Preparation of TiB₂ Coatings on Graphite via Electrophoretic Deposition in NaCl-KCl-AlF₃ Molten Salts

The combination of molten salt synthesis of nanoparticles and electrophoretic deposition of them is a novel method for preparing transition metal boride coatings. Herein, TiB₂ nanoparticles were synthesized in NaCl-KCl-AlF₃ molten salts and they were electrophoretically deposited on the graphite substrate to form a TiB₂ coating in the same molten bath. Through the borothermal reduction reaction in this molten system, TiB₂ nanoparticles with a size ranging from 50 to 150 nm were produced. Then, via electrophoretic deposition the prepared TiB₂ coating exhibited excellent corrosion resistance to liquid zinc. In the cell voltage of 1.0–1.4 V, the thickness of TiB₂ coatings first increased, and then decreased with the rise of voltage and reached a peak value of 28 μm at 1.3 V. The coating prepared at 1.2 V exhibited optimal quality. At a cell voltage of 1.2 V, as the EPD duration increased from 1 to 10 min, the amount of TiB₂ deposited on the graphite substrate was linearly related to the total charge consumption, corresponding to 16.6 C for 1 mg of TiB₂ deposition. This study offered fundamental guidance for preparing high-quality coatings through the molten salt synthesis and electrophoretic deposition process.