Surface Technology (表面技术)•2026•DOI: 10.16490/j.cnki.issn.1001-3660.2026.09.006
Glass-ceramics, multiphase composites combining amorphous and crystalline phases, exhibit disparate mechanical responses that induce subsurface damage and surface defects during conventional polishing. This study fabricates magnetic abrasive particles (MAPs) via a bonding process with three variants: unmodified, hydrophilic nano-silica (20 nm) modified, and hydrophobic nano-silica (20 nm) modified. Base composition comprises iron powder (75 μm) and CeO2 abrasives (15 μm) at a 12:3 mass ratio. Polishing tests on glass-ceramics using an N-S array tool reveal that hydrophobic modified MAPs achieve the lowest surface roughness (Sa = 17 nm) and highest material removal depth (2.5 μm), compared to hydrophilic (Sa = 24 nm) and unmodified (Sa = 48 nm) MAPs. Dynamic friction coefficients measured in situ are 0.31, 0.35, and 0.42 for hydrophobic, hydrophilic, and unmodified MAPs, respectively. Surface and subsurface damage analyses show hydrophobic MAPs minimize pits, micro-cracks, and brittle fractures, while hydrophilic MAPs exhibit brittle spalling and unmodified MAPs show point defects. Wear tests confirm that nano-silica addition enhances bond strength and extends abrasive lifespan. The hydrophobic modification promotes surface hydration and formation of a lubricating silicate gel layer, reducing mechanical plowing and friction, thereby enabling high-quality surface integrity. These findings demonstrate that nano-silica modification effectively tunes MAP hydrophobicity, offering a viable route for ultra-smooth, low-damage polishing of glass-ceramics.
Surface Technology (表面技术)•2026•DOI: 10.16490/j.cnki.issn.1001-3660.2026.09.007
TC4 titanium alloy, a representative α+β dual-phase alloy, exhibits high specific strength, corrosion resistance, and biocompatibility but remains a classic difficult-to-machine material due to high chemical reactivity, low thermal conductivity, and complex phase-dependent mechanical behavior. Conventional polishing routes yield low material removal rates and poor surface consistency. This work formulates a graphene-assisted chemical magnetorheological polishing fluid comprising 0.40 wt.% monolayer graphene flakes, 15 wt.% carbonyl iron powder, 5 wt.% alumina abrasives, and 3.0 wt.% hydrogen peroxide as the primary oxidant. The catalytic role of graphene in the Fenton reaction is quantified via real-time oxidation-reduction potential (ORP) monitoring, immersion tests, and X-ray photoelectron spectroscopy (XPS). Graphene elevates the ORP from 337 mV to 347 mV at 30 min and increases the high-valence Ti4+ fraction in the surface oxide layer from 54.81 at.% to 60.13 at.%. Concurrently, graphene reduces the average polishing force by 50% (from 0.26 N to 0.13 N) and improves force stability, confirming a lubrication effect at the pad-workpiece interface. Single-factor experiments on machining gap and spindle speed identify an optimized condition of 1.0 mm gap and 400 rad/min, under which surface roughness Sa decreases from 350 nm to 75 nm within 15 min. The results establish that graphene delivers dual catalytic-oxidation and lubrication functions, enabling efficient, high-integrity finishing of TC4 titanium alloy and offering a viable route for ultra-precision surface treatment of complex hard-to-machine materials.
Surface Technology (表面技术)•2026•DOI: 10.16490/j.cnki.issn.1001-3660.2026.11.007
The cam-tappet friction pair in internal combustion engines experiences severe wear under excessive loads and complex lubrication, reducing engine efficiency. This study employs laser surface texturing to fabricate biomimetic wavy textures on GCr15 steel, varying texture spacing to investigate the influence of area fraction on tribological performance. Ball-on-disk tests simulated cam-tappet point contact using AISI 1045 steel balls under 10 N load, 1.038 GPa contact stress, 150 r/min, and oil lubrication. Friction coefficient and wear rate were monitored, with surface morphology and elemental composition analyzed by SEM, 3D profilometer, and EDS. Fluent simulations modeled oil film pressure distribution for different spacings. All textured samples outperformed the untextured substrate. Optimal area fraction of 15–20% reduced friction coefficient by ~50% and wear rate by 60% compared to the substrate, while oil film pressure increased by 20% relative to a 9.75% area fraction texture. Simulation and experimental results concur. Excessive texture area fraction increases contact stress and wear, whereas insufficient area fraction yields low oil film pressure and poor hydrodynamic effects. Laser-fabricated biomimetic wavy textures effectively enhance the friction and wear performance of GCr15 steel through abrasive particle storage and hydrodynamic pressure augmentation, with an optimal area fraction of 15–20%.