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.

scholarly journals Plasma Spheroidisation of Irregular Ti6Al4V Powder for Powder Bed Fusion

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1763
Author(s):  
Nthateng Nkhasi ◽  
Willie du Preez ◽  
Hertzog Bissett
Keyword(s):  
Particle Size ◽  
Additive Manufacturing ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Metal Powder ◽  
Weight Ratio ◽  
High Strength ◽  
Powder Bed Fusion ◽  
Metal Powders ◽  
Powder Bed

Metal powders suitable for use in powder bed additive manufacturing processes should ideally be spherical, dense, chemically pure and of a specified particle size distribution. Ti6Al4V is commonly used in the aerospace, medical and automotive industries due to its high strength-to-weight ratio and excellent corrosion resistance properties. Interstitial impurities in titanium alloys have an impact upon mechanical properties, particularly oxygen, nitrogen, hydrogen and carbon. The plasma spheroidisation process can be used to spheroidise metal powder consisting of irregularly shaped particles. In this study, the plasma spheroidisation of metal powder was performed on Ti6Al4V powder consisting of irregularly shaped particles. The properties of the powder relevant for powder bed fusion that were determined included the particle size distribution, morphology, particle porosity and chemical composition. Conclusions were drawn regarding the viability of using this process to produce powder suitable for additive manufacturing.

Chemically activated combustion synthesis of AlON under high nitrogen pressure

2021 ◽  
Vol 232 ◽  
pp. 111560
Author(s):  
Tigran G. Akopdzhanyan ◽  
Sergey I. Rupasov ◽  
Stepan Vorotilo
Keyword(s):  
Combustion Synthesis ◽  
Nitrogen Pressure ◽  
High Nitrogen ◽  
High Nitrogen Pressure

Combustion Synthesis of Si3N4 from Si/NH4Cl at Low Nitrogen Pressure

2008 ◽  
Vol 368-372 ◽  
pp. 1767-1770 ◽  
Author(s):  
Yi Xiang Chen ◽  
Jiang Tao Li ◽  
Zhi Ming Lin ◽  
Guang Hua Liu ◽  
S.L. Yang ◽  
...  
Keyword(s):  
Combustion Synthesis ◽  
Combustion Temperature ◽  
Profile Analysis ◽  
Combustion Velocity ◽  
Nitrogen Pressure ◽  
Analysis Method ◽  
Α Phase ◽  
Steady Combustion ◽  
Combustion Wave Velocity ◽  
Low Nitrogen

Combustion synthesis (CS) of Si3N4 was accomplished by using as-milled Si/NH4Cl as reactants at low nitrogen pressure. The additive of NH4Cl decreased the combustion temperature and promoted the Si nitridation. Full nitridation of Si was achieved by burning Si in pressurized nitrogen with 10 ~ 25 wt. % NH4Cl as additives while no Si3N4 diluent added. The maximum combustion temperature (Tc), the combustion velocity (u) together with the α-Si3N4 content and mean particle size (d50) of the powder products were found to be great dependent on the NH4Cl content added in the reactants. Fine Si3N4 powder products with α-phase content up to 85 wt. % were obtained via steady combustion mode. A mathematical approach named combustion wave velocity methods for the analysis of temperature profiles in CS was proposed and the reaction kinetics was discussed. The apparent activation energy calculated according to the temperature profile analysis method is 29.7 kJ/mol, which agrees well with the corresponding low temperature nitriding combustion of Si.

Microstructure and Mechanical Properties of the Wide-Gap Region Brazed with Various Powder Mixing Ratios of Additive to Filler Metal Powders

2006 ◽  
Vol 118 ◽  
pp. 479-484 ◽  
Author(s):  
Yong Hwan Kim ◽  
S.I. Kwun
Keyword(s):  
Mechanical Properties ◽  
Metal Powder ◽  
Room Temperature ◽  
Filler Metal ◽  
Metal Powders ◽  
Powder Mixing ◽  
Factors Affecting ◽  
Mixing Ratios ◽  
Microstructure And Mechanical Properties ◽  
Wide Gap

This study investigated the microstructure and mechanical properties of the wide-gap region brazed with various powder mixing ratios of additive powder (IN738) to filler metal powder (DF4B). The wide-gap brazing process was carried out in a vacuum of 2×10-5 torr at 1230°C for 1 hr. The microstructure of the brazed region was analyzed by FESEM and AES. The wide-gap region brazed with 60wt.% IN738 additive powder and 40 wt.% DF 4B filler metal powder had a microstructure consisting of Ni solid solution + γ' and (Cr, W)2B. The fracture strength of the wide-gap region brazed with 60 wt.% IN738 additive and 40 wt.% DF 4B powder was as high as 832 MPa at room temperature. It was found that the (Cr, W)2B and pores in the brazed region are important microstructural factors affecting the mechanical properties of the wide-gap brazed region.

