Smoke generators. IV. The ignition of loose powder mixtures of pyrotechnic white smoke compositions containing hexachloroethane and silumin in sealed tubes

1984 ◽  
Vol 9 (3) ◽  
pp. 108-114 ◽  
Author(s):  
F. R. Hartley ◽  
S. G. Murray ◽  
M. R. Williams
Keyword(s):  
Powder Mixtures ◽  
Loose Powder

Catalytically active coatings for steam reforming systems: synthesis and catalytic properties

2019 ◽  
pp. 96-105
Author(s):  
M. L. Shishkova ◽  
N. V. Yakovleva
Keyword(s):  
Catalytic Properties ◽  
Raw Materials ◽  
Cold Gas Dynamic Spraying ◽  
Hydrogen Fuel ◽  
Functional Coatings ◽  
Science And Engineering ◽  
Powder Mixtures ◽  
Conversion Of Methane ◽  
Catalytically Active ◽  
Metal Support

The paper considers science and engineering aspects of catalytically active compositions creation as regards immobilized catalysts for reforming hydrocarbon raw materials into hydrogen fuel. The authors investigate synthesis of catalytic powder mixtures and manufacturing of functional coatings by supersonic cold gas dynamic spraying. Research results in the field of creation of catalysts for steam conversion of methane to hydrogenous fuel on the metal support (Cr15Al15 tape support) are given. Composite powder mixtures (Ni–Al–Al(OH)3– Ca(OH)2–Mg(OH)2) were used as starting materials.

scholarly journals Tetracalcium Phosphate/Monetite/Calcium Sulfate Hemihdrate Biocement Powder Mixtures Prepared by the One-Step Synthesis for Preparation of Nanocrystalline Hydroxyapatite Biocement-Properties and In Vitro Evaluation

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2137
Author(s):  
Lubomir Medvecky ◽  
Maria Giretova ◽  
Radoslava Stulajterova ◽  
Lenka Luptakova ◽  
Tibor Sopcak
Keyword(s):  
Simulated Body Fluid ◽  
Body Fluid ◽  
Calcium Sulfate ◽  
Powder Mixtures ◽  
Liquid Component ◽  
Tetracalcium Phosphate ◽  
Nanocrystalline Hydroxyapatite ◽  
One Step ◽  
Calcium Sulfate Hemihydrate

A modified one-step process was used to prepare tetracalcium phosphate/monetite/calcium sulfate hemihydrate powder cement mixtures (CAS). The procedure allowed the formation of monetite and calcium sulfate hemihydrate (CSH) in the form of nanoparticles. It was hypothesized that the presence of nanoCSH in small amounts enhances the in vitro bioactivity of CAS cement in relation to osteogenic gene markers in mesenchymal stem cells (MSCs). The CAS powder mixtures with 15 and 5 wt.% CSH were prepared by milling powder tetracalcium phosphate in an ethanolic solution of both orthophosphoric and sulfuric acids. The CAS cements had short setting times (around 5 min). The fast setting of the cement samples after the addition of the liquid component (water solution of NaH2PO4) was due to the partial formation of calcium sulfate dihydrate and hydroxyapatite before soaking in SBF with a small change in the original phase composition in cement powder samples after milling. Nanocrystalline hydroxyapatite biocement was produced by soaking of cement samples after setting in simulated body fluid (SBF). The fast release of calcium ions from CAS5 cement, as well as a small rise in the pH of SBF during soaking, were demonstrated. After soaking in SBF for 7 days, the final product of the cement transformation was nanocrystalline hydroxyapatite. The compressive strength of the cement samples (up to 30 MPa) after soaking in simulated body fluid (SBF) was comparable to that of bone. Real time polymerase chain reaction (RT-PCR) analysis revealed statistically significant higher gene expressions of alkaline phosphatase (ALP), osteonectin (ON) and osteopontin (OP) in cells cultured for 14 days in CAS5 extract compared to CSH-free cement. The addition of a small amount of nanoCSH (5 wt.%) to the tetracalcium phosphate (TTCP)/monetite cement mixture significantly promoted the over expression of osteogenic markers in MSCs. The prepared CAS powder mixture with its enhanced bioactivity can be used for bone defect treatment and has good potential for bone healing.

