Effects of yttrium addition on thermoplastic formability of Zr-Cu-Ni-Al amorphous alloy under non-isothermal condition

Compared with traditional crystalline materials, amorphous alloys have excellent corrosion and wear resistance and high elastic modulus, due to their unique short-range ordered and long-range disordered atomic arrangement as well as absence of defects, such as grain boundaries and dislocations. Owing to the limitation of the bulk size of amorphous alloys as structural materials, the application as functional coatings can widely extend their use in various engineering fields. This review first briefly introduces the problems involved during high temperature preparation processes of amorphous coatings, including laser cladding and thermal spraying. Cold spray (CS) is characterized by a low-temperature solid-state deposition, and thus the oxidation and crystallization related with a high temperature environment can be avoided during the formation of coatings. Therefore, CS has unique advantages in the preparation of fully amorphous alloy coatings. The research status of Fe-, Al-, Ni-, and Zr-based amorphous alloy coatings and amorphous composite coatings are reviewed. The influence of CS process parameters, and powders and substrate conditions on the microstructure, hardness, as well as wear and corrosion resistance of amorphous coatings is analyzed. Meanwhile, the deposition mechanism of amorphous alloy coatings is discussed by simulation and experiment. Finally, the key issues involved in the preparation of amorphous alloy coatings via CS technology are summarized, and the future development is also being prospected.

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Core Stress Analysis of Amorphous Alloy Transformer for Rail Transit under Different Working Conditions

Energies ◽

10.3390/en14010164 ◽

2020 ◽

Vol 14 (1) ◽

pp. 164

Author(s):

Jianwei Shao ◽

Cuidong Xu ◽

Ka Wai Eric Cheng

Keyword(s):

Amorphous Alloy ◽

Working Conditions ◽

Short Circuit ◽

Element Model ◽

Operating Conditions ◽

Iron Core ◽

Rail Transit ◽

Transit System ◽

The Core ◽

Distribution Transformers

The rail transit system is a large electric vehicle system that is strongly dependent on the energy technologies of the power system. The use of new energy-saving amorphous alloy transformers can not only reduce the loss of rail transit power, but also help alleviate the power shortage situation and electromagnetic emissions. The application of the transformer in the field of rail transit is limited by the problem that amorphous alloy is prone to debris. this paper studied the stress conditions of amorphous alloy transformer cores under different working conditions and determined that the location where the core is prone to fragmentation, which is the key problem of smoothly integrating amorphous alloy distribution transformers on rail transit power supply systems. In this study, we investigate the changes in the electromagnetic field and stress of the amorphous alloy transformer core under different operating conditions. The finite element model of an amorphous alloy transformer is established and verified. The simulation results of the magnetic field and stress of the core under different working conditions are given. The no-load current and no-load loss are simulated and compared with the actual experimental data to verify practicability of amorphous alloy transformers. The biggest influence on the iron core is the overload state and the maximum value is higher than the core stress during short circuit. The core strain caused by the side-phase short circuit is larger than the middle-phase short circuit.

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Effects of Yttrium Addition on the Microstructure Evolution and Electrochemical Corrosion of SN-9zn Lead-Free Solders Al-Loy

Materials ◽

10.3390/ma14102549 ◽

2021 ◽

Vol 14 (10) ◽

pp. 2549

Author(s):

Wenchao Yang ◽

Jun Mao ◽

Yueyuan Ma ◽

Shuyuan Yu ◽

Hongping He ◽

...

Keyword(s):

Corrosion Resistance ◽

Microstructure Evolution ◽

Electrochemical Corrosion ◽

Lead Free ◽

Nacl Solution ◽

Rich Phase ◽

Yttrium Addition ◽

Electrochemical Corrosion Behavior ◽

Lead Free Solders ◽

Addition Amount

Electrochemical corrosion behavior of ternary tin-zinc-yttrium (Sn-9Zn-xY) solder alloys were investigated in aerated 3.5 wt.% NaCl solution using potentiodynamic polarization techniques, and the microstructure evolution was obtained by scanning electron microscope (SEM). Eight different compositions of Sn-9Zn-xY (x = 0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, and 0.30 wt.%) were compared by melting. The experimental results show that when the content of Y reached 0.06 wt.%, the grain size of Zn-rich phase became the smallest and the effect of grain refinement was the best, but there was no significant effect on the melting point. With the increases of Y content, the spreading ratio first increased and then decreased. When the content of Y was 0.06 wt.%, the Sn-9Zn-0.06Y solder alloy had the best wettability on the Cu substrate, which was increased by approximately 20% compared with Sn-9Zn. Besides, the electrochemical corrosion experimental shows that the Y can improve the corrosion resistance of Sn-9Zn system in 3.5 wt.% NaCl solution, and the corrosion resistance of the alloy is better when the amount of Y added is larger within 0.02–0.30 wt.%. Overall considering all performances, the optimal performance can be obtained when the addition amount of Y is 0.06.

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Validation of MATLAB algorithm to implement a two-step parallel pyrolysis model for the prediction of maximum %char yield

Discover Chemical Engineering ◽

10.1007/s43938-021-00003-w ◽

2021 ◽

Vol 1 (1) ◽

Author(s):

Ibiba Taiwo Horsfall ◽

Macmanus Chinenye Ndukwu ◽

Fidelis Ibiang Abam ◽

Ololade Moses Olatunji ◽

Ojong Elias Ojong ◽

...

Keyword(s):

Experimental Data ◽

Isothermal Condition ◽

Char Yield ◽

Experimental Investigations ◽

Time Saving ◽

Pyrolysis Products ◽

Pyrolysis Model ◽

Experimental Yield ◽

By Products ◽

Good Agreement

AbstractNumerical modeling of biomass pyrolysis is becoming a cost and time-saving alternative for experimental investigations, also to predict the yield of the by-products of the entire process. In the present study, a two-step parallel kinetic model was used to predict char yield under isothermal condition. MATLAB ODE45 function codes were employed to solve a set of differential equations that predicts the %char at varying residence times and temperatures. The code shows how the various kinetic parameters and mass of pyrolysis products were determined. Nevertheless, the algorithm used for the prediction was validated with experimental data and results from past works. At 673.15 K, the numerical simulation using ODE45 function gives a char yield of 27.84%. From 573.15 K to 673.15 K, char yield ranges from 31.7 to 33.72% to 27.84% while experimental yield decreases from 44 to 22%. Hence, the error between algorithm prediction and experimental data from literature is − 0.26 and 0.22. Again, comparing the result of the present work with the analytical method from the literature showed a good agreement.

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