Photoflash and laser ignition of full density nano-aluminum PVDF films

2021 ◽  
Vol 233 ◽  
pp. 111570
Author(s):  
Kyle E. Uhlenhake ◽  
Daniel Olsen ◽  
Mateo Gomez ◽  
Metin Örnek ◽  
Min Zhou ◽  
...  
Keyword(s):  
Full Density ◽  
Laser Ignition

Amorphous silica coating on α-alumina particles

1995 ◽  
Vol 53 ◽  
pp. 210-211
Author(s):  
J. W. Mellowes ◽  
C. M. Chun ◽  
I. A. Aksay
Keyword(s):  
Amorphous Silica ◽  
Heterogeneous Nucleation ◽  
Homogeneous Nucleation ◽  
Silica Coating ◽  
Full Density ◽  
Optimal Conditions ◽  
Fine Grained ◽  
Alumina Particles ◽  
Complete Mullitization ◽  
Powder Compacts

Mullite (3Al2O32SiO2) can be fabricated by transient viscous sintering using composite particles which consist of inner cores of a-alumina and outer coatings of amorphous silica. Powder compacts prepared with these particles are sintered to almost full density at relatively low temperatures (~1300°C) and converted to dense, fine-grained mullite at higher temperatures (>1500°C) by reaction between the alumina core and the silica coating. In order to achieve complete mullitization, optimal conditions for coating alumina particles with amorphous silica must be achieved. Formation of amorphous silica can occur in solution (homogeneous nucleation) or on the surface of alumina (heterogeneous nucleation) depending on the degree of supersaturation of the solvent in which the particles are immersed. Successful coating of silica on alumina occurs when heterogeneous nucleation is promoted and homogeneous nucleation is suppressed. Therefore, one key to successful coating is an understanding of the factors such as pH and concentration that control silica nucleation in aqueous solutions. In the current work, we use TEM to determine the optimal conditions of this processing.

Microstructural and fractographic characterization of B4C-Al cermets tested under dynamic and static loading

1989 ◽  
Vol 47 ◽  
pp. 562-563
Author(s):  
Gyeung Ho Kim ◽  
Mehmet Sarikaya ◽  
D. L. Milius ◽  
I. A. Aksay
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Static Loading ◽  
Carbon Deposition ◽  
Full Density ◽  
Unique Combination ◽  
Strong Component ◽  
Reaction Products

Cermets are designed to optimize the mechanical properties of ceramics (hard and strong component) and metals (ductile and tough component) into one system. However, the processing of such systems is a problem in obtaining fully dense composite without deleterious reaction products. In the lightweight (2.65 g/cc) B4C-Al cermet, many of the processing problems have been circumvented. It is now possible to process fully dense B4C-Al cermet with tailored microstructures and achieve unique combination of mechanical properties (fracture strength of over 600 MPa and fracture toughness of 12 MPa-m1/2). In this paper, microstructure and fractography of B4C-Al cermets, tested under dynamic and static loading conditions, are described.The cermet is prepared by infiltration of Al at 1150°C into partially sintered B4C compact under vacuum to full density. Fracture surface replicas were prepared by using cellulose acetate and thin-film carbon deposition. Samples were observed with a Philips 3000 at 100 kV.

Ultra-Fine Grained Ti-15Mo Alloy Prepared by Powder Metallurgy

2018 ◽  
Vol 941 ◽  
pp. 1276-1281
Author(s):  
Anna Terynková ◽  
Jiří Kozlík ◽  
Kristína Bartha ◽  
Tomáš Chráska ◽  
Josef Stráský
Keyword(s):  
Powder Metallurgy ◽  
Bulk Material ◽  
Alpha Phase ◽  
Full Density ◽  
Fine Grained ◽  
Cryogenic Milling ◽  
Aircraft Manufacturing ◽  
Plasma Sintering ◽  
Beta Matrix ◽  
Spark Plasma

