Fabrication of aluminium covetic casts under different voltages and amperages of direct current

Abstract

<jats:title>Abstract</jats:title><jats:p>Aluminium Covetic metallurgical synthesis along with the characterization of cast material results were presented in this paper. Aluminium- 3% graphite (carbon) composites were fabricated by applying different voltages and amperages of direct current through the stir-casting process. This process, called Covetic based on patent applications of Third Millennium Metals. Obtained casts were tested for their chemical composition, density, tensile strength, hardness, microstructures, and electrical conductivity measurements using an Oxford PMI-Master Pro spark emission spectrometer, a DA-300M density measurement device, a WDW-200 universal tensile test machine, a HBA-3000S automatic Brinell Hardness Tester, a scanning electron microscope with Energy-Dispersive Spectroscopy and an AT512 Precision Ohmmeter, respectively. Moreover, increasing of amperages and/or decreasing of voltages of direct current ensured considerable increasing of electrical conductivity (≈ 34%), the notable decrement in the density (≈ 0.94%), an enhancement in the tensile strength (≈ 18%) and the hardness (≈ 15%) of aluminium Covetic casts compared to the parent metal. In summary, results show that the increasing of amperages and/or decreasing of voltages of direct current has a superior influence on improving electrical conductivity of aluminium-graphite Covetic casts with better mechanical properties.</jats:p>

A review of covetics – current understanding and future perspectives

“…In a parallel study, Kareem et al fabricate Al-6061 covetics with 3 wt% carbon with a 20% increase in Young's modulus. 17 The hardness of all covetics, shown in Table 2 , is greater than their non-covetic controls. For example, the hardness of Al-6061 covetic with 2 and 3 wt% carbon is 111–375% greater than non-covetic.…”

“…In prior covetic syntheses, liquid aluminum (MP: 660 °C) and carbon are mixed at 900 °C. 15,17 The final temperature reaches 1100 °C after DC application. 15 X-ray diffraction, electron diffraction, and Raman spectroscopy highlight characteristic carbide phases within aluminum covetics, after casting and cooling.…”

“…Secondary ion mass spectroscopy on the surface of sample slices detects carbon-rich and carbon-poor regions proving inhomogeneous carbon distribution. Kareem et al 17 fabricate aluminum covetics in an electric furnace, using an electric blender, graphite crucible, and four Solite® batteries as the DC power source. The graphite is rolled within aluminum foil and placed into the furnace at 850 °C.…”

“…The electrical conductivities of aluminum covetic with 3 wt% carbon synthesized under 290 A/36 V and 400 A/36 V are 38.07% and 45.57% IACS, respectively. 17 Aluminum covetic electrical conductivity increases with increasing voltage and/or current during synthesis.…”