The method of calculating the bearing capacity of rolling bearings is described in the ISO 281 standard. The calculation procedure for roller thrust bearings presented there, depending on the value of the nominal bearing angle, requires the selection of one of two formulas. Then, using the table, one reads the value of the factor depending on the geometry of the bearing components. To facilitate and speed up calculations (and perhaps also increase their accuracy), this article proposes a formula that is adapted to numerical applications, replaces linear interpolation with a proper non-linear function and allows calculations to be made for a specific value of the nominal bearing angle, but not within the range of 15°. The difference between the values calculated according to the proposed formula and the value calculated according to ISO 281 is, on average, around 3%.
Ladies and Gentlemen,
I am pleased to announce that on December 1st, 2021, the Ministry of Education and Science has published a new list of bulleted journals,
according to which the TRIBOLOGIA journal is currently assigned 70 points.
Marian Szczerek
Dear Authors, Reviewers and Readers of the TRIBOLOGIA journal
As you know, our journal has survived another breakthrough in shaping the Polish scientific publishing environment and is one of the few national scientific journals in the field of technical sciences to be included on the list of the Ministry of Science and Higher Education (currently 70 points).
There is another challenge ahead of us - qualification to the Web of Science and / or SCOPUS databases. It is not an easy process; it requires the effort of all of us. We must take care of the scientific level, the level of publishing work, including the quality of reviewing, do not forget to cite the articles published in it, encourage outstanding collaborators, especially from foreign centers, to publish in TRIBOLOGY. We also count on supporting the Editorial Board in attracting foreign reviewers.
Important arguments in qualifying publications and scientific journals to global databases are the quality and efficiency of the publishing process, including the interactive computer publishing system already implemented by the Editorial Board, integrating articles into the global circulation of scientific information, as well as the scientific activity (publishing and reviewing) of the members of the editorial team - Editorial Board and Scientific Council. Many thanks are due to the members of the Council who made the difficult task of being active in the publishing process.
Very warm thanks go especially to the members of the Council and the Editorial Board who have supported the journal for many, many years in the past with their work, advice and authority. We look forward to further ad hoc cooperation in the future.
Yours sincerely,
Marian SZCZEREK
Editor-in-chief of TRIBOLOGIA
In the paper the results of tribological, microscopic, and mechanical research of Al2O3 + TiO2 coatings manufactured by plasma spraying are presented. The feeding material was a powder Al2O3 + 13 wt.% TiO2 (Metco 6221, OerlikonMetco) with grain size – 45 ± 15 μm. The cylinder substrates made from stainless steel (X5CrNi18-10) had a diameter equal to 25 mm and 2 mm of thickness. The variable spray parameters were plasma torch velocity in terms of substrate and spray distance. The morphology of obtained coatings was tested by scanning electron microscope (SEM), and the microstructure was investigated by light optical microscopy (LOM) and SEM. The results of mechanical properties examinations revealed the dependence of the microhardness and fracture toughness on the spray parameters. Tribological examinations were made in the ball-on-disc mode in technical dry friction conditions. Two loads were used, 5 N and 10 N. Based on the carried out tests, it could be concluded that a shorter spray distance and a reduction of the torch velocity allows one to achieve a more compact structure, which is characterized by good adhesion at the coating-substrate interface (in range from 11 to 14 MPa) and good wear resistance.
DLC coatings are widely used in engineering as they are resistant to abrasive wear. However, they exhibit an increased coefficient of friction at temperatures of around 300°C. Soft MoS2 coatings are known to maintain a low coefficient of friction at temperatures up to about 350°C, but suffer from relatively high abrasive wear. Publications from the last decade report a synergistic improvement in the tribological performance of a coating consisting of both these materials. The aim of this study was to investigate the wear resistance of coatings composed of different a-C and MoS2 contents applied by magnetron sputtering on steel. The results obtained in tribological tests conducted using the ball-and-disk method showed at least 20% better adhesion to the substrate of the two-component nanocomposite coating and its increased wear resistance from 15% to as much as 700%, compared to single-component coatings in tests conducted at 20°C and 250°C. The tests showed no deterioration of the two-component coating's coefficient value compared to DLC.