Effect of Mechanical Activation and Combustion Parameters on SHS Compaction of Titanium Carbide

Abstract

We present the results of a study on the preparation of dense titanium carbide by SHS compaction. It was found that the use of a mechanically activated reaction mixture of titanium and carbon black powders made it possible to obtain titanium carbide samples with a maximum relative density of 95%. The specific feature of this work is that the mechanical activation of the components of the Ti + C mixtures was carried out in a ball mill for several tens of hours. The influence of the modes of activated mixing on the characteristics of the reaction mixture and combustion parameters was studied. The influence of technological parameters on combustion characteristics and structure of consolidated titanium carbide was also investigated. It was found that the rate and temperature of combustion strongly depend on the size, mass, and density of charge compacts. With an increase in the diameter (20–58 mm) and weight (10–70 g) of pressed samples from mixtures with activated reagents, the combustion rate varied from 10 to 100 cm/s, and the combustion temperature varied from 2200 to 3100°C. A strong influence of the prepressing pressure (applied at the combustion stage) on the combustion rate and temperature was shown: in the pressure range of 0–10 MPa, the combustion rate sharply decreases from 100 to 10 cm/s. In the pressure range of 0–40 MPa, the combustion temperature decreases monotonically from 3000 to 2000°C. A mechanism of high-speed combustion of the reaction mixture of titanium and soot has been proposed, in which the determining factors are the mechanical activation of the components of the mixture (titanium and soot) and the formation of radial cracks (channels) in the pressed samples, which ensure the propagation of incandescent impurity gases into the inner layers and the initiation of the carbidization reaction in the volume of charge compacts.