▎ 摘　　要

NOVELTY - The joint (10) has a fluid path (210) connected with a fluid port (110) and formed in an inside. A pocket (120) for a sealing is formed with a ring-shaped groove according to an inner circumference of housing (100) with machining and arranged in an equal space according to an axial direction of the housing. A substrate maintaining airtightness (300) is inserted within the pocket for the sealing, and surrounds a circumference of a shaft (200). An exterior of the shaft is coated with a coating layer provided with a nano-composite material, where graphene or copper nano is contained. USE - Rotary joint for connecting a pipe and a rotor. ADVANTAGE - The joint forms the pocket for sealing in the housing, so that the substrate maintaining airtightness covering the shaft is inserted in the pocket for sealing. The joint provides high airtightness as the substrate maintaining airtightness closely adhered to the exterior of the shaft with a possession of the pocket for such sealing through a structure improvement of the substrate maintaining airtightness, and an edge adheres closely to the inner surface of the pocket for sealing at the same time. The joint accommodates the fluid pocket in the shaft and a grease leak generated according to a load of an operation of the shaft or fluid by a trace amount, and removes the grease leak and the substrate maintaining airtightness that is generated when the outlet of the fluid path formed in the fluid port and shaft of the housing, so that the airtightness is more improved. The joint makes the wear-resistant coating processing by the nano-composite material, so that the sealing is improved even when lubrication is smoothly made, and prevention and durability of the abrasion of the substrate maintaining airtightness is increased. DESCRIPTION OF DRAWING(S) - The drawing shows a cross sectional view of a rotary joint. Rotary joint (10) Housing (100) Fluid port (110) Pocket (120) Shaft (200) Fluid path (210) Substrate maintaining airtightness (300)