How Tribo‐Oxidation Alters the Tribological Properties of Copper and Its Oxides

Lehmann, Julia; Schwaiger, Ruth; Rinke, Monika; Greiner, Christian

doi:10.1002/admi.202001673

Cited by 15 publications

(12 citation statements)

References 57 publications

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“…Apart from the tribolayer formation, the mixture of the original substrate with amorphous and nanocrystalline zones may further positively affect the tribological performance. 52 The microstructure underneath the tribolayer is highly deformed for all samples, evidenced by grain refinement.…”

Section: Resultsmentioning

confidence: 95%

“…In contrast, the tribolayer detected on the MXene-coated sample (Figure b,c and Supporting Information, Figure S5e–j) is smaller and presents more mechanical intermixing of the original substrate material with the formed tribolayer. Apart from the tribolayer formation, the mixture of the original substrate with amorphous and nanocrystalline zones may further positively affect the tribological performance . The microstructure underneath the tribolayer is highly deformed for all samples, evidenced by grain refinement.…”

Section: Resultsmentioning

confidence: 99%

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Superior Wear-Resistance of Ti₃C₂T_x Multilayer Coatings

et al. 2021

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Owing to MXenes’ tunable mechanical properties induced by their structural and chemical diversity, MXenes are believed to compete with state-of-the-art 2D nanomaterials such as graphene regarding their tribological performance. Their nanolaminate structure offers weak interlayer interactions and an easy-to-shear ability to render them excellent candidates for solid lubrication. However, the acting friction and wear mechanisms are yet to be explored. To elucidate these mechanisms, 100-nm-thick homogeneous multilayer Ti3C2T x coatings are deposited on technologically relevant stainless steel by electrospraying. Using ball-on-disk tribometry (Si3N4 counterbody) with acting contact pressures of about 300 MPa, their long-term friction and wear performance under dry conditions are studied. MXene-coated specimens demonstrate a 6-fold friction reduction and an ultralow wear rate (4 × 10–9 mm3 N–1 m–1) over 100 000 sliding cycles, outperforming state-of-the-art 2D nanomaterials by at least 200% regarding their wear life. High-resolution characterization verified the formation of a beneficial tribolayer consisting of thermally/mechanically degraded MXenes and amorphous/nanocrystalline iron oxides. The transfer of this tribolayer to the counterbody transforms the initial steel/Si3N4 contact to tribolayer/tribolayer contact with low shear resistance. MXene pileups at the wear track’s reversal points continuously supply the tribological contact with fresh, lubricious nanosheets, thus enabling an ultra-wear-resistant and low-friction performance.

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Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

Superior Wear-Resistance of Ti₃C₂T_x Multilayer Coatings

et al. 2021

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“…The COF of CuO was found to be ≈0.1 higher (≈0.27) than the COF of Cu 2 O (≈0.18). [ 27 ] One could speculate that this explains the higher COF at 150 °C, with the highest CuO surface coverage (Figure 3d), in comparison with the other experiments. However, the COFs for the 125 °C experiments are the lowest despite the larger surface coverage than for the 100 °C experiments.…”

Section: Discussionmentioning

confidence: 51%

“…Instead, a beneficial friction behavior of copper oxides in comparison with high‐purity copper was previously reported. [ 27 ] Hence, along with the formation of copper oxides, lower COFs are expected. Here, temperatures up to 100 °C led to thicker oxides, while above 100 °C, the oxide thickness decreased, along with the appearance of dark oxide areas.…”

Section: Discussionmentioning

confidence: 99%

Three Regimes in the Tribo‐Oxidation of High Purity Copper at Temperatures of up to 150 °C

et al. 2022

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Surface oxidation of high‐purity copper is accelerated under tribological loading. Tribo‐oxide formation at room temperature is associated with diffusion processes along defects, such as dislocations or grain boundaries. Herein, the additional influence of temperature on the tribo‐oxidation of copper is investigated. Dry, reciprocating sliding tests are performed with a variation of the sample temperature between 21 and 150 °C. Microstructural changes are monitored and analyzed with state‐of‐the‐art electron microscopy techniques. Oxide layer formation through thermal oxidation is observed for 150 °C, but not for lower temperatures. As the temperature increases from room temperature up to 100 °C, a significantly stronger tribo‐oxidation into deeper material layers and an increase in the amount of formed pores and oxides is detected. Up to 75 °C, diffusional processes of oxygen along grain boundaries and dislocation pipes are identified. Starting at 100 °C, CuO is detected. Hence, tribological loading significantly alters the CuO formation in comparison with static oxidation. Along with the CuO formation at temperatures ≥90 °C, the oxide layer thickness decreases while the friction coefficient increases. The observations broaden the understanding of the elementary mechanisms of tribo‐oxidation in copper. Eventually, this will allow to systematically customize surfaces showing tribo‐oxidation for specific tribological applications.

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“…7. EDS revealed an increase in oxygen content after the experiment which most probably is due to tribochemically assisted oxidation [14,39].…”

Section: Contact Charactermentioning

confidence: 98%

Variations in strain affect friction and microstructure evolution in copper under a reciprocating tribological load

Becker

Schulz

Scherhaufer

et al. 2021

Journal of Materials Research

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The microstructure of the materials constituting a metallic frictional contact strongly influences tribological performance. Being able to tailor friction and wear is challenging due to the complex microstructure evolution associated with tribological loading. Here, we investigate the effect of the strain distribution on these processes. High-purity copper plates were morphologically surface textured with two parallel rectangles—referred to as membranes—over the entire sample length by micro-milling. By keeping the width of these membranes constant and only varying their height, reciprocating tribological loading against sapphire discs resulted in different elastic and plastic strains. Finite element simulations were carried out to evaluate the strain distribution in the membranes. It was found that the maximum elastic strain increases with decreasing membrane stiffness. The coefficient of friction decreases with increasing membrane aspect ratio. By analyzing the microstructure and local crystallographic orientation, we found that both show less change with decreasing membrane stiffness. Graphic abstract

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How Tribo‐Oxidation Alters the Tribological Properties of Copper and Its Oxides

Cited by 15 publications

References 57 publications

Superior Wear-Resistance of Ti₃C₂T_x Multilayer Coatings

Superior Wear-Resistance of Ti₃C₂T_x Multilayer Coatings

Three Regimes in the Tribo‐Oxidation of High Purity Copper at Temperatures of up to 150 °C

Variations in strain affect friction and microstructure evolution in copper under a reciprocating tribological load

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How Tribo‐Oxidation Alters the Tribological Properties of Copper and Its Oxides

Cited by 15 publications

References 57 publications

Superior Wear-Resistance of Ti3C2Tx Multilayer Coatings

Superior Wear-Resistance of Ti3C2Tx Multilayer Coatings

Three Regimes in the Tribo‐Oxidation of High Purity Copper at Temperatures of up to 150 °C

Variations in strain affect friction and microstructure evolution in copper under a reciprocating tribological load

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Superior Wear-Resistance of Ti₃C₂T_x Multilayer Coatings

Superior Wear-Resistance of Ti₃C₂T_x Multilayer Coatings