Plasma treatment method, method of producing plasma-treated hexagonal boron nitride powder, and plasma treatment device

A method of producing a plasma-treated hexagonal boron nitride powder, the method comprising:

• storing a hexagonal boron nitride powder as a raw material in a treatment container;
• supplying a plasma generating gas into the treatment container and maintaining inside of the treatment container at a pressure lower than atmospheric pressure;
• applying high frequency waves to an electrode installed outside the treatment container while rotating the treatment container about a central axis of the treatment container as a rotation axis in a state in which the rotation axis of the treatment container is inclined with respect to horizontal, to plasma-treat the hexagonal boron nitride powder in the treatment container and obtain a plasma-treated hexagonal boron nitride powder;
• and
• cooling one or both of the treatment container and the electrode during the plasma treatment.

A plasma treatment device configured to plasma-treat a hexagonal boron nitride powder under reduced pressure, the plasma treatment device comprising:

• a treatment container configured to store the hexagonal boron nitride powder;
• a gas supplier configured to supply a plasma generating gas into the treatment container;
• a pressure reducer configured to maintain inside of the treatment container at a pressure lower than atmospheric pressure;
• a rotation mechanism configured to rotate the treatment container about a central axis of the treatment container as a rotation axis in a state in which the rotation axis is inclined with respect to horizontal;
• an electrode installed outside the treatment container;
• a high frequency power source configured to apply high frequency waves to the electrode;
• and
• a cooler configured to cool one or both of the treatment container and the electrode.