Surface Technology (表面技术)•2026•DOI: 10.16490/j.cnki.issn.1001-3660.2026.10.007
Arc ion plating of chromium coatings on 40CrNi alloy steel was systematically investigated as a function of target surface magnetic field intensity (3, 6, 9, and 12 Gs). Scanning electron microscopy, X-ray diffraction, microhardness testing, tribological analysis, scratch adhesion testing, and electrochemical polarization were employed to correlate arc spot dynamics with coating microstructure, mechanical properties, and corrosion resistance. Increasing the magnetic field from 3 to 12 Gs initially reduced and then increased surface roughness and macroparticle density, while deposition rate peaked and grain size reached a minimum at intermediate field strengths. The optimal field intensity of 9 Gs produced a maximum hardness of 470.84 HV0.05, a minimum friction coefficient of 0.42, a minimum wear volume of 1.06×10−7 mm3/(N·m), a maximum adhesion strength of 40.3 N, a corrosion potential of 76.1 mV, and a corrosion current density of 7.57×10−10 A/cm2. At 3 and 12 Gs, fatigue wear dominated; at 6 and 9 Gs, abrasive wear prevailed. These results demonstrate that target magnetic field intensity is a decisive process parameter for tailoring arc spot motion, refining grain structure, suppressing macroparticle emission, and enhancing the combined mechanical and corrosion performance of arc ion plated Cr coatings.
Int. Journal of Minerals, Metallurgy and Materials (矿物冶金与材料学报)•2025•DOI: 10.1007/s12613-024-3053-y
Hydrogen-based mineral phase transformation (HMPT) technology has demonstrated its effectiveness in separating iron and enriching rare earths from Bayan Obo refractory ores. However, further research is needed to clarify the phase composition and floatability of rare earths obtained after HMPT owing to the associated phase transformations. This study explored the mineralogical characteristics and separation behavior of rare earths in HMPT-treated iron tailings. Process mineralogy studies conducted via BGRIMM process mineralogy analysis and X-ray diffraction revealed that the main valuable minerals in the tailings included rare-earth oxides (9.15wt%), monazite (5.31wt%), and fluorite (23.52wt%). The study also examined the impact of mineral liberation and gangue mineral intergrowth on flotation performance. Flotation tests achieved a rare-earth oxide (REO) grade of 74.12wt% with a recovery of 34.17% in open-circuit flotation, whereas closed-circuit flotation resulted in a REO grade of 60.27wt% with a recovery of 73%. Transmission electron microscopy and scanning electron microscopy coupled with energy-dispersive spectroscopy revealed that monazite remained stable during the HMPT process, while bastnaesite was transformed into Ce7O12 and CeF3, leading to increased collector consumption. Nonetheless, the HMPT process did not significantly affect the flotation performance of rare earths. The enrichment of fluorite in the tailings highlighted its further recovery potential. The integration of HMPT with magnetic separation and flotation presents an efficient strategy for recovering rare earths, iron, and fluorite from Bayan Obo ores.