Title: Friction and anti-wear property of aqueous tri-block copolymer solutions in metal forming

Authors: Buyung Kosasih; Oyong Novareza; Anh Kiet Tieu; Hongtao Zhu

Addresses: School of Mechanical, Materials and Mechatronics Engineering, University of Wollongong, Northfields, Wollongong, NSW 2500, Australia ' School of Mechanical, Materials and Mechatronics Engineering, University of Wollongong, Northfields, Wollongong, NSW 2500, Australia; Department of Engineering, The University of Brawijaya, Jln. MT Haryono 167, Malang 65145, Indonesia ' School of Mechanical, Materials and Mechatronics Engineering, University of Wollongong, Northfields, Wollongong, NSW 2500, Australia ' School of Mechanical, Materials and Mechatronics Engineering, University of Wollongong, Northfields, Wollongong, NSW 2500, Australia

Abstract: Friction and anti-wear property of aqueous symmetrical tri-block normal PEO_m-PPO_n-PEO_m and reverse PPO_n-PEO_m-PPO_n copolymer solutions have been studied. The study focuses on the effect of the solution bulk temperatures and the copolymer block structures. It was found that the concentration and the length of the copolymer blocks affect the solution cloud points, friction and anti-wear property. When solution was supplied at bulk temperature above their cloud point, aqueous copolymer solutions were not able to develop effective adsorbed film resulting in high friction and severe wear. When the bulk temperatures were below the cloud point, the anti-wear property improved significantly and the dynamic friction is lower than that when the temperatures were above the cloud point. This demonstrates the importance of the supply temperature of this type of lubricant in metal forming. However by adding ethyl phosphate ester to the copolymer solutions further improved friction reducing property of the solutions was observed and the friction and anti-wear property of the lubricant become insensitive to bulk temperature. In the effort to understand the lubrication mechanism of the aqueous solutions, wear tracks were studied using scanning electron microscope (SEM) and atomic force microscope (AFM), and the surface wetting ability via contact angle measurements.

Keywords: anti-wear properties; aqueous solutions; cloud point; friction; wear; tri-block copolymers; metal forming; bulk temperature; lubrication mechanism; surface wetting.

DOI: 10.1504/IJSURFSE.2014.060480

International Journal of Surface Science and Engineering, 2014 Vol.8 No.2/3, pp.109 - 123

Received: 25 Jan 2013
Accepted: 20 Jun 2013
Published online: 17 May 2014 *

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