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Nickel slag is the solid waste obtained from the nickel smelting process. Based on the magnetic elements in nickel slag, it is a potential ingredient that could be used in magnetic compound fluid (MCF) polishing. This work discusses polishing in MCF using nickel slag and modified slag. Investigations are conducted into how MCF is affected by the amount of modified slag and nickel slag present during polishing. The connections between shear force, position, material removal rate, morphological characteristics, and polishing quality are covered. Nickel slag is mixed with CaO, the alkalinity is adjusted, and the mixture is heated to 1500 °C to fully melt and oxidize it. The resulting product is modified slag. The morphological changes in MCF slurry before and after polishing were examined using an industrial camera, and the effect of different MCF slurry components on polishing performance was analyzed throughout the polishing process. In addition, the positioning of modified slag within the magnetic cluster formed during the polishing process was determined through a scanning electron microscope and by energy dispersive x-ray spectroscopy mapping of MCF slurry. The aforementioned research establishes the polishing mechanism for nickel slag and modified slag. The experimental results indicate that the polishing effect of the experimental group with added modified slag is better than that of added nickel slag. Under the same conditions, the surface roughness was reduced by 60% when modified slag was used instead of nickel slag. It was found that the optimal process is where the modified slag content is 10%, where the material removal rate is 1.207 × 108 µm3/min and the surface roughness decrease rate is 95.482%. The polishing shear force is around 2.7N, which is twice as much as that of nickel slag.

A novel magnetic field-assisted polishing technique was proposed for finishing 3D structured surface using a magnetic compound (MC) slurry. The MC slurry was prepared by blending carbonyl-iron-particles, abrasive grains and α-cellulose into a magnetic fluid which contains nano-scale magnetite particles. An experimental setup was constructed firstly by installing an oscillation worktable and a unit onto a polishing machine. Then, experimental investigations were conducted on oxygen-free copper workpiece with parallel distributed linear V-grooves to clarify the influence of the polishing time and abrasive impact angle on the grooves surface qualities. It was found that (1) the groove form accuracy, i.e. the form retention rate η varied with the polishing locations. Although the form retention rate η deteriorated during the polishing process, the final η was greater than 99.4%; (2) the effective impact angle θm affected the material removal and form accuracy seriously. An increase of the absolute value θm resulted with an increase of material removal rate and a decrease of the form accuracy; (3) the work-surface roughness decreased more than 6 times compared with the original surface after MC slurry polishing. These results confirmed the performance of the proposed new magnetic field-assisted polishing method in the finishing of 3D-structured surface.