SHS process application in Ti3SiC2–Ni composite fabrication

Abstract

The paper reviews the results of using the process of self-propagating high-temperature synthesis (SHS) to obtain high-temperature nickel alloys and composites based on titanium carbide (TiC) and nickel. In order to reduce the brittleness of these composites, it was proposed to replace the TiC ceramic phase by the MAX phase of titanium silicon carbide (Ti3SiC2) and use the SHS process to obtain a Ti3SiC2–Ni skeleton composite. Nickel for Ti3SiC2skeleton infiltration was introduced in three variants: by introducing to the reaction mixture; in the form of a briquette located between two SHS charge briquettes; and similar to the second variant, but with the barrier layers of paper between the Ni and SHS charge briquettes. It was shown that Ni melt in all three variants prevents the formation of the titanium silicon carbide MAX phase thus leading to its degradation. Ni introduction into the reaction mixture according to the first variant made it possible to obtain a homogeneous composite, which became almost non-porous with an increase in Ni concentration up to 50 %. When the Ni briquette was placed between two compacted briquettes of SHS charge, it was possible to melt a relatively small amount of Ni (23–29 % of the mass of synthesized composite samples), which was not enough to completely fill the porous layered skeletons of Ti3SiC2. 20 % of Si added to the Ni briquette increased infiltration depth, lowered the degree of MAX phase degradation at the infiltration point, and formed a more homogeneous composite consisting of a porous skeleton of TiC, TiSi2and Ti3SiC2phases partially filled with metallic nickel during Ni(Si) melt infiltration.