Fig . 5 . Static COF µ о vs normal load P

2nd Austrian-Indian-Symposium on Materials Science and TribologyWiener Neustadt, 26th – 29th May 2014

MaTri'14

Static and Dynamic Friction of Sphero-graphite Cast Iron with Sn Microalloy

Mara Kandeva1, Boryana Ivanova2, Dimitar Karastoyanov3, Emilia Assenova4

1Tribology Center, Technical University - Sofia, 2Dept. Material Science and Technology, Technical University – Sofia

3Institute for Information and Communication Technologies, Bulgarian Academy of Sciences, Sofia

4Society of Bulgarian Tribologists, Sofia

2nd Austrian-Indian-Symposium on Materials Science and TribologyWiener Neustadt, 26th – 29th May 2014MaTri'14

Introduction Sphero-graphite cast iron is a composite construction material with good mechanical characteristics. Sn microalloying improves of strength, hardness, etc., but also tribological characteristics friction and wear.Aim: study of the influence of Sn quantity in sphero-graphite cast iron during : preliminary displacement (static friction) and motion (dynamic friction). Tasks:1. Development of procedures and devices for static and dynamic dry friction study at various normal loads and sliding velocity;2. Study of friction force and coefficient at static friction and dynamic friction.


Materials, procedures and devices

Fig.1. Scheme of the device for static friction study

Fig.2. Scheme of the device for dynamic friction study

Specimen № 0 1 2 3 4

Sn, % 0 0,018 0,020 0,032 0,051

НВ 179 197 203 262 277

Table 1: Specimens’ Sn content and hardness HB


Materials, procedures and devices

Fig.3 Microstructure of the specimens:

(a) 0% Sn , (b) 0,018 % Sn, (c) 0,020 % Sn, (d) 0,032% Sn, (e) 0,051% Sn


Experimental: Static Friction 1

Sphero-graphite non-heated cast iron specimens, Sn content: 0%, 0.018%, 0.020%, 0.032%, 0.051%Counterbody: Steel alloy, НВ 450 ; roughness Ra = 0,432 µmNormal loads Р1 = 98,1 N; Р2 = 196,2 N; Р3 = 245,25 N; Р4 = 294,3 N

0,1

0,12

0,14

0,16

0,18

0 50 100 150 200 250 300стат

ичен

кое

фиц

иент

на

трие

не µ

о

нормално натоварване, P

0% Sn 0,018% Sn 0,02% Sn

0,032% Sn 0,051% Sn

0,1

0,12

0,14

0,16

0,18

0 0,01 0,02 0,03 0,04 0,05

коеф

ицие

нт н

а тр

иене

µо

съдържание на калай, % Sn

Р=98 N P=196 N P=245 N P=294 N

Fig.5. Static COF µо vs normal load P Fig.6. Static COF µо vs Sn content


Static Friction 2

0,0020,0070,0120,0170,0220,0270,032

0 0,01 0,02 0,03 0,04 0,05

скок

на

коеф

ицие

нта

на

трие

не Δ

µ

съдържание на калай % Sn

98 N 196 N 245 N 294 N

Fig. 7. COF jump Δµ vs load P Fig. 8 . COF jump Δµ vs Sn content

05

10152025303540

0 10 20 30 40 50стат

ична

сила

на

трие

не, N

Време на неподвижен контакт, s

P=98 N P=196 N P=294 N

05

101520253035

0 10 20 30 40 50стат

ична

сил

а на

три

ене,

N

време на неподвижен контакт, s

P=98 N P=196 N P=294 N

Fig. 9. Static friction force То vs static contact duration Fig.10. Static friction force То vs static contact duration

for specimen without Sn for specimen with 0,051% Sn content


Static friction conclusion …..


Dynamic friction 1

Fig. 2 Device for dynamic friction study: one way translation at various loads and sliding speeds

0,02

0,04

0,06

0,08

0,1

50 100 150 200 250 300коеф

ицие

нт н

а тр

иене

µ

нормално натоварване Р

0%Sn 0,018%Sn 0,02%Sn

0,032%Sn 0,051%Sn

Fig.11.COF vs load P, sliding speed V = 7,2 cm/min Fig.12 COF vs Sn content P, sliding speed V = 7,2 cm/min for specimen without Sn for specimen with 0,051% Sn content

05

101520253035

0 10 20 30 40 50стат

ична

сил

а на

три

ене,

N

време на неподвижен контакт, s

P=98 N P=196 N P=294 N


Dynamic friction 2

0,05

0,07

0,09

0,11

5 7 9 11 13 15коеф

ицие

нт н

а тр

иене

, µ

скорост на плъзгане V cm/min

0% Sn 0,051% Sn

0,03

0,05

0,07

0,09

5 7 9 11 13 15коеф

ицие

нт н

а тр

иене

µ

скорост на плъзгане V, cm/min

0% Sn 0,051% Sn

Fig.13. COF vs sliding speed at Р = 98 N load Fig.14. COF vs sliding speed at Р = 294 N load

Conclusion Dynamic friction


Conclusion1. Results are obtained for the variation of static and dynamic friction coefficient in function of load and Sn content in the cast iron. 2. Increasing of Sn leads to nonlinear decrease in static COF and friction jump passing through a minimum. 3. A minimum is also observed in the variation of the dynamic COF at small sliding speeds.


Acknowledgements

Part of the study is related to the 7 FP Project „Acom In (Advanced Computing Innovations)” coordinated by the Institute of Information and Communication Technologies at the Bulgarian Academy of Science and the project No BG051PO001-3.3.06-0046 “Development support of PhD students, postdoctoral researchers and young scientists in the field of virtual engineering and industrial technologies”. The project is realized with the financial support of the Operational Program Human Resources Development, co-financed by the European Union through the European Social Fund.


THANK YOU FOR YOUR ATTENTION

Mara Kandeva, Tribology Center, Dept., Technical University-Sofia, [email protected]

Boryana Ivanova, Dept. Material Science and Technology, Technical University-Sofia [email protected]

Dimitar Karastoyanov, Institute for Information and Communication Technologies, Bulgarian Academy of Sciences, Sofia, [email protected]

Emilia Assenova, Society of Bulgarian Tribologists, [email protected]


Slide 13


Slide 14


Slide 15, proba


THANK YOU FOR YOUR ATTENTION

Fig . 5 . Static COF µ о vs normal load P

Documents

Transcript of Fig . 5 . Static COF µ о vs normal load P