Studying the self-healing reaction based on zirconium silicide in the Thermal Barrier Coating system

Z. I. Zaki,Q. Mohsen,S. H. Alotaibi,M. H. El-Sadek 한양대학교 세라믹연구소 2020 Journal of Ceramic Processing Research Vol.21 No.2

This work investigated the behaviour of introducing ZrSi2 layer between the top coat layer Yttria-stabilized zirconia (YSZ)and the bond coat layer CoNiCrAlY in thermal barrier coatings where ZrSi2 layer helped self-healing of the cracks. Powdermixtures of ZrSi2/8YSZ and ZrSi2 /CoNiCrAlY were used to imitate the real case. At 800 °C under argon, there was no changein the chemical composition of both ZrSi2 and 8YSZ. ZrSi2 was oxidized in case of treatment in air atmosphere at 800 °C withno evidence for any self-healing reactions. At 1000 and 1200 °C under argon the formation of ZrSiO4 phase was detected whichwas a strong evidence of self-healing reaction. ZrSiO4 phase was also detected at 1200 °C in air with the appearance of SiO2phase. A limited interaction was detected at 1000 °C between ZrSi2 and CoNiCrAlY under vacuum. Si was detected in thesurface of CoNiCrAlY grains and Ni was detected in the composition of ZrSi2. This behavior could contribute to a chemicalbonding between ZrSi2 and CoNiCrAlY layers. The obtained data were confirmed by XRD, SEM and EDX analyses.

Effect of ZrC additives on the microstructure and hardness of ZrN-ZrSi2 composite

Z. I. Zaki,S. H. Alotaibi,M. Alsawat,B. A. Alhejji 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.4

High-density zirconium nitride ZrN/ZrSi2 composite reinforced with different fractions of insitu formed ZrC were synthesizedby dynamic-compaction combustion synthesis from Zr–Si3N4–C powder blends. The effect of ZrC fractions, compressionloads, and delay time on the composite properties was investigated. ZrC additives were found to decrease the sample porosityand improve the sample hardness. Increasing the compression load greatly enhanced the sample hardness and reduced thesample porosity. The samples were characterized using XRD, SEM, hardness and porosity. The attained composite having 20wt% ZrC was found to furnish a highly homogeneous microstructure with less than 1.0 vol open porosity and a maximumhardness value of 1308 HV achieved at 234 MPa compression load.

Silver Nanoparticles Effect on Antimicrobial and Antifungal Activity of New Heterocycles

Kandile, Nadia G.,Zaky, Howida T.,Mohamed, Mansoura I.,Mohamed, Hemat M. Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.12

In this study 1-[4-(2-methoxy benzyl)-6-aryl-pyridazin-3(2H)-ylidene] hydrazines were used for the synthesis of new heterocyclic systems such as thiazolidine, phthalazine, pyrazolo, tetrazolo, hydrazide and new pyridazine derivatives to explore the effect of silver nanoparticles on their biological activity efficiency. Structures of the new heterocycles were characterized by the aid of several analytical techniques including; $^1H$-NMR, FTIR and mass spectra. Silver nanoparticles were synthesized by a simple methodology and the formation of silver nanoparticles was confirmed by transmission electron microscopy (TEM) and UV studies. Most of the new prepared heterocycles were evaluated in vitro as new antimicrobial agents. Combination effects of the silver nanoparticles on the antimicrobial activity of the new heterocycles were investigated using the disk diffusion method. Compound 10a exhibited the strongest enhancing effect of silver nanoparticles solution against Aspergillus flavus and Candida albicans.

Influence of Aging on Microstructure, Martensitic Transformation and Mechanical Properties of NiTiRe Shape Memory Alloy

Nader El-Bagoury,M. M. Hessien,Z. I. Zaki 대한금속·재료학회 2014 METALS AND MATERIALS International Vol.20 No.6

Aging is an effective way to adapt the microstructure, phase transformation and consequently the mechanicalproperties of NiTi shape memory alloys. In the present study, Ni52Ti47.7Re0.3 shape memory alloy was solutiontreated at 1000 °C for 24 h then aged at various temperatures of 300, 400, 500 and 600 °C for 3 h. The influenceof aging treatment on microstructure, martensitic transformation and mechanical properties of Ni52-Ti47.7Re0.3 was investigated. The microstructure of the solution treated alloy was martensite as a matrix phaseand precipitates of Ti2Ni phase. The aged alloys had a microstructure as same as that of solution treatedalloy in addition to the existence of other types of precipitates like Ni4Ti3 and Ni3Ti. The martensitic - austenitictransformation during heating and cooling was going through one stage of transformation. The martensiticphase transformation temperature increased by the increase of aging temperature but still lowerthan that of solution treated alloy.

