Nickel silicon or boron nitride abradable sealing coating and preparation method thereof

The nickel silicon or boron nitride abradable sealing coating is characterized in that nickel silicon or boron nitride powder is compactly agglomerated composite powder, and the structure of the nickel silicon or boron nitride powder is a regular sphere-like particle structure formed by taking a nickel silicon intermediate and superfine aluminum powder as a framework structure. The nickel silicon or boron nitride powder comprises the following components in percentage by mass: 5.0 to 11.0 percent of BN, 0.2 to 1.0 percent of Al, 1.0 to 2.0 percent of C, 4.0 to 11.0 percent of SiO2 and the balance of Ni. The preparation method comprises the following steps: keeping a steel ball with the diameter of 10mm for 60s under the load of 250kg, wherein the diameter of an indentation is 3.8-6.3 mm; and the bonding strength of the coating should be greater than or equal to 4MPa. When the coating is put into cold water for quenching, the coating is free of peeling and layering. The method has the advantages that large par