Ti-15Mo alloy belongs to metastable β-Ti alloys that are currently used in aircraft manufacturing and Ti15Mo alloy is a perspective candidate for the use in medicine thanks to its biotolerant composition. In this study, Ti15Mo alloy was prepared by advanced techniques of powder metallurgy. The powder of gas atomized Ti-15Mo alloy was subjected to cryogenic milling to achieve ultra-fine grained microstructure within the powder particles. Powder was subsequently compacted using spark plasma sintering (SPS). The effect of cryogenic milling on the microstructure and phase composition of final bulk material after SPS was studied by scanning electron microscopy. Sintering at 750°C was not sufficient for achieving full density in gas atomized powder, while milled material could be successfully sintered at this temperature. Alpha phase particles precipitated during sintering and their size, as well as the size of beta matrix grains, was strongly affected by the sintering temperature.

Melt Modification and Microstructure Homogeneity of Solidified TiC-TiB2 Composites Prepared by Combustion Synthesis in Ultrahigh Gravity Field

2013 ◽  
Vol 833 ◽  
pp. 125-129
Author(s):  
Hao Zhang ◽  
Zhong Min Zhao ◽  
Long Zhang ◽  
Shuan Jie Wang
Keyword(s):  
Gravity Field ◽  
Combustion Synthesis ◽  
Stokes Flow ◽  
High Energy ◽  
Adiabatic Temperature ◽  
Full Density ◽  
Reactive System ◽  
Refined Microstructure ◽  
Ultrafine Grained ◽  
Ultrafine Grained Microstructure

By introducing (CrO3+Al) high-energy thermit into (Ti+B4C) system and designing adiabatic temperature of reactive system as 3000°C,3200°C, 3400°C, 3600°C and 3800°C respectively, a series of solidified TiC-TiB2were prepared by combustion synthesis in ultrahigh gravity field with the acceleration 2000 g. XRD, FESEM and EDS results showed that the solidified TiCTiB2were composed of a number of TiB2primary platelets, irregular TiC secondary grains, and a few of isolated Al2O3inclusions and Cr-based alloy. Because of the enhanced Stokes flow in mixed melt with the increased adiabatic temperature, Al2O3droplets were promoted to float up and separate from TiC-TiB2-Me liquid while constitutional distribution became more and more uniform in TiC-TiB2-Me liquid, resulting in not only the sharply-reduced Al2O3inclusions in the solidified ceramic but also the refined microstructure and the improved homogeneity in the ceramic, and ultrafine-grained microstructure with a average thickness of TiB2platelets smaller than 1μm began to appear in near-full-density ceramic as the adiabatic temperature exceeded 3600°C, so the densification, fracture toughness and flexural strength of the ceramic were enhanced with the increased adiabatic temperature of the reactive system.

Laser ignition for artillery cannon

2005 ◽  
Author(s):  
Richard A. Beyer
Keyword(s):  
Laser Ignition

Laser Ignition of Surgical Drape Materials in Air, 50% Oxygen, and 95% Oxygen

2004 ◽  
Vol 100 (5) ◽  
pp. 1167-1171 ◽  
Author(s):  
Gerald L. Wolf ◽  
George W. Sidebotham ◽  
Jackson L. P. Lazard ◽  
Jean G. Charchaflieh
Keyword(s):  
Carbon Dioxide ◽  
Operating Room ◽  
Oxygen Concentration ◽  
High Energy ◽  
Ignition Source ◽  
Laser Ignition ◽  
Surgical Tools ◽  
Time To Ignition ◽  
Room Fires ◽  
Surgical Laser

