Three dimensional mapping of corrosion pits in cast iron pipe using the remote field effect
: The remote field effect is an electromagnetic method for inspecting pipes and tubing. It has recently been commercialised as a technique for inspecting gray cast iron and ductile iron water mains. How-ever, commercial tools provide information on pits depths in the pipe and overall wall loss. Models of the mechanical behaviour of cast iron pipe also require information on pit width and length. This paper discusses remote field effect apparatus and experimental techniques used in the laboratory to produce three dimensional electromagnetic field maps. The maps shown in the paper indicate that sizing corrosion pits in three dimensions is possible using the remote field effect. Further research needs are also discussed.
The phantom exciter: high resolution measurements of RFEC slit defect interactions
In order to obtain a better understanding of defect interactions associated with the Remote Field Eddy Current technique, a new exciter/detector geometry has been used. The Phantom Exciter geometry uses a single through-wall transmission and allows high resolution measurements to be made in the region of a defect. Strong response to axial slits in nonferrous pipes due to eddy current interaction has been demonstrated. Magnetic interactions in ferrous pipe has lead to good responses to circumferential slits
Selective etching of InP in NaF solution
Abstract The crossing porous structure of InP has been obtained by electrochemical etching in NaF solutions. The behavior of the periodic oscillation occurs at different potential ranges for the different concentrations of solutions, and it will disappear with the concentration of the solution decreased. The scanning electron microscope (SEM) image shows that the pores have two directions on the surface and are perpendicular to each other. The two directions are assigned to [0 1 1] and [ 0 1 ¯ 1 ], respectively. The SEM image of the cross-section also shows that the two directions are assigned to [1 1 1]B and [ 1 1 ¯ 1 ¯ ]B. Both are due to the selective etching of F− ions. The crossing porous structure of InP is a very promising feature for the three-dimensional structure of III–V compound semiconductors for photonic band gap materials.