Self-propagating reaction induced by ball milling in a mixture of Cu2O and Al powders

Abstract

The mechanochemical reduction of Cu 2 O with Al was induced via ball milling. A self-propagating reaction took place in two distinctly different ways. If the mass of the reactant powder mixture was large enough, ignition happened within a few seconds after starting the mill. Neither the activation of the reactants nor the formation of a powder layer covering the surfaces of the milling tools were necessary. If the mass of the charge is smaller than a critical value, the self-propagating reaction is ignited only after several minutes of mechanical activation. A slight excess of Al promoted an immediate reaction. The mechanism of the process is determined by the balance of the reaction heat, the heat transfer within the powder, and the heat loss to the environment. Local melting plays an important role, especially by promoting the formation of partially molten aggregates from free particles.

In situ synthesis of nanocrystalline Al6063 matrix nanocomposite powder via reactive mechanical alloying

“…This method can be combined with a solid-state reaction [6]. Processing of aluminum matrix nanocomposites by mechanically driven reduction of metal oxides with aluminum has been frequently studied [7][8][9][10][11][12][13][14][15][16][17][18][19]. Fine dispersions can also be produced by a reaction between the powder particles and milling atmosphere during the course of milling.…”

Mechanical induced reaction in Al–CuO system for in-situ fabrication of Al based nanocomposites

“…It is suggestible that, the reaction between the substances at the high temperature (>840 • C) occurs abruptly with a high reaction rate which can be accompanied by melting of product copper [15]. Under this condition, the higher interfacial energy of Al 2 O 3 /solid-Al compared with Al 2 O 3 /liquid-Al serves as a driving force for "particle pushing" [16]. In other words, the alumina particles are pushed into the liquid aluminum to form agglomerates.…”

“…A number of reports are available in open literature on the fabrication of Al-Al 2 O 3 nanocomposites through the reaction between Al melt and CuO; for instance, Kobashi and Choh [10] have studied the in-situ process and shown that the formed alumina particles were fine, but the macroscopic distribution was not uni- form; Chen and Sun [11] have examined the in-situ synthesis of Al 2 O 3 /Al-Cu composite by initiating the reaction in compact of mixed Al and CuO powders in molten aluminum; Hoseini and Meratian [12] have fabricated a Al-Al 2 O 3 composite by reduction of copper oxide via melting and casting aluminum through a squeeze casting system. Synthesis of Al based nanocomposites by mechanically induced solid-state reaction has recently been examined by some researchers, e.g., Wu and Li [13] have synthesized nanostructured aluminum matrix composite reinforced with CuAl 2 (100-500 nm in size), Al 2 O 3 and Al 4 C 3 (10-50 nm in size); Shengqi et al [14] have investigated the mechanical driven reduction reaction of CuO and Al powder; the solid reactions between CuO and Cu-14 at.%Al alloy or Cu 9 Al 4 inermetallic compound during high energy mechanical milling have been studied by Ying and Zhang [15]; the self-propagating reaction between CuO and Al by mechanical milling was demonstrated by Bakhshai et al [16]. It is known that when the enthalpy of the reaction is sufficiently high ( H = −1209 kJ/mol Al 2 O 3 in Al-CuO system [4]) and a critical milling energy is applied, the self-propagation combustion reaction can be ignited during synthesizing.…”

An investigation on the mechanochemical behavior of the Ca–C–Cu2O–WO3 quaternary system to synthesize the Cu–WC nanocomposite powder

“…To overcome these disadvantages, metallothermic reduction of the tungsten oxide during milling has been proposed with magnesium [15] and aluminum [16] as reducing agents. Mechanochemical method was also applied to prepare the Cu powder by milling the copper oxides with Mg [17] or Al [18]. The feasibility of carbothermal reduction during milling was separately investigated in the Cu 2 O-C [19] and WO 3 -C [20] binary systems.…”