The kinetic frictional shear stress of ZnO nanowires on graphite and mica substrates

Abstract

The frictional shear stress between a nanostructure and a smooth substrate plays a crucial role in the development of nanodevices; however, it is extremely difficult to measure. In this work, the kinetic frictional shear stress of hexagonal ZnO nanowires on graphite and mica substrates was measured in an ambient atmosphere by optical microscope based nanomanipulation. Both substrates have similar surface roughness values of sub-angstrom-scale and interfacial adhesion energies with ZnO nanowires. Yet, a kinetic frictional shear stress of 0.51 MPa was obtained for the ZnO-graphite system, significantly lower than that of 5.1 MPa for the ZnO-mica system. The results demonstrate that the kinetic friction at a perfectly smooth contact interface may not be controlled by the adhesion, whilst being commonly referred to as adhesive friction or adhesion-dominated fiction. Similar to the combining equations for adhesion, we propose two empirical combining equations to estimate the frictional shear stress between two smooth surfaces using results more simply obtained from a reference surface. The validity of the equations is supported by our experimental results and recently published data for atomically smooth interface systems obtained under the similar environmental conditions.

Graphitic carbon nitride with different dimensionalities for energy and environmental applications

“…Quantum dots, nanoparticles and nanopowders are the few examples of 0D materials [3][4][5]. Materials are considered as 1D materials in which one dimension is outside the nanoscale wherein electrons have confinement in two directions and nanowires, nanotube and nanorod are all typical 1D materials [6][7][8][9][10][11][12]. The 2D materials refer to the materials in which electrons are confined at a non-nanoscale, such as nanofilm, nanosheet, superlattice and quantum well [13][14][15][16][17][18][19][20][21][22][23][24][25][26].…”

The Shearing Behavior of Nanowire Contact Pairs in Air and the Role of Humidity

“…The NW have a single‐crystalline cubic structure grown along the [111] direction and usually exhibit hexagonal cross sections. [ 58,59 ] The frictional behavior between two individual SiC NWs was characterized by an OM‐based nanomanipulation system, as shown in Figure a. The whole testing system was placed in a home‐made polymethyl methacrylate chamber ( 3 ) with a door for sample transfer and two gas outlets for humidity control.…”

“…Testing was carried out using an electrochemically etched tungsten (W) tip (200 diameter) via an adhesion‐assisted pick‐and‐place assembly technique with direct visual feedback provided by OM (Lens: Mitutoyo M Plan APO 50×). [ 43,55,56,58,59 ] Fine positioning was achieved by mounting the W tip to a NanoCube nanopositioner that provides three‐axis continuous movements ( P ‐616.3C, Physik Instrumente; closed‐loop resolution: ≈0.4 ; travel range: per axis; linearity error: ). The NanoCube was mounted onto a low‐resolution positioner to enable coarse movement of the tip.…”

Lateral Bending of Ag Nanowires toward Controllable Manipulation

“…Adhesion exists widely in nanoscale contact and can be affected by the sliding velocity of a nanoscale tip. 23,24 Such adhesion would play an important role in governing interfacial interactions between the NW and the substrate (or the tip). For instance, SPM is inefficient in manipulating an individual NW due to the adhesion between the NW and the substrate (or the tip), resulting in the inability to drive NWs at times.…”

“…Even though SPM provides much flexibility for NW manipulation, the underlying issues, including interfacial interactions and mechanical performances at the nanoscale, remain to be fully investigated and clarified for controllable manipulation and assembly of NWs. Adhesion exists widely in nanoscale contact and can be affected by the sliding velocity of a nanoscale tip. , Such adhesion would play an important role in governing interfacial interactions between the NW and the substrate (or the tip). For instance, SPM is inefficient in manipulating an individual NW due to the adhesion between the NW and the substrate (or the tip), resulting in the inability to drive NWs at times .…”