Abstract: Provided is a composite nanometal paste which, when a layer of the paste interposed between upper and lower bodies is sintered in an inert gas under no load until the layer turns to a metal layer, attains a shear bond strength between the upper and lower bodies of 10 MPa or higher. The composite nanometal paste contains, as metallic components, composite metallic nanoparticles comprising metal cores with an average particle diameter of X (nm) and an organic coating layer formed around the circumference, metallic nanofiller particles having an average particle diameter of d (nm), and metallic filler particles having an average particle diameter of D (nm), and satisfies the first relation X<d<D and the second relation X<d<100 (nm).

Abstract: Provided is a composite nanometal paste which, when a layer of the paste interposed between upper and lower bodies is sintered in an inert gas under no load until the layer turns to a metal layer, attains a shear bond strength between the upper and lower bodies of 10 MPa or higher. The composite nanometal paste contains, as metallic components, composite metallic nanoparticles comprising metal cores with an average particle diameter of X (nm) and an organic coating layer formed around the circumference, metallic nanofiller particles having an average particle diameter of d (nm), and metallic filler particles having an average particle diameter of D (nm), and satisfies the first relation X<d<D and the second relation X<d<100 (nm).

Abstract: A method of joining a ball member to an end of a cylindrical matrix plunger body by resistance welding thereby to make a plunger for use in a directional control valve for controlling fluid communication in said valve is disclosed. A resistance welder for the method has a pair of electrodes. The ball member is placed in contact with a conical recess within the matrix plunger body and with a conforming surface of one of said electrodes so as to form a circular first contact between the ball member and the matrix plunger body and a spherical second contact between the ball member and the one electrode such that electrical contact resistance at the first contact is greater than that at the second contact. Then, an electric current at a constant rate flows for a controlled period of time through the first and second contacts with the ball member which is kept in contact with the matrix plunger body under pressure by the electrode.