Fabrication of nano-rod array structure by using aluminizing and internal oxidation of Ni with micro-channels

A metallurgical method for preparing oxide nano-rod array structure was developed with internal oxidation of Ni(Al) solid solution obtained by aluminizing Ni with a pack cementation technique. The present method was applied in order to fabricate nano-rod array on the micro-channel surface of microreactor. A micro-channel with 1 mm in depth, 1mm in width and 10 mm in length was fabricated on the Ni disk by an electric discharge machining and electropolishing. The Ni disk with a micro-channel was annealed at 1300 degrees C for 12 h in vacuum. The sample was aluminized by a pack cementation using pack powder mixture consisting of 10 mass% of Ni3Al, 88 mass% of Al2O3 and 2 mass% of NaCl at 1100 degrees C for 12 h in a flow of argon gas. The sample was oxidized from 1000 to 1200 degrees C for 6 h with the Co/CoO buffer. Ni matrix in internally oxidized zone was removed by electropolishing to expose nano-rods. Al2O3 nano-rod array located on the micro-charnel surface was successfully fabricated with the proposed technique. Diameter and height of nano-rods were ranged from 100 to 300 nm and from 1.5 to 3 mu m, respectively.