Experimental and Numerical Studies on Self-Propagating High-Temperature Synthesis of Ta 5 Si 3 Intermetallics
Formation of Ta5Si3 by self-propagating high-temperature synthesis (SHS) from elemental powder compacts of Ta:Si = 5:3 was experimentally and numerically studied. Experimental evidence showed that the increase of either sample density or preheating temperature led to the increase of combustion wave velocity and reaction temperature. The apparent activation energy, Ea ≈ 108 kJ/mol, was determined for the synthesis reaction. Based upon numerical simulation, the Arrhenius factor of the rate function, K0 = 2.5 × 10 s, was obtained for the 5Ta + 3Si combustion system. In addition, the influence of sample density on combustion wave kinetics was correlated with the effective thermal conductivity (keff) of the powder compact. By adopting 0.005 ≤ keff/kbulk ≤ 0.016 in the computation model, the calculated combustion velocity and temperature were in good agreement with experimental data of the samples with compaction densities between 35% and 45% theoretical maximum density (TMD).
Nitride Ceramics: Combustion Synthesis, Properties and Applications
Foreword Preface COMBUSTION SYNTHESIS OF NITRIDES FOR DEVELOPMENT OF CERAMIC MATERIALS OF NEW GENERATION Introduction Peculiarities of Phase and Structure Formation of Metal and Nonmetal Nitrides in Combustion Mode Dependence of SHS Nitride Composition and Structure on Infiltration Combustion Mode SHS Equipment for Powder Synthesis Synthesis of SHS-Ceramics Based on Silicon and Aluminum Nitrides and SiAlON Powders Direct Production of Materials and Items Based on Nitride Ceramics by SHS Gasostating Conclusion COMBUSTION SYNTHESIS OF BORON NITRIDE CERAMICS: FUNDAMENTALS AND APPLICATIONS Introduction Combustion in Boron-Nitrogen System Mechanism of Structure Formation in CS Wave Combustion Synthesis of Nitride-Based Ceramics Final Remarks COMBUSTION SYNTHESIS OF ALUMINUM NITRIDE (AIN) POWDERS WITH CONTROLLED GRAIN MORPHOLOGIES Introduction Combustion Synthesis of Quasi-Aligned AlN Nanowhiskers Enhanced Thermal Conductivity of Polymer Composites Filled with 3D Brush-Like AlN Nanowhiskers by Combustion Method Growth of Flower-Like AlN by Combustion Synthesis Assisted with Mechanical Activation Combustion Synthesis of AlN Porous-Shell Hollow Spheres Summary and Conclusions COMBUSTION SYNTHESIS AND SPARK PLASMA SINTERING OF ss-SiAlON Introduction CS of High-Purity ss-SiAlON and Densification by SPS Physical Properties of CS-SPSed ss-SiAlON Corrosion Resistance Conclusions of This Chapter COMBUSTION SYNTHESIS OF AlN (Al3O3N), BN, ZrN, AND TiN IN AIR AND CERAMIC APPLICATION Thermochemical Features of Aluminum Particles Combustion (Theoretical Background) Chemical Features of Metals Combustion in Air (Experimental Background) Nitrides (Oxynitrides) Formation by Metal Powder Combustion in Air Applcation of the Synthesized Nitrides and Oxynitrides in Dense Ceramics COMBUSTION SYNTHESIS OF NITRIDES OF VANADIUM, NIOBIUM, AND TANTALUM Introduction Experimental Methods of Approach Results and Discussion Conclusions SYNTHESIS OF NITRIDES BY SHS OF FERROALLOYS IN NITROGEN Introduction Synthesis of Silicon Nitride by Combustion of Ferrosilicon in Nitrogen Synthesis of Vanadium Nitride by Combustion of Ferrovanadium in Nitrogen Synthesis of Niobium Nitride by Combustion of Ferrovniobium in Nitrogen Synthesis of Titanium Nitride by Combustion of Ferrovtitanium in Nitrogen Combustion of Ferrochromium in Nitrogen and Synthesis of Chromium Nitride Combustion of Ferroboron in Nitrogen and Synthesis of Boron Nitride Application Prospects of Products of Combustion of Ferroalloys in Nitrogen Conclusions HALIDES IN SHS AZIDE TECHNOLOGY OF NITRIDES OBTAINING Introduction The Use of Ammonia Halides The Use of Halides of Elements to be Nitrided The Use of Complexing Halides of Elements to be Nitrided and Alkaline Metals The Use of Complexing Halides of Ammonia and Elements to be Nitrided The Use of Halides for Obtaining Refractory Compositions Efficiency of Use of Halides in Azide SHS Systems Chemical Stages of Formation of Nitrides in a Mode SHS-Az Property of SHS-Az Powders Property of SHS-Az Ceramics The Synthesis of Nanostructural SHS-Az Powders Conclusion AlN CERAMICS FROM NANOSIZED PLASMA PROCESSED POWDER, ITS PROPERTIES AND APPLICATION Introduction: AlN Ceramics, its Characteristics and Application Production of AlN Ceramics from Nanosized Plasma Processed Powder Properties of AlN Ceramics from Nanosized Plasma Processed Powder Practical Application of Luminescence Properties of AlN Ceramics Conclusions AN OVERVIEW OF THE APPLICATION OF NITRIDES AND OXYNITRIDES IN PHOTOCATALYSIS AND ELECTROCATALYSIS Introduction Preparation Photocatalysis Electrocatalysis Conclusion CONCLUSION Index
Single step formation of biocompatible bimetallic alloy nanoparticles of gold and silver using isonicotinylhydrazide.
Manufacturing nanoparticles with controlled physicochemical properties using environment-friendly routes have potential to open new prospects for a variety of applications. Accordingly, several approaches have been established for manufacturing metal nanoparticles. Many of these approaches entail the use of hazardous chemicals and could be toxic to the environment, and cannot be used readily for biomedical applications. In the present work, we report a single step bio-friendly approach to formulate gold (Au), silver (Ag), and Au-Ag alloy nanoparticles with desired surface corona and composition using isonicotinylhydrazide (INH) as a reducing agent. INH also functioned as a stabilizing agent by enabling a surface corona around the nanoparticles. Remarkably, within a single step INH could also provide a handle in regulating the composition of Au and Ag in bimetallic systems without any additional chemical modification. The physicochemical and surface properties of the different nanoparticles thus obtained have been examined by analytical, spectroscopic and microscopic techniques. Cell cytotoxicity (release of lactate dehydrogenase), cell viability and intracellular reactive oxygen species (ROS) assays confirmed that the Au, Ag, and Au-Ag bimetallic nanoparticles prepared with INH are biocompatible. Finally, the presence of organic surface corona of INH on the nanoparticles was found to impart nanozyme activity and antimycobacterial sensitivity to the nanoparticles.