Effect of SiC nanowires on performance of atmosphere plasma sprayed Si coatings
This work aims at improving the toughness of Si coatings in C/SiC composite surface and the bonding strength between them.C/SiC composites with the sizes of 10 mm × 10 mm × 10 mm were used as the matrix and a 20 μm SiC nanowire(SiCnws)porous layer was in-situ generated on the matrix surface;then,Si coatings with different thicknesses(30,60,and 90 μm)were sprayed on the matrix with or without the SiC nanowire porous layer by the atmosphere plasma sprayed method.The effect of the SiCnws on the bonding strength and oxidation resistance of the coated samples were investigated.The phase and mor-phology of the SiCnws and SiCnws/Si coatings were characterized by XRD,SEM,TEM and EDS.The re-sults show that(1)the obtained SiCnws have flat shapes,smooth surface,random orientation,with diame-ters of 100-200 nm,which are β-SiC with a preferential growing direction along[111];(2)the bonding strength of the SiCnws/Si with the matrix is higher than that of the Si coating with the matrix,so the intro-duction of SiCnws increases the bonding strength;(3)the mass loss of the SiCnws/Si coatings is 20.7％-37.2％lower than that of the Si coatings after suffering 12 cycles of thermal shocks between the room tem-perature and 1 400 ℃,indicating that SiCnws release the thermal stress,prevent the formation and growth of cracks,and enhance the oxidation resistance.
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