High-Performance Ceramic-Lined Composite Pipes with ZrO₂ Additive Prepared by Centrifugal-SHS Process

Abstract

High-performance ceramic-lined composite steel pipes (CLCSPs) were fabricated by self-propagating high-temperature synthesis and centrifugal casting technique. ZrO₂ powders doped by 3 mol% Y₂O₃ were added into Al-Fe₂O₃ thermit to improve the mechanical properties of CLCSPs. The phase constituents and microstructural evolution of ceramic layers after addition of ZrO₂ were analyzed by means of X-ray diffractometer, optical microscope, scanning electron microscope and energy dispersive X-ray spectrometer. The effects of ZrO₂ on fracture toughness of ceramic layers, and crushing strength as well as mechanical shock of CLCSPs were investigated using Vickers indentation microfracture method, squeezing test and repetitive impacting method. The results show that addition of ZrO₂ changes the morphology and preferential orientation of Al₂O₃ dendrites, and reduces the width of Al₂O₃ dendrites, leading to the microstructure of Al₂O₃ dendrites with fine t-ZrO₂ phase particles distributed at boundaries. The hardness of ceramic layer decreases, while the crushing strength of CLCSP changes slightly after addition of ZrO₂. The fracture toughness of ceramic layer is significantly enhanced; meanwhile the mechanical shock resistance of CLCSPs was also greatly improved by adding more than 2% ZrO₂. The optimum adding amount of ZrO₂ is 4%–6%.