Tribologia - Finnish Journal of Tribology

Foreword No 4 (2023)

Vuokko Marjamaa — Sat, 23 Dec 2023 00:00:00 +0200

Dear Readers,

As the year is nearing its end, we are publishing our latest issue for you to explore.

This current issue is the second issue to be published during December. On 1^st of December, we published our special issue related to the history of tribology in Finland and the Finnish Society for Tribology. What made the publishing special was the fact we published it together during our history seminar held in Espoo. During our seminar we had joyful time remembering the old times. I believe we all got younger by years.

The issue we are publishing today contains interesting topics related to the tribology and tribology related research which combines the tribology to Hall-Patch effect for example.

We want to thank our authors for their contributions and hope the next year will be prosperous for us all.

All the best,

Vuokko Marjamaa
Editor-in-Chief

A critical review of the effect of nano-lubricant on the performance of hydrodynamic journal bearing

Santwna Mishra, Shipra Aggarwal — Sat, 23 Dec 2023 00:00:00 +0200

The applications of nano-lubricants in journal bearing are found to be capable of improving load-carrying capacity and reducing friction. Many numerical and experimental investigations have been performed to find the effect of nano-lubricants on the performance of the journal bearing. In this paper, a state-of-the-art review is done of the articles of numerical and experimental assessments of the effect of nano-lubricants on the performance of journal bearings. Here research articles are classified on the basis of nanoparticles used as nano-additive, which are further classified in the category of numerical and experimental study. It is seen that the application of nano TiO₂, CuO and Al₂O₃ based nano-lubricants gives much higher load-carrying capacity than the base lubricants. This article concludes by discussing the effect of different nanoparticle-based nano-lubricants on the performance characteristics of the journal bearing and mathematical models used for numerical investigations.

Subsurface zone detected in pure nickel by positron annihilation; Hall-Patch effect notification

Jerzy Dryzek — Sat, 23 Dec 2023 00:00:00 +0200

A dry sliding test and sequential etching technique, combined with positron lifetime measurements on pure nickel, revealed an area of damage below the worn surface extending to a depth of hundreds of micrometers. Some correlation was found between the value of the mean positron lifetime measured directly on the worn surface and the coefficient of friction. The obtained dependency rather confirms the normal Hall-Patch regime. There was no correlation with the specific wear rate.