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%.