R. Gharehbaghi

Bio: R. Gharehbaghi is an academic researcher from University of Johannesburg. The author has contributed to research in topics: Titanium alloy & Indentation hardness. The author has an hindex of 3, co-authored 3 publications receiving 70 citations.

Experimental investigation of laser metal deposited icosahedral Al-Cu-Fe coatings on grade five titanium alloy

Abstract: Laser Additive Manufacturing is relatively new in the manufacturing industry. This paper focuses on the effect of hybrid coatings of Al-Cu-Fe on a grade five titanium alloy (Ti6Al4V) using laser metal deposition (LMD) process at different laser power and scanning speeds. Icosahedral Al-Cu-Fe as quasicrystals are a relatively new class of materials which exhibit unusual atomic structure and useful physical and chemical properties. Ti6Al4V/Al-Cu-Fe composite were analysed using Optical microscopy, Scanning electron microscopy (SEM) with energy dispersive microscopy (EDS), indentation testing, X-Ray Diffraction (XRD), corrosion and wear testing. deposit width and height, heat affected zone (HAZ) height), dilution rate, aspect ratio and powder efficiency of each sample remarkably increased with increasing laser power due to the laser-material interaction. It was observed that there are higher number of aluminium and titanium presented in the formation of the composite. The indentation testing reveals that for both scanning speed of 0.8m/min and 1m/min, the mean hardness value decreases with increasing laser power. It was found that due to dilution effect, a part of Ti entered into molten pool from the substrate. The results indicate that Ti, Al 3 Ti, Ti 3 Al, CuTi 2 can be produced through the in situ metallurgical reactions during the LMD process.

Influence of scanning speed on the microstructure of deposited Al-Cu-Fe coatings on a titanium alloy substrate by laser metal deposition process

Abstract: Laser Additive Manufacturing is relatively new in the manufacturing industry. This paper focuses on the influence of scanning speed on Al-Cu-Fe coating powders on a titanium alloy using laser metal deposition (LMD) process. Al-Cu-Fe as quasicrystals are a relatively new class of materials which exhibit unusual atomic structure and useful physical and chemical properties. The intermetallic section where the hybrid coating bonded into grade five titanium alloy substrate were observed. It was found that the geometrical properties of the deposits such as deposit width, deposit height and the Heat Affected Zone (HAZ) of each sample decreases with increasing scanning speed due to the laser-material interaction. It was observed that an increase in scanning speed results in an increase in both dilution and aspect ratio. However, this is not true for the graph of powder efficiency as a function of scanning speed, increasing scanning speed decreases the powder efficiency. The smoother surface observed at low scanning speed that is as a result of proper melting of Ti powder due to the large laser material interaction time. As the scanning speed increases, the laser material interaction time reduces causing more and more unmelted Ti powder to be seen. The mean hardness value decreases with increasing scanning speed. XRD analysis showed that increasing scanning speed will significantly increase the diffraction peak of Ti and Ti 3 Al.

Comparative Analysis on the Structure and Properties of Iron-Based Amorphous Coating Sprayed with the Thermal Spraying Techniques

Abstract: Iron-based amorphous coatings are getting attention owing to their attractive mechanical, chemical, and thermal properties. In this study, the comparative analysis between high-velocity oxy-fuel (HVOF) and atmospheric plasma (APS) spraying processes has been done. The detailed structural analysis of deposited coatings were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Mechanical and electrochemical properties were investigated by using micro-Vickers hardness testing, pin-on-disc tribometry and potentiodynamic analysis. The microstructure comparison revealed that HVOF-coated samples had better density than that of APS. The porosity in APS-coated samples was 2 times higher than that of HVOF-coated samples. The comparison of tribological properties showed that HVOF-coated samples had 3.9% better hardness than that of coatings obtained via APS. The wear test showed that HVOF-coated samples had better wear resistance in comparison to APS coatings. Furthermore, the potentiodynamic polarization and electrochemical impedance spectroscopy showed that the HVOF-coated samples had better corrosion resistance in comparison to APS-coated samples.