Assessment of Water Contamination on Grease Using the Contact Angle Approach
- PDF / 2,847,569 Bytes
- 12 Pages / 595.276 x 790.866 pts Page_size
- 46 Downloads / 190 Views
ORIGINAL PAPER
Assessment of Water Contamination on Grease Using the Contact Angle Approach K. P. Lijesh1 · M. M. Khonsari1 · Roger A. Miller2 Received: 18 July 2020 / Accepted: 6 September 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Many grease-lubricated machinery components operate in wet environments, making them susceptible to water contamination. It has been reported that the presence of a mere 1% water contamination in grease reduces the life of a bearing by 90%. Yet there are only a few standards available to characterize grease performance in the presence of water, most of which are primarily qualitative, providing inconclusive information, often relative to standard samples, at a significant cost in time and materials. In this paper, a unique approach is proposed for evaluating grease capability for repelling water. The method utilizes the contact angle of a water droplet on a grease surface to quantify grease water resistance. It is hypothesized that the higher the hydrophobic nature of the grease, the greater the resistance to water and vice versa. The validation of the hypothesis is established by performing extensive contact angle measurements on seven types of commercially available greases. The efficacy of contact angle results is established by measuring the change in the yield stress values obtained using a rheometer. From the obtained results, it is shown that the proposed approach is reliable and capable of distinguishing greases as water repellent/attractive. Graphic Abstract Sample stage
θ
Mold with hexagon shape
(c) Water resistant grease (θ>90o) θ Grease
(f) Mold on sample stage
(e) Grease in hexagon slot
(d) Water droplet on the grease surface
(a) Water absorbing grease (θ≤90o) ( )
Keywords Grease performance · Contact angle · Rheological properties · Water contamination · Water resistance
1 Introduction * M. M. Khonsari [email protected] Extended author information available on the last page of the article
Grease is a highly complex lubricant composed of thickener, additives, and base oils [1]. Compared to lubricating oil, grease provides good sealing properties, requires less
13
Vol.:(0123456789)
103
Page 2 of 12
maintenance, and can even operate in a solid-contaminated environment [1]. Further, the availability of greases in a range of viscosities offers application flexibility that satisfies the requirement of different industry sectors ranging from automotive, chemical processing, metalworking, power generating, and food and beverage processing factories [2]. Research shows that the working life of grease is profoundly affected by contaminants [3], such as water, which tends to modify their chemical structure and degrade their rheological properties, which, in turn, negatively affects the performance of the machinery components [4]. The significance of water contamination can be comprehended from the findings provided in many reports; some of the findings are summarized below: • Duncanson [5] reported deprivation of the greas
Data Loading...
