12045-63-5Relevant academic research and scientific papers
Optimization and characterization of LPCVD TiB2 for ULSI applications
Choi,Ruggles,Osburn,Xing
, p. 3053 - 3061 (1991)
The chemical vapor deposition of TiB2 from gaseous mixtures of TiCl4, B2H6, and H2 onto various substrates was studied. A thermodynamic analysis using the SOLGASMIX computer program indicated that at an input gas ratio corresponding to the stoichiometry of TiB2, the amount of secondary-phase deposition would be considerably reduced compared to that of TiB2. For nonstoichiometric input gas mixtures, other solid phases, including oxides and silicides, are expected to result from the reaction with substrates. Experimental depositions of films were carried out in a cold wall system over a broad range of temperatures, pressures, and input gas flow rates. X-ray diffraction and x-ray photoelectron spectroscopy data indicate that the as-deposited films are very fine grained polycrystalline or amorphous, and the films RTA-annealed above 900°C are crystalline TiB2. Below 550°C, surface reactions are the dominant factor for the kinetics of TiB2 deposition, while mass transport is a limiting step for deposition above 550°C. At higher temperatures the deposition rate increases linearly with flow rate and total pressure, suggesting the deposition mechanism is reactant limited. The B/Ti ratio determined via Auger electron spectroscopy approaches the stoichiometric value of two in higher temperature films, while the presence of excess boron and chlorine was detected for low-temperature films. Stoichiometric TiB2 films were deposited over a wide range of input gas mixture B/B + Ti ratios ranging from 0.4 to 0.71. Depletion effects of input gas were observed at low flow rate and high pressure where the residence time of reactants is longer than 10 s.
Effect of Ni content on the products of Ni-Ti-B system via self-propagating high-temperature synthesis reaction
Huang,Wang,Li,Yin,Jiang
, p. 286 - 291 (2008)
The effect of Ni content on the products of Ni-Ti-B system via self-propagating high-temperature synthesis (SHS) reaction has been investigated in this research. The results show that the products of SHS reactions consist mainly of TiB2 and Ni.
Chemical and electrochemical behavior of titanium diboride in cryolite-alumina melt and in molten aluminum
Devyatkin,Kaptay
, p. 107 - 109 (2000)
Titanium diboride is the most perspective material for protection of the cathode lining of aluminum electrolysis cells. One of the possible methods for obtaining a titanium diboride coating is an electrochemical synthesis from cryolite melt containing oxides of titanium and boron. In the present paper the behavior of oxides of titanium and boron in cryolite melt is considered. Coherent coating of titanium diboride has been deposited from the molten system Na3AlF6 - Al4B2O9 - CaTiO3. (C) 2000 Academic Press.
High critical current density of MgB2 bulk superconductor doped with Ti and sintered at ambient pressure
Zhao,Feng,Cheng,Zhou,Wu,Machi,Fudamoto,Koshizuka,Murakami
, p. 1154 - 1156 (2001)
Ti-doped MgB2 superconductors with different doping levels were prepared by solid-state reaction at ambient pressure. The density, diamagnetic signal, and Jc of the samples change significantly with the doping level, with the best result achieved at cursive chi = 0.1. At 5 K, the Jc reaches 2 × 106 A/cm2 in the self-field and 5 × 104 A/cm2 in 5 T. At 20 K, the Jc is still as high as 1.3 × 106 A/cm2 in the self-field and 9.4 × 104 A/cm2 in 2 T. It is observed that partial melting occurs in the Ti-doped samples, resulting in an excellent grain connection and extremely high density. In addition, some fine particles (with sizes from 10 to 100 nm) of the second phases induced by Ti doping are distributed in the MgB2 matrix, and this may play an important role in flux pinning enhancement.
Preparation of TiB2 and ZrB2. Influence of a mechano-chemical treatment on the borothermic reduction of titania and zirconia
Millet,Hwang
, p. 351 - 355 (1996)
TiB2 and ZrB2 have been synthesized by a mechano-chemical treatment of a mixture of titania or zirconia powder and amorphous boron followed by a relatively low temperature annealing (1100°C). Both the temperature and the kinetics of the borothermic transformations are affected by the mechano-chemical treatment when the size of the particles obtained after thermal annealing of the sample milled for a short time remains in the sub-micron range. The reaction paths are different for TiB2 and ZrB2 with the formation of TiBO3 and Ti2O3 as intermediate compounds in the case of the borothermic reduction of titania, while in the zirconia/boron system a direct borothermic reduction of zirconium oxide is observed.
