Paleo-tribology: development of wear measurement techniques and a three-dimensional model revealing how grinding dentitions self-wear to enable functionality

Erickson, Gregory M.; Sidebottom, Mark A.; Curry, John F.; Kay, David Ian; Kuhn-Hendricks, Stephen; Norell, Mark A.; Sawyer, W. Gregory; Krick, Brandon A.

doi:10.1088/2051-672x/4/2/024001

Cited by 27 publications

(19 citation statements)

References 56 publications

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“…, where A is the average worn cross-sectional area, F n is normal force, and N is number of cycles 71 . The associated uncertainty in reported specific wear rate is discussed elsewhere 72 .…”

Section: Methodsmentioning

confidence: 99%

Evidence of Inverse Hall-Petch Behavior and Low Friction and Wear in High Entropy Alloys

Jones

Nation

Wellington-Johnson

et al. 2020

Sci Rep

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We present evidence of inverse Hall-petch behavior for a single-phase high entropy alloy (cocrfeMnni) in ultra-high vacuum and show that it is associated with low friction coefficients (~0.3). Grain size measurements by STEM validate a recently proposed dynamic amorphization model that accurately predicts grain size-dependent shear strength in the inverse Hall-Petch regime. Wear rates in the initially soft (coarse grained) material were shown to be remarkably low (~10-6 mm 3 /n-m), the lowest for any HEA tested in an inert environment where oxidation and the formation of mixed metal-oxide films is mitigated. the combined high wear resistance and low friction are linked to the formation of an ultra-nanocrystalline near-surface layer. The dynamic amorphization model was also used to predict an average high angle grain boundary energy (0.87 J/m 2). this value was used to explain cavitationinduced nanoporosity found in the highly deformed surface layer, a phenomenon that has been linked to superplasticity. Since their discovery in 2004 1,2 , high entropy alloys (HEAs) have been extensively investigated and shown to exhibit remarkable thermomechanical properties 3,4. Studies of grain-size dependent mechanical behavior are limited 5,6 , however, especially in the regime of ultra-nanocrystalline grain size where softening (i.e. inverse Hall-Petch behavior) occurs. Recent work has also shown that these alloys are ideally suited for processing using laser-based additive manufacturing techniques 7-9 , as they exhibit high phase stability and derive much of their strength from thermal history-insensitive mechanisms like solution strengthening 10. While recent publications have presented experimental evidence of low friction or high wear resistance (but typically not both) with HEAs 11-25 , they were performed in environments where oxidation and the formation of mixed metal-oxide surface films was prevalent. These phenomena can greatly impact strength and deformation/wear resistance. We show that in an ultra-high vacuum (UHV) environment, i.e., in the absence of chemically reactive species, an additively manufactured initially coarse grained (soft), single-phase HEA exhibited a tendency toward low friction coefficients (i.e., low shear strength) and some of the lowest wear rates currently reported for these materials. The low friction and wear are attributed to a propensity for extreme grain refinement under sliding contact. Specifically, we present evidence of that this high strain rate shear leads to dynamic amorphization and inverse Hall-Petch behavior in the surface layer. In the present context of sliding contacts, dynamic amorphization refers to the continuous shear-induced generation of a structurally amorphous layer that accommodates deformation 26. This is in competition with stress-and temperature-driven grain growth and recrystallization, all of which reestablish crystallinity and order in the shear layer. The shear layer must be amorphized again in subsequent contact passes, thus we refer to this process as dynam...

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Section: Methodsmentioning

confidence: 99%

Evidence of Inverse Hall-Petch Behavior and Low Friction and Wear in High Entropy Alloys

Jones

Nation

Wellington-Johnson

et al. 2020

Sci Rep

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“…The stage rotation step of 3° was used to achieve a full profilometric scan. Then Archard wear rate was used for deriving the wear rate 35 . Five line scans within each single profilometric scan were made to get data that is statistically representative of the local material wear properties 36 .…”

Section: Methodsmentioning

confidence: 99%

Crystal Orientation Dependence of Gallium Nitride Wear

Zeng¹,

Sun²,

Song³

et al. 2017

Sci Rep

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We explore how crystallographic order and orientation affect the tribological (friction and wear) performance of gallium nitride (GaN), through experiments and theory. Friction and wear were measured in every direction on the c-plane of GaN through rotary wear experiment. This revealed a strong crystallographic orientation dependence of the sliding properties of GaN; a 60° periodicity of wear rate and friction coefficient was observed. The origin of this periodicity is rooted in the symmetry presented in wurtzite hexagonal lattice structure of III-nitrides. The lowest wear rate was found as 0.6 × 10−7 mm3/Nm with <100>, while the wear rate associated with <110> had the highest wear rate of 1.4 × 10−7 mm3/Nm. On the contrary, higher friction coefficient can be observed along <100> while lower friction coefficient always appeared along <110>. We developed a simple molecular statics approach to understand energy barriers associated with sliding and material removal; this calculated change of free energy associated with sliding revealed that there were smaller energy barriers sliding along <110> as compared to the <100> direction.

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“…Tests were performed for 10 k bidirectional sliding cycles at normal loads of 10 mN, 100 mN, and 1 N, with a new, unworn sapphire sphere used for each load. A custom-built microtribometer, similar in design to those described by Krick et al [41], and Erickson et al [42], was used to acquire normal and tangential forces at a data acquisition rate of 500 Hz. The friction coefficient, μ, was calculated as the ratio of tangential (friction) force to applied normal force.…”

Section: Materials Description and Tribological Test Methodsmentioning

confidence: 99%

“…The stitching feature on the Vision64 software was employed at both 10 × and 1 × magnifications to measure topographical data with approximately 1 nm vertical and 1 µm lateral resolutions. Average cross-sectional topographical data was used to calculate the specific wear rate, K = A F n ⋅N ⋅ 10 3 mm m , as the ratio of average worn area (A) to the product of normal force (F n ) and number of bidirectional sliding cycles (N) [40,42]. Details of reported uncertainty in specific wear rates are discussed elsewhere [42].…”

Section: Microscopy and Microstructure Characterization Techniquesmentioning

confidence: 99%

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Environment-Dependent Tribological Properties of Bulk Metallic Glasses

Jones

Kustas

et al. 2020

Tribol Lett

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The macroscale friction and wear properties of the Zr 44 Cu 10 Ni 10 Ti 11 Be 25 metallic glass were investigated as a function of environmental oxygen concentration and contact force. We found remarkably low and predictable friction when both oxidation and frictional heating (that can lead to thermomechanically-driven crystallization) were supressed. Conversely, oxidation and the formation of a mixed metal-oxide layer was shown to increase the friction coefficient while significantly reducing wear rates. Depending on conditions, the wear rates ranged from values comparable to highly wear-resistant materials like polymer and 2D solid lubricant nanocomposites to those that are found with soft, pure, high-wear metals. These results reveal that the competition between material removal and the deformation-induced mixing of oxide particles can dramatically reduce wear rates, suggesting opportunities for optimization of tribological performance.

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Paleo-tribology: development of wear measurement techniques and a three-dimensional model revealing how grinding dentitions self-wear to enable functionality

Cited by 27 publications

References 56 publications

Evidence of Inverse Hall-Petch Behavior and Low Friction and Wear in High Entropy Alloys

Evidence of Inverse Hall-Petch Behavior and Low Friction and Wear in High Entropy Alloys

Crystal Orientation Dependence of Gallium Nitride Wear

Environment-Dependent Tribological Properties of Bulk Metallic Glasses

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