Abstract
Polymer matrix composites (PMC), despite their many advantages, have limited use at elevated temperatures. To expand the scope of their uses, it becomes necessary to use thermal barrier coatings (TBC). In addition to elevated temperatures, composite structures, and thus TBC barriers, can be exposed to damage from impacts of foreign objects. Therefore, before using the thermal barrier in practice, knowledge about its behavior under high-speed loads is necessary. The paper presents results for samples with the PMC/TBC system subjected to dynamic compression using a split Hopkinson pressure bar (SHPB). The substrate was made of CFRP (carbon reinforced polymer) with epoxy matrix and twill fabric. TBC was made of ceramic mat saturated by commercial hardener from Vitcas company. The tests were carried out at ambient temperature and elevated temperature—55 °C and 90 °C. Tests at ambient temperature were carried out for three pressure levels: 1, 1.5, and 2 bar. Only the pressure of 1 bar was used for the elevated temperature. Studies have shown that the limit load is 1 bar for ambient temperature. At 1.5 bar, cracks occurred in the TBC structure. Increased temperature also adversely affects the TBC barrier strength and it is damaged at a pressure of 1 bar.
Highlights
Thermal barrier coatings [1] have been used for many years in the aviation industry, mainly in turbine engine designs
Applied by the air plasma spray (APS) method on the MCrAlY bond coat, which is produced by the high velocity oxy fuel (HVOF) method on a metal substrate
The samples were characterized by a large difference in the modulus of elasticity of the substrate samples were characterized by a large difference in 10 thetimes modulus elasticity of the and the The protective layer, while the Polymer matrix composites (PMC) material was more than stiffer.ofThus, the deformations substrate and the protective layer, while the material was more than times stiffer
Summary
Thermal barrier coatings [1] have been used for many years in the aviation industry, mainly in turbine engine designs. Applied by the air plasma spray (APS) method on the MCrAlY bond coat, which is produced by the high velocity oxy fuel (HVOF) method on a metal substrate Both the APS and HVOF methods cannot be directly applied to a substrate made of polymer matrix composites. In the worst case, hitting the protective coating may cause its erosion or surface damage, causing cracks [7,8] These are very complex phenomena; in order to build a numerical model, material data is necessary regarding the behavior of the protective coating for different strain rates and temperatures. For this purpose, the SHPB device was used in the work to reach high strain rates. Tests were carried out for three strain rate levels (≈1500, ≈2000, ≈2500 l/s) and three temperatures (room, 55 ◦ C and 90 ◦ C)
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