Influence of Factors Affecting the Parameters of Combustion of Aluminum Nanopowders in the Bulk Layer

2019 ◽  
Vol 970 ◽  
pp. 257-264
Author(s):  
Alexander I. Sechin ◽  
Olga B. Nazarenko ◽  
Yuliya A. Amelkovich ◽  
Andrey A. Sechin
Keyword(s):  
Thermal Explosion ◽  
Substrate Surface ◽  
Combustion Process ◽  
Temperature Synthesis ◽  
Factors Affecting ◽  
Bulk Layer ◽  
Second Stage ◽  
High Temperature Synthesis ◽  
Surface Burning ◽  
Synthesis Of Nanomaterials

The article presents the study of factors affecting the ability to control the self-propagating high-temperature synthesis of nanomaterials. It is established that there are two steps in the combustion process nanomaterial: burning of surface layer and deep combustion area, which can be considered as the thermal explosion. It was found that the surface roughness and the thermal conductivity of the substrate do not affect the combustion front velocity. The presence of glass transition on the substrate surface also does not affect the velocity of the front. It was established that the parameters of the deep combustion area do not depend on the nature of the initiation of combustion, being the second stage of the development of combustion; in all cases this stage is characterized by the same parameters. When varying the type of ignition source, the length of the surface burning front can vary up to 33%. The time of induction of a thermal explosion increases when the bulk layer of powder ignites from above.

Investigation of the Possibility for Control of High-Temperature Synthesis of Nanomaterials

2019 ◽  
Vol 942 ◽  
pp. 1-10 ◽  
Author(s):  
Alexander I. Sechin ◽  
Olga B. Nazarenko ◽  
Yuliya Amelkovich
Keyword(s):  
High Temperature ◽  
Thermal Explosion ◽  
Combustion Wave ◽  
Induction Time ◽  
Temperature Synthesis ◽  
High Temperature Synthesis ◽  
Combustion Wave Propagation ◽  
Heated Body ◽  
Aluminum Nanopowder ◽  
Synthesis Of Nanomaterials

The feasibility of creating conditions for control of high-temperature synthesis (SHS) of nanomaterials has been studied. Experiments were carried out to determine the velocity of the combustion wave propagation of aluminum nanopowder obtained by electric explosion. In the course of the study, the factors influencing formation of the induction time: the thermal diffusivity of the substrate, the method of initiation of the combustion wave (flame, spark, heated body), the induction time between the initiating front and the front of the thermal explosion were considered. The relation describing the time of induction of thermal explosion is established.

Study on Preparation of Ti Powder by Self-Propagating High-Temperature Synthesis (SHS) with Magnesiothermit Reductive Process

2008 ◽  
Vol 575-578 ◽  
pp. 1086-1092
Author(s):  
Peng Lin Zhang ◽  
Tian Dong Xia ◽  
Guo Dong Zhang ◽  
Li Jing Yan
Keyword(s):  
Reaction Rate ◽  
Combustion Temperature ◽  
Combustion Process ◽  
Green Compact ◽  
Reaction Products ◽  
Technological Parameters ◽  
Solid Reaction ◽  
Temperature Synthesis ◽  
High Temperature Synthesis ◽  
Ti Powder

The combustion process of Mg-TiO2 system was preliminarily investigated from three aspects of thermodynamics, reaction kinetics and the technological parameters. The result indicates that the adiabatic temperature of Mg-TiO2 system is between 2060K and 2140K because the major existent modalities of TiO2 is the rutile and anatase, this meets the empirical criterion that the SHS reaction will be self-sustaining; The solid-solid reaction occurs at about 767K; Ti powders can be produced only when the ratio between Mg and TiO2 arrives at 2.9:1; The higher the vacuum, the more complete the reaction; The combustion temperature arrives at its peak when the pressure of green compact arrives at 250MPa; the velocity of the combustion wave increases with the augmentation of the pressure of green compact. So the proper control of the technological parameters can change the reaction temperature, reaction rate and the components of reaction products.

Effect of Ti Contents on the Microstructure and Mechanical Properties of Ni˗Al˗Ti System

2020 ◽  
Vol 991 ◽  
pp. 24-29
Author(s):  
Dhimas Wicaksono ◽  
Xiao Meng Zhu ◽  
Mohammad Sukri Mustapa ◽  
Sulis Yulianto ◽  
Ahmad Yunus Nasution ◽  
...  
Keyword(s):  
Vickers Microhardness ◽  
Combustion Process ◽  
Intermetallic Phases ◽  
External Heat ◽  
Temperature Synthesis ◽  
Mixed Powder ◽  
External Heat Source ◽  
High Temperature Synthesis ◽  
Ti Content ◽  
Heat Released

In this work, a ternary system prepared by Ni-Al-Ti mixed powder was synthesized using self-propagation high-temperature synthesis (SHS) process. The weight of the reactant was varied using 3%, 10%, 20% and 30% of the Ti content. The mixtures were compressed in a steel die to form compacted pellets, and subsequently ignited using an external heat source to initiate the combustion process. The synthesized products were characterized using SEM, EDS, and XRD, whereas the mechanical property of the product was measured using a Vickers microhardness test. The identification of the formed phase indicates that Ni-Al, Ti-Al and Ti-Ni systems were formed during the reaction. An increase of Ti content from 3% to 10% improves the density of the synthesized product. Further increase of Ti content to 20% results in the generation of cracks. The addition of Ti with 30% leads to the formation of a porous product. The heat released by the SHS process due to the formation of several intermetallic phases was responsible for the formation of defect products. The highest hardness of the product was achieved in the product prepared by 20% Ti content. However, the higher Ti content than 20% results in hardness reduction. This work shows that the content of 10% of Ti produced a dense and hard product.

