Stress-enhanced dissolution and delamination wear of crystal CaF2 in water condition

Gong, Jian; Xiao, Chen; Yu, Jiaxin; Peng, Jinfang; Yu, Bingjun; Chen, Lei; Qian, Linmao

doi:10.1016/j.wear.2018.11.006

Cited by 7 publications

(5 citation statements)

References 39 publications

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“…Finally, besides interfacial forces, surface wear caused by frictional shear stress is likely to complicate the dynamics [4,159]. Tribochemical reactions may occur between water molecules and the solid surface when the activation energy of these reactions is reduced by an external mechanical action [5,[160][161][162][163][164][165][166][167]. The structure and surface energy of the adsorbed water layer on dynamically changing tribological interfaces may also play vital roles in the mechanochemistry involved in the material removal phenomenon.…”

Section: Perspectivesmentioning

confidence: 99%

Thickness and Structure of Adsorbed Water Layer and Effects on Adhesion and Friction at Nanoasperity Contact

Xiao

Shi

et al. 2019

Colloids and Interfaces

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Most inorganic material surfaces exposed to ambient air can adsorb water, and hydrogen bonding interactions among adsorbed water molecules vary depending on, not only intrinsic properties of material surfaces, but also extrinsic working conditions. When dimensions of solid objects shrink to micro- and nano-scales, the ratio of surface area to volume increases greatly and the contribution of water condensation on interfacial forces, such as adhesion (Fa) and friction (Ft), becomes significant. This paper reviews the structural evolution of the adsorbed water layer on solid surfaces and its effect on Fa and Ft at nanoasperity contact for sphere-on-flat geometry. The details of the underlying mechanisms governing water adsorption behaviors vary depending on the atomic structure of the substrate, surface hydrophilicity and atmospheric conditions. The solid surfaces reviewed in this paper include metal/metallic oxides, silicon/silicon oxides, fluorides, and two-dimensional materials. The mechanism by which water condensation influences Fa is discussed based on the competition among capillary force, van der Waals force and the rupture force of solid-like water bridge. The condensed meniscus and the molecular configuration of the water bridge are influenced by surface roughness, surface hydrophilicity, temperature, sliding velocity, which in turn affect the kinetics of water condensation and interfacial Ft. Taking the effects of the thickness and structure of adsorbed water into account is important to obtain a full understanding of the interfacial forces at nanoasperity contact under ambient conditions.

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Section: Perspectivesmentioning

confidence: 99%

Thickness and Structure of Adsorbed Water Layer and Effects on Adhesion and Friction at Nanoasperity Contact

Xiao

Shi

et al. 2019

Colloids and Interfaces

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“…The essential difference between the deformed and the annealed states lies in the dislocation content and arrangement. 18 The observed deformation of the lens surface also resembles, by its orientation and symmetry, the slip steps and cleavage steps observed on the deformed or indented CaF 2 (111) surfaces [21][22][23] and their possible step-crossing patterns. 24 The periodically varying regions of highs and lows after annealing coincide with a characteristic surface shape after mechanical processing of lens shapes (Fig.…”

Section: Discussionmentioning

confidence: 81%

Minimization of CaF2 spherical surface deformation caused by annealing

et al. 2021

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“…Since the elastic modulus and hardness of Ga-and N-faced surfaces are always close for the given penetration depth, the mechanical property should not be the key factor that leads to the different material removal behaviors between these two GaN substrates with different polarities. Previous studies revealed that, even in the purely elastic contact region, the mechanical shear stress can promote surface damage by accelerating the hydrolysis reaction of the chemical bonds of the substrate, which is called stress corrosion [22,43]. To verify whether the promotion of environmental water content on the removal rate of N-face is attributed to stress corrosion, the nanowear tracks were produced in dry air and high humidity conditions using the diamond AFM tip, where the contact pressures under these two conditions were the same and much lower than the plastic yield of GaN.…”

Section: Nanoindentation and Nanoscratching On Ga-and N-faced Gan Surfacesmentioning

confidence: 99%

“…The shear-induced formation of oxide and hydroxide layers on GaN surface with the aid of water molecules in high humidity conditions distinctly improved the removal rate by two orders of magnitude compared with that in dry air conditions, and the removal process was described as the mechanical abrasive removal of the continuously oxidized layer on GaN substrate. However, the mechanochemical removal and the stress corrosion-induced mechanical removal process are difficult to distinguish under the plastic yield contact situation [22,23]. Besides, the wurtzite GaN single crystal has a spontaneous polarization along the <0001> crystal orientation and exhibits two different polar faces with distinct polarization orientations, i.e., Ga-polar (0001) and N-polar (0001) crystal faces.…”

Section: Introductionmentioning

confidence: 99%

Mechanochemical reactions of GaN-Al2O3 interface at the nanoasperity contact: Roles of crystallographic polarity and ambient humidity

et al. 2021

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Mechanochemical reactions of the GaN-Al2O3 interface offer a novel principle for scientific and technological merits in the micro-/nano-scale ultra-precision surface machining. In this work, the mechanochemical reactions on Ga- and N-faced GaN surfaces rubbed by the Al2O3 nanoasperity as a function of the environmental humidity were investigated. Experimental results indicate that the N-face exhibits much stronger mechanochemical removal over the relative humidity range of 20%–80% than the Ga-face. Increasing water molecules in environmental conditions significantly promotes the interfacial mechanochemical reactions and hence accelerates the atomic attrition on N-face. The hypothesized mechanism of the selective water-involved mechanochemical removal is associated with the dangling bond configuration, which affects the mechanically-stimulated chemical reactions via altering the activation energy barrier to form the bonding bridge across the sliding interface. These findings can enrich the understanding of the underlying mechanism of mechanochemical reactions at GaN-Al2O3 interface and a broad cognition for regulating the mechanochemical reactions widely existing in scientific and engineering applications.

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Stress-enhanced dissolution and delamination wear of crystal CaF2 in water condition

Cited by 7 publications

References 39 publications

Thickness and Structure of Adsorbed Water Layer and Effects on Adhesion and Friction at Nanoasperity Contact

Thickness and Structure of Adsorbed Water Layer and Effects on Adhesion and Friction at Nanoasperity Contact

Minimization of CaF2 spherical surface deformation caused by annealing

Mechanochemical reactions of GaN-Al2O3 interface at the nanoasperity contact: Roles of crystallographic polarity and ambient humidity

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