Fabrication of NiAl/Steel Cladding by Reactive Casting.

Abstract

A novel joining process based on reactive casting is proposed. By pouring molten aluminum and nickel onto a steel block, molten nickel monoaluminide, NiAl, is exothermically synthesized, and is joined to the steel block when it solidifies on the steel block. Heat generated by an exothermic reaction, NiϩAl→ NiAlϩDH p298 , is transferred from the synthesized NiAl to the steel block, and the surface layer of the steel block is melted. The depth of the melted steel increases with both the preheating temperature of the steel block and the thickness of the synthesized NiAl. Iron from the melted steel dissolves in the molten NiAl, and an NiAl-base intermetallic compound, (Ni, Fe)Al, is produced. Cracks or other intermetallic phases such as NiAl 3 or FeAl are not formed at all at the joint interface between the (Ni, Fe)Al and the steel block. The synthesized (Ni, Fe)Al has an excellent resistance to corrosion and oxidation.

Uses of Concentrated Solar Energy in Materials Science

“…Although its low ductility at room temperature could limit its applications as structural material its good tribological properties and excellent oxidation resistance justify its use as a protective coating for metallic components. Cladding, and self-propagating high temperature synthesis (SHS) processes are among the other techniques used currently for coating this intermetallic compound (Matsuura et al, 2000). SHS is an energy efficient method to process advanced ceramic materials and intermetallic compounds.…”

Nickel-aluminides/steel clad pipe fabricated by reactive centrifugal casting method from liquid aluminum and solid nickel

“…This value is similar to that of NiAl containing some iron, which is reported in the literature. [5] The hardness of layer 2 was much higher than that of layer 1, which implies that a different kind of intermetallic compound was formed in layer 2. The chemical composition of this layer shown in Figure 7(a) corresponded to 2 phase, Fe 3 NiAl 10 .…”

“…Recently, Matsuura et al [3][4][5][6][7] developed a new technique named reactive casting, which involves an exothermic reaction between elemental liquids, and enables one to produce the liquid of a high melting point intermetallic compound without the need for external heating. For example, they produced a NiAl liquid of 2876 K by simply mixing aluminum liquid of 1023 K and nickel liquid of 1773 K. An increment in temperature over 1000 K was achieved by heat generation from an exothermic reaction of Ni ϩ Al : NiAl, which is characterized as the self-propagating high-temperature synthesis (SHS) reaction.…”

NiAl intermetallic coatings elaborated by a solar assisted SHS process

“…Currently, NiAl coatings can be manufactured by using several techniques such as PVD [7], reactive sintering [10], reactive casting [11], etc. However, the elevated cost of the equipment, the high required process temperatures, or the ultra high vacuum necessary for some applications strongly reduce their scope.…”