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Wear Behavior of Graphene-Reinforced Alumina–Silicon Carbide Whisker Nanocomposite

Nanomaterials(WoS, Q1, IF=3,504), 2019, Volume 9, Issue 2

 

Abstract. In the present work, the tribological properties of graphene-reinforced Al2O3-SiCw ceramic nanocomposites fabricated by spark plasma sintering were studied against alumina ball. Compared with pure ceramic, the wear resistance of these nanocomposites was approximately two times higher regardless of the applied load. It was confirmed by Raman spectroscopy that the main factor for the improvement of the wear resistance of the Al2O3-SiCw/Graphene materials was related to the formation of protecting tribolayer on worn surfaces, which leads to enough lubrication to reduce both the friction coefficient, and wear rate

Keywords. wear-resistance; friction coefficient; ceramic nanocomposites; graphene.

Friction coefficient as a function of the sliding distance registered during the wear test for both materials when worn against the alumina ball (A). Raman spectrum for worn surface of counterpart (Al2O3 ball), which shows transferred graphene (“D”, “G”, and “2D”) from the nanocomposites (B). “■” label denotes the alumina peak.

Исполнители: Anton Smirnov, Pavel Peretyagin, Nestor Washington Solís Pinargote, Iosif Gershman, Jose F. Bartolomé

Дата публикации: 25-01-2019

Источник: https://www.mdpi.com/2079-4991/9/2/151/htm

Mechanisms Involved in the Formation of Secondary Structures on the Friction Surface of Experimental Aluminum Alloys for Monometallic Journal Bearings

Lubricants(WoS), 2018, Volume 6, Issue 4

Abstract. The processes taking place on the friction surface of high-alloyed aluminum alloys working with steel whilst replacing bronze journal bearings with aluminum are investigated. In this regard, eight experimental aluminum alloys with an Sn content from 5.4% to 11.0%, which also included Pb, Zn, Si, Mg, and Cu, were cast. The surface and subsurface layer of experimental aluminum bearings were studied before and after tribological tests with a 38HN3MA steel counterbody by scanning electron microscopy including energy-dispersive analysis. The best aluminum alloy, which had an Sn content of 5.8% after the friction tests, showed 6.5-times better wear resistance and steel counterbody wear rate than the bronze reference. Both structural and compositional changes in the surface layer were observed. It was revealed that secondary structures formed on the surface during the friction process and included all of the chemical elements in the tribosystem, which is a consequence of its self-organization. Generally, the secondary structures are thin metal-polymer films generated as a result of the high carbon and oxygen content. The interaction behavior of some of the chemical elements in the tribosystem is shown and discussed. In addition, the influence that Sn, Pb, Cu, and C content in the secondary structures has on the tribological properties of low-tin and medium-tin alloys is shown.

Keywords. aluminum alloys; bronze; journal bearings; tribological alloys; friction; friction surface; secondary structures; self-organization.

AO-5.8 alloy surface. (a) Scanning Electron Microscope (SEM) image of surface structure before friction; (b) SEM image of surface structure after friction; (c) tin distribution map (energy-dispersive analysis (EDX)) on the friction surface; (d) calcium distribution map (EDX).

Исполнители: Pavel Podrabinnik , Iosif Gershman, Alexander Mironov, Ekaterina Kuznetsova, Pavel Peretyagin

Дата публикации: 28-11-2018

Источник: https://www.mdpi.com/2075-4442/6/4/104/htm

Spark plasma and conventional sintering of ZrO2-TiN composites: A comparative study on the microstructure and mechanical properties

MATEC Web of Conferences(WoS), 2018, Volume 224, Article Number 01055, Page 7

Abstract. Spark plasma sintering (SPS) is an extremely fast solidification technique for compounds that are difficult to sinter within the material group metals, ceramics or composites. SPS uses a uniaxial pressure and a very rapid heating cycle to consolidate these materials. This direct way of heating allows the application of very high heating and cooling rates, enhancing densification over grain growth promoting diffusion mechanisms allowing maintaining the intrinsic properties of nanopowders in their fully dense products. The ZrO2-TiN cermets prepared by SPS processing achieves the enhanced mechanical properties with the hardness of 15.1 GPa and the fracture toughness of 9.1 MPa∙m1/2 in comparison to standard reference ZrO2-TiN material.

SEM images of polished and thermally etched sections of SPS sintered (1300°C (a), 1400°C (b) and 1500°C (c)) ZrO2 composites.

Исполнители: Y. Pristinskiy, W. Solis, A. Smirnov

Дата публикации: 30-10-2018

Источник: https://www.matec-conferences.org/articles/matecconf/abs/2018/83/matecconf_icmtmte2018_01055/matecconf_icmtmte2018_01055.html