Tribologia - Finnish Journal of Tribology <p>An open access&nbsp;journal publishing both practical and scientific articles&nbsp;related to tribology: wear,&nbsp;friction and lubrication.</p> <p>Benefits to Authors:</p> <ul> <li class="show">No publication fees</li> <li class="show">Authors remain as copyright owners</li> <li class="show">Peer reviewed publishing process</li> <li class="show">Prompt publishing</li> <li class="show">Free printed copy for the corresponding author</li> </ul> <p>The flyer of the journal can be downloaded in pdf-form by clicking the picture below:</p> <p><img src="/public/site/images/jannej/flyer_2019_image.png"></p> The Finnish Society for Tribology en-US Tribologia - Finnish Journal of Tribology 0780-2285 <p>The authors of the publication retain the copyrights and the author can publish the article also in other media, such as in her/his PhD thesis or open access databases, such as ResearchGate.</p> <p>The license of the published metadata is Creative Commons CC0 1.0 Universal (CC0 1.0).</p> Foreword No 1−2 (2019) <p>Dear Readers,</p> <p>As Year 2019 is soon passing by and Year 2020 knocking on the door with Nordtrib arranged in Norway at Geiranger with the spectacular views. It will be hosted by&nbsp;the joint effort of&nbsp;NTNU&nbsp;and&nbsp;SINTEF&nbsp;and the Norwegian Tribology Center (NTC). Nordtrib is well-known Nordic Symposium on Tribology held biennially in one of the Nordic countries; Finland, Sweden, Norway and Denmark. It was originally hosted in Tampere, Finland in 1984. Next conference will be devoted to show the impact of women in tribology.</p> <p>While waiting the next Nordtrib, we have collected extended abstracts from our Finnish Fellow Tribologists presented in last Nordtrib 2018 in Uppsala, Sweden and they are now published in our latest special issue. Our latest issue is double issue involving the Nordtrib Special Issue and the section with peer-reviewed full-length articles we have had pleasure to receive.</p> <p>During this year, we also had some editorial changes in our journal as I started working as Editor-in-Chief. Many thanks to our previous Editor-In-Chief for all the efforts she had done during past years.</p> <p>Wish You All Merry Christmas and All the Best for the Year 2020,</p> <p><em>Vuokko Heino</em> <br>Editor-in-Chief of Finnish Journal of Tribology</p> Vuokko Heino Copyright (c) 2019-12-17 2019-12-17 36 1−2 3 3 Two-Body Abrasive Wear Behaviour of In-Situ Al-TiC Particle Composites: Influence of TiC Reinforcement and Content in the Alloy Matrix and Experimental Parameters <p>This study pertains to observations made on the abrasive wear response of Al-TiC composites under varying applied load and traversal distance conditions. The influence of TiC particle reinforcement and its content in the matrix on the abrasion characteristics of the samples was investigated. The composites were prepared by generating the reinforcement phase (TiC particles) from within the matrix employing a hybrid in-situ technique consisting of a combination of steps involved in powder and liquid metallurgy routes of synthesizing metal matrix composites. The unreinforced matrix alloy (AA2014) was also tested under identical experimental conditions for comparison purposes. Properties characterized were wear rate, frictional heating and friction coefficient. Microstructural features of the samples and characteristics of wear surfaces, subsurface regions and abrasive medium have also been examined.</p> <p>&nbsp;</p> <p>The TiC reinforcement led to improved abrasion resistance (inverse of wear rate), the degree of improvement increasing further with the rising concentration of the TiC particles in the alloy matrix. Increasing applied load led to deterioration in the wear behaviour of the samples while a reverse trend was followed as the traversal distance was raised. The severity of frictional heating was noted to increase with load. On the contrary, friction coefficient tended to decrease with increasing load except for the composite containing the highest concentration of TiC wherein a reverse trend was noticed. Both frictional heating and friction coefficient increased sharply with traversal distance initially. This was followed by a reduction in the rate of temperature increase at longer traversal distances whereas friction coefficient was observed to attain steady state condition after showing a decrease in some cases. The presence of TiC reinforcement in the alloy matrix and its increasing content led to a decrease in the friction coefficient and the severity of frictional heating. The observed wear behaviour has been substantiated through the characteristics of abraded surfaces and subsurface regions of the samples and degradation of the abrasive medium. Operating material removal mechanisms have also been examined. &nbsp;</p> B K Prasad S Rathod O P Modi G K Gupta M S Yadav Copyright (c) 2019 B.K. Prasad 2019-12-17 2019-12-17 36 1−2 4−23 4−23 10.30678/fjt.74449 Multiphysics modelling of a hybrid magnetic bearing (HMB) for calculating power loss and temperature with different loss minimization strategies <p>This paper represents a multiphysics modelling for calculating loss and temperature of a hybrid magnetic bearing (HMB) using finite element method (FEM). It also addresses the different loss minimization strategies for the HMB. The main sources of losses are identified as eddy current loss in permanent magnets, flywheel and copper loss in electromagnet. Due to these losses, the temperature distribution in different portions of HMB is computed using coupled field analysis. To minimize the eddy current loss, slits are fabricated in flywheel plate instead of a solid flywheel. The improvement of the control current is investigated by providing a coating of different metal, like copper, brass and stainless steel on the flywheel. A zero bias current (ZBC) scheme has been introduced where no bias current is required to levitate the rotor or to avoid singularity due to external disturbances, thus reducing the copper loss.