Effects of TiC addition on formation of Ti3SiC2 by self-propagating high-temperature synthesis

Abstract

Formation of Ti 3 SiC 2 was conducted by self-propagating high-temperature synthesis (SHS) from both the elemental powder compacts of Ti:Si:C = 3:1:2 and the TiC-containing samples compressed from powder mixtures of Ti/Si/C/TiC with TiC content ranging from 4.3 to 33.3 mol%. The effect of TiC addition was studied on combustion characteristics and the degree of phase conversion. For the elemental powder compacts, with the progress of combustion wave the sample experiences substantial deformation, including axial elongation and radial contraction. The extent of sample deformation and flame-front propagation velocity were considerably reduced for the samples with TiC addition, because the dilution effect of TiC lowered the reaction temperature. Two reaction mechanisms were adopted to explain the formation of Ti 3 SiC 2 , one involving the reaction of a Ti-Si liquid phase with solid reactants for the elemental powder compact and the other dominated by the interaction of solid-phase species for the TiC-containing sample. For all products synthesized in this study, the XRD analysis identifies formation of Ti 3 SiC 2 along with a major impurity TiC and a small amount of Ti 5 Si 3 . The resulting Ti 3 SiC 2 is typically elongated grains. Based upon the XRD profile, the Ti 3 SiC 2 content at a level of 71.5 vol.% was obtained in the product from the elemental powder compact. With the addition of TiC, an improvement in the yield of Ti 3 SiC 2 was observed and an optimal conversion reaching 85 vol.% was achieved by the sample with 20 mol% of TiC. However, further increase of the TiC amount led to a decrease in the Ti 3 SiC 2 content, because of the low reaction temperature around 1150 • C.

Effects of SiC addition on formation of Ti3SiC2 by self-propagating high-temperature synthesis

“…Since first introduced by Jeitschko and Nowotny [6] in 1967, Ti 3 SiC 2 has been prepared through a variety of processing techniques, such as chemical vapor deposition (CVD) [7,8], arcmelting [9], reactive hot pressing (HP) and hot isostatic pressing (HIP) [2,10,11], reactive sintering [12][13][14][15][16][17], pulse discharge sintering (PDS) [18][19][20][21][22], and combustion synthesis in the modes of thermal explosion [23] and self-propagating high-temperature synthesis (SHS) [23][24][25][26][27][28][29][30][31]. Moreover, several different combinations of the powder mixtures including Ti/Si/C, Ti/SiC/C, and Ti/Si/TiC have been employed as the reactant materials.…”

Formation of TiAl–Ti2AlC in situ composites by combustion synthesis

“…1(b) reveals that the powder compact is subjected to an axial elongation, which is typical of SHS formation of the ternary carbide Ti 2 AlC. Due to the growth of synthesized carbide grains into a layered structure, elongated products have been commonly obtained from combustion synthesis of various ternary carbides, such as Ti 2 AlC [32], Ti 3 AlC 2 [33], and Ti 3 SiC 2 [34].…”

Effect of Excess Silicon on the Formation of Ti3SiC2Using Free Ti/Si/C Powders Synthesized via Arc Melting

“…Two types of heating sources are frequently employed in this reaction: (1) electric induction, where the heat is thermally propagated through the sample, that is, selfpropagating high-temperature synthesis (SHS) [13,[22][23][24][25][26], thermal explosion (TE) [21], and SHS coupled with hot isostatic pressing (SHS-HIP) [13,27], and (2) electriccharge, where heat is generated from electrodischarge among particles [28] which is due to the current flowing between two polling sites (anode and cathode), that is, pulse discharge sintering (PDS) [11,[29][30][31], spark plasma sintering (SPS) [28,32] or plasma-activated sintering [33][34][35], arc melting [17], and also from welding methods. Most researchers followed these methods to synthesize Ti 3 SiC 2 single phase by using several starting mixtures (e.g., TiH 2 /Si/C [14], Ti/Si/C [9, 10, 18-20, 23, 24, 27, 29, 36-47], Ti/SiC/C [25], Ti/Si/TiC [26,31], and TiC/Si [48]) and varying the composition of the starting reactant powders (e.g., Ti, Si, C, SiC, TiC, Al, etc.).…”

“…Most researchers followed these methods to synthesize Ti 3 SiC 2 single phase by using several starting mixtures (e.g., TiH 2 /Si/C [14], Ti/Si/C [9, 10, 18-20, 23, 24, 27, 29, 36-47], Ti/SiC/C [25], Ti/Si/TiC [26,31], and TiC/Si [48]) and varying the composition of the starting reactant powders (e.g., Ti, Si, C, SiC, TiC, Al, etc.). Unfortunately, some of these methods required the assistance of external pressure together with a hightemperature (>1500…”

“…The addition of excess Si is required in self-ignition reactions since the reactant sample has been subjected to extreme temperatures and high heating rates. In most syntheses, TiC and Ti-Si binary phases were always present in the synthesized products [26]. On the other hand, graphite (C g ) selection is basically used to facilitate the passing of currents through the sample [25], especially when using an electric charge as a heating source.…”