Details

Autor(en) / Beteiligte

• Hafner, Tom
• Heberle, Johannes
• Hautmann, Hubert
• Zhao, Rong
• Tenner, Jennifer
• Tremmel, Stephan
• Merklein, Marion
• Schmidt, Michael

Titel

Effect of Picosecond Laser Based Modifications of Amorphous Carbon Coatings on Lubricant-free Tribological Systems

Ist Teil von

• Journal of laser micro nanoengineering, 2017-09, Vol.12 (2), p.132-140

Ort / Verlag

Ibaraki: Japan Laser Processing Society

Erscheinungsjahr

2017

Link zum Volltext

Quelle

Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals

Beschreibungen/Notizen

• Motivated by the efficient usage of resources, friction and wear between tool and workpiece are increased by the abandonment of lubricants in metal forming processes. To substitute the functions of lubricants and to control the material flow in dry deep drawing processes surface modifications such as tetrahedral amorphous carbon (ta-C) coatings are essential. Local tailored tribological conditions can be realized by selective ultrashort laser based treatment of ta-C coatings. The effects of picosecond laser processing on the surface morphology, chemical and mechanical properties of the coatings are presented. The analysis of wavelength dependent threshold fluences for graphitization and ablation and the quality of ta-C coatings reveals that homogenous heat treatment and partial material removal can be achieved by processing with λ = 355 nm. The proper adjustment of fluence and pulse overlap enables heat treatment of the coating surface due to heat accumulation. The induced structural changes of the treated coating decrease elastic indentation modulus and affect the friction coefficient which is evaluated in flat strip drawing tests. Beyond that, laser structuring of the coated surfaces leads to either friction decrease or increase depending on the degree of coverage and the orientation of the microstructures.