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Go to Editorial ManagerDesired mechanical properties like microstructure, micro hardness and wear resistance are the key parameters for which low carbon steel (AISI 1006) are widely selected. Surface heat treatment applied to improve these properties; traditionally surface heat treatments like induction hardening, in recent time’s laser surface hardening. In this work, thermochemical treatment (liquid nitriding) by using mixture from 61% NaCN, 15% K2CO3 and 24% KCL and followed by Nd:YAG laser surface treatment was done . The laser parameter were energy (0.89, 2, 4 and 9) J, spot diameter (0.790 ,0.33, 0.283 and 0.224) mm, pulses duration (1, 2.33, 4.47 and 9.87) ms with fix wavelength 1604nm. Laser surface treatment cycle was melting the layer surface, holding and rapid cooling in air medium. Optical microscopy (OM) and scanning electron microscope (SEM) has been used to study the microstructures and cross-sectional of molted and heat affected zones respectively. The wear test was done to measure the wear rate by using pin -on-disk principles were satisfied. The result shown that increasing in laser energy effects to increase in the area of melted and heat affected zones of nitriding steel. Also increasing in laser energy led to increase micro hardness about 61%, while wear rate decrease about 40 % and increased depth of molted zone.
In the present study, magnesium-based composites reinforced with different volume fractions (3, 5, 10, and 15) vol.% of micro sized Al2O3 particulates were fabricated by powder metallurgy technique which involves mixed, compacted and sintered. Powders were mixed by ball milling (without balls) for 6 hours at rotation speed 60 rpm. Then powder was compacted at 550 MPa and sintered at 530?C for 2 hours. Microstructures of sintered composites have been investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) energy dispersive. SEM image of sinter samples exhibit good bonding between the magnesium matrix and the alumina. The microhardness and wear resistance of micro composites has been improved significantly compared to that of pure magnesium. Highest value of microhardness is 97 HV at the volume fraction of 10 vol.% Al2O3.
Corrosion in turbine blades may be considered the most crucial problems in power plants. Corrosion may lead to unbalance masses in turbine blades and therefor serious vibration problems. In this study coating nanomaterials namely Al2O3 and TiO2 are used to resist the corrosion. Coatings consist of Al2O3 with 13 wt% TiO2 are generally used to improve the corrosion, erosion and wear resistance. Tests specimens were taken from the portion of turbine blades in Al-Doura station which located in the south of Baghdad. The specimens are divided into two groups, the first group without coating and the second group with nanoparticale coating including alumina (Al2O3) and (Al2O3-13 % wt TiO2), the coating applying by airbrush device using atomization technique with the aid of nitrogen 2 bar pressure . The properties of coated specimens have been investigated by SEM. The SEM showed that the deposition of nanoparticles on the surface of the samples was uniform and homogeneous. The thickness of coated layers was obtained using gravimetric method. Nano alumina with 13% wt of Titanum oxide coating gave the highest thickness 7.1 µm because of agglomeration of these particles comparing with other particales. Electrochemical properties was achieved by corrosion test at 90 ° for 20 min, the properties indicated that the corrosion resistance increased for coated specimens and these properties showed that the nano alumina with 13% wt of nano Titanium oxide was better than other coating and get a protection efficiency equal to 85.56%.