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Integration and Test
Published in M. Ann Garrison Darrin, Patrick A. Stadter, Aerospace Project Management Handbook, 2017
Thermal Cycling: Thermal cycling tests are performed after the completion of Thermal Balance. The purpose of the Thermal Cycling is to thermally stress all components (subsystems and instruments) to reveal any manufacturing weaknesses such as cold solder joints. Thermal cycles may range from four to six full cycles, typically with plateaus at the hot and cold levels. Since the thermal cycling can last several weeks, the S/C often exercises representative mission simulations during the test. CPTs are performed at HOT and COLD plateaus. RF and timekeeping tests are conducted across the entire temperature range.
Thermo-mechanical effects caused by martensite formation in powder metallurgy FeMnSiCrNi shape memory alloys
Published in Powder Metallurgy, 2018
Bogdan Pricop, Elena Mihalache, George Stoian, Firuța Borza, Burak Özkal, Leandru-Gheorghe Bujoreanu
Specimens, with nominal chemical composition 66Fe–14Mn–6Si–9Cr–5Ni (wt. %), were pressed and sintered under argon atmosphere, from elemental powders, into five groups, designated as (i) 0_MA, from as-blended elemental powders prepared in turbula blender and (ii) 10_MA, (iii) 20_MA, … , (iv) 40_MA, comprising mixtures of as-blended with 10, 20, … , 40 vol.-% MA’ed powders, respectively. All details concerning purity, particle shape and granulometry as well as class of purity of Ar, cooling mode after sintering and final relative density after rolling were previously specified [21]. In MA’ed powders, magnetic transition of Ni and glass-transition of amorphous regions were observed during thermal cycling performed by differential scanning calorimetry [22], together with surface oxidation, mostly in the as-blended pure Fe particles [23]. MA was finalised after 4 h by high-energy ball milling under Ar atmosphere performed in a SPEXTM D8000 high-energy ball mill, using stainless steel vials and stainless steel milling balls, which allowed obtaining the lowest particle diameters [24].
Erosion behavior of Ni-based coating under high-speed hot airflow
Published in Surface Engineering, 2019
Xiangdong Men, Fenghe Tao, Lin Gan, Fang Zhao
The use of nickel-based superalloys is usually in the form of surface coatings [11,12] or alloy castings [6,13], which is often affected by temperature, mechanical stress and environmental conditions in the above engineering applications. Various erosion modes may occur including solid particle erosion, oxidation and hot corrosion. Nickel-based alloys exhibit different erosion processes and degradation modes under different erosion conditions. The solid-particles erosion of nickel-based alloys at high temperatures depends largely on the impact kinetic energy of the erosive particles and the angle of erosion. The removal of the surface material is caused by micro-cutting and microcracking due to the impinging particles [14–18]. High-temperature oxidation of nickel-based alloys preferentially occurs on the Ni and Cr elements, and the enhancement of the oxidation reaction is mainly caused by the rupture of the oxide layer, which allows oxygen to pass through the crack to the interface between the oxide and the metal, which is especially evident in the case of solid particle erosion [19]. The alloy undergoes a compositional transformation of carbides caused by the migration of Cr under thermal cycling conditions [20], and cracking due to the embrittlement of crystal grains at low temperature under the action of thermal stress during the thermal cycling between low-temperature and high-temperature regimes [21–23]. The high-temperature airflow erosion caused by propellant combustion is not a single erosion process, but a synergistic effect of various factors, including thermal shock, heat flow erosion on the surface of the material and possible chemical erosion [24], thus the erosion process and degradation mechanisms are also more complex.
Comprehensive review of phase change material based latent heat thermal energy storage system
Published in International Journal of Ambient Energy, 2022
Pitambar Gadhave, Firojkhan Pathan, Sandeep Kore, Chandrakant Prabhune
Zhu et al. (2018a) fabricated new polymer hybrid shelled nano encapsulated PCMs (NanoPCMs). The thermal energy storage, thermal cycling and thermal conductivity tested by differential scanning calorimetry (DSC) accelerated thermal cycling test and heat flux method, respectively. The thermal conductivities of n-octadecane/polystyrene- and n-octadecane/poly hydroxyl ethyl methacrylate (PHEMA)- were 15.4% and 14.7% than n-octadecane/.