Influence of fluoride phase on the tribological behaviour of Si3N4–SiC composites under extreme operating conditions

• Published in: Wear 2023-09, Vol.528-529, p.204970, Article 204970
• Main Authors: Mazumder, Subhrojyoti, Metselaar, Hendrik Simon Cornelis, Sukiman, Nazatul Liana, Zulkifli, Nurin Wahidah Mohd
• Format: Article
• Language: English
• Subjects: Fluoride additives; High load; High temperature; Non-oxide ceramics; Wear characteristics
• ISSN: 0043-1648; 1873-2577
• DOI: 10.1016/j.wear.2023.204970

For extreme operating conditions such as high temperature and load, Si3N4–SiC composite is often used as wear resistant material. However, it suffers from a moderately high friction coefficient and wear rate at such working conditions; therefore, it is still an ongoing area of research for further development. This work strives to develop a state-of-the-art wear-resistant Si3N4 composite with SiC nanowire as reinforcement phase and MgF2 as an internal lubricating additive, particularly suitable for harsh operating conditions at both high temperatures and high loads. A significant improvement in tribological characteristics is observed when MgF2 is added into the composite matrix tested at 500 °C as compared to its parent Si3N4–SiC composite. When the load is increased from 6 to 14 N, the composite shows better wear resistance by forming a lubricious tribolayer at the contacting surface. Delamination is found to be the dominating wear mode for composites containing fluoride phase as identified by the morphological characterization of the worn surfaces. A comprehensive analysis of the evolution of different wear modes with respect to the variation in extreme operating conditions is articulated here. •At 500 °C, the Si3N4–SiC composite with 5 wt% MgF2 shows the best wear-resistant characteristics.•When the operating load increases from 6 N to 14 N, the Si3N4–SiC–MgF2 composite exhibits better tribological performance.•Delamination is found to be the dominant wear submechanism due to surface fatigue at elevated temperatures.•The higher amount of fluoride additive shows an abrasive wear mechanism under extreme operating conditions.