Background Operating room fires fueled by surgical drapes and ignited by high-energy surgical tools in air and oxygen-enriched atmospheres continue to occur. Methods The authors examined the time to ignition of huck towels and three commonly used surgical drape materials in air, 50% oxygen, and 95% oxygen using a carbon dioxide surgical laser as an ignition source. In addition, a phenol-polymer fabric was tested. Results In air, polypropylene and phenol polymer do not ignite. For polypropylene, the laser instantly vaporized a hole, and therefore, interaction between the laser and material ceased. When tested in combination with another material, the polypropylene time to ignition assumed the behavior of the material with which it was combined. For phenol polymer, the laser did not penetrate the material. Huck towels, cotton-polyester, and non-woven cellulose-polyester ignited in air with decreasing times to ignition. All tested materials ignited in 50% and 95% oxygen. Conclusion The results of this study reveal that with increasing oxygen concentration, the time to ignition becomes shorter, and the consequences become more severe. The possibility exists for manufacturers to develop drape materials that are safer than existing materials.

Effect of TiO2 doping on rapid densification of alumina by plasma activated sintering

1996 ◽  
Vol 11 (5) ◽  
pp. 1144-1148 ◽  
Author(s):  
R. S. Mishra ◽  
A. K. Mukherjee ◽  
K. Yamazaki ◽  
K. Shoda
Keyword(s):  
Dielectric Properties ◽  
Full Density ◽  
Activated Sintering ◽  
Sintering Kinetics ◽  
Temperature Range ◽  
Plasma Activated Sintering

The effects of plasma cycle and TiO2 doping on sintering kinetics during plasma activated sintering (PAS) of γ−Al2O3 have been studied in the temperature range of 1473–1823 K. Multiple plasma cycle leads to higher densification. Also, TiO2 doping enhances the sintering kinetics during PAS. In TiO2 doped specimens, near full density was obtained at 1673 K in less than 6 min using multiple plasma cycle. It is suggested that the dielectric properties of a material are critical for the success of the PAS process.

Laser ignition of nickel-aluminum powder systems

1994 ◽  
Vol 30 (2) ◽  
pp. 147-150 ◽  
Author(s):  
M. I. Shilyaev ◽  
V. É. Borzykh ◽  
A. R. Dorokhov
Keyword(s):  
Aluminum Powder ◽  
Laser Ignition ◽  
Nickel Aluminum

Syntheses of full-density nanocrystalline titanium nitride compacts by plasma-activated sintering of mechanically reacted powder

1998 ◽  
Vol 29 (7) ◽  
pp. 1973-1981 ◽  
Author(s):  
M. Sherif El-Eskandarany ◽  
M. Omori ◽  
T. Hirai ◽  
T. J. Konno ◽  
K. Sumiyama ◽  
...  
Keyword(s):  
Titanium Nitride ◽  
Full Density ◽  
Activated Sintering ◽  
Nanocrystalline Titanium ◽  
Plasma Activated Sintering

scholarly journals Effect of Particle Size Distribution on Powder Packing and Sintering in Binder Jetting Additive Manufacturing of Metals

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
Yun Bai ◽  
Grady Wagner ◽  
Christopher B. Williams
Keyword(s):  
Particle Size ◽  
Additive Manufacturing ◽  
Large Degree ◽  
Full Density ◽  
Powder Particle Size ◽  
Powder Mixtures ◽  
Fine Powders ◽  
Sintering Shrinkage ◽  
The Impact ◽  
Binder Jetting

The binder jetting additive manufacturing (AM) process provides an economical and scalable means of fabricating complex parts from a wide variety of materials. While it is often used to fabricate metal parts, it is typically challenging to fabricate full density parts without large degree of sintering shrinkage. This can be attributed to the inherently low green density and the constraint on powder particle size imposed by challenges in recoating fine powders. To address this issue, the authors explored the use of bimodal powder mixtures in the context of binder jetting of copper. A variety of bimodal powder mixtures of various particle diameters and mixing ratios were printed and sintered to study the impact of bimodal mixtures on the parts' density and shrinkage. It was discovered that, compared to parts printed with monosized fine powders, the use of bimodal powder mixtures improves the powder's packing density (8.2%) and flowability (10.5%), and increases the sintered density (4.0%) while also reducing the sintering shrinkage (6.4%).

Sign in / Sign up

Export Citation Format

Share Document