</p> Tapan Santra D Roy A B Choudhury S Yamada Copyright (c) 2019 TAPAN SANTRA 2019-12-17 2019-12-17 36 1−2 24−35 24−35 10.30678/fjt.60402 Experimental investigation of ball bearing lubrication conditions by shock pulse method <p>Lubricant (grease) is a vital requirement of ball bearing system. Grease not only protects ball bearing from wear and tear but performs various other functions that are essential for proper functioning of ball bearings. The lubricant (grease) under different conditions attains different properties which in turn affect the performance of the ball bearings. The effect of the condition of the lubricants on the performance of the ball bearings is well documented. the work reports about the investigation of ball bearing using shock pulse method by using two different instruments (Tester T2000 Model and Shock Pulse Meter 43A) of different operating conditions of ball bearing the condition such as used the quantity of grease as different percentage (0%, 25%, 50%, 75%, 100%) and bad quality grease (burn grease) at different rpm at a fixed load (10kg) and compare the normalized shock pulse value (dB) at different operating conditions. This method uses a piezo-electric accelerometer superimposed electrically as well as mechanically to about 32 kHz of resonant frequency. The result will help in bearing related to quantity as well as quality condition based maintenance choosing the optimum conditions for detecting the lubricant problem in ball bearing.</p> Ratnesh Kumar Gupta Vikas Rastogi R C Singh N Tandon Copyright (c) 2019 RATNESH KUMAR GUPTA 2019-12-17 2019-12-17 36 1−2 36−44 36−44 10.30678/fjt.79897 Research methods for the evaluation of the relevance of application oriented laboratory wear tests <p>In this work, different research methods and test procedures were examined and compared in order to have a better understanding of the relevance of various application oriented laboratory wear tests relative to the in-service performance of the steels in mining conditions. One of the important results of this study is that quite different wear events can be compared, when the wear rates are presented as the mass loss of the sample divided by the wear area, contact time, and density of the material. However, this kind of information is commonly very difficult to obtain for the in-service samples, and thus normalizing of the results with a reference material is often an easier route. On the other hand, thorough characterization and comparison of the wear surfaces and deformations is essential for the confirmation of the similarity of the wear mechanisms in different cases or different tests. In the studied case of the wear plate of a dumper truck body, several test methods were needed for the experimental simulation of the complex wear environment in the haulage of minerals.</p> Kati Valtonen Vilma Ratia Veli-Tapani Kuokkala Copyright (c) 2019 Kati Valtonen, Vilma Ratia, Veli-Tapani Kuokkala 2019-12-17 2019-12-17 36 1−2 46−53 46−53 10.30678/fjt.82438 Effect of microstructure on the abrasive wear resistance of steels with hardness 450 HV <p class="AbstractTextNordtrib"><span lang="EN-US">Hardness has been considered the main factor controlling the abrasive wear of steels. However, microstructure also affects the wear behavior. Four steels with different microstructures were produced with a Gleeble 3800 thermomechanical simulator and tested for abrasive wear behavior. Different cooling rates and heat treatments were applied to obtain a surface hardness of approximately 450 HV. Mainly tempered martensite, pearlite and some bainite could be observed in the microstructures. Scratch testing with a CETR UMT-2 tribometer was conducted to produce wear tracks. The results revealed that each steel showed distinct wear behavior. </span></p> Oskari Haiko Vuokko Heino David A Porter Juha Uusitalo Jukka Kömi Copyright (c) 2019 Oskari Haiko 2019-12-17 2019-12-17 36 1−2 54−57 54−57 10.30678/fjt.82443 Slurry and dry particle erosion wear properties of WC-10Co4Cr and Cr3C2-25NiCr hardmetal coatings deposited by HVOF and HVAF spray processes <p class="AbstractTextNordtrib"><span lang="EN-US">Thermally sprayed hardmetal coatings were produced to provide improved erosion wear compared to conventional cast GX4CrNi13-4 martensitic steel (CA6NM) used in hydro turbine components. Sprayed coatings and reference materials were tested with high-speed slurry pot tester using either fine or coarse quartz as the erosive media. Additional erosion tests were carried out with centrifugal dry erosion tester. Tungsten carbide based coatings provided the highest wear resistance due to the high hardness and even distribution of the fine carbide particles. The cast 13-4 steel samples experienced up to 180 times higher wear rates in fine quartz slurry and up to 36 times higher wear rates in coarse slurry compared to the sprayed coatings.</span></p> Ville Matikainen S Rubio Peregrina N Ojala H Koivuluoto J Schubert Š Houdková P Vuoristo Copyright (c) 2019 Ville Matikainen 2019-12-17 2019-12-17 36 1−2 58−61 58−61 10.30678/fjt.83590 Comparison between tribocorrosion behaviour of aluminium bronze and leaded tin bronze in simulated sea water <p>This paper summarises the main findings of the presentation given in NordTrib2018 conference held in Uppsala, Sweden, on 18-21 June 2018. The presentation concentrated on the comparison of the overall tribocorrosion behaviour of aluminium bronze and leaded tin bronze, the original pieces of research of which have been reported elsewhere. Here, the main results are presented and evaluated.</p> Elina Huttunen-Saarivirta Copyright (c) 2019 Elina Huttunen-Saarivirta 2019-12-17 2019-12-17 36 1−2 62−64 62−64 10.30678/fjt.86164