Triboemission as a basic part of the boundary friction regime: A review

Abstract

This paper reviews selected phenomena related to the boundary friction process. The central thrust is on triboemission, defined as emission of electrons, charged particles, photons, etc., under conditions of boundary friction and/or surface damage caused by fracture processes. Low‐energy electrons are one of the most important particle components in triboemission. Accordingly, the triboemission process is of particular significance for (i) the boundary friction process as such, and (ii) the tribochemistry of the boundary lubrication process. This review considers all the major issues of triboemission and related phenomena/processes. It is shown that, in the boundary lubrication regime with hydrocarbon lubricants, charge intensities decrease with an increase in lubricant molecular weight. The paper also includes some recent information concerning research on triboemission along with a newly developed apparatus.

Oxidative Stability of Vegetal Oil-Based Lubricants

“…Under boundary lubrication regime, interaction between asperities results in high friction and severe wear, which encompass high temperature, triboemission and tribochemical reactions. 30 Triboemission is defined as an emission of electrons, charged particles, lattice components, photons, etc., under conditions of boundary friction conditions and/or surface damage caused by fracture processes. Figure 4 illustrates the triboemission process associated with the surface changes during friction.…”

Molecular Science of Lubricant Additives

“…Exo-electrons could be emitted from rubbing surfaces. Those electrons have low energy to promote chemical reactions but can produce radical intermediates for further chemical reactions [21].…”

Divalent Europium, NIR and Variable Emission of Trivalent Tm, Ho, Pr, Er, Nd, and Ce in 3D Frameworks and 2D Networks of Ln–Pyridylpyrazolates

“…The data were fitted for 3-Dy, 3-Ho, and 3-Er in the given temperature range with an effective magnetic moment μeff of 10.651(2), 10.09(1), and 7.855 (9) μB and a Weiss constant θ of −4.41(1), −5.77 (7), and −5.72(8) K, as well as a temperature-independent paramagnetic susceptibility ꭕ0 of 4.03(3) × 10 −3 , 6.18(2) × 10 −3 , and 11.52(8) × 10 −3 cm 3 mol −1 . The small, negative Weiss constants θ are the results of spin-orbit coupling as well as the crystal field effect [54,55].…”

“…Divalent europium, the mildest reducing agent of the redox-sensitive divalent lanthanide ions, has been successfully used in a wide variety of material applications such as medical imaging [1,2], photochemistry [3,4], lanthanide-activated phosphors [5,6], and sensing [7,8]. Trivalent lanthanides are known for their luminescence properties, with f-f based emission covering the spectrum from the ultraviolet (UV) to the near-infrared (NIR) spectral region, characteristic for each metal ion [9,10].…”