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Formation and Characterization of Titanium Modified Aluminide Coatings on IN738LC

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材料热处理学报 2004年第5B期25卷 661-665页

作者： Mohammad Moradi fakhreddin ashrafizadeh Iranian Surface Research & Engineering Centre (ISREC) Isfahan IranDept. of Materials Engineering Isfahan University of Technology Isfahan Iran

Up to now, the aluminide coatings used to protect industrial components at high temperature and corrosive environments have been modified by Pt, Cr, Si and Ni. In this investigation, aluminide coatings were modified by titanium and the microstructural feature and formation mechanism were evaluated. The coatings were formed on a Ni-based superalloy(IN738LC) by a two stage process including titanizing at first and aluminizing thereafter. Pack cementation titanizing performed at temperatures 950° C and 1050° C in several mixtures of Ti, A12O3 and NH^Cl. At the second stage, aluminum diffused into surface of the specimens by an industrial aluminizing process known as Elcoatl01(4 hrs at 1050° C). The modified coatings were characterized by means of standard optical microscopy, scanning electron microscopy, energy dispersive spectroscopy and X-Ray diffraction methods. The results show that Ti in the coatings is mainly present in the form of TiNi and Al67Cr8Ti25. Titanium modified coatings grew with a mechanism similar to simple aluminizing; this includes inward diffusion of Al from the pack to the substrate and then outward diffusion of Ni from the substrate to the coating. The advantages and characteristics of this two-stage modified coating is discussed and the process parameters are proposed to obtain a coating of optimum microstructure.

关键词：扩散涂层钛铝涂层 IN738LC 超级合金扩散渗碳处理

Formation and Characterization of Titanium Modif Aluminide Coatings on IN738LC

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材料热处理学报 2004年第5期 661-665页

作者： Mohammad Moradi,fakhreddin ashrafizadeh Iranian Surface Research & Engineering Centre (ISREC) Isfahan Iran Dept. of Materials Engineering Isfahan University of Technology Isfahan Iran

关键词： diffusion coating titanium aluminide superalloy pack cementation

A novel approach for evaluation of load bearing capacity of duplex coatings on aluminum alloy using PLS and SVR models

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Transactions of Nonferrous Metals Society of China 2022年第6期32卷 1834-1851页

作者： Farideh DAVOODI fakhreddin ashrafizadeh Masoud ATAPOUR Reyhaneh RIKHTEHGARAN Department of Materials Engineering Isfahan University of TechnologyIsfahan 84156-83111Iran Department of Mathematical Sciences Isfahan University of TechnologyIsfahan 84156-83111Iran

Duplex NiP/TiN coatings consisting of the electroless intermediate layers and the physical vapor deposition(PVD) top layers were fabricated on the AA6061 aluminum alloy in order to enhance the load bearing capacity. The main objective of this study was to model the load bearing based on the thickness, adhesion and elastic modulus of the coatings. For this purpose, partial least square(PLS) and support vector regression(SVR) approaches were *** results showed that both models had an acceptable performance;however, the PLS model outperformed SVR. The correlation coefficients between thickness, adhesion and elastic modulus with load bearing were 0.841, 0.8092 and 0.7657, respectively;so, thickness had the greatest effect on the load bearing capacity. The composition and structure of the samples were evaluated using XRD and SEM. The load capacity of the coated samples was also discussed based on the wear and adhesion evaluations. Dry sliding wear tests, under a load of 2 N and a sliding distance of 100 m,demonstrated the complete destruction of the coated specimens with low load capacity. The samples with high load capacity showed not only a superior tribological performance, but also a remarkable adhesion according to the Rockwell superficial hardness test.

关键词： load bearing aluminum alloys NiP interlayer TiN coating partial least square support vector regression

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Incorporation mechanism of colloidal TiO_(2) nanoparticles and their effect on properties of coatings grown on 7075 Al alloy from silicate-based solution using plasma electrolytic oxidation

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Transactions of Nonferrous Metals Society of China 2021年第12期31卷 3659-3676页

作者： Mehri HASHEMZADEH Keyvan RAEISSI fakhreddin ashrafizadeh Amin HAKIMIZAD Monica SANTAMARIA Department of Materials Engineering Isfahan University of TechnologyIsfahan 84156-83111Iran Yekta Mobaddel Pars Co. Science and Technology CampusYazd UniversityYazd 89158-18411Iran Dipartimento di Ingegneria Universitàdi PalermoViale Delle ScienzeEd.690128PalermoItaly

