Adding another texture to fluid power systems: CCEFP research focuses on the potential benefits of nano-texturing for hydraulic lines and system components.
Research on the use of nano-texturing for fluid power lines and system components is one of the latest developments undergoing testing through the Center for Compact and Efficient Fluid Power (CCEFP), Minneapolis, Minn. The CCEFP brings together a network of researchers, educators, students and industry to continue the advancement of hydraulic and pneumatic technologies.
For the nano-texturing of fluid power lines and system components project, Professor Eric Loth, research scientist Dr. Ilker Bayer, doctoral graduate student Adam Steele and masters graduate student Phil Martorana have joined forces at the Dept. of Aerospace Engineering at the University of Illinois at Urbana-Champaign. Together, the group has worked to prove the benefits of using nano-texturing in hydraulic systems.
Nano-texturing uses a superoleophobic (oil repellent) coating developed from polymer suspensions that are spray casted on a specific component or system path. Nanoparticles are blended with waterborne perfluoroacrylic polymer emulsions using cosolvents and other additives.
Once the coating is applied to the desired surface, it creates what is known as the lotus effect. The micro-and nano-textures allow for an air layer to be maintained in the space between the asperities during liquid contact. It creates nano-encapsulated air pockets to reduce friction in fluid power components. The result is a very high repellency.
Historically, superoleophobicity has required complicated and costly fabrication methods based on the difficulty to create suitable nano-morphology designed specifically for low surface tension oils. Until now, the majority of work was done with superhydrophobic (water repellent) surfaces, as this proved to be an easier outcome to obtain. The nano-texturing research the University of Illinois has focused on includes superoleophobic surfaces and the benefits it offers to a hydraulic system in a piece of machinery.
Nanocomposites have been spray coated in a variety of other applications including solar cells, dielectric materials and cylinder bore wall coatings. Such coatings can be applied to a large surface area and do not typically require complicated and costly application methods.
The nano-textured coating also has properties enabling the surface to be self-cleaning, as dirt particles are picked up by liquid droplets when they roll off the surface.
The coating also needed to be flexible to adapt to a variety of surface types. The University of Illinois research group was able to develop a spray technique that could be applied to plastic, wood, rubber and metal. The orientation of the surface proved to be a challenge as the polymer base needed to stick to the curved and linear surfaces of a hydraulic system and its varying dimensions.
By using nano-texturing to coat hydraulic lines and the internal working of other hydraulic components such as pumps and seals, a range of benefits has emerged. The repellency that is created by the nano-coating creates a resistance to corrosion. The polymer base also provides a protective coating inside the component, which hydraulic fluid is unable to penetrate or break down, increasing the lifespan of system components.
Another benefit to using the superoleophobic nanocomposite coating on hydraulic system lines is the energy efficiency that comes from the lotus effect of the coating. As hydraulic fluid passes through a hydraulic line, it is able to run freely and efficiently because of the coating's repellency. The ease of the passing fluid is expected to provide significant increase in the efficiency of the complete hydraulic system. It may also create improved lubricity on the sliding surface, helping to improve overall system efficiency and reduce wear.
While beneficial results of the superoleophopic nanocomposite coating have been proven in lab testing, the group's work with industrial hydraulic manufacturers and their components has shown great promise. Manufacturers such as Gates Corp., Sauer-Danfoss, Eaton Corp. and Caterpillar Inc. are participating in the research of nano-texturing by providing hydraulic components and real-world application data, which has enabled some of the CCEFP group's R&D work.
In one example, Gates has provided samples of its hydraulic hose products to which the nanocomposite coating was applied. The coating easily adhered to the hose material and induced a much lower flow resistance of hydraulic fluid on the interior surface, demonstrating the potential of nano-texturing the product.
Together with industry, the CCEFP group is continuing its efforts to improve the performance and durability of the nanocomposite coating. The group has been working on the project for four years and is currently one of several projects funded by the CCEFP through a $5 million grant to the university.
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|Title Annotation:||HYDRAULIC HORIZONS|
|Author:||Geske, dawn M.|
|Publication:||Diesel Progress North American Edition|
|Date:||Dec 1, 2009|
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