A method of manufacturing a permanent magnet comprises a solution heat treatment. The solution heat treatment includes: performing a heat treatment at a temperature T.sub.ST; placing a cooling member including a first layer and a second layer on the first layer between the heater and the treatment object so that the first layer faces the treatment object; and transferring the treatment object together with the cooling member to the outside of a heating chamber, and cooling the treatment object until a temperature of the treatment object becomes a temperature lower than a temperature T.sub.ST200 C. In the step of cooling the treatment object, a cooling rate until the temperature of the treatment object becomes the temperature T.sub.ST200 C. is 5 C./s or more.

A method for heat treatment, a heat treatment apparatus, and a heat treatment system that is capable of performing highly precise and efficient control of heat treatment. A heat treatment furnace has in-furnace structures made of graphite and has a heat-treatment chamber in which heat treatment of materials to be treated is performed. A value of G.sup.0 (standard formation Gibbs energy) is computed with reference to the sensor information from respective sensors, and an Ellingham diagram, a control range, and a status of the heat treatment furnace in operation expressed by G.sup.0 are displayed on a display device. A control unit controls a flow rate of neutral gas or inactive gas as atmosphere gas or a flow velocity of the gas so that G.sup.0 is within the control range.

A method for heat treatment, a heat treatment apparatus, and a heat treatment system that is capable of performing highly precise and efficient control of heat treatment. A heat treatment furnace has in-furnace structures made of graphite and has a heat-treatment chamber in which heat treatment of materials to be treated is performed. A value of G.sup.0 (standard formation Gibbs energy) is computed with reference to the sensor information from respective sensors, and an Ellingham diagram, a control range, and a status of the heat treatment furnace in operation expressed by G.sup.0 are displayed on a display device. A control unit controls a flow rate of neutral gas or inactive gas as atmosphere gas or a flow velocity of the gas so that G.sup.0 is within the control range.

A rotary kiln includes: a heating tube; a material feeding unit disposed on a first end of the heating tube; a material collection unit disposed on a second end of the heating tube; an inner cylinder supported at the second end of the heating tube with the inner cylinder being inserted in a central portion of the heating tube; a plurality of branch tubes disposed circumferentially on an outer circumferential surface of the inner cylinder, each of the branch tubes branching from the inner cylinder and extending in an axial direction along an inner circumferential surface of the heating tube; a hot air supply tube supported to be relatively rotatable with respect to the inner cylinder with the hot air supply tube being inserted in one end of the inner cylinder that extends outside the heating tube; and a drive mechanism that rotates the heating tube.

A heat treatment system may include: a heat treatment furnace; a return line; and a processor. The return line may include: a first processing line; a second processing line; an entrance line connected to the first processing line and the second processing line and located upstream of the first processing line and the second processing line on the return line; and an exit line connected to the first processing line and the second processing line and located downstream of the first processing line and the second processing line on the return line. The processor may include: a configured to process the saggar on the first processing line; and a configured to process the saggar on the second processing line.

A heat treatment system may include: a heat treatment furnace; a return line; and a processor. The return line may include: a first processing line; a second processing line; an entrance line connected to the first processing line and the second processing line and located upstream of the first processing line and the second processing line on the return line; and an exit line connected to the first processing line and the second processing line and located downstream of the first processing line and the second processing line on the return line. The processor may include: a configured to process the saggar on the first processing line; and a configured to process the saggar on the second processing line.

A continuous, high-temperature preheating plant for preheating flat semi-finished steel products has a conveying line suitable to transfer the flat semi-finished steel products from an inlet to an outlet of the continuous, high-temperature preheating plant, and a plurality of heating devices arranged along the conveying line to heat the semi-finished steel products from an inlet temperature to a predetermined final temperature. The plurality of heating devices has, arranged in sequence between the inlet and the outlet along the conveying line, a first induction furnace, a second induction furnace, and at least one electric resistance radiation furnace. The continuous, high-temperature preheating plant has a cutting apparatus suitable to cut a starting flat semi-finished steel product into a plurality of cut segments having a predetermined length less than a length of the starting flat semi-finished steel product. The cutting apparatus is arranged between the first induction furnace and the second induction furnace.

A method for holding a saggar conveyed out from a heat treatment furnace is disclosed. The method may include: holding the saggar by a pair of holding members configured to be movable in a left-right direction; and positioning the saggar held by the pair of holding members in an up-down direction at a predetermined position by moving the saggar in the up-down direction perpendicular to the left-right direction relative to the pair of holding members.

A method for holding a saggar conveyed out from a heat treatment furnace is disclosed. The method may include: holding the saggar by a pair of holding members configured to be movable in a left-right direction; and positioning the saggar held by the pair of holding members in an up-down direction at a predetermined position by moving the saggar in the up-down direction perpendicular to the left-right direction relative to the pair of holding members.

The baked object taking-out apparatus is an apparatus that takes out a baked object from a baking base plate including a disposing surface on which the baked object is disposed. The baked object taking-out apparatus includes a robot arm, a holding member that is provided on the robot arm, that is formed of a metal material, and that is capable of holding the baking base plate, and a protective member that is formed at a portion of the holding member which comes into contact with the baking base plate and that is configured with a ceramic coating which contains a ceramic component.