Characterization of cnt reinforced aluminum foam produced by using urea

Abstract: In this study, 99.5% purity Al (<44 µm),> 95% purity (average outer diameter> 50 nm, length 10–20 µm) multi-walled carbon nanotubes (MWCNT) and average diameter 1.5 mm spherical shaped urea (CH4N2O) granules were used as starting materials. Experimental studies started primarily by mixing aluminum and CNT particles. For this purpose, CNT particles with varying weight ratios (0, 0.5, 1 and 2%) were added to the aluminum powders and mixed in a stainless steel vessel on a ball mixer for 60 minutes. The powder/ball ratio used in the mixture is 5/1. 1% stearic acid was added to the mixture for process control during mixing. The urea (15%, 30% and 50% by weight) was chosen as the space-holder. Ethanol (2 vol%) was sprayed onto the urea granules prior to mixing to obtain an adhesive surface for adhering the Al / CNT mixture powders. Thus, an even distribution of the mixture powders over urea was achieved. The mixture was then uniaxially compressed under a pressure of 600 MPa. For the dissolution of urea in the compacted compacts, the samples were incubated at 80 ° C for 3 hours in a water bath. The samples were then washed with ethanol and then dried. After the solution step, the samples were sintered at 650°C for 2 hours to produce foam samples. Macro-micro structural analyzes, density measurements, hardness measurements and compression tests were used for characterization of the samples. According to the experimental results; the amount of porosity increased with increase in the amount of urea. Density values were also decreased. The maximum porosity and density of the samples produced with 50% urea were obtained as 69% and 0.84 g.cm-3, respectively. In addition, it was determined that CNT particles had no significant effect on porosity but had a significant effect on hardness change. Maximum hardness (65 HV) was obtained in foam samples containing 2% CNT produced with 15% urea. The crushing properties of the samples decreased with the decrease in the relative density of the foams. Minimum plastic collapse strength (3.4 MPa) was obtained in samples containing 1% CNT produced with 50% urea.