Static and Dynamic Friction of Spherographite Cast Iron with Sn Microalloy

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1 Static and Dynamic Friction of Spherographite Cast Iron with Sn Microalloy Mara Kandeva 1, Boryana Ivanova 2, Dimitar Karastoyanov 3, Emilia Assenova 4 1 Tribology Center, Technical University - Sofia, 2 Dept. Material Science and Technology, Technical University Sofia 3 Institute for Information and Communication Technologies, Bulgarian Academy of Sciences, Sofia 4 Society of Bulgarian Tribologists, Sofia

2 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.

3 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 Sn, % 0 0,018 0,020 0,032 0,051 НВ Table 1: Specimens Sn content and hardness HB

4 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

5 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 µm Normal loads Р 1 = 98,1 N; Р 2 = 196,2 N; Р 3 = 245,25 N; Р 4 = 294,3 N 0% Sn 0,018% Sn 0,02% Sn Р=98 N P=196 N P=245 N P=294 N статичен коефициент на триене µо 0,18 0,16 0,14 0,12 0,1 0,032% Sn 0,051% Sn нормално натоварване, P коефициент на триене µо 0,18 0,16 0,14 0,12 0,1 0 0,01 0,02 0,03 0,04 0,05 съдържание на калай, % Sn Fig.5. Static COF µ о vs normal load P Fig.6. Static COF µ о vs Sn content

6 Static Friction 2 скок на коефициента на триене Δµ 0,032 0,027 0,022 0,017 0,012 0,007 0, N 196 N 245 N 294 N 0 0,01 0,02 0,03 0,04 0,05 съдържание на калай % Sn Fig. 7. COF jump Δµ vs load P Fig. 8. COF jump Δµ vs Sn content статична сила на триене, N P=98 N P=196 N P=294 N Време на неподвижен контакт, s статична сила на триене, N P=98 N P=196 N P=294 N време на неподвижен контакт, s Fig. 9. Static friction force Т о vs static contact duration for specimen without Sn Fig.10. Static friction force Т о vs static contact duration for specimen with 0,051% Sn content

7 Static friction conclusion..

8 Dynamic friction 1 Fig. 2 Device for dynamic friction study: one way translation at various loads and sliding speeds коефициент на триене µ 0%Sn 0,018%Sn 0,02%Sn 0,032%Sn 0,051%Sn 0,1 0,08 0,06 0,04 0, нормално натоварване Р статична сила на триене, N P=98 N P=196 N P=294 N време на неподвижен контакт, s Fig.11.COF vs load P, sliding speed V = 7,2 cm/min for specimen without Sn Fig.12 COF vs Sn content P, sliding speed V = 7,2 cm/min for specimen with 0,051% Sn content

9 Dynamic friction 2 0% Sn 0,051% Sn 0% Sn 0,051% Sn коефициент на триене, µ 0,11 0,09 0,07 0, коефициент на триене µ 0,09 0,07 0,05 0, скорост на плъзгане V cm/min скорост на плъзгане V, cm/min 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

10 Conclusion 1. 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.

11 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 BG051PO 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.

12 THANK YOU FOR YOUR ATTENTION Mara Kandeva, Tribology Center, Dept., Technical University-Sofia, Boryana Ivanova, Dept. Material Science and Technology, Technical University-Sofia Dimitar Karastoyanov, Institute for Information and Communication Technologies, Bulgarian Academy of Sciences, Sofia, Emilia Assenova, Society of Bulgarian Tribologists,

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ANALYTICAL MODEL FOR FRICTION FORCE BETWEEN A STEEL ROLLER AND A PLANE POLYMER SAMPLE IN SLIDING MOTION

6 th International Conference Computational Mechanics and Virtual Engineering COMEC 015 15-16 October 015, Braşov, Romania ANALYTICAL MODEL FOR FRICTION FORCE BETWEEN A STEEL ROLLER AND A PLANE POLYMER