PURPOSE: To improve seizing property between a sleeve and an arbor by forming a hard covering layer of a prescribed thickness on the fitting surface of the arbor with the hard sleeve and containing a metallic bond phase of a hard material such as metal carbide, etc., whose hardness is nearly equal to that of WC by a specific weight percentage in the covering layer.

CONSTITUTION: A hard covering layer 5 of a prescribed thickness is formed on the fitting surface of an arbor 1 with a hard sleeve 2. Powder hard materials such as carbide, oxide, or carbo-nitride of metal in which the ratio of carbon to nitrogen is ≥0.5 and whose hardness is nearly equal to that of WC and higher than that of Ni, Cr and lower than that of WC is used for the hard covering layer. The powder hard material has a composition containing a bond phase of one or more metals by 50-90%. A covering method employs thermal spraying, etc. when the hardness of the layer is closed to that of WC being an essential component of the sleeve 2, a friction surface is not broken before a stress of the surface reaches a prescribed value. Seizing is effectively prevented because metal carbide, etc., resist heat and are hardly soluble in WC.