Mechanical Properties Improvement of Al–Li 8090 Alloy by Using the New Proposed Method of Directional Quenching

S. Nouri,S. Sahmani,M. Hadavi,Sh. Mirdamadi 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.8

Due to having low density as well as high specific modulus and fatigue toughness, Al–Li alloys have been targeted as anadvanced material for using in aerospace applications. In the current investigation, a new heat treatment method namelyas directional quenching process is proposed to improve the mechanical properties of the Al–Li 8090 alloy, the results ofwhich are compared with those of T6 and T8 aging heat treatment techniques. For this purpose, aging process at 170 °C isconducted in all of the three heat treatment methods, but the solutionizing treatment and quenching are performed alonga specific direction in the introduced directional quenching method. The mechanical properties and fracography of crosssectionalfracture pattern of the heat treated samples are studied corresponding to the various heat treatments. Based on theobtained results, it is found that in comparison with the two conventional T6 and T8 heat treatment methods, the proposeddirectional quenching technique has the capability to increase simultaneously both of the ductility and strength of Al–Li 8090alloy. Also, according to the performed finite element based thermal stress analysis, it is observed that a uniform distributionand high volume fraction of strengthening δ′ (Al3Li) precipitates are acquired via the directional quenching technique.

The effects of zinc aluminum phosphate (ZPA) and zinc aluminum polyphosphate (ZAPP) mixtures on corrosion inhibition performance of epoxy/polyamide coating

S.M. Mousavifard,M.M. Attar,P. MalekMohammadi Nouri,B. Ramezanzadeh 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.3

The epoxy/polyamide coating was loaded with different pigment mixtures of the zinc phosphate (ZP),zinc aluminum phosphate (ZPA) and zinc aluminum polyphosphate (ZAPP) pigments. The electrochemical impedance spectroscopy (EIS) and salt spray test were used to investigate corrosion inhibition performance of the coatings. The adhesion strengths of the coatings were measured by a pull-off test. Results revealed lower coating pull-off strength loss when the ZPA and ZAPP pigments were used. A significant decrease in number of blisters together with low pull-off strength loss and best corrosion inhibition properties were observed when the mixture of 80:20 of ZAPP:ZPA was used.

Numerical solution of non-Fourier heat transfer during laser irradiation on tooth layers

S. Falahatkar,A. Nouri-Borujerdi,M. Najafi,A. Mohammadzadeh 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.12

This study reports on the simulation of temperature distribution of human tooth under a laser beam based on non-Fourier models. The temperature in the tooth depth that directly results from the conduction heat transfer process is caused by the lengthy thermal relaxation time in the tooth layers. A detailed tooth composed of enamel, dentin, and pulp with unstructured shape, uneven boundaries, and realistic thicknesses was considered. A finite difference scheme was separately adopted to solve time-dependent equations in solid layers and soft tissue of the tooth. In this study, a dual-phase-lag non-Fourier heat conduction model was applied to evaluate temperature distribution induced by laser irradiation. Results show that for the laser-irradiated tooth, the phase lag time of heat flux (τ q ) greatly affects the temperature of the early stage, whereas the phase lag time of the temperature gradient (τ T ) significantly influences the temperature of the later stage. Prediction of temperature profile in the tooth based on this investigation is more real using the non-Fourier model (i.e., τ q = 16 and τ T = 2 millisecond) compared with experimental studies. Meanwhile, the Fourier model (τ q = τ T ) or classical Fourier form (τ q = τ T = 0) and the thermal wave model (τ q = 16 and τ T = 0) led to unreal heated point on the enamel. The effects of laser parameters, such as laser exposure time and laser intensity on the pulp, were also investigated. Increasing the laser duration and simulation time after laser irradiation was a logical approach to pulp ablation compared with increasing the laser intensity.

An investigation on the properties and microstructure of mullite-bonded cordierite ceramics

M.Nouri. Khezrabadi,R. Naghizadeh,P. Assadollahpour,S.H. Mirhosseini 한양대학교 세라믹연구소 2007 Journal of Ceramic Processing Research Vol.8 No.6

The fabrication of a mullite-bonded cordierite body suitable for use as kiln furniture has been investigated in this article. First of all cordierite powder was synthesized by mixing talc, kaolin and alumina as starting materials, pressing and firing up to 1325oC. The amount of cordierite phase was estimated by an X-ray diffraction technique. The synthesized cordierite was then mixed with certain amounts of kaolin and alumina as the starting materials for mullite formation and the mixture was shaped by a pressing method, following by firing at different temperatures. The changes of density, porosity and cold crushing strength of the samples were measured as a function of heat treatment temperature. The results showed that these properties improve by a rise in temperature. The mullite formation within the samples was confirmed by an XRD method. The thermal expansion coefficient of the samples fired at 1350oC was determined by a dilatometer having an average value of 3.18×10−6 (1/K), which indicates an excellent thermal shock resistant for the samples. The microstructure of the fired samples was studied using scanning electron microscopy (SEM), which showed interesting results. The fabrication of a mullite-bonded cordierite body suitable for use as kiln furniture has been investigated in this article. First of all cordierite powder was synthesized by mixing talc, kaolin and alumina as starting materials, pressing and firing up to 1325oC. The amount of cordierite phase was estimated by an X-ray diffraction technique. The synthesized cordierite was then mixed with certain amounts of kaolin and alumina as the starting materials for mullite formation and the mixture was shaped by a pressing method, following by firing at different temperatures. The changes of density, porosity and cold crushing strength of the samples were measured as a function of heat treatment temperature. The results showed that these properties improve by a rise in temperature. The mullite formation within the samples was confirmed by an XRD method. The thermal expansion coefficient of the samples fired at 1350oC was determined by a dilatometer having an average value of 3.18×10−6 (1/K), which indicates an excellent thermal shock resistant for the samples. The microstructure of the fired samples was studied using scanning electron microscopy (SEM), which showed interesting results.

Measurements of Inelastic Neutron Scattering at 96 MeV from Carbon, Iron, Yttriumand Lead

A. Ohrn,C. Gustavsson,M. Blann,V. Blideanu,J. Blomgren,S. Chiba,H. Duarte,F. Haddad,C. Kalbach,J. Klug,A. Koning,C. Le brun,C. Lebrun,F. -R. Lecolley,X. Ledoux,N. Marie-noury,P. Mermod,L. Nilsson,M. O 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

Inelastic neutron scattering for ^(12)C, ^(56)Fe, ^(89)Y and ^(208)Pb have been measured at 96 MeV at the The Svedberg Laboratory in Uppsala and double-differential cross sections are reported. Data cover an excitation energy range of 0-45 MeV and the angular intervals are 28 - 58˚ for ^(12)C, 26 - 65˚ for ^(56)Fe and 26 - 52˚ for ^(89)Y and ^(208)Pb. In this experiment, neutron detection is based on conversion to protons in an active scintillator converter. An analysis technique in which the neutron spectra have been obtained through a folding procedure using the response of the detector system has been used. The results are compared to and are in reasonable agreement with several model predictions and with inelastic neutron scattering data at 65 MeV from University of California, Davis, USA.