scholarly journals Influence of the Oxide and Ethanol Surface Layer on Phase Transformation of Al-Based Nanocomposite Powders under High-Energy Milling

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1305 ◽  
Author(s):  
Dora Janovszky
Keyword(s):  
Particle Size ◽  
Milling Time ◽  
High Energy ◽  
Amorphous Structure ◽  
Control Agent ◽  
Dry Milling ◽  
Process Control Agent ◽  
Composite Powders ◽  
High Energy Milling ◽  
Nanocomposite Powders

Pure Al particles reinforced with amorphous-nanocrystalline Cu36Zr48Ag8Al8 particles composite powders were prepared by high-energy milling without and with ethanol. The mechanical milling procedures were compared so that in the case of dry milling the particle size increased owing to cold welding, but the crystallite size decreased below 113 nm. The amorphous phase disappeared and was not developed until 30 h of milling time. Using ethanol as a process control agent, the particle size did not increase, while the amorphous fraction increased to 15 wt.%. Ethanol decomposed to carbon dioxide, water, and ethane. Its addition was necessary to increase the amount of the amorphous structure.

Influence of High Energy Milling on the Airflow Sensorproperty of the NBCa Ceramic

2012 ◽  
Vol 727-728 ◽  
pp. 499-504 ◽  
Author(s):  
C. Caldart ◽  
J. Souza ◽  
M.Z. Pellegrin ◽  
Glaucea Warmeling Duarte ◽  
M.R. Rocha ◽  
...  
Keyword(s):  
Particle Size ◽  
Milling Time ◽  
Weather Forecasting ◽  
High Energy ◽  
Monitoring And Control ◽  
Sem Images ◽  
High Energy Milling ◽  
Reliable Temperature ◽  
Precursor Powders ◽  
Airflow Sensor

Some materials have been applied in many surrounding conditions as sensors, electronic devices and other applications. Inexpensive and reliable temperature and flow measurement are important in many applications including, for example, environmental monitoring and control, indoor air conditioning, weather forecasting, automotive and aerospace systems. Special ceramics are an example of such materials. Neodymium-Barium-Copper is a special ceramic that has high electrical conductivity and airflow sensor characteristics. This property is influenced by high energy milling of the powder, when it is not sintered. To evaluate the influence of this type of milling it was carried out an analysis of particle size as a function of milling time. SEM images and granulometric analysis showed significant reduction of particle size with the increase of milling time. For longer times of milling the mixture of precursor powders is favored, resulting in better homogeneity of the ceramic. This is reflected in the properties of airflow sensor.

Densification Study of Cu-Al-SiC Composite Powders Prepared by Mechanical Milling

2014 ◽  
Vol 793 ◽  
pp. 37-44
Author(s):  
C.A. León-Patiño ◽  
D. Ramírez-Vinasco ◽  
E.A. Aguilar-Reyes
Keyword(s):  
Milling Time ◽  
Maximum Load ◽  
High Energy ◽  
Milling Process ◽  
Homogeneous Distribution ◽  
Composite Powders ◽  
Coarse Aggregates ◽  
High Energy Milling ◽  
Compaction Behavior ◽  
The Matrix

This work involves the preparation of Cu-Al-SiC composite powders by a high-energy milling process and the study of their densification behavior by cold compaction. The goal of the milling process is to get embedded the ceramic particles in the metal matrix to enhance the distribution of the metal and ceramic phases in the compacts, an important condition to derive in isotropic properties of consolidated materials. For comparison purposes, compressibility tests of a Cu-5Al matrix prepared by high-energy milling were performed; while additions of 1, 5 and 10 vol.% SiC were added to the matrix. It was found that the high-energy milling process leads to Cu-Al-SiC composite powders with a homogeneous distribution of the reinforcement in the matrix. Compressibility essays showed that densification of the powders decreased with SiC content; a densification of 73.7% was obtained for composites with 10% SiC compared to 76.0% for samples with 1% SiC at the maximum load applied. Milling time reduced the plastic deformation capacity of the matrix leading to fracture of the cold welded aggregates; the fracture process was accelerated by the addition of the hard reinforcement particles. Thus, morphology of the powders changed from laminar, to fine fragments and coarse aggregates, affecting the compaction behavior.

