Structural and mechanical properties of TiB2 and TiC prepared by self-propagating high-temperature synthesis/dynamic compaction

Abstract

Titanium-diboride and titanium-carbide compacts with diameters of 1 O0 mm and thicknesses of 25 mm were fabricated by self-propagating high-temperature synthesis/dynamic compaction (SHS/DC) of the elemental powders. Under the best conditions, the densities were greater than 99% and 96.8% of the theoretical densities for TiB 2 and TiC, respectively. The microhardness, compressive strength, and elastic modulus of the TiB 2 prepared by the SHS/DC method were comparable to reported values for hot-pressed TiB 2. While the microhardness and elastic modulus of the TiC compacts were comparable to those for hotpressed TiC, the compressive strength was lower due to extensive cracks in the compacts. The TiB 2 prepared using a low-purity boron powder (1-5% carbon impurity) compacted to higher densities and had less cracking than that prepared using a high-purity boron powder (0.2% carbon). This result could have an impact on the cost of producing TiB2/TiC structural components by the SHS/DC process.

The mechanism of formation of TiB2 particulates prepared by In Situ reaction in molten aluminum

“…[13,15] For Al ϭ 5.0 wt pct, we have ␥" Ϸ 154.33 pct from Eqs. [7] and [8]. The physical meaning for ␥" Ͼ 100 pct lies in the fact that not only are all of the TiB 2 particulates to be molten in this case, but also the adiabatic temperature (T ad ) will exceed the melting point of TiB 2 .…”

“…Additionally, these processes also have problems such as interfacial reactions leading to undesirable products, thermodynamic and mechanical incompatibility, and internal stresses resulting from the mismatch of thermal expansion coefficients of various phases. Recent studies [6][7][8][9][10][11][12] have shown that in situ fabrication for producing aluminum matrix composites can produce a new class of naturally stable composites for advanced structural and wear application. More recently, we used a novel technique to generate fine particulates in the parent matrix.…”

Study on the adiabatic temperature of Al-Ti-C grain refiner synthesized by SHS technique

“…Based on the thermodynamics data relevent to Al-Ti-C system [10], the adiabatic temperature T d1 of reactant under different composition proportion factors was calculated according to formula (1) and is shwon in Table 3. The maximum temperature, i.e., the adiabatic temperature, for the synthesis reaction of reactant can be estimated directly using this method.…”

“…SHS-casting method and SHS-hot pressing sintering process are hotspots for the preparation of densification materials by SHS method. At present, SHS technique has been used in the preparation of metallic base TiC, TiB 2 reinforced composites et al [1][2][3][4][5][6][7][8].…”

Burning velocities in catalytically assisted self-propagating high-temperature combustion synthesis systems

“…Variations include fluidized-bed combustion synthesis [3], electric-field activated SHS [4], dynamic-compaction SHS [5], and catalytically assisted SHS [6 -8]. These variants hold high promise for control of product microstructure and composition, which is critical to enabling combustion synthesis technologies.…”