SEPARATION MECHANISM OF CU/CERAMICS MA COMPOSITE POWDERS IN DC PLASMA SPRAYING

The separation phenomena of ceramic phase from metal phase have been often recognized in the DC plasma spraying of uniformely mixed mechanically alloyed (MA) metal-ceramic powders. The separation mechanism of the MA composite powder materials during plasma spraying was mainly investigated in this work. Some methods for restrain the separation were also applied. The results obtained are summarized as follows. (1) The wettability between metal and ceramic material, surface tension of each material melted as well as the accelaration force of the plasma to the molten particles have affected this separation phenomena. (2) Separation was recognized even in the Cu/TiC MA powder material system, which had good wettability between metal and ceramic materials. (3) Separation was well restrained by both the application of the CuO/alumina power materials system and spraying in the low power plasma conditions.