Silver Nanoparticles Effect on Antimicrobial and Antifungal Activity of New Heterocycles

Nadia G. Kandile,Howida T. Zaky,Mansoura I. Mohamed,Hemat M. Mohamed 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.12

In this study 1-[4-(2-methoxy benzyl)-6-aryl-pyridazin-3(2H)-ylidene] hydrazines were used for the synthesis of new heterocyclic systems such as thiazolidine, phthalazine, pyrazolo, tetrazolo, hydrazide and new pyridazine derivatives to explore the effect of silver nanoparticles on their biological activity efficiency. Structures of the new heterocycles were characterized by the aid of several analytical techniques including; 1H-NMR, FTIR and mass spectra. Silver nanoparticles were synthesized by a simple methodology and the formation of silver nanoparticles was confirmed by transmission electron microscopy (TEM) and UV studies. Most of the new prepared heterocycles were evaluated in vitro as new antimicrobial agents. Combination effects of the silver nanoparticles on the antimicrobial activity of the new heterocycles were investigated using the disk diffusion method. Compound 10a exhibited the strongest enhancing effect of silver nanoparticles solution against Aspergillus flavus and Candida albicans.

Experimental Verification for Active Power Filter based Four-Leg Inverter with SUI-PI Controller

El-sotouhy Mohamed M.,Mansour Ahmed A.,Marei Mostafa I.,Zaki Aziza M.,EL-Sattar Ahmed A. 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.5

Four-leg active power fi lter (4-LAPF) is considered one of the vital active fi lters that are frequently used in industrial applications, especially those that need to be controlled in each phase. In addition to control the neutral current that is created because of unbalanced and non-linear loads. In this paper, the active fi lter is controlled by a proposed control method that can achieve simplicity and intelligence at the same time. The novelty of this paper is simulation and experimental verifi cation for the proposed controller with 4-LAPF. This controller relies on instantaneous reactive power theory, which is used to create the reference currents for the 4-LAPF to inject into the network to mitigate problems associated with unbalanced and non-linear loads. As a result, the supply current is maintained a pure sinusoidal wave. The system is simulated using Matlab/Simulink and experimentally verifi ed. The simulation and experimental results prove the preference of the proposed controller over the conventional proportional-integration controller, where it reduces the total harmonic distortion of the supply current and enhance the power quality.

Low temperature synthesis of nano-crystalline h-boron nitride from boric acid/ urea precursors

Dina H.A. Besisa,Mahmoud A. A. Hagras,Emad M.M. Ewais,Yasser M. Z. Ahmed,Zaki I. Zaki,Adel Ahmed 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.12

Nano-crystalline hexagonal-boron nitride (h-BN) have promised a broad range of interesting applications due to its uniquecharacteristics. In this work, nano-structured h-BN has synthesized by a low temperature-one step reaction of completelydissolved solution of commercial and low cost boric acid and urea fertilizer. Effect of different concentrations of urea, reactionatmosphere (air-N2) and firing temperature (600, 800 oC) on the production of h-BN and type of yield were investigated. Theformation of hexagonal boron nitride was proved from the binding energy for boron and nitrogen obtained from the X- rayphotoelectron spectrum (XPS). The structural phase of the product was confirmed by X-ray diffraction (XRD), Fourier transforminfrared (FT-IR) and differential thermal analysis (DTA). Transmission electron microscopy (HRTEM) has revealed the nanostructure nature of the synthesized boron nitride. The results indicated that, nano-crystalline h-BN with a crystallite size of ≈ 4.5nm has formed at low temperature of 800 oC. Moreover, a good thermal stability and oxidation resistance of h-BN can besynthesized with low cost and at low temperature in the nanoscale and has high potential to be used in advanced applications.