PURPOSE: To coat ultrafine grain powder of a metal or metallic compd. to be used for joining metals, etc. to the joint part of members to be joined in a clean state without decreasing the activity thereof by inserting the members to be joined in the state of shielding said members from the atm. air into a conveying path for the ultrafine particles of said metal or metallic compd.

CONSTITUTION: The ultrafine grain powder of a metal or metallic compd. which has high activity and is used for joining metals and ceramics is coated on members to be joined and is joined by sintering and melting at a low temp. Since the ultrafine grain powder decreases the activity thereof by combining with O2 and N2 in the atm. air, the powder is coated to the joint part in a clean state. A vacuum valve 2 and a connecting pipe 3 are connected to a path 1 for conveying the ultrafine particles of the metal, etc. and a sampler 7 is connected to the pipe 3 for the above-mentioned purpose. The valve 2 is closed and after the inside of the pipe 3 is evacuated to vacuum by a vacuum valve 5, the valve 5 is closed and the valve 2 is opened and at the same time a convering member 9 is pushed by a rod 9 moved by an iron piece 10 moving with the movement of of a magnet 1, by which the member 9 is pushed into the path 1 and the ultrafine particles in the path 1 are coated on the surface of the member 9 in the state of shielding said member from the atm. air.