In the current investigation, a monolithic TiN- and TiN-based nanocomposites, with addition of 5 wt% Al2O3 and 5 wt% Y2O3, 20 wt% TiB2 and 20 wt% Si3N4 as additives respectively were developed using microwave energy at 0.9 kW in air at ~ 1500 °C without soaking time. Green compacts were sintered using modified domestic microwave applicator through susceptor-assisted microwave heating using solid SiC and graphite powder. Graphite powder envelop facilitated the processing of the compacts in air further inhibiting oxidation. The microwave sintered nanocomposites attained a relative density in the range of ~ 87–93%. The XRD analyses confirmed that all the sintered compositions retained the major TiN phase. Microstructural analyses showed better bonding between all the constituents of the microwave sintered nanocomposites. Monolithic TiN and TiN with oxide additives exhibited better density and mechanical properties compared to the TiN nanocomposites with boride and nitride additives. Friction and wear characterization (ball-on-disc) under dry sliding with bearing steel counterbody showed encouraging tribological behaviour. The lowest friction coefficient after 45 min of sliding (unlubricated) was observed within 0.5 – 0.6 for both monolithic TiN and TiN with oxide additives, whereas for the TiN with boride and nitride additives, it was observed marginally higher. Wear rate for the TiN nanocomposite with oxide additives was the lowest among all composites owing to grain boundary strengthening caused by intergranular phases. Addition of Al2O3 improved overall tribological performance of the composites, barring marginal increase in the COF. Further, inclusion of the harder TiB2 phase enhanced abrasive wear resistance of the fabricated composites owing to the formation of intermediate B2O3 phase which facilitated better interface between the matrix (TiN) and the reinforcement (TiB2). Significant pull-outs and chip outs in case of other composites resulted in higher wear rate. Oxides of iron on the mating surfaces post wear trials indicate transfer of mass between the steel counterbody and the surfaces of the nanocomposite. Analyses confirmed that the wear mechanisms were abrasion and adhesion dominant. The study revealed potentials of a faster processing route for relatively less explored ceramic composites which can be tailored for hybrid bearing applications. Graphical Abstract

Effect of ceramic additives on mechanical and tribological behaviour of microwave sintered binderless TiN nanocomposites

期刊论文
发表日期：

2025年11月28日

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Chintam Suresh Kumar,
Apurbba Kumar Sharma,
Ostap Zgalat-Lozynskyi,
Andrey V. Ragulya

摘要

In the current investigation, a monolithic TiN- and TiN-based nanocomposites, with addition of 5 wt% Al₂O₃ and 5 wt% Y₂O₃, 20 wt% TiB₂ and 20 wt% Si₃N₄ as additives respectively were developed using microwave energy at 0.9 kW in air at ~ 1500 °C without soaking time. Green compacts were sintered using modified domestic microwave applicator through susceptor-assisted microwave heating using solid SiC and graphite powder. Graphite powder envelop facilitated the processing of the compacts in air further inhibiting oxidation. The microwave sintered nanocomposites attained a relative density in the range of ~ 87–93%. The XRD analyses confirmed that all the sintered compositions retained the major TiN phase. Microstructural analyses showed better bonding between all the constituents of the microwave sintered nanocomposites. Monolithic TiN and TiN with oxide additives exhibited better density and mechanical properties compared to the TiN nanocomposites with boride and nitride additives. Friction and wear characterization (ball-on-disc) under dry sliding with bearing steel counterbody showed encouraging tribological behaviour. The lowest friction coefficient after 45 min of sliding (unlubricated) was observed within 0.5 – 0.6 for both monolithic TiN and TiN with oxide additives, whereas for the TiN with boride and nitride additives, it was observed marginally higher. Wear rate for the TiN nanocomposite with oxide additives was the lowest among all composites owing to grain boundary strengthening caused by intergranular phases. Addition of Al₂O₃ improved overall tribological performance of the composites, barring marginal increase in the COF. Further, inclusion of the harder TiB₂ phase enhanced abrasive wear resistance of the fabricated composites owing to the formation of intermediate B₂O₃ phase which facilitated better interface between the matrix (TiN) and the reinforcement (TiB₂). Significant pull-outs and chip outs in case of other composites resulted in higher wear rate. Oxides of iron on the mating surfaces post wear trials indicate transfer of mass between the steel counterbody and the surfaces of the nanocomposite. Analyses confirmed that the wear mechanisms were abrasion and adhesion dominant. The study revealed potentials of a faster processing route for relatively less explored ceramic composites which can be tailored for hybrid bearing applications.

Graphical Abstract