| 摘要 |
<p>A method of immersing an iron member in a molten salt bath containing Li, Na and K as cation components and CNO- and CO¿3?2- to form a nitride layer on the surface thereof, characterized in that one or more selected from among lithium hydroxide, sodium hydroxide and potassium hydroxide is further added to the molten salt bath, to thereby form a nitride layer on the surface of the iron member and simultaneously a iron lithium composite oxide layer on the uppermost surface thereof. A bath-preparing agent or a component-replenishing agent containing a hydrate or free water may be added to the molten salt bath in place of the sodium hydroxide or the like. The salt bath is preferably agitated with a wet air having (1 X 10-2 kg or more of H¿2?O)/(1 kg of dry air). Li, Na and K components are preferably present in the salt bath in such a range that provides a mixture of carbonates of the three elements having a solidifying point of 500 ° C or lower and the mole ratio of Na : K is preferably 2:8 to 8:2. CNO?-¿ is preferably contained in an amount of 5 to 35 wt %. The accumulation of by-produced CN- in the salt bath is preferably suppressed to a content of 2 wt % or less. The salt bath preferably has a temperature of 450 to 650 ° C. The resultant iron member exhibits improved wear resistance and also improved corrosion resistance.</p> |
