Deposition behavior of glass thick film formation on substrates with different hardness by aerosol deposition (original) (raw)
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Journal of the American Ceramic Society, 2019
Aerosol deposition is a feasible method of fabricating dense ceramic films at room temperature by the impact consolidation of submicron-sized particles on ceramic, metal, glass, and polymer substrates at a rapid rate. Despite the potential usefulness of the aerosol deposition process, there are issues, such as deposition mechanisms and structure of the filmsubstrate interface, that are not well understood. We have used complementary structural and microstructural analysis to capture the state of the substrate surface after the aerosol deposition process. The results reveal that modification of the substrate surface by the ejected submicron-sized particles is essential for the formation of anchoring layer, thereby, a change in internal residual stress state and surface free energy of the substrate is required to deposit film using AD process. Our analysis also suggests that the adhesion between the metal substrate and ceramic particles is possibly contributed by both physical bonding and mechanical interlocking.
Deposition behavior of cold-sprayed metallic glass particles onto different substrates
Surface and Coatings Technology, 2018
The deposition behavior of cold-sprayed metallic glass particles onto different metallic substrates was studied by numerical analysis and simulation using the ABAQUS/Explicit software. The mechanical response of a Vitreloy-1 particle was modeled accounting for the non-Newtonian and Newtonian regime of metallic glasses in the undercooled liquid state. The spreading, viscous dissipation and stress distribution of the metallic glass particle at impact showed a strong dependence on the substrate properties. By describing the rheological behavior of metallic glass particles according to the dynamics of viscous fluids, defining the impact Reynolds (Re) number, the Weissenberg (Wi) number and the Elasticity (El) number, the simulation results prove that shear thinning is the main deformation mechanism of metallic glass particles during impact, regardless of the substrate used. Specifically, a threshold value of Re exists, above which the MG particles undergo homogeneous flow, regardless of the substrate material. The generality of this finding is confirmed by its independence of the mathematical model used to describe substrate plasticity. However, the
Controlling factors of film-thickness in improved aerosol deposition method
Journal of the Ceramic Society of Japan, 2009
To understand the controlling factor of film thickness in aerosol deposition method (ADM), the deposition apparatus was improved at first and the effect of pretreatment of raw barium titanate powder was studied. A developed aerosol generator where the carrier gas was separated from the aerosol generating gas was effective to avoid the agglomeration of powders during the deposition. Two dimensional scanning of the substrate decreased the film-thickness distribution caused by the imhomogeneity of deposition rate in a line-type nozzle. Effect of pretreatments of raw powders, including sieving, drying, planetary ball milling and heating was examined, respectively. There was an optimum rotational velocity of planetary milling to increase the film thickness, indicating that adequate agglomeration of raw powders enhance the film deposition. The film thickness decreased as the heating temperature increased. The heating strengthened the agglomeration of raw powders which restricted the film deposition because the kinetic energy of particles in the aerosol was consumed to break the agglomerations rather than making film. Weakly agglomerated powders with optimum size enhanced the film thickness in ADM.
Influence of the Substrate on the Formation of Metallic Glass Coatings by Cold Gas Spraying
Journal of Thermal Spray Technology, 2016
Cold gas spray technology has been used to build up coatings of Fe-base metallic glass onto different metallic substrates. In this work, the effect of the substrate properties on the viscoplastic response of metallic glass particles during their impact has been studied. Thick coatings with high deposition efficiencies have been built-up in conditions of homogeneous flow on substrates such as Mild Steel AISI 1040, Stainless Steel 316L, Inconel 625, Aluminum 7075-T6, and Copper (99.9%). Properties of the substrate have been identified to play an important role in the viscoplastic response of the metallic glass particles at impact. Depending on the process gas conditions, the impact morphologies show not only inhomogeneous deformation but also homogeneous plastic flow despite the high strain rates, 10 8 to 10 9 s 21 , involved in the technique. Interestingly, homogenous deformation of metallic glass particles is promoted depending on the hardness and the thermal diffusivity of the substrate and it is not exclusively a function of the kinetic energy and the temperature of the particle at impact. Coating formation is discussed in terms of fundamentals of dynamics of undercooled liquids, viscoplastic flow mechanisms of metallic glasses, and substrate properties. The findings presented in this work have been used to build up a detailed scheme of the deposition mechanism of metallic glass coatings by the cold gas spraying technology.
