Novel chemical process for preparing h-BN solid lubricant coatings on titanium-based substrates for high temperature tribological applications

• Published in: Surface & coatings technology Vol. 272; pp. 366 - 372
• Main Authors: Yuan, S., Toury, B., Benayoun, S.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 25-06-2015; Elsevier
• Subjects: Annealing; Boron nitride; Chemical Sciences; Coating; Coatings; Cylinders; Disks; Friction; PDCs; RTA; Solid lubricant; Titanium; Tribology; Wear; Solid lubricant; PDCs; Coating; BN; Wear; RTA
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2015.03.040

Hexagonal boron nitride (h-BN) coatings prepared from a polyborazylene (PBN) polymeric precursor were deposited on titanium-based substrates and annealed via infra-red irradiation in a rapid thermal annealing (RTA) furnace. Crystallized h-BN coatings were obtained by adding Li3N as a catalyst at a relatively low annealing synthesized temperature (~1200°C). The resulting coatings had a thickness of 15μm and were evenly coated and homogenous. The coating/substrate adhesion was evaluated by the micro-scratch test, with the value of best critical load occurring at approximately 12N against a Rockwell C diamond point. This adhesion increased with the growth of the additive ratio of Li3N. The friction coefficient measurements were carried-out by tribological testing at 360°C using a cylinder/disk configuration. Stainless steel 15-5PH cylinders were used as counter bodies to the titanium disk. The friction coefficient was reduced from 0.72 for the Ti/stainless tribosystem to 0.35 for the Ti/h-BN/stainless tribosystem.
•Well crystallized hexagonal boron nitride (h-BN) coatings were deposited on Ti-based substrates.•RTA furnace and Li3N were used to decrease the onset temperature of h-BN crystallization reaction.•So-received h-BN coatings display good adhesion with the substrates.•Tribological tests were carried out at 360°C on a reciprocating cylinder/disk tribosystem.•Friction coefficient decreases from 0.72 (bare substrate) to 0.35 for the tribo test at 360°C.