The invention discloses a composite
abrasive grain in a grain /
alumina core-shell structure and a preparation method and the application of the composite
abrasive grain. An inner core of the composite
abrasive grain is selected from
diamond,
carbide and the like serving as abrasive grains, and an outer shell of the composite abrasive grain is an
alumina-coated layer. The preparation method includes: firstly, adding pretreated
powder into
buffer solution of a certain pH (potential of
hydrogen) value, ultrasonically dispersing for 1h, and heating to 50-80 DEG C; secondly, preparing a
coating precursor into 0.05-0.4mol / L solution, dripping the solution drop by drop into the
buffer solution, violently stirring and keeping the pH value constant; and finally, separating reactants,
drying for 24h at 120 DEG C, and performing heat treatment at 300-550 DEG C for more than one hour to obtain the composite abrasive grain in the grain /
alumina core-shell structure. Holding power of an abrasive tool base to abrasive grains can be improved to effectively solve the problem of shedding of the abrasive grains,
utilization rate of the abrasive grains is increased, the service life of an abrasive tool is prolonged, and uniformity in distribution of the abrasive grains can be remarkably improved.