In-situ deposition of boric acid in dry powder form is investigated as a potential environmentally benign solid lubricant for sliding metal contacts. Boric acid is widely used in industrial processes and agriculture, is not classified as a pollutant by EPA, and produces no serious illnesses or carcinogenic effects from exposure to solutions or aerosols. In this study, boric acid powder 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-disk tribometer. The effects of powder flow rate, sliding speed, normal load, and track diameter on coefficient of friction and wear rate are investigated. Friction coefficients below µ=0.1 can be consistently reached and maintained as long as the powder flow continues. Wear rates are reduced over 2 orders of magnitude.

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Tribology Transactions
vol 49 (2006) pp. 290-296