Research on the Influence of the Manufacturing Process Conditions of Iron Sintered with the Addition of Layered Lubricating Materials on its Selected Properties

Wieslaw Urbaniak; Tomasz Majewski; Ryszard Wozniak; Judyta Sienkiewicz; Jozef Kubik; Aneta D Petelska

doi:10.3390/ma13214782

Research on the Influence of the Manufacturing Process Conditions of Iron Sintered with the Addition of Layered Lubricating Materials on its Selected Properties

Materials (Basel). 2020 Oct 26;13(21):4782. doi: 10.3390/ma13214782.

Authors

Wieslaw Urbaniak¹, Tomasz Majewski², Ryszard Wozniak², Judyta Sienkiewicz², Jozef Kubik¹, Aneta D Petelska³

Affiliations

¹ Faculty of Mechatronics, Kazimierz Wielki University, Chodkiewicz 30, 85-867 Bydgoszcz, Poland.
² Faculty of Mechatronics, Armament and Aerospace of MUT, Military University of Technology, Kaliskiego 2, 01-489 Warsaw, Poland.
³ Faculty of Chemistry, University of Bialystok, Ciolkowskiego 1K, 15-245 Bialystok, Poland.

Abstract

The purpose of the conducted experiments was to test the selected properties of materials intended for porous sintered bearings containing layered materials in the form of powders with an average particle size of 0.5-1.5 μm, with very good tribological properties. The subject of the research was a sinter based on iron powder with the addition of layered materials; molybdenum disulfide MoS₂ (average particle size 1.5 μm), tungsten disulfide WS₂ (average particle size 0.6 μm), hexagonal boron nitride, h-BN (average particle size 0.5 and 1.5 μm) with two different porosities. The article presents the results of density and porosity tests, compressive strength, metallographic and tribological tests and the assessment of changes in the surface condition occurring during the long storage period. The use of layered additives allows for an approximately 20% lower coefficient of friction. In the case of sulfides, the technological process of pressing 250 MPa, 350 MPa, and sintering at a temperature of 1120 °C allows us to obtain a material with good strength and tribological properties, better than in the case of h-BN. However, the main problem is the appearance of elements from the decomposition of sulfide compounds in the material matrix, which results in rapid material degradation. In hexagonal boron nitride, such disintegration under these conditions does not occur; the material as observed does not degrade. In this case, the material is characterized by lower hardness, resulting from a different behavior of hexagonal boron nitride in the pressing and sintering process; in this case, pressing at a pressure of 350 MPa seems to be too low. However, taking into account that even with these technological parameters, the obtained material containing 2.5% h-BN with an average grain size of 1.5 μm allowed obtaining a coefficient of friction at the level of 0.41, which, with very good material durability, seems to be very positive news before further tests.

Keywords: friction; hexagonal boron nitride; lubricant additives; molybdenum disulfide; sintered iron; tungsten disulfide.