Colloidal Stability of Metal Nanoparticles in Engine Oil under Thermal and Mechanical Load

Abstract

Extended colloidal stability and high dispersion degree of nanolubricants are required to avoid nanoparticle deposition in combustion engines and to reduce friction and wear. The simple and rapid one-step technique of pulsed laser ablation in liquids is employed to synthesize precursor-free and highly dispersed gold nanoparticles in lubricants while the colloidal stability is measured by optical spectroscopy and transmission electron microscopy. A remarkable colloidal stability is determined under engine-like and ambient conditions for nine months in terms of constant primary particle size. In contrast to additive-free oils, almost no agglomeration is observed, which might be attributed to the attachment of engine oil additives or pyrolyzed/oxidized molecules to the nanoparticles preventing attractive nanoparticle interactions.

The Effect of Addition of Nanoparticles, Especially ZrO2-Based, on Tribological Behavior of Lubricants

“…Jendrzej et al [89] dispersed in engine oil gold nanoparticles synthesized by pulsed laser ablation. After nine months, almost no agglomeration occurred.…”

Dynamics of laser-induced cavitation bubbles at a solid–liquid interface in high viscosity and high capillary number regimes

“…The dynamics of the cavitation bubble and its influence on the nanoparticle formation has been investigated by many researchers 28,[37][38][39][42][43][44] . Surprisingly, there is a lack of literature investigating cavitation bubbles in highly viscous liquids, although viscous liquids are becoming more and more interesting for LAL applications in oils 45,46 or monomers 47 through offering the possibility for one-step synthesis of colloids. For example, nanoparticles as additives in engine oil are relevant for the automotive industry, where nanoparticles are often used to enhance the tribological properties of the lubricant 46,48 .…”

How the Physicochemical Properties of the Bulk Material Affect the Ablation Crater Profile, Mass Balance, and Bubble Dynamics During Single‐Pulse, Nanosecond Laser Ablation in Water

“…Cavitation effects further play an important role in the field of liquid‐assisted laser applications, e.g., medical laser applications, [9, 10] laser‐micromachining, [11–13] or laser ablation in liquids (LAL) [14] . In the latter case, laser pulses are focused onto a bulk target immersed in a liquid, enabling the cost‐effective [15] production of colloids on the gram‐scale [16, 17] from a wide range of different material classes such as metals, [18–20] oxides [21–23] or alloys [24–28] in different liquids [29–32] . These synthesized nanoparticles typically are of high purity [33] and are promising materials for application fields such as biomedicine, [24, 34] catalysis, [35–38] or 3D printing [39–43] …”

“…[14] In the latter case, laser pulses are focusedo nto ab ulk target immersed in a liquid, enabling the cost-effective [15] production of colloidso n the gram-scale [16,17] from aw ide range of different material classes such as metals, [18][19][20] oxides [21][22][23] or alloys [24][25][26][27][28] in different liquids. [29][30][31][32] These synthesized nanoparticles typically are of high purity [33] and are promising materials for application fields such as biomedicine, [24,34] catalysis, [35][36][37][38] or 3D printing. [39][40][41][42][43] Generally,L AL is characterized by differentc ompeting physical and chemical phenomena that are determined by the interaction between the laser,t he target,a nd the liquid.…”