| 摘要 |
The present invention is a method of cooling. The method comprises the steps of positioning material in a liquid state within a chamber. Then, there is the step of providing pressurized fluid about the chamber to form a thermal gradient across the chamber to directionally cool the material within. Preferably, the positioning step includes the step of positioning a mold with a mold chamber having material in a liquid state in the mold chamber, within an interior of a pressure vessel. Preferably, the providing step includes the step of introducing fluid, such as gas, into the pressure vessel such that the fluid that initially enters the pressure vessel is heated to a greater temperature than fluid subsequently introduced into the pressure vessel due to the fluid absorbing heat from the interior of the pressure vessel. The fluid at the greater temperature rises to the top of the pressure vessel and forces cooler fluid down so that a thermal gradient is formed in the pressure vessel such that the temperature of the fluid about the top of the mold allows the material within the top of the mold to remain at a higher temperature than the material within the bottom of the mold to induce directional cooling of the material in the mold from the bottom of the mold. For instance, a thermal gradient can be formed which allows the material in the top of the mold to remain molten while the material in the bottom of the mold directionally solidifies. The cooling of a casting in a pressurized environment drastically reduces the cooling time of the casting to room temperature. In a preferred embodiment, the step of introducing fluid into the pressure vessel can serve the dual purpose of forcing the liquid material into the mold chamber and forming the thermal gradient.
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