Laser cladding, a novel surface treatment technology, utilizes a high-energy laser beam to melt diverse alloy compositions and form a specialized alloy-cladding layer on the surface of the substrate to enhance its property. However, it can generate substantial residual stresses during the rapid cooling and heating stages, due to inadequate selection of cladding process parameters and disparities in thermophysical properties between the clad layer and substrate material, leading to the formation of various types of cracks. These cracks can significantly impact the quality and performance of the coating. This paper presents a comprehensive review of crack types and their causes in laser cladding coatings, and identifies that three primary sources of residual stresses, thermal stress, organizational stress, and restraint stress, are the fundamental causes of crack formation. The study proposes several strategies to control coating cracks, including optimizing the coating layer material, refining the coating process parameters, incorporating heat treatment, applying auxiliary fields, and utilizing numerical simulations to predict crack initiation and propagation. Additionally, the paper summarizes crack control methods for emerging structural materials and novel preparation processes. Lastly, the paper analyzes the prospects, technical approaches, and key research directions for effectively controlling cracks in laser cladding coatings.
Aiming at the problem of vibration and bounce caused by the collision and contact of the moving and static contacts of the electrical switching device during the closing process, based on the comprehensive consideration of the nonlinear electromagnetic force and the collision contact force, the two-degree-of-freedom coupled motion differential equation of the contact system is established, and to solve and experimental analysis. The theoretical and experimental results show that the contact has not separated after the collision, and the iron core has collided, which further intensifies the contact bounce; when the iron core bounces for the second time, it does not affect the bounce of the contact; the contactor is in operation In this case, the movement of the moving iron core will cause slight jitter of the system. The research results provide a theoretical basis for further control and reduction of contact bounce.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.