High temperature mechanical properties and microstructure of hard TaSiN coatings

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:797

Article

Monclus, M. A.¹  Yang, L.²  Lopez-Cabanas, I^1,3  Castillo-Rodriguez, M.¹  Zaman, A.³  Wang, J.²  Meletis, E., I³  Gonzalez-Arrabal, R.^4,5  Llorca, J.^1,6  Molina-Aldareguia, J. M.¹ 

[1] IMDEA Mat Inst, C Eric Kandel 2, Madrid 28906, Spain

[2] China Aerodynam Res & Dev Ctr, Mianyang 621000, Sichuan, Peoples R China

[3] Univ Texas Arlington, Dept Mat Sci & Engn, Arlington, TX 76019 USA

[4] UPM, Inst Fus Nucl Guillermo Velarde, Jose Gutierrez Abascal 2, Madrid 28006, Spain

[5] ETSII UPM, Dept Ingn Energet, Jose Gutierrez Abascal 2, Madrid 28006, Spain

[6] Univ Politecn Madrid, Dept Mat Sci, ETS Ingenieros Caminos, Madrid 28040, Spain

关键词: Coatings;    Tantalum silicon nitride;    Magnetron sputtering;    High temperature hardness;    Toughness;   

DOI  :  10.1016/j.msea.2020.139976

来源: Elsevier

【 摘 要 】

Room and high temperature mechanical properties of reactive magnetron sputtered TaSiN coatings were measured using nanoindentation (between 25 degrees C and 500 degrees C). Fracture toughness was also evaluated at a similar temperature range using the micropillar splitting method. The influence of the nitrogen concentration on the evolving phases and microstructure of the TaSiN coatings, before and after the high temperature testing, were examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis. XRD spectra showed broad peaks with hexagonal gamma-Ta2N as the main phase, with the cubic delta-TaN phase emerging for higher N contents. Phase composition remained unchanged before and after the 500 degrees C tests. However, after the high temperature tests, TEM analysis showed the presence of an oxide surface layer, with a thickness that decreased (from 42 to 15 nm) with N content, due to residual oxygen diffusion, which replaces nitrogen to form amorphous SiOx. Beneath the oxide-rich surface layer, coatings exhibited a stable nanocrystalline columnar microstructure. Hardness and fracture toughness increased with N content, initially due to the formation of an amorphous Si-N tissue at grain boundaries, and for even higher N contents, due to the appearance of the hard cubic delta-TaN phase. Hardness at 500 degrees C decreased only by 15%, while fracture toughness followed the opposite trend, due to increased plasticity with temperature. The optimum composition turned out to be Ta55Si10N35, which retained a hardness of 30 GPa at 500 degrees C, being also the toughest. These observations make this system very interesting for high temperature applications.

【 授权许可】

Free