The formation of carbon nanostructures byin situTEM mechanical nanoscale fatigue and fracture of carbon thin films

Abstract

A technique to quantify in real time the microstructural changes occurring during mechanical nanoscale fatigue of ultrathin surface coatings has been developed. Cyclic nanoscale loading, with amplitudes less than 100 nm, is achieved with a mechanical probe miniaturized to fit inside a transmission electron microscope (TEM). The TEM tribological probe can be used for nanofriction and nanofatigue testing, with 3D control of the loading direction and simultaneous TEM imaging of the nano-objects. It is demonstrated that fracture of 10-20 nm thick amorphous carbon films on sharp gold asperities, by a single nanoscale shear impact, results in the formation of <10 nm diameter amorphous carbon filaments. Failure of the same carbon films after cyclic nanofatigue, however, results in the formation of carbon nanostructures with a significant degree of graphitic ordering, including a carbon onion.

Dynamical Evolution of Wear Particles in Nanocontacts

“…Hence, the macroscopic laws of friction and wear generally do not apply to nanoscale contacts [6][7][8][9][10][11][12]. Some specific experimental evidence on the mechanisms of nanotribology has been recently emerging from careful experiments [13][14][15][16][17][18][19][20][21][22]. In situ TEM experiments have enabled direct observation of atomic scale wear [16], abrasive wear [17], abrasion of amorphous carbon films [18], gold contacts [19], recrystallisation [20] and interaction of a nanoparticle during nanoscale sliding experiments [21].…”

Influence of test methodology and probe geometry on nanoscale fatigue failure of diamond-like carbon film

“…[4][5][6][7][8][9][10][11][12][13][14][15][16]. These investigations take advantage of the features in the real time force-displacement (P-h), displacement-time (h-t) or stiffness curves recorded during repeated loading/unloading of bulk materials and thin films.…”

“…The third one is contact stiffness based evaluations as indicated by Bhushan and Li [4,13,17] where failure is defined as the change in contact stiffness of probe. A more recent development is the use of in-situ transmission electron microscopy (TEM) for nano-fatigue investigations by Wang et al [15] where phase transformations in thin carbon films were investigated. A different approach was adapted by Liou et al [18] for 545 nm thick SiO 2 film on Si wafer, where oscillating loads were used to evaluate the work required to delaminate the film.…”

NanoLAB Triboprobe: Characterizing Dynamic Wear, Friction and Fatigue at the Nanoscale

“…Here we have developed new functionality for combined scanning probe microscopy (TEM-SPM) which allows a miniaturized probe inside a TEM to do cyclic motion in three dimensions with precise control of the 3D position, speed and number of cycles [5][6]. By bringing the TEM probe into contact with a nanostructure under an electron beam, it is possible to observe in realtime the microstructural changes of a nanostructure during both uni-directional and cyclic loading [6][7][8][9].…”

“…By bringing the TEM probe into contact with a nanostructure under an electron beam, it is possible to observe in realtime the microstructural changes of a nanostructure during both uni-directional and cyclic loading [6][7][8][9]. The TEM tribological probe thus opens up the opportunity for real-time nanofriction and nanofatigue testing [6], with simultaneous TEM imaging of the nanoobjects under test. This in-situ nanoscale imaging capability is a significant advance over the traditional micro-and macro-scale tribological tests when investigating real-time microstructure evolution.…”