| Popis: |
Molybdenum is one of the refractory metals which has high melting point, 2620oC, and good mechanical properties. Unfortunately, oxidation resistance of molybdenum is not satisfactory for certain applications which involves high temperatures; therefore, an oxidation resistant coating is necessary. Molybdenum di-silicide (MoSi2) was coated on pure molybdenum and TZM alloy to increase oxidation resistance at high temperatures by electroless molten salt method. A molten salt solution containing NaCl, KCl and NaF was used to apply coating at temperatures above 600oC. Silicon powder and Na2SiF6 were used as silicon source during coating process. Experiments were carried out at different temperatures, durations and salt compositions. Coating thickness, surface roughness, resulting phases and coating behavior of pure molybdenum and TZM alloy were evaluated. X-ray diffraction (XRD), Inductively Coupled Plasma – Mass Spectrometer (ICP-MS) and scanning electron microscope (SEM) were conducted in characterization of the silicide coatings. |
