Pressure heat treatment apparatus employed for preparing oxide superconducting wire

A pressure heat treatment apparatus comprising:

• a pressure heat treatment furnace storing a target for heat treating said target in a pressurized atmosphere;
• a pressure regulator for measuring the total pressure in said pressure heat treatment furnace and for regulating same;
• oxygen gas feeding means for feeding oxygen gas into said pressure heat treatment furnace;
• oxygen concentration measuring means for measuring the oxygen concentration in said pressure heat treatment furnace;
• and
• oxygen partial pressure control means, connected to receive an input from said pressure regulator and an input from said oxygen concentration measuring means and providing a control signal to said oxygen gas feeding means, for controlling the oxygen partial pressure in said pressure heat treatment furnace within a prescribed range in response to the total pressure measure by said pressure regulator and the oxygen concentration measured by said oxygen concentration measuring means, wherein
• said oxygen partial pressure control means operatively cooperating with said pressure regulator so that said total pressure is maintained equal to or greater than 0.5 MPa from the beginning to the end of heat treating said target while maintaining said oxygen concentration within said prescribed range.