stleBoricAcid2006 - Downloaded By: [University of Florida]...

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Downloaded By: [University of Florida] At: 17:52 27 February 2008 Tribology Transactions, 49: 284-290, 2006 Copyright C ° Society of Tribologists and Lubrication Engineers ISSN: 1040-2004 print / 1547-357X online DOI: 10.1080/05698190600639939 In Situ Lubrication with Boric Acid: Powder Delivery of an Environmentally Benign Solid Lubricant W. GREGORY SAWYER, JOHN C. ZIEGERT, TONY L. SCHMITZ and TIMOTHY BARTON Department of Mechanical and Aerospace Engineering University of Florida Gainesville, FL 32611 In situ deposition of boric acid in dry powder form is in- vestigated as a potential environmentally benign solid lubricant for sliding metal contacts. Boric acid is widely used in industrial processes and agriculture, is not classiFed as a pollutant by EPA, and produces no serious illnesses or carcinogenic effects from exposure to solutions or aerosols. In this study, boric acid pow- der is aerosolized and entrained in a low-velocity jet of nitrogen gas, which is directed at a self-mated 302 SS sliding contact in a rotating pin-on-disc tribometer. The effects of powder ±ow rate, sliding speed, normal load, and track diameter on coefFcient of friction and wear rate are investigated. ²riction coefFcients below µ = 0.1 can be consistently reached and maintained as long as the powder ±ow continues. Wear rates are reduced over 2orders of magnitude. KEY WORDS Solid Lubrication; Powder Delivery; Environmentally Friendly; Green Manufacturing INTRODUCTION Petroleum-based lubricants are widely used in the manufactur- ing and industrial sectors, as well as in automotive and many other mass market products. It is well recognized that use of these lu- bricants introduces signi±cant quantities of used petroleum-based substances into the waste stream (Sutherland, et al. (1) ). These lu- bricants impose signi±cant negative impacts to environment and health both during their primary use and after disposal (Allen, et al. (2) ). This article introduces a lubrication concept aimed at reducing the need for petroleum-based ²uids in a wide range of industrial processes and consumer applications by delivery of boric acid, an environmentally benign solid lubricant, in powder form. The proposed lubricant and delivery method will avoid the waste stream and environmental and health impacts associated with other lubricants used in many industrial processes and prod- ucts. This technique is not tied to any particular process or product, but rather it has broad applicability, although customized delivery strategies will need to be developed for the various applications. Manuscript received April 18, 2005 Final manuscript approved January 21, 2006 Review led by Paul Bessette Boric Acid Boric acid is the common term for orthoboric (or boracic) acid H 3 BO 3 , which is a hydrate of boric oxide B 2 O 3 .When in contact with water, boric oxide will readily hydrate, converting to boric acid. Boric acid is a weakly acidic white powder that is soluble in water (about 27% by weight in boiling water and about 6% at room temperature), soft, ductile, stable, free ²owing, and easily handled. Finely ground technical grade boric acid powder (
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stleBoricAcid2006 - Downloaded By: [University of Florida]...

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