scholarly journals Characteristics of Cu-Al2O3 composites of various starting particle size obtained by high-energy milling

2009 ◽  
Vol 74 (5) ◽  
pp. 595-605 ◽  
Author(s):  
Viseslava Rajkovic ◽  
Dusan Bozic ◽  
Milan Jovanovic
Keyword(s):  
Particle Size ◽  
Internal Oxidation ◽  
Lattice Distortion ◽  
Copper Matrix ◽  
High Energy ◽  
Lattice Parameter ◽  
Constant Amount ◽  
High Energy Milling ◽  
Al2o3 Composite ◽  
Powder Particles

The powder Cu-Al2O3 composites were produced by high-energy milling. Various combinations of particle size and mixtures and approximately constant amount of Al2O3 were used as the starting materials. These powders were separately milled in air for up to 20 h in a planetary ball mill. The copper matrix was reinforced by internal oxidation and mechanical alloying. During the milling, internal oxidation of pre-alloyed Cu-2 mass %-Al powder generated 3.7 mass % Al2O3 nano-sized particles finely dispersed in the copper matrix. The effect of different size of the starting copper and Al2O3 powder particles on the lattice parameter, lattice distortion and grain size, as well as on the size, morphology and microstructure of the Cu-Al2O3 composite powder particles was studied.

scholarly journals Fabrication of Ti3AlC2/Al2O3 nanocomposite by a novel method

2011 ◽  
Vol 43 (3) ◽  
pp. 289-294 ◽  
Author(s):  
J. Zhu ◽  
L. Ye ◽  
F. Wang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Hot Pressing ◽  
Reaction Path ◽  
Raw Materials ◽  
High Energy ◽  
Good Combination ◽  
High Energy Milling ◽  
Al2o3 Composite ◽  
Novel Method

A Ti3AlC2/Al2O3 nanocomposite was synthesized using Ti, Al, C and TiO2 as raw materials by a novel combination of high-energy milling and hot pressing. The reaction path of the 3Ti-8C-16Al-9TiO2 mixture of powders was investigated, and the results show that the transitional phases TiC, TixAly and Al2O3 are formed in high-energy milling first, and then TixAly is transformed to the TiAl phase during the hot pressing. Finally, a reaction between TiC and TiAl occurs to produce Ti3AlC2 and the nanosized Ti3AlC2/Al2O3 composite is synthesized. The Ti3AlC2/Al2O3 composite possessed a good combination of mechanical properties with a hardness of 6.0 GPa, a flexural strength of 600 MPa, and a fracture toughness (K1C) of 5.8 MPa?m1/2. The strengthening and toughening mechanisms were also discussed.

High Energy Milling of WС-FeСr Cemented Carbide

2019 ◽  
Vol 799 ◽  
pp. 136-141
Author(s):  
Marek Tarraste ◽  
Jakob Kübarsepp ◽  
Kristjan Juhani ◽  
Märt Kolnes ◽  
Mart Viljus
Keyword(s):  
Particle Size ◽  
Ball Mill ◽  
Size Range ◽  
High Energy ◽  
Cemented Carbide ◽  
Cemented Carbides ◽  
Binder Phase ◽  
Metal Powders ◽  
Powder Mixtures ◽  
High Energy Milling

During production of cemented carbides hard and brittle tungsten carbide (WC) and ductile metal powders (mainly from Fe-group) are milled together. Complete milling results in a Gaussian distribution and narrow particle size range of the milled powder which promote the homogeneity and improve the properties of sintered composites. Cobalt, conventional metal employed in cemented carbides, possesses good comminution characteristics with WC powder. However, its toxicity and fluctuating price pushes researchers to find suitable alternatives and Fe-based alloys have shown most promising results. Cemented carbides with the Fe-Cr system as metal binder phase have potential to perform better than regular WC-Co composites in corrosive and oxidative environments. The goal of this paper was to prepare uniform cemented carbides powders with relatively high fraction of stainless Fe-Cr steel. To achieve a uniform powder mixture is a challenge at high ductile steel fraction. High energy milling (HEM) is a powerful technique for achieving (ultra) fine powder mixtures with narrow powder size range. HEM was carried out in a novel high energy ball mill RETSCH Emax. Milling in tumbling ball mill, which is the most widely used method, was employed for reference. Prepared powder mixtures were characterised in terms of particle size, size distribution and shape. In addition, powder mixtures were consolidated via spark plasma sintering to evaluate the effect of the milling method and the duration on the microstructure of final cemented carbide.

The Phase Evolution in the Si3N4-AlN System after High-Energy Mechanical Treatment of the Precursor Powder

2008 ◽  
Vol 403 ◽  
pp. 7-10 ◽  
Author(s):  
Malgorzata Sopicka-Lizer ◽  
Tomasz Pawlik ◽  
Tomasz Włodek ◽  
Marta Tańcula
Keyword(s):  
Structural Changes ◽  
Mechanical Energy ◽  
Phase Evolution ◽  
High Energy ◽  
Precursor Powder ◽  
Standard Mixture ◽  
High Energy Milling ◽  
Significant Damage ◽  
Powder Particles ◽  
Lower Temperature