scholarly journals Formation of metal composites by detonation spray of powder mixtures

2021 ◽  
Author(s):  
Vladimir Yu. Ulianitsky ◽  
Denis K. Rybin ◽  
Alexey Sova ◽  
Ahmad Ostovari Moghaddam ◽  
Marina Samodurova ◽  
...  
Keyword(s):  
Metal Composites ◽  
Powder Mixtures ◽  
Detonation Spray

An innovative sampling interface for monitoring flowing pharmaceutical powder mixtures

2021 ◽  
Vol 194 ◽  
pp. 113785
Author(s):  
Pedro A. Martínez-Cartagena ◽  
Nobel O. Sierra-Vega ◽  
Bárbara B. Alvarado-Hernández ◽  
Rafael Méndez ◽  
Rodolfo J. Romañach
Keyword(s):  
Powder Mixtures ◽  
Pharmaceutical Powder ◽  
Sampling Interface

scholarly journals Combustion Synthesis of Aluminum Oxynitride in Loose Powder Beds

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4182
Author(s):  
Alan Wilmański ◽  
Magdalena Zarzecka-Napierała ◽  
Zbigniew Pędzich
Keyword(s):  
Combustion Synthesis ◽  
Metal Powder ◽  
Weight Ratio ◽  
Nitrogen Pressure ◽  
Alumina Powder ◽  
Metal Powders ◽  
Aluminum Oxynitride ◽  
Synthesis Conditions ◽  
Aluminum Metal ◽  
Loose Powder

This paper describes combusting loose powder beds of mixtures of aluminum metal powders and aluminum oxide powders with various grain sizes under various nitrogen pressure. The synthesis conditions required at least 20/80 weight ratio of aluminum metal powder to alumina powder in the mix to reach approximately 80 wt% of γ-AlON in the products. Finely ground fused white alumina with a mean grain size of 5 μm was sufficient to achieve results similar to very fine alumina with 0.3 μm grains. A lower nitrogen pressure of 1 MPa provided good results, allowing a less robust apparatus to be used. The salt-assisted combustion synthesis upon addition of 10 wt% of ammonium nitrite resulted in a slight increase in product yield and allowed lower aluminum metal powder content in mixes to be ignited. Increasing the charge mass five times resulted in a very similar γ-AlON yield, providing a promising technology for scaling up. Synthesis in loose powder beds could be utilized for effective production of relatively cheap and uniform AlON powder, which could be easily prepared for forming and sintering without intensive grounding and milling, which usually introduce serious contamination.

Analysis of Fractional Composition and Specific Surface of Silicone Dioxide Nanopowders

2020 ◽  
Vol 992 ◽  
pp. 551-555
Author(s):  
O.N. Kravtsova ◽  
G.G. Vinokurov ◽  
N.F. Struchkov
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Fractional Composition ◽  
Nanosized Powder ◽  
Nanosized Powders ◽  
Powder Mixtures ◽  
Angle Scattering ◽  
Intermediate Value ◽  
Particle Shapes

For the development of new compositions of modified powder mixtures a comprehensive analysis of the technical characteristics of powder additives is required. The specific surfaces of nanosized powders of "Tarkosil" silicone dioxide were determined by the experimental method. Therefore, at present, the estimating relationships of sizes, particles shapes and specific surface area of nanosized powder is relevant scientific and practical task. And the particles shape was evaluated by the values of these surfaces. Using the method of small-angle scattering the functions of distribution of the modifying powders particles on their sizes were estimated, and the average values of particles size of "Tarkosil" powder were specified The particle shape of the modifying powders has been estimated according to the specific surface values. The particle shapes of T50 powders are close to isometric (a ball, a cube); particle shapes of T150 powders correspond to a tetrahedron, the particle size T80 and T110 corresponds to the intermediate value of the specific surface area.

scholarly journals Melt-driven mechanochemical phase transformations in moderately exothermic powder mixtures

2016 ◽  
Vol 15 (12) ◽  
pp. 1280-1286 ◽  
Author(s):  
Samuel A. Humphry-Baker ◽  
Sebastiano Garroni ◽  
Francesco Delogu ◽  
Christopher A. Schuh
Keyword(s):  
Phase Transformations ◽  
Powder Mixtures
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