Wear 466–467 (2021) 203558 Available online 25 November 2020 0043-1648/© 2020 Elsevier B.V. All rights reserved. Effect of grain fractions of crushed carbon foam on morphology and thermomechanical and tribological properties of random epoxy-carbon composites Urszula Szeluga a, * , Karolina Olszowska a , Sławomira Pusz a , Jerzy Myalski b , Marcin Godzierz b , Anastasiia Kobyliukh a , Boyko Tsyntsarski c a Centre of Polymer and Carbon Materials, Polish Academy of Sciences, Zabrze, M. Curie-Sklodowska str. 34, Zabrze 41-819, Poland b Silesian University of Technology, Department of Materials Science and Metallurgy, Krasinski str. 8, 40-019, Katowice, Poland c Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., BL. 9, 1113, Sofa, Bulgaria A R T I C L E INFO Keywords: Polymer-carbon composites Carbon foam Porous particle reinforcement Thermomechanical properties Friction coeffcient Wear characteristic ABSTRACT The effect of dimension of carbon foam (CF) grains used as a fller of epoxy matrix on the morphology and thermomechanical and tribological properties of fnal composites was described. The carbon foam proposed as particle reinforcement of composites was prepared from epoxy resin of diglycidyl ether of bisphenol A type cured with phenol-formaldehyde resin (novolac) in a self-foaming process followed by carbonization. Structures of the carbon foam fller and resultant composites were studied by microscopic and spectroscopic methods. Three different carbon foam grain fractions, below 200 μm, 200–315 μm and below 315 μm, keeping CF porous structure and specifc properties, were used to obtain new composite materials. There were observed good quality dispersion of CF grains in epoxy matrix and excellent adhesion at interfacial areas, regardless of carbon foam fraction. In the effect, these composites have enhanced thermomechanical and tribological properties and relatively low density compared to carbon-polymer composites produced so far. It was found that all CF fractions used reduced friction coeffcient of resultant composites compared to pure epoxy matrix, however the infuence of individual fller fraction on composite’s COF was different. The morphology of worn surfaces of epoxy composites after friction tests showed that the effect depends on grain fraction of CF fller as well as on the load used. 1. Introduction Despite intensive research on polymer composite materials since the middle of the last century, there is still a need for new high-performance materials. An effective way to achieve this goal seems to be choosing reinforcing constituents (fllers) for polymer matrices with a specifc structure and properties, which allows modeling the fnal composite’s parameters. An important group of composite materials is polymer- carbon composites composed of a polymer matrix and various forms of carbon, such as carbon fbers, carbon black, and graphite, have been widely used as fllers for a large spectrum of polymers [1,2]. Recently, carbon nanomaterials, i.e. nanofbers, nanotubes, graphene materials, and other forms of nanocarbons [3–5], have received widespread in- terest. The specifc type of carbon materials researched in this article is carbon foams (CFs), new generation materials characterized by a very high degree of porosity, even up to ~99%. CF morphology is described, on the one hand, by a system of porosity, i.e. total porosity, character of pores (open, closed), average pore size, and distribution of pores in the carbon matrix, and, on the other hand, by the solid matrix structure (ordered, unordered). There are numerous examples of applying various precursors and the production methods for carbon foams in the litera- ture [5–10] and other papers cited there. The porosity and structure of CFs, in turn, defne their properties. The most important properties of CFs are low density, high thermal stability, high sound wave, and electromagnetic wave absorption, etc. The structure, surface properties, and features of CFs differ from the previously mentioned carbon fllers, which creates opportunities for developing novel polymer-carbon composites with unique properties. Additionally, the presence of various functional moieties on the surface of carbon foams results in a good affnity for various polymer matrices. The properties of CFs may be * Corresponding author. E-mail address: uszeluga@cmpw-pan.edu.pl (U. Szeluga). Contents lists available at ScienceDirect Wear journal homepage: http://www.elsevier.com/locate/wear https://doi.org/10.1016/j.wear.2020.203558 Received 24 August 2020; Received in revised form 19 November 2020; Accepted 20 November 2020