Preparation Of Fe/Al Clad Pipe Fittings And Ceramic Coatings On Inner Surface

To prepare the ceramic barrier on the surface of structural materials with low tritium permeability is an effective way to increase the tritium penetration resistance of the materials in fusion reactors. In this work, the cold processing of Fe/Al clad pipe fittings was investigated based on the results of FE simulation, and tritium penetration barrier Al2O3 on the inner surface of the fittings was prepared by the ion oxidization of Al layer.Firstly, the Fe/Al clad tube blank was prepared by explosive welding. The adhesion property of the tube was evaluated respectively by compression-shear test, flattening test and compression test. The results showed that the clad tube had better bonding strength than pure aluminum and could bear certain deformation without cracks occurring in the interface. The microstructure and the composition in the interface were characterized respectively by scanning electron microcopy (SEM) and energy dispersion spectrum (EDS). It was detected that the interface of the clad tube was bonded directly in the head, in a wavy shape in the middle and with the melt layer in the end. The thickness of wave shaped interface was about 2.5μm.Then the hydroforming of Fe/Al clad tube T-shape and the pushing bending of Fe/Al clad tube elbows were simulated by the MSC.Marc software to determine the processing parameters. The clad pipe fittings were fabricated eventually under the guidance of the FE simulation results. The work hardening of the clad tube T-shape was severe after forming. The two layers of the clad tube T-shape combined well enough that there was no crack between them. For the clad tube elbow, the grain of the layer Fe changed slightly after forming, and the work hardening of the elbow was low. But some cracks appeared at exterior arc zone near the interface.The oxidation of the aluminum layer inner clad pipe fittings was conducted by ion oxidizing processing. The morphology and the phases of the coatings were analyzed individually by SEM and XRD. And the scratch test, wear test, polarization test and thermal shock test were performed respectively. The results proved that the ceramic coatings were compact with the thickness about 1μm and possessed good bonding strength, anti-wear property, corrosion resistance and thermal shock resistance.