Synthesis of TiN/Si3N4 composite powders by mechanically activated annealing

2005 ◽  
Vol 20 (4) ◽  
pp. 864-873 ◽  
Author(s):  
J.M. Córdoba ◽  
R. Murillo ◽  
M.D. Alcalá ◽  
M.J. Sayagués ◽  
F.J. Gotor
Keyword(s):  
Mechanical Activation ◽  
Room Temperature ◽  
Milling Time ◽  
Isothermal Annealing ◽  
High Energy ◽  
Nitrogen Atmosphere ◽  
Composite Powders ◽  
High Energy Milling ◽  
Synthetic Reaction

TiN/Si3N4 composite powders were obtained by a process that combines the mechanical activation of titanium and silicon powders at room temperature through high-energy milling with an isothermal annealing in a nitrogen atmosphere to complete the synthetic reaction. Mechanical activation has allowed us to complete the synthesis at 1350 °C only. The β–Si3N4 content in the final powder tends to increase as the milling time is prolonged. The microstructure of the TiN/Si3N4 composite powders has a bimodal character composed of TiN and β–Si3N4 grains and α-Si3N4 nanowires. Diameters of the nanowires range from 10 to 70 nm.

Effect of Milling Time on Microstructure of CNTs/Al5083 Composites Powder by High Energy Milling

2014 ◽  
Vol 788 ◽  
pp. 608-612
Author(s):  
Zheng Li ◽  
Xiao Lan Cai ◽  
Feng Yi ◽  
Ming Jun Yu ◽  
Chui Hu
Keyword(s):  
Particle Size ◽  
Crystallite Size ◽  
Composite Powder ◽  
Milling Time ◽  
Average Crystallite Size ◽  
High Energy ◽  
High Energy Milling ◽  
Medium Particle ◽  
Medium Particle Size ◽  
Time Lead

The 2wt%CNTs/Al5083 composite powder was prepared by High Energy Milling, and the effect of the milling time on microstructure of the 2wt.%CNTs/Al5083 composite powder was investigated. The Microstructure was observed by SEM, TEM and XRD. The result showed that prolonging the milling time lead to the reduction of the Medium particle size D50. The best D50 was obtained at milling 2.5h with the particle size of 22.33μm. CNTs homogeneous embedded into the Al-matrix when the milling time was 2.5h. The average crystallite size of Al was 46.4nm after milling for 2.5h, and the average crystallite size of Al also increased as the recrystallization.

The Influence of the Milling Media Environment on the Characteristics of a W-Cu Composite Powder

2008 ◽  
Vol 591-593 ◽  
pp. 154-159 ◽  
Author(s):  
Franciné Alves Costa ◽  
W.M. de Carvalho ◽  
A.G.P. Silva ◽  
Uilame Umbelino Gomes ◽  
José F. Silva ◽  
...  
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
Composite Powder ◽  
High Energy ◽  
Composite Particles ◽  
Dry Milling ◽  
Wet Milling ◽  
Composite Powders ◽  
Media Environment ◽  
The Mean

W-Cu composite powders were prepared by high energy milling under two milling environments: cyclohexane and air. Composite particles are formed in both cases. The W particles are fragmented and embedded into the Cu particles. Both, W and Cu, are heavily strained, mainly in the first hours of milling. The composite powder has high homogeneity and is much finer than the original Cu powder. The mean particle size of the powders milled in both conditions is very close, but the wet milling was near 25% longer than dry milling and the size distribution is wider. This is consequence of the higher milling intensity of dry milling.

Impact of the SiC addition on the morphological, structural and mechanical properties of Cu-SiC composite powders prepared by high energy milling

2021 ◽  
Author(s):  
Nailton T. Câmara ◽  
Rafael A. Raimundo ◽  
Cleber S. Lourenço ◽  
Luís M.F. Morais ◽  
David D.S. Silva ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Energy ◽  
Composite Powders ◽  
High Energy Milling

Development of Ni/h-BN Self-Lubricating Composite Powder by High-Energy Ball Milling

2016 ◽  
Vol 869 ◽  
pp. 277-282
Author(s):  
Moisés Luiz Parucker ◽  
César Edil da Costa ◽  
Viviane Lilian Soethe
Keyword(s):  
Ball Milling ◽  
Milling Time ◽  
Solid Lubricants ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Second Phase ◽  
Average Particle ◽  
Composite Powders ◽  
The Matrix ◽  
Energy Ball

Solid lubricants have had good acceptance when used in problem areas where the conventional lubricants cannot be applied: under extreme temperatures, high charges and in chemically reactive environments. In case of materials manufactured by powder metallurgy, particles of solid lubricants powders can be easily incorporated to the matrix volume at the mixing stage. In operation, this kind of material provides a thin layer of lubricant that prevents direct contact between the surfaces. The present study aimed at incorporating particles of second phase lubricant (h-BN) into a matrix of nickel by high-energy ball milling in order to obtain a self-lubricating composite with homogeneous phase distribution of lubricant in the matrix. Mixtures with 10 vol.% of h-BN varying the milling time of 5, 10, 15 and 20 hours and their relationship ball/powder of 20:1 were performed. The effect of milling time on the morphology and microstructure of the powders was studied by X-ray diffraction, SEM and EDS. The composite powders showed reduction in average particle size with increasing milling time and the milling higher than 5 hours resulted in equiaxial particles and the formation of nickel boride.

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