The Transition Metal Nitrides Synthesis And Chacterization By Precursoy Method

Transition-metal nitrides have attracted much attention because of the compoundspossessing high melting point, high hardness, wear resistance, good mechanical strengthand thermal stability. In this dissertation, a precursor method has been explored tosynthesize a series of transition-metal nitrides.Transition-metal nitride powders, including titanium nitride, iron nitride, chromiumnitride and nickel nitride, have been synthesized using urea/metal complexes as precursors.The effect of the urea/metal precursor molar ratio (R), reaction temperature, reaction timeand solvent on the crystal structure and morphology of synthesized powders have beeninvestigated. The preferred heat treatment temperature and suitable synthesis conditions ofthe product were ascertained by TG-DTA, XRD, SEM and EDS techniques.Titanium nitride was synthesized by the urea/metal chloride precursor. It has beenfound that the pure phase powder can acquired when R is 4 to 12. Otherwise, titaniumoxides would appear in the product. The results show that 800℃～900℃is in favor ofhigh-purity titanium nitride powders.As for iron nitride, compared with the sample made by the urea/metal chlorideprecursor, that synthesized by the urea/metal nitrate precursor exhibits more pure phasestructure.Chromium nitride and nickel nitride were prepared by the nitrate precursor andchloride precursor, respectively. With regard to chromium nitride, the suitable reactiontemperature is above 800℃and the reaction time is at least 3 hours to acquire high-puritypowders. While for nickel nitride temperature, the preferred reaction temperature isbetween 110℃and 150℃. When the temperature is higher than 400℃，all the product ischanged into Ni.