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Abstract:
In this paper, dynamic interactions between the FeAl particles and the gaseous detonation stream during supersonic D-gun spraying (DGS) conditions into the water are discussed in detail. Analytical and numerical models for the prediction of momentum and complex heat exchange, that includes radiative effects of heat transfer between the FeAl particle and the D-gun barrel wall and phase transformations due to melting and evaporation of the FeAl phase, are analyzed. Phase transformations identified during the DGS process impose the limit of FeAl grain size, which is required to maintain a solid state of aggregation during a collision with the substrate material. The identification of the characteristic time values for particle acceleration in the supersonic gas detonation flux, their convective heating and heat diffusion enable to assess the aggregation state of FeAl particles sprayed into water under certain DGS conditions

Keywords:
D-gun spraying, FeAl intermetallic powder, gas detonation flux, heat transfer, two-phase metallization stream, particle thermal history

Abstract:
Ceramic two-phases composites are used in such industries as the armaments industry, aviation, automotive, nuclear power, and space exploration. In several areas, they stand as the source of technological progress. The material is often subjected to extreme loads, such as variable dynamic loads and high temperatures. The paper presents experimental investigations of ballistic impact on ceramic /metal composites. The internal structure of the novel material consists of ceramic foam made of SiC and filled with Al alloy. The experiment was performed using the ballistic stand and spherical impactor of diameter 5 mm and mass 0.5 g. The impactor hit the sample of diameter 30 mm and thickness 4 mm with a velocity of 600 m/s. Fig. 1 presents crater after impact and defragmented sample. The numerical analysis of the fragmentation process was performed using the finite element method. The internal structure of the composite was assessed using micro-CT selecting both phases, i.e., ceramic foam and AL alloy. The phases are joined by a continuous very small thickness interface. The numerical calculations allow for the description of the whole degradation process of the analysed interpenetrating composite up to the final failure by fragmentation and confirm the novel applicability of the material as a protective layer against the high-velocity impact. Acknowledgement The work has been performed under the research grants 2019/33/B/ST8/01263, National Science Centre, Poland. The analyses were done in the ICM UW in Warsaw and in CI TASK in Gdańsk, Poland. References [1] T. Ohji and M. Singh, Engineered Ceramics: Current Status and Future Prospects: Wiley, 2015.

Keywords:
two-phase metal/ceramic composites, penetration experiments, numerical modelling