The high-energy milling uses the mechanical energy to activate chemical reactions by developing structural changes in the powder particles. High-energy milling with an acceleration of 28g was applied for the mechanical activation of the aluminium and silicon nitrides mixture with yttria additive. The activated powders showed the significant damage of the crystal structure and limited formation of a solid solution. Sintering of the activated precursor demonstrated higher ability for densification and started at 300 °C lower temperature in comparison to the standard mixture. The phase evolution during sintering was dependent on the starting composition and degree of powder activation.

scholarly journals The properties of high-energy milled pre-alloyed copper powders containing 1 wt.% Al

2007 ◽  
Vol 72 (1) ◽  
pp. 45-53 ◽  
Author(s):  
Viseslava Rajkovic ◽  
Dusan Bozic ◽  
Aleksandar Devecerski
Keyword(s):  
Thermal Stability ◽  
Electrical Conductivity ◽  
Grain Size ◽  
Morphological Changes ◽  
Milled Powder ◽  
Copper Matrix ◽  
High Energy ◽  
Lattice Parameter ◽  
Good Thermal Stability ◽  
Before And After

The microstructural and morphological changes of inert gas atomized pre-alloyed Cu-1 wt.% Al powders subjected to hith-energy milling were studied. The microhardness of hot-pressed compacts was measured as a function of milling time. The thermal stability during exposure at 800 ?C and the electrical conductivity of compacts were also examined. During the high-energy milling, severe deformation led to refinement of the powder particle grain size (from 550 nm to about 55 nm) and a decrease in the lattice parameter (0.10 %), indicating precipitation of aluminium from the copper matrix. The microhardness of compacts obtained from 5 h-milled powders was 2160 MPa. After exposure at 800?C for 5 h, these compacts still exhibited a high microhardness value (1325 MPa), indicating good thermal stability. The increase of microhardness and good thermal stability is attributed to the small grain size (270 and 390 nm before and after high temperature exposure, respectively). The room temperature electrical conductivity of compacts processed from 5 h-milled powder was 79% IACS. .

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.

Production of Al–20 wt.% Al2O3 composite powder using high energy milling

2009 ◽  
Vol 192 (3) ◽  
pp. 346-351 ◽  
Author(s):  
S.S. Razavi Tousi ◽  
R. Yazdani Rad ◽  
E. Salahi ◽  
I. Mobasherpour ◽  
M. Razavi
Keyword(s):  
Composite Powder ◽  
High Energy ◽  
High Energy Milling ◽  
Al2o3 Composite

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.

Impurity Tracing in Nanostructured Al and Al/Al2O3 Composite Prepared by High Energy Milling

2010 ◽  
Vol 19 (4) ◽  
pp. 393-402 ◽  
Author(s):  
S. S.Razavi Tousi ◽  
R.Yazdani Rad ◽  
M. S. Abdi
Keyword(s):  
High Energy ◽  
High Energy Milling ◽  
Al2o3 Composite

Electrochemical Properties of LiFePO4/C Composite Improved by High Energy Milling

2009 ◽  
Vol 620-622 ◽  
pp. 41-44 ◽  
Author(s):  
Chang Sam Kim ◽  
Sung Ik Hwang ◽  
Shin Woo Kim
Keyword(s):  
Particle Size ◽  
Electrochemical Properties ◽  
Sucrose Solution ◽  
Ultrasonic Spray Pyrolysis ◽  
Lithium Ion ◽  
High Energy ◽  
Milling Process ◽  
Spray Pyrolysis Method ◽  
High Energy Milling ◽  
Ultrasonic Spray

The electrochemical properties of LiFePO4 as a cathode of lithium ion batteries considerably depend on a particle size of LiFePO4 and a condition of carbon coating. In this study, LiFePO4 powders were prepared using ultrasonic spray pyrolysis method, and then LiFePO4/C composites were made by infiltrating sucrose solution into LiFePO4 powders, drying, high-energy milling and annealing. The effects of high-energy milling were analyzed by comparing with electrochemical properties of powders synthesized without high-energy milling. It was found that the milling process drastically reduced the particle size of synthesized powders and electrical conductivity, and improved discharge capacity, cycle stability and rate performance.

scholarly journals Characterization of high-energy milled alumina powders

Cerâmica ◽  
1998 ◽  
Vol 44 (289) ◽  
pp. 166-170 ◽  
Author(s):  
Roberto Tomasi ◽  
Adriano A. Rabelo ◽  
Adriana S. A. Chinelatto ◽  
Laudo Reis ◽  
Walter J. Botta Fo
Keyword(s):  
Particle Size ◽  
Metal Oxides ◽  
High Energy ◽  
Ceramic Powders ◽  
Nanosized Powders ◽  
Metal Compounds ◽  
Powder Surface ◽  
High Energy Milling ◽  
Energy Impact

The utilization of reactive high-energy milling has been reported for the synthesis of ceramic powders namely, metal oxides, carbides, borides, nitrides or mixtures of ceramics or ceramic and metal compounds. In this work, high-energy milling was used for reduction of alumina powders to nanometric particle size. The ceramic characteristics of the powders were analyzed in terms of the behavior during deagglomeration, compaction curves, sintering and microstructure characterization. It was observed that the high energy milling has strong effect in producing agglomeration of the nanosized powders. This effect is explained by the high-energy impact of the balls, which may fracture particles or just cause the particles compacting. In this case, strong agglomerates are produced. As the powder surface area increases, stronger agglomerates are produced.

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