SHS-Aided Joining of Ceramic Materials with the Ta Substrate

Experiments on evaluating the possibility of joining ceramic materials with a Ta substrate under conditions of self-propagating high-temperature synthesis (SHS) are explored. The sample consists of tantalum foils and pellets Ti + 0.65C and 5T + 3Si, between which a Ti + 2B igniting tape is laid. The sample is installed on a boron nitride support. A chamotte brick plate (SiO2 + Al2O3) with a load of 3360 g placed on its top is placed on a sample to decrease the heat sink. The experiments are performed in a reaction chamber in argon under a pressure of 1 atm. The samples are preheated from the bottom, and the reaction is initiated from their butt. The sample temperature is measured using W–Re thermocouples. The temperature gradient over the sample thickness, depending on the heating rate, is 50–150 K/mm. The samples with strong joining of the tantalum foil with Ti + 0.65C, as well as between two pellets, are formed. The top foil is not welded to the 5Ti + 3Si pellet, which is explained by a rather low temperature (1600°C) at the interface. When studying the interface of the tantalum foil with titanium carbide, the formation of Ti–Ta and (Ta,Ti)C interlayers is found. The possibility of joining the tantalum foil with ceramic materials during SHS is shown by investigations. The main conditions of such joining are the presence of the liquid phase and correspondence of the combustion temperature of the Ti + 0.65C composition to the melting point of the tantalum substrate. These results can be useful when fabricating multilayered functional coatings and functionally graded materials.