Tribological characteristics, phase composition and microhardness of subsurface regions of WC – (Fe – Mn – C) composites after high-speed sliding on steel

The authors investigated tribological characteristics, phase composition of friction surfaces and microhardness of near-surface regions of WC – (Fe – Mn – C) composites with a two-phase (γ + α′) matrix containing 4 % wt. Mn (WC – 80G4), and a single-phase matrix of γ-iron containing 20 % wt. Mn (WC – 80G20) after friction on a disk of high-speed steel at a contact pressure of 5 MPa and sliding speeds in the range from 10 to 37 m/s. The wear intensity of WC – 80G4 and WC – 80G20 increased with increasing sliding speed, while the wear rate of WC – 80G20 at fixed sliding speeds was approximately three times higher than that of WC – 80G4. The values of the friction coefficient decrease with increasing sliding speed in such a way that at fixed sliding speeds the values of the friction coefficient of WC – 80G4 were lower than those of WC – 80G20. The amount of complex oxide FeWO₄ formed during tribo-oxidation of the composites’ worn surface increased with the sliding speed and was directly proportional to the wear intensity and inversely proportional to the friction coefficient values. At fixed sliding speeds, tribooxidation of WC – 80G4 leads to the formation of a larger amount of FeWO₄ on the friction surface, compared to the WC – 80G20 composite. Indentation of worn surfaces with a Vickers pyramid showed that the nature of indentation resistance of tribolayers formed at high sliding speeds (30 m/s and 37 m/s) differs from that for tribolayers obtained at relatively low sliding speeds (10 and 20 m/s), namely, the friction surfaces after high sliding speeds were characterized by a more tough behavior. Measurement of microhardness values of the WC – 80G4 and WC – 80G20 composites obtained after indentation from the friction surface into the depth of the material recorded the fact of hardening of the near-surface regions of the WC – 80G4 composites and, on the contrary, softening in the case of WC – 80G20. Thus, under conditions of strong heating and severe plastic deformation of the surface, structural-phase state of the substrate of WC – (Fe – Mn – C) composites, on which this viscous protective tribolayer is formed, turns out to be a very important factor. It is the two-phase (γ + α′) steel matrix that, under conditions of strong frictional heating, provides the conditions for effective formation of a heterophase composite layer that reduces the friction coefficient and has a high resistance to fracture upon indentation.

1. Kübarsepp J., Juhani K. Cermets with Fe-alloy binder: A review. International Journal of Refractory Metals and Hard Materials. 2020, vol. 92, article 105290. https://doi.org/10.1016/j.ijrmhm.2020.105290

2. Zhang X., Yang F., Zeng C., Ma W., Guo Z. Fabrication and properties of TiC-high manganese steel cermet processed by 3D gel printing. Journal of Materials Science. 2021, vol. 56, no. 25,

3. pp. 19709–19722. https://doi.org/10.1007/s10853-021-06563-0

4. Li G., Jia J., Lyu Y., Zhao J., Lu J., Li Y., Luo F. Effect of Mo addition mode on the microstructure and mechanical properties of TiC–high Mn steel cermets. Ceramics International. 2020, vol. 46, no. 5, pp. 5745–5752. https://doi.org/10.1016/j.ceramint.2019.11.023

5. Savchenko N.L., Gnyusov S.F., Kul’kov S.N. Structures formed during the friction of a metal-ceramic composite on steel under high-velocity sliding conditions. Technical Physics Letters. 2009, vol. 35, pp. 107–110. https://doi.org/10.1134/S1063785009020035

6. Kumar R., Antonov M. Self-lubricating materials for extreme temperature tribo-applications. Materials Today: Proceedings. 2021, vol. 44, part 6, pp. 4583–4589. https://doi.org/10.1016/j.matpr.2020.10.824

7. Zhai W., Bai L., Zhou R., Fan X., Kang G., Liu Y., Zhou K. Recent progress on wear-resistant materials: Designs, properties, and applications. Advanced Science. 2021, vol. 8, no. 11, article 2003739. https://doi.org/10.1002/advs.202003739

