Abstract: A heat-transfer material includes a tubular body made of a metal. The body includes on an inner surface thereof a porous electroplated layer having re-entrant cavities. A heat transfer material is produced by: preparing a body of a metal serving as a cathode and forming a hydrophobic film on a surface of the body; subsequently keeping the surface of the body and an anode in contact with a plating aqueous solution; and subsequently applying a direct electrical potential betwee the anode and the cathode to cause plating current to flow through the plating solution to lay deposits of plating metal on the surface of the body and laying a number of particulate bubbles on the hydrophobic film on the surface of the body so that the bubbles are enveloped by the metal deposits to form on the surface of the body a porous plated layer having re-entrant cavities.

Abstract: A heat-transfer material includes a tubular body made of a metal. The body includes on an inner surface thereof a porous electroplated layer having re-entrant cavities. A heat transfer material is produced by: preparing a body of a metal serving as a cathode and forming a hydrophobic film on a surface of the body; subsequently keeping the surface of the body and an anode in contact with a plating aqueous solution; and subsequently applying a direct electrical potential between the anode and the cathode to cause plating current to flow through the plating solution to lay deposits of plating metal on the surface of the body and laying a number of particulate bubbles on the hydrophobic film on the surface of the body so that the bubbles are enveloped by the metal deposits to form on the surface of the body a porous plated layer having re-entrant cavities.

Abstract: A heat-transfer material is produced by: preparing a body of metal serving as a cathode; subsequently keeping a surface of the body and an anode in contact with a plating aqueous solution; and applying a direct electrical potential between the anode and the cathode to cause a plating current to flow through the plating solution to produce slime from the anode and to lay deposits of plating metal on the surface of the body and moving the slime to the surface of the body to lay deposits of the slime on the surface of the body, so that the deposits of plating metal and the deposits of the slime jointly form on the surface of the body a porous layer which has minuscule projections of electrodeposits densely formed on one surface of the layer directed away from the body.

Abstract: A heat-transfer material is produced by: preparing a body of metal serving as a cathode; subsequently keeping a surface of the body and an anode in contact with a plating aqueous solution; and applying a direct electrical potential between the anode and the cathode to cause a plating current to flow through the plating solution to produce slime from the anode and to lay deposits of plating metal on the surface of the body and moving the slime to the surface of the body to lay deposits of the slime on the surface of the body, so that the deposits of plating metal and the deposits of the slime jointly form on the surface of the body a porous layer which has minuscule projections of electrodeposits densely formed on one surface of the layer directed away from the body.

Abstract: An apparatus for working a surface of a metal pipe is provided. The apparatus comprises a drawing unit for drawing a metal pipe to reduce a diameter thereof, and a working assembly for working the diameter-reduced metal pipe to form an inner surface and/or an outer surface thereof into a predetermined configuration. The working assembly includes a rolling unit and a driving mechanism therefor. The rolling unit includes a housing, a plurality of rolling rolls rotatably disposed within the housing and outside the metal pipe so that the rolling rolls have their respective axes extending at an inclination angle with respect to an axis of the metal pipe. The rolling rolls are respectively mounted on support shafts rotatably supported in the housing through thrust bearings. The driving mechanism drivingly rotates the rolling unit to revolve the rolling rolls around the metal pipe. The rolling unit is removably mounted on the driving mechanism.