Abstract:In order to explore the main factors influencing the thermal conductivity of the cold sprayed Cu coating, four sets of Cu coatings with different deformation and annealing conditions were prepared by high/middle pressure cold spray systems followed by the annealing procedure. Microstructure and recrystallization analysis of the coatings were characterized by SEM and EBSD. Relationship of the thermal conductivity of the coating with the porosity and particle deformation was discussed. Results show that porosity… Show more
“…In the Al/Zn matrix, the widely distributed dendrite morphology of the Al–Zn–Ca phase or Al–Zn–Ca–Ti phase (Figure 1) limits the plastic flow and promotes the brittle characteristic of foams [21]. Furthermore, annealing of the Cu coating enhanced the ductility by grain restructuring [22]. Figure 1 (a) Micrographs of Al–Zn foam matrix and (b) EDS results.…”
In the present study, hybrid closed-cell foams consisting of two materials with different ductilities were manufactured to improve the energy absorption capacity. The mechanical characteristics, deformation modes and energy absorption capacities of the foams were investigated. Furthermore, the energy absorption mechanisms of the hybrid foams were analysed. The results demonstrated a significant synergistic effect between the foams and coating with different ductilities during deformation. Their combination increased the densification strain and improved the energy absorption capacity of the samples. Among the specimens investigated, the Al/Zn-Cu(A) foam showed the best densification strain (0.75) and presented superior energy absorption capacities (energy absorption capacity per unit volume (U v ) = 4.5 J cm -3 ; energy absorption capacity per unit mass (U m ) = 8.4 J g -1 ). The intrinsic mechanism of energy absorption optimisation is a combination of the advantages of brittle and ductile deformation modes.
“…In the Al/Zn matrix, the widely distributed dendrite morphology of the Al–Zn–Ca phase or Al–Zn–Ca–Ti phase (Figure 1) limits the plastic flow and promotes the brittle characteristic of foams [21]. Furthermore, annealing of the Cu coating enhanced the ductility by grain restructuring [22]. Figure 1 (a) Micrographs of Al–Zn foam matrix and (b) EDS results.…”
In the present study, hybrid closed-cell foams consisting of two materials with different ductilities were manufactured to improve the energy absorption capacity. The mechanical characteristics, deformation modes and energy absorption capacities of the foams were investigated. Furthermore, the energy absorption mechanisms of the hybrid foams were analysed. The results demonstrated a significant synergistic effect between the foams and coating with different ductilities during deformation. Their combination increased the densification strain and improved the energy absorption capacity of the samples. Among the specimens investigated, the Al/Zn-Cu(A) foam showed the best densification strain (0.75) and presented superior energy absorption capacities (energy absorption capacity per unit volume (U v ) = 4.5 J cm -3 ; energy absorption capacity per unit mass (U m ) = 8.4 J g -1 ). The intrinsic mechanism of energy absorption optimisation is a combination of the advantages of brittle and ductile deformation modes.
“…These advantages result in the efficient preposition of the nickel-based intermediate layer without affecting the organization and performance of the Cu substrate. Although cold spraying or laser cladding has been used to prepare nickel-based coatings on copper-based surfaces, the combination of the cold spraying pre-deposition with laser cladding has not been used for the preparation of nickel-based gradient wear-resistant coatings [ 14 , 27 , 28 , 29 , 30 , 31 ].…”
A cold spray–laser cladding composite gradient coating (CLGC) was successfully formed on a Cu substrate. In comparison with traditional laser cladding gradient coatings (LGC), cold spraying the pre-set Ni-Cu alloy’s intermediate transition layer not only mitigates the negative impacts due to the high reflectivity of the copper substrate but also helps to minimize the difference in the coefficients of thermal expansion (CTE) between the substrate and coating. This reduces the overall crack sensitivity and improves the cladding quality of the coating. Besides this, the uniform distribution of hard phases in CLGC, such as Ni11Si12 and Mo5Si3, greatly increases its microhardness compared to the Cu substrate, thus resulting in the value of 478.8 HV0.5 being approximately 8 times that of the Cu substrate. The friction coefficient of CLGC is lowered compared to both the Cu substrate and LGC with respective values of 0.28, 0.54, and 0.43, and its wear rate is only one-third of the Cu substrate’s. These results suggest CLGC has excellent anti-wear properties. In addition, the wear mechanism was determined from the microscopic morphology and element distribution and was found to be oxidative and abrasive. This approach combines cold spraying and laser cladding to form a nickel-based gradient coating on a Cu substrate without cracks, holes, or other faults, thus improving the wear resistance of the Cu substrate and improving its usability.
Cermet materials comprising ceramic and metallic constituents demonstrate superior mechanical properties, rendering them highly appropriate for demanding applications. Studies have shown that cold spray (CS) technology is a viable method for producing cermet coatings and components. CS effectively embeds the ceramic phase, which acts as reinforcement, within the metallic matrix. Herein, a comprehensive review of diverse aspects of cermet deposits obtained using CS technology is provided, with particular emphasis on feedstock preparation methodologies and their subsequent impact on deposit characteristics. It examines the effects of several spray process parameters, feeding modes, and postprocessing techniques on the compositional and structural characteristics of the cermet deposits. The challenges and potentials are critically discussed, and future trends in the growing applications are highlighted. Aim of this study is to provide a comprehensive view on the current state of the art to facilitate the modulation of cermet deposits' performance produced using CS technology.
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