8. Torres H., Ripoll M.R., Prakash B. Tribological behaviour of self-lubricating materials at high temperatures. International Materials Reviews. 2018, vol. 63, no. 5, pp. 309–340. https://doi.org/10.1080/09506608.2017.1410944

9. Zhu S., Cheng J., Qiao Z., Yang J. High temperature solid-lubricating materials: A review. Tribology International. 2019, vol. 133, pp. 206–223. https://doi.org/10.1016/j.triboint.2018.12.037

10. Kumar R., Hussainova I., Rahmani R., Antonov M. Solid lubrication at high-temperatures – A Review. Materials. 2022, vol. 15, no. 5, article 1695. https://doi.org/10.3390/ma15051695

11. Voevodin A.A., Muratore C., Aouadi S.M. Hard coatings with high temperature adaptive lubrication and contact thermal management: Review. Surface and Coatings Technology. 2014, vol. 257, pp. 247–265. https://doi.org/10.1016/j.surfcoat.2014.04.046

12. Savchenko N., Sevostyanova I., Tarasov S. Self-lubricating effect of FeWO4 tribologically synthesized from WC–(Fe–Mn–C) compo­site during high-speed sliding against a HSS Disk. Lubricants. 2022, vol. 10, no. 5, article 86. https://doi.org/10.3390/lubricants10050086

13. Basu S.N., Sarin, V.K. Oxidation behavior of WC–Co. Materials Science and Engineering: A. 1996, vol. 209, no. 1–2, pp. 206–212. https://doi.org/10.1016/0921-5093(95)10145-4

14. Sharma S.K., Kumar B.V.M., Kim, Y.-W. Tribology of WC reinforced SiC ceramics: Influence of counterbody. Friction. 2019, vol. 7, pp. 129–142. https://doi.org/10.1007/s40544-017-0194-2

15. Yang G., Liu X., Sun X., Liang E., Zhang W. Synthesis process control of low-thermal-expansion Fe2W3O12 by suppressing the intermediate phase Fe2WO6 . Ceramics International. 2018, vol. 44, no. 17, pp. 22032–22035. https://doi.org/10.1016/j.ceramint.2018.08.274

16. Sevostyanova I.N., Savchenko N.L., Kul’kov S.N. Structural and phase binder state and behavior during friction of WC–(Fe–Mn–C) composites. Journal of Friction and Wear. 2010, vol. 31,

17. pp. 281–287. https://doi.org/10.3103/S1068366610040069

18. Tai W.-P., Watanabe T. Fabrication and mechanical properties of Al2O3–WC–Co composites by vacuum hot pressing. Journal of the American Ceramic Society. 1998, vol. 81, no. 6, pp. 1673–1676. https://doi.org/10.1111/j.1151-2916.1998.tb02531.x

19. Xia X., Li X., Li J., Zheng D. Microstructure and characterization of WC–2.8 wt % Al2O3 – 6.8 wt % ZrO2 composites produced by spark plasma sintering. Ceramics International. 2016, vol. 42, no. 12, pp. 14182–14188. https://doi.org/10.1016/j.ceramint.2016.06.044

20. Pedzich Z., Haberko K. Toughening mechanisms in the TZP-WC particulate composites. Key Engineering Materials. 1997, vol. 132–136, pp. 2076–2079. https://doi.org/10.4028/www.scientific.net/KEM.132-136.2076

21. Jiang D., Van der Biest O., Vleugels J. ZrO2–WC nanocomposites with superior properties. Journal of the European Ceramic Society. 2007, vol. 27, no. 2-3, pp. 1247–1251. https://doi.org/10.1016/j.jeurceramsoc.2006.05.028

22. Savchenko N., Sevostyanova I., Grigoriev M., Sablina T., Buya­kov A., Rudmin M., Vorontsov A., Moskvichev E., Rubtsov V., Tarasov S. Self-lubricating effect of WC/Y–TZP–Al2O3 hybrid ceramic–matrix composites with dispersed hadfield steel particles during high-speed sliding against an HSS Disk. Lubricants. 2022, vol. 10, no. 7, article 140. https://doi.org/10.3390/lubricants10070140