title: Unoxidized graphene/alumina nanocomposite: fracture- and wear-resistance effects of graphene on alumina matrix.
abstract: It is of critical importance to improve toughness, strength, and wear-resistance together for the development of advanced structural materials. Herein, we report on the synthesis of unoxidized graphene/alumina composite materials having enhanced toughness, strength, and wear-resistance by a low-cost and environmentally benign pressure-less-sintering process. The wear resistance of the composites was increased by one order of magnitude even under high normal load condition (25 N) as a result of a tribological effect of graphene along with enhanced fracture toughness (KIC) and flexural strength (σf) of the composites by ~75% (5.60 MPa·m(1/2)) and ~25% (430 MPa), respectively, compared with those of pure Al2O3. Furthermore, we found that only a small fraction of ultra-thin graphene (0.25-0.5 vol%, platelet thickness of 2-5 nm) was enough to reinforce the composite. In contrast to unoxidized graphene, graphene oxide (G-O) and reduced graphene oxide (rG-O) showed little or less enhancement of fracture toughness due to the degraded mechanical strength of rG-O and the structural defects of the G-O composites.
authors.affiliation: 1] Icheon Branch, Korea Institute of Ceramic Engineering and Technology, Icheon, Republic of Korea [2] School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, Republic of Korea.
authors.forename: Hyo Jin
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Icheon Branch, Korea Institute of Ceramic Engineering and Technology, Icheon, Republic of Korea.
authors.forename: Sung-Min
authors.initials: SM
authors.lastname: Lee
authors.affiliation: Icheon Branch, Korea Institute of Ceramic Engineering and Technology, Icheon, Republic of Korea.
authors.forename: Yoon-Suk
authors.initials: YS
authors.lastname: Oh
authors.affiliation: Icheon Branch, Korea Institute of Ceramic Engineering and Technology, Icheon, Republic of Korea.
authors.forename: Young-Hwan
authors.initials: YH
authors.lastname: Yang
authors.affiliation: Energy and Environmental Division, Korea Institute of Ceramic Engineering and Technology, Seoul, Republic of Korea.
authors.forename: Young Soo
authors.initials: YS
authors.lastname: Lim
authors.affiliation: School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, Republic of Korea.
authors.forename: Dae Ho
authors.initials: DH
authors.lastname: Yoon
authors.affiliation: Department of Mechanical Engineering and SKKU Advanced Institute of Nanotechnology, Sungkyunkwan Univeristy, Suwon, Republic of Korea.
authors.forename: Changgu
authors.initials: C
authors.lastname: Lee
authors.affiliation: Icheon Branch, Korea Institute of Ceramic Engineering and Technology, Icheon, Republic of Korea.
authors.forename: Jong-Young
authors.initials: JY
authors.lastname: Kim
authors.affiliation: Department of Mechanical Engineering and the Materials Science and Engineering Program, The University of Texas, Austin, Texas, USA.
authors.forename: Rodney S
authors.initials: RS
authors.lastname: Ruoff