METHOD FOR TREATING SURFACES

摘要

PURPOSE: A method for treating surfaces is provided to obtain treated surfaces having good wear resistant property, corrosion resistant property and fatigue resistant property. CONSTITUTION: A method for treating surfaces according to the present invention comprises the steps: a) introducing a charge into a plasm nitriding vacuum chamber and heating to the temperature above 300 degees celsius; b) plasma nitriding the charge under the atmosphere containing nitrogen and hydrogen gases; and c) maintaining the partial pressure of nitrogen in the chamber enough high to form a compound in the first half of the plasma nitriding process and carrying out plasma nitriding at partial pressure of nitrogen lower than that of the first half in the latter half of the plasma nitriding process. In a method according to the other embodiment of the present invention comprises the following step c') instead of the said step c): c') carrying out plasma nitriding while the partial pressure of nitrogen in the chamber is periodically changed.