Low-temperature densification of TiN-TiB2 composites through reactive hot pressing with excess Ti additions
Rangaraj, Lingappa,Divakar, Canchi,Jayaram, Vikram
, p. 311 - 317 (2009)
Reactive hot pressing of Ti and BN powder mixtures is used to produce dense TiNx-TiB2 composites. The effect of excess Ti along with a small addition, ～1 wt% Ni, on the reaction and densification of the composite was investigated. A
Processing and properties of TiB2 with MoSi2 sinter-additive: A first report
Murthy,Basu,Balasubramaniam,Suri,Subramanian,Fotedar
, p. 131 - 138 (2006)
The densification of non-oxide ceramics like titanium boride (TiB 2) has always been a major challenge. The use of metallic binders to obtain a high density in liquid phase-sintered borides is investigated and reported. However, a non-metallic sintering additive needs to be used to obtain dense borides for high-temperature applications. This contribution, for the first time, reports the sintering, microstructure, and properties of TiB 2 materials densified using a MoSi2 sinter-additive. The densification experiments were carried out using a hot-pressing and pressureless sintering route. The binderless densification of monolithic TiB2 to 98% theoretical density with 2-5 μm grain size was achieved by hot pressing at 1800°C for 1 h in vacuum. The addition of 10-20 wt% MoSi2 enables us to achieve 97%-99%ρth in the composites at 1700°C under similar hot-pressing conditions. The densification mechanism is dominated by liquid-phase sintering in the presence of TiSi2. In the pressureless sintering route, a maximum of 90%ρth is achieved after sintering at 1900°C for 2 h in an (Ar+H2) atmosphere. The hot-pressed TiB2-10 wt% MoSi2 composites exhibit high Vickers hardness (～26-27 GPa) and modest indentation toughness (～4-5 MPa·m12).
Determination of the thermodynamic stability of TiB2
Jain, Ashish,Pankajavalli,Anthonysamy,Ananthasivan,Babu,Ganesan,Gupta
, p. 747 - 752 (2010)
The standard free energy of formation of titanium boride (TiB2) was measured by the Electro Motive Force (EMF) method (by using yttria doped thoria (YDT) as the solid electrolyte). Two galvanic cells viz. Cell (I): Pt, TiB2 (s), TiO
Effect of KCl, NaCl and CaCl2 mixture on volume combustion synthesis of TiB2 nanoparticles
Nekahi, Atiye,Firoozi, Sadegh
, p. 1377 - 1383 (2011)
Preparation of titanium diboride (TiB2) nanoparticles was carried out by volume combustion synthesis. TiO2, B2O 3 and elemental Mg were mixed with 0-60% salt mixture of KCl, NaCl and CaCl2 with increment of 15% as a low melting temperature diluent. Compressed samples were synthesized in a tubular furnace at a constant heating rate under argon atmosphere. Thermal analysis of the process showed that the addition of the low melting temperature salts mixture led to a significant decrease in ignition and combustion temperatures. Synthesized samples were then leached by nitric and hydrochloric acids to remove impurities. The samples were examined by XRD, SEM and DLS analysis. The results showed the formation of fine deagglomerated particles with the addition of the salts mixture. The results revealed that 45% salts mixture had the smallest average particle size of about 90 nm.
Mechanochemical synthesis and pressureless sintering of TiB2-AlN composites
Kim, Hyung-Jong,Choi, Heon-Jin,Lee, June-Gunn
, p. 1022 - 1024 (2002)
TiB2-AlN composites have been fabricated by the pressureless sintering of a mechanochemically processed Ti, Al, and BN powder mixture. TiB2-AlN powder was obtained from the mixture of Ti, Al, and BN, which had a composition corresponding to 45.7 wt% TiB2-54.3 wt% AlN, after mechanochemical processing for longer than 24 h. X-ray diffraction and transmission electron microscopy analysis showed that the powder subjected to mechanochemical processing for 60 h consisted of crystallites less than 300 nm in size with a disordered crystal structure. TiB2-AlN composites with 95% relative density, a flexural strength of 172 MPa, a fracture toughness of 4.6 MPa·m1/2, a hardness of 12.0 GPa, and an electrical resistivity of 1488 μΩ·cm were obtained by pressureless sintering at 1700°C for 2 h of the powder subjected to mechanochemical processing for 60 h.