Plasma electrolytic oxidation(PEO)was applied using a pulsed unipolar waveform to produce Al_(2)O_(3)−TiO_(2) composite coatings from sol electrolytic solutions containing colloidal TiO_(2) *** sol solutions were produced by dissolving 1,3,and 5 g/L of potassium titanyl oxalate(PTO)in a silicate *** electron microscopy,energy dispersive spectrometry,X-ray diffraction,and Raman spectroscopy were applied to characterizing the *** behavior of the coatings was investigated using polarization and impedance *** results indicated that TiO_(2) enters the coating through all types of micro-discharging and is doped into the alumina *** higher level of TiO_(2) incorporation results in the decrease of surface micro-pores,while the lower incorporation shows a reverse *** was revealed that the higher TiO_(2) content makes a more compact outer layer and increases the inner layer thickness of the *** measurements revealed that the coating obtained from the solution containing 3 g/L PTO exhibits higher corrosion performance than that obtained in the absence of *** coating produced in the absence of PTO consists of γ-Al_(2)O_(3),δ-Al_(2)O_(3) and amorphous phases,while α-Al_(2)O_(3) is promoted by the presence of PTO.

关键词： Al alloy Al_(2)O_(3)−TiO_(2)coating plasma electrolytic oxidation potassium titanyl oxalate corrosion resistance

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Self-repairing AlO-TiOcoatings fabricated through plasma electrolytic oxidation with various cathodic pulse parameters

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Transactions of Nonferrous Metals Society of China 2023年

作者： Mehri Hashemzadeh Keyvan Raeissi fakhreddin ashrafizadeh Frank Simchen Amin Hakimizad Monica Santamaria Thomas Lampke Department of Materials Engineering， Isfahan University of Technology Yekta Mobaddel Pars Co.， Science and Technology Campus， Yazd University Materials and Surface Engineering Group， Institute of Materials Science and Engineering， Chemnitz University of Technology Dipartimento di Ingegneria， Università di Palermo， Viale Delle Scienze

The influence of cathodic pulse parameters was evaluated on PEO coatings grown on 7075 aluminum alloy in a silicate-based electrolyte containing potassium titanyl oxalate (PTO) using pulsed bipolar waveforms with various cathodic duty cycles and cathodic current densities. The coatings were characterized by SEM， EDS， and XRD. EIS was applied for investigating the electrochemical properties. It was observed that the increase of cathodic duty cycle and cathodic current density from 20% and 6 A dm-2to 40% and 12 A dm-2enhances the growth rate of the inner layer from 0.22 μm min-1to 0.75 μm min-1. Adding PTO into the bath showed a fortifying effect on influence of the cathodic pulse and the mentioned change of cathodic pulse parameters resulted in an increase of the inner layer growth rate from 0.25 to 1.10 μm min-1. Based on EDS analysis， Si and Ti were incorporated dominantly in the upper parts of the coatings. XRD technique merely detected γ-Al2O3， and there were no detectable peaks related to Ti and Si compounds. However， the EIS results confirmed that the incorporation of Ti4+into alumina changed the electronic properties of the coating. The coatings obtained from the bath containing PTO using the bipolar waveforms with a cathodic duty cycle of 40% and current density values higher than 6 A dm-2showed highly appropriate electrochemical behavior during 8 months of immersion due to an efficient repairing mechanism. Regarding the effects of studied parameters on the coating properties， the roles of cathodic pulse parameters and PTO in the PEO process were highlighted.

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Formation and Characterization of Titanium Modified Aluminide Coatings on IN738LC

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Formation and Characterization of Titanium Modified Aluminid...

