Anisotropy of selected properties of Al2O3-graphene composite

Piotr Klimczyk 1Sławomir Cygan 1Lucyna Jaworska 1Andrzej Olszyna 2Jerzy Morgiel 3Maciej Szlezynger 3

1. Institute of Advanced Manufacturing Technology (IOS), Wrocławska 37A, Kraków 30-011, Poland
2. Warsaw University of Technology, Faculty of Materials Science and Engineering, Woloska 141, Warsaw 02-507, Poland
3. Polish Academy of Sciences, Institute of Metallurgy and Materials Sciences (IMIM PAN), Reymonta 25, Kraków 30-059, Poland

Abstract

Alumina powder (Al2O3-α, grade A16SG, 0.3-0.6 µm, ALCOA) with addition of 0.3 wt% of MgO nanopowder (Inframat) has been used as a starting material. Multilayer graphene nanoplatelets  (average flake thickness <4  nm , <4 monolayers), average particle (lateral) size 1-2 µm, Cheap Tubes, USA), were used as filler for alumina based composites. The composites were sintered using Spark Plasma Sintering – SPS at 1550 °C during 10 min under 35 MPa of uniaxial pressure during the whole cycle. Sintered specimens were disk-shaped with dimensions of 20 mm in diameter and ~5 mm in thickness. Graphene participation was 0.5wt%, 1wt% and 2wt%. Selected physical and mechanical properties like: Vickers hardness with 9.8 N load, Young’s modulus, Poisson’s ratio measured by means of ultrasonic method, coefficient of friction for contact with a Al2O3 ceramic ball in ball-on-disc test and density were determined. Modulus of elasticity (Young’s modulus) of the tested composites was determined by measuring the transmission velocity of longitudinal and transversal ultrasonic waves through the sample. The SEM and TEM microstructural analysis show that the applied pressure during the sintering process (SPS) leads to the orientation of the graphene phase and in consequence to anisotropy of the composite. For example, for a composite with 2 wt% graphene , the hardness HV1 in the direction of the pressing axis is 15.5±0.2, and for the perpendicular direction to the pressing axis is 16.8±0.3. The microstructure, mechanical and tribological properties of the graphene reinforced Al2O3 ceramic, taking into account the direction of the measurement, are presented.

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Presentation: Poster at Nano PL 2014, Symposium A, by Sławomir Cygan
See On-line Journal of Nano PL 2014

Submitted: 2014-09-23 10:42
Revised:   2014-09-25 09:27
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