Combustion synthesis of mechanically activated powders in the Nb–Si system

2002 ◽  
Vol 17 (8) ◽  
pp. 1992-1999 ◽  
Author(s):  
Filippo Maglia ◽  
Chiara Milanese ◽  
Umberto Anselmi-Tamburini ◽  
Stefania Doppiu ◽  
Giorgio Cocco
Keyword(s):  
Mechanical Activation ◽  
Single Phase ◽  
Milling Time ◽  
Combustion Process ◽  
Temperature Wave ◽  
The Self ◽  
Temperature Synthesis ◽  
High Temperature Synthesis ◽  
Niobium Silicides ◽  
Reactant Powder

The effect of the mechanical activation of the reactants on the self-propagating high-temperature synthesis (SHS) of niobium silicides was investigated. SHS experiments were performed on reactant powder blends of composition Nb:Si = 1:2 and Nb:Si = 5:3 pretreated for selected milling times. A self-sustaining reaction could be initiated when a sufficiently long milling time was employed. At short milling times, the reactions self-extinguished or propagated in an unsteady mode. Combustion peak temperature, wave velocity, and product composition were markedly influenced by the length of the milling treatment. Single-phase products could be obtained for sufficiently long milling times. Observation of microstructural evolution in quenched reactions together with isothermal experiments allowed clarification of the mechanism of the combustion process and the role played by the mechanical activation of the reactants.

Kinetics of mechanically activated high temperature synthesis of Ni3Al in the thermal explosion mode

2011 ◽  
Vol 19 (7) ◽  
pp. 833-840 ◽  
Author(s):  
Valery Yu. Filimonov ◽  
Michail A. Korchagin ◽  
Evgeny V. Smirnov ◽  
Alexander A. Sytnikov ◽  
Vladimir I. Yakovlev ◽  
...  
Keyword(s):  
High Temperature ◽  
Thermal Explosion ◽  
Temperature Synthesis ◽  
High Temperature Synthesis ◽  
Kinetics Of

Synchrotron in situ studies of mechanical activation treatment and γ-radiation impact on structural-phase transitions and high-temperature synthesis parameters during the formation of γ-(TiAl) compound

2019 ◽  
Vol 26 (5) ◽  
pp. 1671-1678 ◽  
Author(s):  
Marina Loginova ◽  
Alexey Sobachkin ◽  
Alexander Sitnikov ◽  
Vladimir Yakovlev ◽  
Valeriy Filimonov ◽  
...  
Keyword(s):  
High Temperature ◽  
Mechanical Activation ◽  
Thermal Explosion ◽  
Powder Mixture ◽  
Maximum Temperature ◽  
Γ Irradiation ◽  
Temperature Synthesis ◽  
High Temperature Synthesis ◽  
The Impact

In situ synchrotron studies of structure and phase formation dynamics in mechanically activated (t = 7 min, power density 40 g) and mechanically activated with subsequent irradiation by γ-quanta 60Co powder mixture (Ti 64 wt% + Al) during high-temperature synthesis by the method of thermal explosion using induction heating are described. In situ high-temperature synthesis was carried out on the created experimental complex adapted for synchrotron X-ray diffraction methods. The sequence of formation and time–temperature interval of the metastable and main phases were determined. The impact of preliminary mechanical activation and of γ-irradiation on the macrokinetic parameters of the synthesis were studied experimentally in situ. It has been established that the impact of γ-irradiation on the mechanically activated powder mixture of the composition Ti 64 wt% + Al leads to a change in the thermal parameters of combustion: the maximum synthesis temperature and the burning rate decrease. The heating rate for the non-irradiated mixture is 204.8 K s−1 and that for the irradiated mixture is 81.6 K s−1. The dependences of mass fractions of the synthesized compounds on time and temperature were calculated from the stage of preheating until completion of the thermal explosion. A single-phase equilibrium product of the composition γ-(TiAl) is formed in γ-irradiated mechanically activated mixture when the system reaches maximum temperature. The synthesized product of the mechanically activated mixture without γ-irradiation contains 72% γ-(TiAl); TiAl3 (26%) and residual Ti (2%) are also observed.

The Obtaining of the Intermetallic Compounds of Ni-Al System by Self-Propagating High Temperature Synthesis and Thermal Explosion

2015 ◽  
Vol 1114 ◽  
pp. 135-142
Author(s):  
Mihai Cojocaru ◽  
Florică Tudose
Keyword(s):  
High Temperature ◽  
Intermetallic Compounds ◽  
Thermal Explosion ◽  
Melting Temperature ◽  
Aerospace Industry ◽  
Point Of View ◽  
Temperature Synthesis ◽  
Practical Point ◽  
High Temperature Synthesis

The intermetallic compounds (IMC) of Ni-Al system exhibit interest both by theoretical and practical point of view: theoretically, due to particular aspects in relation to their synthesis and practically, due to their qualities that recommend them for the top industries such as, for example, the aerospace industry. In this paper are shown the results of researches on obtaining of high temperature compounds of Ni-Al system by self-propagating high temperature synthesis and thermal explosion, through the initiation of process at a temperature below the melting temperature of the easy fusible component.

Sign in / Sign up

Export Citation Format

Share Document