Modeling of moisture loss kinetics and color changes in the surface of lemon slice during the combined infrared-vacuum drying

14～(th) Congress of International Federation for Heat Treament and Surface Engineering

作者： Mohammad Moradi fakhreddin ashrafizadeh Iranian Surface Research ＆ Engineering Centre （ISREC） Isfahan Iran Dept.of Materials Engineering Isfahan University of Technology IsfahanIran

＜正＞ Up to now, the aluminide coatings used to protect industrial components at high temperature and corrosive environments have been modified by Pt, Cr, Si and Ni. In this investigation, aluminide coatings were modified by titanium and the microstructural feature and formation mechanism were evaluated. The coatings were formed on a Ni-based superalloy（IN738LC） by a two stage process including titanizing at first and aluminizing thereafter. Pack cementation titanizing performed at temperatures 950℃and 1050℃in several mixtures of Ti, Al2O3 and NH4Cl. At the second stage, aluminum diffused into surface of the specimens by an industrial aluminizing process known as Elcoat101（4 hrs at 1050℃）. The modified coatings were characterized by means of standard optical microscopy, scanning electron microscopy, energy dispersive spectroscopy and X-Ray diffraction methods. The results show that Ti in the coatings is mainly present in the form of TiNi and Al67Cr8Ti25. Titanium modified coatings grew with a mechanism similar to simple aluminizing;this includes inward diffusion of Al from the pack to the substrate and then outward diffusion of Ni from the substrate to the coating. The advantages and characteristics of this two-stage modified coating is discussed and the process parameters are proposed to obtain a coating of optimum microstructure.

关键词： diffusion coating titanium aluminide superalloy pack cementation

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Information Processing in Agriculture 2018年第4期5卷 516-523页

作者： fakhreddin Salehi Mahdi Kashaninejad Department of Food Industry Machines Bu-Ali Sina UniversityHamedanIran Faculty of Food Science Gorgan University of Agricultural Sciences and Natural ResourcesGorganIran

Color is one of the most important appearance attributes of food materials,since it influences consumer *** this study the effects of combined infrared-vacuum drying on the drying kinetics,moisture diffusivity,surface changes(shrinking)and color changes kinetics of lemon slices were *** the infrared lamp power and vacuum pressure influenced the drying time of lemon *** regression results showed that the quadratic model satisfactorily described the drying behavior of lemon slices with highest R value and lowest SE *** effective moisture diffusivity increased from 2.92×10^-10 and 1.58×10^-9m^2/s when the infrared lamp power was increased from 300 to *** colour parameters L^*(lightness),a^*(redness/greenness),b^*(yellowness/blueness),and DE(total colour difference)were used to estimate colour changes during drying.L^*,a^* and b^* values of dried lemon increased during *** rise in infrared power has a negative effect on the DE and with the increase of infrared radiation power it was *** kinetic models were used to fit the experimental data and the results revealed that the power model was the most suitable to describe the color change intensity(DE).

关键词： Colour parameters Image processing Infrared drying Kinetic Lemon

Color changes and drying kinetics modeling of basil seed mucilage during infrared drying process

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Information Processing in Agriculture 2022年第3期9卷 397-405页

作者： Ghazale Amini fakhreddin Salehi Majid Rasouli Faculty of Agriculture Bu-Ali Sina UniversityHamedanIran

The physicochemical properties and color of dried seed mucilage (gums) depend on thecondition and method of drying. So, in this study, the effects of infrared (IR) dryer systemparameters such as IR power (150, 250, and 375 W), distance of mucilage from lamp surface(4, 8, and 12 cm), mucilage thickness (0.5, 1.0, and 1.5 cm) on drying kinetics and colorindexes (L*a*b*) of basil seed mucilage (BSM) were examined in an IR dryer system. IR dry-ing kinetic of BSM was modeled using mathematical approach. Thus, experimental mois-ture ratio data were fitted to 8 various empirical models. It was found that Page model hasthe best fit to show the kinetic behavior and acceptably described the IR drying behavior ofBSM with the highest correlation coefficient values and the lowest standard error *** average effective moisture diffusivity (Deff) increased from 1.69×10^(-9)to 9.21×10^(-9)m^(2)/s with increasing lamp power from 150 W to 375 W, while it was decreased from7.93×10^(-9)to 2.65×10^(-9)m^(2)/s and 7.81×10^(-9)to 1.82×10^(-9)m^(2)/s with increasing the dis-tance of mucilage from 4 to 12 cm and the reduction of mucilage thickness from 1.5 to0.5 cm, respectively. The increasing in IR radiation power has a positive influence on thelightness (increasing L* index) of dried BSM and it reduced color changes index (DE) from13.04 to 11.51. The results showed that IR drying method has great industrial potential insaving processing time as well as energy with better maintenance of color and quality ofdried BSM.

关键词： Basil seed gum Drying kinetics Moisture ratio Page model