Applied Surface Science, 2007
In this study, a comprehensive examination of the deformation behavior of Al particles impacting on Al substrate was conducted by using the Arbitrary Lagrangian Eulerian (ALE) method to clarify the deposition characteristics of Al powder and the effect of surface oxide films in cold spraying. It was found that the deformation behavior of Al particles is different from that of Cu particles under the same impact conditions owing to its lower density and thus less kinetic energy upon impact. The results indicated that a higher velocity was required for Al particles to reach the same compression ratio as that of Cu particles. On the other hand, the numerical results showed that the oxide films at particle surfaces influenced the deformation and bonding condition between the particle and substrate. The inclusions of the crushed oxide films at the interfaces between the depostied particles inhibit the deformation. #
Materials Science and Engineering: A, 2013
To evaluate the surface fatigue resistance of some thin nitride films obtained by Physical Vapour Deposition (PVD) techniques, repeated impact tests have been performed under controlled impact conditions. Short and long duration tests have revealed the occurrence of an original damage phenomenon likely linked to a mechanical blistering of the films. As these blisters appear to be the first damage step, their formation has to be understood in order to be avoided in industrial applications. In particular, the role of the mechanical properties of the substrate has to be clarified as thin protective coatings may be used on pieces prepared using various heat treatments. finite element method (FEM) analysis has been conducted in order to better understand the specific mechanical conditions in the substrate and at the film-substrate interface that could lead to such blistering phenomena. Correlations with the experimental results have been evidenced. From the modelling results the substrate properties have been shown to be of significant influence on the blister formation. However as they do not fully explain the origin of this phenomenon, the influence of the substrate microstructure has also been studied and the presence of vanadium carbides appears to be of major effect.
Characteristics and Mechanism of Cu Films Fabricated at Room Temperature by Aerosol Deposition
Nanoscale research letters, 2016
We were successful in growing a dense Cu film on Al2O3 substrates at room temperature using an aerosol deposition (AD) method. The characteristics of Cu films were investigated through electrical resistivity and X-ray photoelectron spectroscopy (XPS). The resistivity of Cu films was low (9.2-12.5 μΩ cm), but it was five to seven times higher than that of bulk copper. The deterioration of the resistivity indicates that a Cu2O phase with CuO occurs due to a particle-to-particle collision. Moreover, the growth of Cu films was investigated by observing their microstructures. At the initial stage in the AD process, the impacted particles were flattened and deformed on a rough Al2O3 substrate. The continuous collision of impacted particles leads to the densification of deposited coating layers due to the plastic deformation of particles. The bonding between the Cu particles and the rough Al2O3 substrate was explained in terms of the adhesive properties on the surface roughness of Al2O3 su...
Impact Conditions for Cold Spraying of Hard Metallic Glasses
Journal of Thermal Spray Technology, 2012
As compared to thermal spray techniques, cold spraying allows to retain metastable phases of the feedstock material like amorphous structures, due to lower process gas temperatures. Compared to crystalline metals, metallic glasses are brittle at ambient temperature but viscous at higher temperatures. Therefore, cold spray parameters must be optimized for conditions that allow softening of the amorphous spray material for successfully producing coatings. For this study, a FeCoCrMoBC metallic glass was used that in comparison to others offers advantages with respect to higher hardness, less costly feedstock powder, and minimum reactivity with the environment. Necessary impact conditions were investigated to meet the window of deposition in cold gas spraying. According to calculations and cold spray experiments, neither the glass transition temperature T g nor the melting temperature T m can describe required conditions for bonding. Thus, a so called softening temperature between the glass temperature and the melting temperature had to be defined to calculate the critical velocity of metallic glasses. With respect to the bonding mechanism, impact morphologies could prove that a transition to viscous flow gets more prominent for harsher spray conditions. By sufficiently exceeding the critical condition for bonding, coatings with rather dense microstructures can be processed at deposition efficiencies of about 70%. The coatings have a hardness of 1100 HV 0.3, but the results also demonstrate that further work is still needed to explore the full potential for bulk metallic glasses.
The Research of Properties of the Al Coating Evaporated Onto Glass Substrate
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