Carbon-based thin films possess unique and adjustable combination of properties such as high hardness and wear resistance, chemical resistance and good tribological performances Among critical variables to tailor a-C film’s properties for specific application is the distribution of the carbon hybridization states (sp 1 , sp 2 and sp 3 bonds), the atomic H content, the content in dopants such as Si, F, N, B and O Here we focus on: (i) a-C and hydrogenated amorphous carbon (a-C:H) films with a mixture of sp 2 and sp 3 bonding, highly sp 3 -boned material (ta-C) and sp 2 -bonded carbon, (ii) carbon nitride (CN x ) coatings and (iii) metal/amorphous carbon (a-C:M) composite films The study is focused on the review of the nanomechanical properties and analysis of the nanoscratching processes at low loads to obtain quantitative analysis, the comparison of their elastic/plastic deformation response, and nanotribological behavior of the a-C, ta-C, a-C:H, CN x , and a-C:M films For ta-C and a-C:M films new data are presented and discussed

Nanomechanical and nanotribological properties of carbon-based thin films: A review

https://air.unimi.it/bitstream/2434/211901/2/1-s2.0-S0040609097007396-main.pdf

Simulation of Berkovich nanoindentation experiments on thin films using finite element method

CrN, CrTiN, CrAlN and CrTiAlN coatings were deposited on Si (100) wafers, and their microstructure, mechanical properties, fracture toughness and adhesive strength were investigated via X-ray diffraction (XRD), nanoindentation and micro-scratch tests. Besides an F.C.C. crystal structure, TiN0.3 (004) and AlN (222) phases were found in the CrTiN and CrAlN coatings while the crystallinity of the CrTiAlN coating decreased. The hardness of the CrN (14.5 GPa), CrTiN (13.9 GPa) and CrAlN (17.7 GPa) coatings was determined by their grain sizes while the CrTiAlN coating with the most compact morphology exhibited the highest hardness of 22.0 GPa. In addition, CrTiN (KIc = 2.73 MPa· m ), CrAlN (KIc = 2.70 MPa· m ) and CrTiAlN coatings showed a stronger crack resistance than the CrN coating (KIc = 1.06 MPa· m ), especially the CrTiAlN coating without any radial cracks. However, the CrTiAlN coating encountered circumferential cracks and premature delamination (Adhesive energy Gc = 70 J/m2) because of its highest compressive stress (4.64 GPa). Based on the results here, it is concluded that a decent compressive stress of 3.0 GPa is expected to help thin films prevent from radial and circumferential cracks simultaneously.

Evaluating mechanical properties and crack resistance of CrN, CrTiN, CrAlN and CrTiAlN coatings by nanoindentation and scratch tests

https://estudogeral.sib.uc.pt/bitstream/10316/4231/1/file4bfba951540b41fdb54b59795a38455b.pdf

H. Bangert

Papers

Hardness measurements of thin films-determining the critical ratio of depth to thickness using FEM