The Effect Of Ce Element On The Microstructure And Properties Of Hot Dip Aluminized Tritium Pemeation Barrier

In this dissertation, The effect of rare element Ce on the microstructure and propertiesof coatings was also investigated systematically. The gradient tritium penetration barrierin which Al concentration has a gradient distribution was fabricated on CLAM steelsubstrate by hot dip aluminizing (HDA) and subsequent high-temperature diffusiontreatment. The coatings were characterized by X-ray diffraction (XRD), scanningelectron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), the bondingstrength, thermal shock resistance and oxidation resistance at high temperature of thecoating were investigated by tensile way tests, thermal shock tests and oxidation kineticcurves. The main results are as follows.The fabricated coating included Al layer and Fe-Al layer. The thickness of Fe-Allayer was larger and serrated interface bonding with the substrate was achieved when thecontent of Ce increase, which is the most obvious when the content is1%. The gradientdistribution of Al in aluminized coating from surface to inter was obtained after thermaldiffusion at850℃for4h, which reduced the thermal stress effectively. However, a lotof cracks were found after diffusion from face to substrate of the coating with lessaddition of Ce, while they are much less in the coatings after diffusion with0.5%and1%addition of Ce. This indicated that the addition of Ce significantly suppressed the growthof cracks.The bonding strength tests indicated that bonding strength of coatings was largerwhen the content of Ce increased. The bonding strength of coatings without addition ofCe was12MPa,while it increased to27MPa when the addition of Ce was1%. Theaddition of Ce in the coatings enhanced the bonding strength. The thermal shockresistance of the coatings were also improved because after13times thermal shock thecracking and peeling off the coatings without Ce addition occurs, while the coatings with 1%addition of Ce were cracked after35times thermal shock. The oxidation kineticcurves showed that, at a high temperature800℃, the weight-added of the coatings werethe reduced when the addition of Ce were from0%to0.5%, the abilities of oxidationresistance were improved. When the addition of Ce was1%, the coating had a lessoxidation-added weight than the coating with0.5%Ce addition, almost the same as thecoating with0.1%Ce addition.The above results indicated that the proper Ce addition in the hot-dip-aluminizedcoatings could improved their properties. As a tritium permeation barrier, thehot-dip-aluminized coating was promised.