Electrophoretic deposition of TiB2 coatings on cemented carbide in molten fluorides

TiB 2 -coated cemented carbide cutting tools perform excellently in machining difficult-to-process metals such as titanium and aluminum alloys. We fabricated TiB 2 coatings on cemented carbides using molten salt electrophoretic deposition, consisting of in-situ synthesis of TiB 2 nanoparticles by borothermal reduction of TiO 2 in NaF-AlF 3 molten salts and subsequent electrophoretic deposition of the as-synthesized TiB 2 nanoparticles to form TiB 2 coatings in the same molten bath. This technique prepares a fully dense TiB 2 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  mm 3 /(N∙m)) compared with those of WC-8wt% Co substrate(coefficient of friction, 0.58; wear rate, 9.14 × 10 −7  mm 3 /(N∙m)).