Closed-cell aluminum foams with different percentages of zinc content were successfully prepared and investigated. The foamable precursors were prepared in a pit furnace by adding calcium as thickening agent, calcium carbonate as blowing agent and different percentages (0 wt.%, 0.5 wt.% and 1 wt.%) of zinc particles at 650–750°C. The distribution of Zn elements and quassi-static behavior of the foams at room temperature were investigated. The experimental results show that Zn element is uniformly distributed in cell wall matrix. The distribution of Zn elements had a significant effect on the quasi-static compressive behavior of aluminum foams; from the results, it is obvious that zinc-containing foams possessed higher compressive strength and energy absorption capacities than pure aluminum foams. Hence, it can be concluded that increase in percentage of Zn particles helps to increase the compressive strength, plateau region and energy absorption, in addition to providing better and uniform pores.
Metal foams are cellular solids in which gas is uniformly distributed throughout the metal matrix. One of the cheapest ways of evolving the gas is introducing the blowing agent in parent metal in liquid state. A blowing agent is defined as a material that decomposes under the presence of heat and releases gas which then propels the foaming process. The quality of final foam is influenced by several parameters such as composition, size and volume fraction of the blowing agent used. Different chemicals which can evolve gases such as carbonates and metal hydrides fit into the description of blowing agent. Hydrides during decomposition releases H2 gas while carbonates release CO2 or CO gases which are responsible for foaming process. To produce good quality metal foam, the blowing agent must be a compound that does not detriment the foam metallic matrix and must have decomposition temperature closed to the melting point of the metal. This review paper covers the manufacturing processes which uses blowing agent in the formation of metal foam. Furthermore, the paper provides the detail information about the foaming physics, blowing agent’s type and selection criteria of blowing agents to produce amorphous metal foam.
Metal foams are a unique material that is gaining attraction in various industries due to their multifunctional features. This work focuses on understanding the tribological behavior of aluminum-based close-cell metal foams where Zn is added as reinforcement in different weight percentages (0, 0.5, and 1 wt.%). Dry sliding wear tests are performed at varying loads (5, 10, 15, and 20 N) and sliding distances (1000, 2000, 3000, and 4000 m). During the tests, two limiting conditions are considered: the sliding speed of the rotating disc and its track diameter, which are set at 2.5 m s −1 and 10 cm, respectively. The result reveals that specific wear rate (SWR) is a function of porosity, which increases with an increase in porosity. It was discovered that wear occurs when asperities of varying hardness come into contact at lower stress levels. However, at greater load values, the mechanism shifts from abrasion to plastic flow and delamination. K e y w o r d s : metal foam, specific wear rate (SWR), SEM
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