.
In addition, in previous studies the authors [23–30] reported that these reinforced
polymer materials and bearings could be used in industry applications. This situation is
important for less bearing wear. The differences in our results and those of other
previous studies may be attributed to the fact that their materials were different from
the materials, used by us.
CONCLUSIONS
When wear surfaces of samples were examined by optical microscope and scan-
ning electron microscope, the adhesive wear of pure PTFE bearing sample were ob-
tained higher than those of the other filled PTFE bearings. Adhesive wear decreased in
particle filled bearings, because bronze, glass and graphite had better wear resistance
property and graphite solid lubrication properties. Consequently, surface wear proper-
ties of particle filled PTFE bearings were significantly improved.
РЕЗЮМЕ. Вивчено спеціальні полімери підвищеної довговічності, які можуть забез-
печити бажані властивості для буксових підшипників, зокрема, зносотривкість. За допо-
могою оптичної та електронної мікроскопії досліджено мікроструктурні властивості мате-
ріалів на політетрафторетиленовій основі після зношування.
РЕЗЮМЕ. Изучены специальные полимеры повышенной долговечности, которые мо-
гут обеспечить желаемые свойства для буксовых подшипников, в частности, износостой-
кость. С помощью оптической и электронной микроскопии исследованы микроструктурные
свойства материалов на политетрафторэтиленовой основе после износа.
Acknowledgement. I would like to thank Ersel Obuz for editing the language of the
manuscript.
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Received 04.03.2011
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