Characterisation of multiphase ceramic coatings fabricated via laser in situ reaction technology

摘要

Coatings are pre-fabricated on the China low activation martensitic (CLAM) steel via thermal spraying using Cr-Fe-Al-Ti mixed powders. Crystalline and amorphous multiphase ceramic coatings are formed by a new laser surface in situ prefabricated coatings in situ reaction technology under atmospheric environments based on the Standard Gibbs free-energy theory. The grain boundary of incomplete recrystallisation section and perfect crystallisation section can be observed clearly by high-resolution transmission electron microscopy. The Al2O3 and TiO2 are found to be formed in the crystallisation section. In addition, we adopt a new method to measure bonding strength of coating and base material, and the average shear strength is found to be 290 MPa. Further finite-element analysis shows that the shear stress distribution between the coatings and substrate is consistent with the experimental data. The average microhardness of the coatings is found to reach 1864.19 HV0.2.The coatings also exhibit the strongest liquid Pb corrosion resistance. This technique may be important in technological improvement of surfaces of the candidate structural materials for the accelerator-driven sub-critical system, which is usually applied to handle the nuclear waste under extreme conditions.