Electrophoretic deposition of TiB2 coatings on cemented carbide in molten fluorides

Abstract

TiB₂-coated cemented carbide cutting tools perform excellently in machining difficult-to-process metals such as titanium and aluminum alloys. We fabricated TiB₂ coatings on cemented carbides using molten salt electrophoretic deposition, consisting of in-situ synthesis of TiB₂ nanoparticles by borothermal reduction of TiO₂ in NaF-AlF₃ molten salts and subsequent electrophoretic deposition of the as-synthesized TiB₂ nanoparticles to form TiB₂ coatings in the same molten bath. This technique prepares a fully dense TiB₂ coating with a thickness of approximately 60 μm on a WC-8wt% Co substrate, exhibiting high hardness (36.7 GPa) and adhesion strength (48 N). Moreover, tribological property testing indicates that it possesses a lower coefficient of friction (0.55) and wear rate (8.69 × 10⁻⁷ mm³/(N∙m)) compared with those of WC-8wt% Co substrate(coefficient of friction, 0.58; wear rate, 9.14 × 10⁻⁷ mm³/(N∙m)).