To solve the problems of slag entrapment risk and frequent bond alarm in the field application of mould flux for high-speed thin slab continuous casting, the idea of ‘non-Newtonian fluid mould flux with shear-thinning property’ is introduced. It was found that with an increase in the Al2O3 content, the shear-thinning behaviour of the mould flux first increased and then decreased. The sample with 8.61% Al2O3 content had the strongest shear-thinning property and the lowest fluidity index, which reached 0.75. With the addition of Al2O3, the degree of polymerization of the mould flux molecules increased, and the relative strength of the Si–O–Al bond increased. It was found that the Al2O3 content has a significant influence on the IVAl complexes. The XPS results showed that Q3(1Al) was the structural unit most easily affected by shear stress, and the higher the content of Q3(1Al), the stronger the shear-thinning property of the mould flux.
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