Showing 3 results for Lotfi
Erfan Lotfi-Khojasteh, Hassan Elmkhah, Meisam Nouri, Omid Imantalab, Arash Fattah-Alhosseini,
Volume 19, Issue 4 (Desember 2022)
Abstract
This paper aims to study the tribological and electrochemical properties of the CrN/AlCrN nano-layer deposited on H13 tool steel. Arc physical technique was employed to deposit multilayer coating. X-ray diffraction technique, thermionic and field emission scanning electron microscopy and energy dispersive spectroscopy have been used to determine the characteristics of the samples. To study the samples' wear behavior, coating adhesion, and surface hardness, reciprocating wear test, Rockwell-C test, and microhardness Vickers tester were employed, respectively. The measured values of the coefficient of friction and the calculated wear rates showed that the CrN/AlCrN multilayer coating has a much higher wear resistance than the uncoated sample. The coefficient of the friction of the coated sample was 0.53 and that of the uncoated sample was 0.78. Moreover, the wear rate of the coated H13 steel was about 127 times lower than the bare H13 steel sample. The results obtained from electrochemical impedance spectroscopy and polarization tests demonstrated that the corrosion current density of the H13 steel sample was 8 μA/cm2 and that of the CrN/AlCrN multilayer-coated sample was 3 μA/cm2. In addition, the polarization resistance of the treated and the substrate specimens was estimated at 4.2 and 2.7 kΩ.cm2, respectively.
Behnam Lotfi,
Volume 21, Issue 0 (IN PRESS 2024)
Abstract
Bulk titanium-based metallic glass with amorphous structure has led to the creation of special properties, which can be used as a suitable alternative to metallic biomaterials with crystalline structure. In the present study, bulk titanium-based metallic glass without Ni and Be elements produced by vacuum arc melting and cast into a 4 mm diameter mold. The evaluation of the results showed that the Ti50Zr15Cu20Mo7Ag4Sn3Si1 metallic glass has a composite structure of dispersed crystalline phases (α-Ti, β-Ti and Ti2Cu) in a glassy field. However, the Ti50Zr25Cu5Mo10Ag6Sn3Si1 alloy has a higher glass formation ability (GFA) and the crystalline phases formed in the Ti50Zr15Cu20Mo7Ag4Sn3Si1 alloy disappeared with increasing the amount of alloying elements Zr, Mo and Ag. The corrosion current (ICorr) of the Ti50Zr25Cu5Mo10Ag6Sn3Si1 alloy (43.28 nA) was lower compared to the corrosion current of the Ti50Zr15Cu20Mo7Ag4Sn3Si1 and Ti6Al4V samples (133.9 and 92.41 nA, respectively) in Hank's solution, hence the Ti50Zr25Cu5Mo10Ag6Sn3Si1 alloy showed better corrosion resistance.
Seyed Ehsan Khadempir, Behnam Lotfi, Zohreh Sadeghian,
Volume 22, Issue 3 (September 2025)
Abstract
Ni-B4C nanocomposite coatings were deposited onto a pure Cu substrate using electroplating. Different types of current, including direct current (DC), pulse reverse current (PRC), and unipolar pulse current (PC), were applied using various concentrations of micron and nano size particles in the electroplating bath. Microstructure, hardness, and wear and corrosion behavior of the coatings were investigated. Microstructural evaluations were performed using scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM). Microhardness, pin-on-disk sliding wear, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) tests were conducted on the coatings. Electrodeposition using PRC resulted in a more uniform distribution of co-deposited B4C microparticles and nanoparticles within the coatings. Nanocomposite coatings reinforced with B4C nanoparticles were obtained using PRC with a bath concentration of 8 g/l, exhibited higher hardness and improved wear properties compared to composite coatings containing B4C micron-sized particles. Moreover, using PRC resulted in higher hardness values and improved wear and corrosion resistance compared to PC and DC.
