Fracture, fatigue, and sliding-wear behavior of nanocomposites of alumina and reduced graphene-oxide. (March 2020)

• Record Type: Journal Article
• Authors: Wang, Qizhong; Ramírez, Cristina; Watts, Connor S.; Borrero-López, Oscar; Ortiz, Angel L.; Sheldon, Brian W.; Padture, Nitin P.
• Is Part Of: Acta materialia. Volume 186(2020)
• Page Start: 29
• Page End: 39
• Publication Date: 2020-03
• Subjects: Alumina -- Graphene -- Toughness -- Fatigue -- Wear; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2019.12.035
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: There is growing interest in using 2D graphene-related reinforcements to toughen brittle ceramics in nanocomposites. However, there is a lack of fundamental understanding of the toughening mechanisms and microstructural effects in such nanocomposites. To address this paucity, fully-dense nanocomposites of aluminum oxide (Al2 O3 ) matrix and reduced graphene-oxide (rGO) reinforcements (~5 vol%) of different average-thicknesses and orientations are fabricated and characterized. The interactions between stably propagating cracks and rGO in the Al2 O3 /rGO nanocomposites are observed in situ inside a scanning electron microscope (SEM). Toughening by pullout of thick rGO in the crack-tip wake in the cross-section orientation is found to be the most effective, which is consistent with the highest fracture toughness ( K IC ~6.7 MPa.m 0.5 ) measured in those Al2 O3 /rGO nanocomposites. Interestingly, upon unloading and reloading, the intact rGO crack-bridges appear to crinkle and uncrinkle without a remnant crease, respectively, which is a unique deformation property of multi-layer graphene-like materials. This points to a possible new cyclic-fatigue resistance mechanism in those nanocomposites. Sliding-wear properties of the Al2 O3 /rGO nanocomposites are also studied, where the hardness and microstructural heterogeneities are found to play dominant roles. The results from this study have implications for the creation of high-toughness, fatigue-resistant, and wear-resistant graphene-reinforced ceramic nanocomposites of the future. Graphical abstract: Image, graphical abstract