Novel Cathode Plasma Electrolysis for Rapid Fabrication of Boronizing Layer on Ti–6Al–4V Titanium Alloy: Enhanced Wear Resistance and Microstructural Characterization

The Ti₂B₅ boronizing layer on Ti–6Al–4 V titanium (TC4) alloy is prepared using cathode plasma electrolytic method. This technique achieves a breakthrough in processing efficiency while achieving high-hardness coatings with low defect density. A systematic investigation is performed to assess the effects of deposition voltage and deposition time on the microhardness and tribological properties of the Ti₂B₅ boronizing layer. Due to the coupling effects of the heat evolution and mechanical shock effect, the deposition voltage and deposition time have a significant influence on the thickness and surface morphology. The results show that the microhardness increases approximately linearly with the thickness of the boronizing layer while the sliding coefficient of friction (COF) values are affected by the bonding interaction, thickness, and surface morphologies of the Ti₂B₅ boronizing layer. Furthermore, the volume wear is found to depend on the microhardness and sliding friction properties of the Ti₂B₅ boronizing layer. The Ti₂B₅ boronizing layer deposited under 125 V and 10 min exhibits the highest thickness of 10.5 μm with a dense surface without holes and cracks. Therefore, it possesses the highest microhardness of 1170 HV_0.3, the lowest COF value of 0.169, and the lowest volume wear of 17.1 E-05 mm³, which is 1/80th of the TC4 alloy.