Combustion synthesis and characteristics of aluminum oxynitride ceramic foams

2012 ◽  
Vol 38 (6) ◽  
pp. 5139-5144 ◽  
Author(s):  
Yongting Zheng ◽  
Hongbo Li ◽  
Wei Zhou ◽  
Xiaonan Zhang ◽  
Guorui Ye
Keyword(s):  
Combustion Synthesis ◽  
Aluminum Oxynitride ◽  
Ceramic Foams

Combination of Spray Forming and Metal Powder Productions by the Internal Mixing Atomizer with a Substrate

2006 ◽  
Vol 505-507 ◽  
pp. 1237-1242 ◽  
Author(s):  
Muh Ron Wang ◽  
Pin Jen Chen ◽  
Je Rei Yang ◽  
Jin Shen Chiu ◽  
Tien Chu Lin ◽  
...  
Keyword(s):  
Particle Size ◽  
Production Rate ◽  
Metal Powder ◽  
Deposition Rate ◽  
Spray Forming ◽  
Metal Powders ◽  
Two Phase ◽  
Powder Production ◽  
Internal Mixing ◽  
Impinging Flow

This paper describes the performance of an atomizer coupled with a substrate which produces metal powder and spray forming materials simultaneous in the spray chamber. Ultra fine metal powders are produced from this process. The melt is atomized by a twin-fluid atomizer with internal mixing mechanisms. The molten spray injected from the swirling chamber of the atomizer is then impinged upon the substrate to form the two phase impinging flow. The deposition rate of the molten spray on the substrate is controlled by the diameter of the substrate, the height of the substrate ring and the distance of the substrate from the outlet of the atomizer. This in turn determines the powder production rate of the spraying processes. Experimental results indicate that the deposition rate of the spray forming material decreases as the distance between the substrate and the atomizer increases. For example, the deposition rate decreases from 48% to 19% as the substrate is placed at a distance from 20cm to 40cm. On the other hand, the metal powder production rate and its particle size increases as the substrate is placed far away from the atomizer. The production of metal powder with mean particle size as low as 3μ m level has been achieved, a level which is not achievable by the conventional gas atomization processes.

Combustion Synthesis of ZrW2O8 and Preparation of its Composite with Near Zero Thermal Expansion

2007 ◽  
Vol 353-358 ◽  
pp. 1235-1238 ◽  
Author(s):  
Xue Yan ◽  
Xiao Nong Cheng ◽  
Xin Bo Yang ◽  
Cheng Hua Zhang
Keyword(s):  
Thermal Expansion ◽  
Combustion Synthesis ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Linear Thermal Expansion Coefficient ◽  
Linear Thermal Expansion ◽  
Weight Ratio ◽  
Combustion Method ◽  
Temperature Range ◽  
Thermal Expansion Property

ZrW2O8 was successfully synthesized via combustion method with (NH4)5H5[H2(WO4)6] ·H2O, ZrOCl2·8H2O, H3BO3, (NH2)2CO and HNO3. The best prescription of combustion synthesizing of ZrW2O8 was obtained. The linear thermal expansion coefficient of synthesized ZrW2O8 is -5.08×10-6oC-1 in the temperature range of 50-600oC. Different weight ratios of ZrW2O8 and ZrO2 were taken into account. Al2O3 was added into the composite during sintering to increase the density of the composites. When the weight ratio of ZrO2 to ZrW2O8 is 2, the composite with near zero thermal expansion can be obtained. 0.25 wt% Al2O3 can effectively increase the density of ZrO2/ZrW2O8 composites with slight influence on the thermal expansion property.

Computational Simulations on Melting Process of Fine Metal Powders With Laser Irradiation Welding

2009 ◽  
Author(s):  
Kazuyuki Takase ◽  
Toshiharu Muramatsu ◽  
Takahisa Shobu ◽  
Kazuyuki Tsukimori
Keyword(s):  
Stainless Steel ◽  
Metal Powder ◽  
Steel Plate ◽  
Numerical Study ◽  
Melting Process ◽  
Metal Powders ◽  
Stainless Steel Plate ◽  
Term Operation ◽  
Breeder Reactors

At the commercial use stage in sodium-cooled fast breeder reactors, securing maintenance and repair better than an equal to that of present water-cooled reactors is needed. Especially a repair technology that secures the plant integrity for long-term operation period becomes indispensable in the heat exchanger tubes of the steam generator that form the boundary of sodium and water coolants. Then the present study focused on the standardization of welding technology with a laser. An experimental study regarding the welding of a stainless steel plate with the laser using fine metal powders is being performed. Moreover, a numerical study is performed to simulate the welding of the fine metal powder on the stainless steel plate. The fine metal powder is made of iron, and is heated by the laser beam, and then melts exceeding the melting temperature. This paper reports the computational results of the welding phenomenon of some metal powders which changes from solid to liquid and liquid to solid. The results were compared with the experimental results qualitatively.

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