Abstract
This study established finite-element models via LS-DYNA software to predict the critical velocity of Ti spray particles under different collision velocities and preheating temperatures. Particle deformation, collision temperature, and bonding types of the Ti coating/Al substrate system were simulated. At the predicted critical velocity (650 m/s) and the corresponding preheating temperature (300 °C), the TC4 titanium coating was fabricated on a 6061 aluminum substrate by high-velocity air fuel (HVAF) spray. The coating’s microstructure and phase transition were analyzed by a scanning electron microscope (SEM) equipped with energy-dispersion X-ray spectroscopy (EDS) and transmission electron microscopy (TEM), revealing that critical velocity decreases with increasing particle velocity and preheating temperature. At 650 m/s, the coating was well-bonded to the matrix in metallurgical bonding type, and mechanical interlock and metallurgical bonding coexisted among particles. Experimental results show that the coating is characterized by the metallurgical bonding type, a fusion layer, and recrystallization, which verifies the simulated collision temperatures.
Highlights
Aluminum (Al) alloys have been widely used in modern industry due to their excellent and comprehensive performance [1]
The coating of TC4 Ti alloy on the 6061 Al alloy was prepared by a high-velocity air-fuel spray (HVAF) system made by the National Key Laboratory for Remanufacturing, Beijing, China
The real critical velocity of the spray particles depends on various factors, e.g., particle/substrate temperature, oxidation of the particles, particles size, and particle physical properties
Summary
Aluminum (Al) alloys have been widely used in modern industry due to their excellent and comprehensive performance (e.g., mechanical and anticorrosion properties) [1]. The preheating of particle/substrate was found to significantly influence the collision velocity, bonding, and deposition behavior Such effects could be interpreted by numerical simulations [23,24]. It is meaningful to characterize the bonding types of coatings by experiments involving the spray parameters under which critical velocity is predicted by numerical simulation. We first predicted the critical velocity of Ti alloy particles on Al substrate under different collision velocities and preheating temperatures by numerical simulation using LS-DYNA software. We verified the different bonding types via experiments by characterizing the TC4 Ti alloy coatings on 6061 Al alloy substrate using HVAF spray using the optimum collision velocity and preheating temperature obtained by the numerical simulation. The preheatin45g0t0emperature of the substrat2e7w70as 150 °C, and Melting point (K)
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