Granule deformation in the dry pressing of ferrite powders

1985 ◽  
Vol 24 (5) ◽  
pp. 345-347
Author(s):  
B. V. Makarov ◽  
V. G. Andreev ◽  
L. M. Letyuk
Keyword(s):  
Dry Pressing ◽  
Granule Deformation

Preparation and Properties of Porous Si3N4/SiO2/BN Composite Ceramics

2012 ◽  
Vol 512-515 ◽  
pp. 828-831 ◽  
Author(s):  
Wei Dong ◽  
Chang An Wang ◽  
Lei Yu ◽  
Shi Xi Ouyang
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
High Strength ◽  
Low Dielectric Constant ◽  
Pressureless Sintering ◽  
Composite Ceramics ◽  
Porous Si ◽  
Low Dielectric ◽  
Dry Pressing ◽  
Porous Si3n4

Porous Si3N4/SiO2/BN composite ceramics with high strength and low dielectric constant were prepared by dry-pressing process and pressureless sintering at 1750°C for 1.5 h in flow nitrogen. The influences of BN content on microstructure, porosity, mechanical and dielectric properties of the porous Si3N4/SiO2/BN composite ceramics were discussed. The results showed that the porous Si3N4/SiO2/BN composite ceramics with porosity ranging from 29% to 48% were fabricated by adjusting the content of BN. The flexural strength of the porous Si3N4/SiO2/BN composite ceramics was 78215 MPa. The dielectric constant of the porous Si3N4/SiO2/BN composite ceramics was 3.9~5 at 1 MHz.

scholarly journals Properties dependence of the lightweight alumina products obtained by a semi-dry pressing method on the alumina type

2020 ◽  
Vol 120 ◽  
pp. 126-133
Author(s):  
V. V. Martynenko ◽  
Yu. A. Krakhmal ◽  
K. I. Kushchenko ◽  
T. G. Tishina
Keyword(s):  
Phase Composition ◽  
High Temperature ◽  
Raw Materials ◽  
Raw Material ◽  
Pressing Method ◽  
Technical Requirements ◽  
Alumina Grade ◽  
Pitch Coke ◽  
Calcium Hexaluminate ◽  
Dry Pressing

Lightweight materials are widely used in industry for thermal insulation of various thermal units. The choice of lightweight material depends on the specific conditions of service. For the lining of high-temperature units operating in reducing environments, alumina lightweight products are used that contain a minimum amount of Fe2O3 impurities and free (unbound in compounds) SiO2. In JSC “URIR named after A. S. Berezhnoy” a technology of alumina lightweight products of grades KLA-1.1 and KLA-1.3 by a semi-dry pressing method with an application temperature of up to 1550 °C has been developed. These products are made from a mixture of ground and no-milled γ-form alumina of grade 0 and α-form alumina of grade S with additives of pitch coke and chalk. The work purpose was improvement of the alumina lightweight products technology and search for new alternative raw materials along with the currently used alumina grade S. The properties dependence of alumina lightweight products, obtained by the semi-dry pressing method, on the type of alumina α-form, was investigated. As a result of the studies, it was found that, for the manufacture of alumina lightweight products of grades KLA-1.1 and KLA-1.3 by the semi-dry pressing method, alumina grades N and NR can be used as an alternative alumina-containing raw material along with alumina grade S. The phase composition of alumina lightweight products of grades KLA-1.1 and KLA-1.3, which are manufactured using alumina grades S, N and NR, was represented mainly by corundum and calcium hexaluminate. The alumina lightweight products, which were manufactured using alumina grades S, N and NR, were characterized by similar high properties and correspond the technical requirements for grades KLA-1.1 and KLA-1.3.

scholarly journals Researches on development of alumina-chromia-zirconium silicate refractories containing 60 % Cr2O3

2020 ◽  
Vol 120 ◽  
pp. 12-28
Author(s):  
P. O. Kushchenko ◽  
V. V. Primachenko ◽  
I. G. Shulyk ◽  
Yu. Ye. Mishnyova ◽  
K. I. Kushchenko ◽  
...  
Keyword(s):  
Corrosion Mechanism ◽  
Pressing Method ◽  
Refractory Structure ◽  
Oxide Addition ◽  
Zirconium Silicate ◽  
Cold Crushing Strength ◽  
Cr2o3 Content ◽  
Corrosive Effect ◽  
Dry Pressing ◽  
Shock Resistance

Researches of a branch composition and firing atmosphere influence on structure and properties of pressed alumina-chromia-zirconium silicate refractories with 60 % Cr2O3 content were carried out. The optimal branch composition which after firing in oxidizing atmosphere provides obtaining of samples with open porosity 24.8 %, apparent density 3.46 g/cm3, cold crushing strength 78 N/mm2 and thermal shock resistance by 950 ºС — water — 7 thermal cycles was established. The phase composition of samples was determined. It has been shown that, firing in a reducing atmosphere, as well as titanium oxide addition, have no significant effect on samples properties. Corrosion resistance comparative researches of alumina-chromia-zirconium silicate refractories with 60 % Cr2O3 content and refractory brand KHTSS-30 with 30 % Cr2O3 content to glass «E» and basalt melts by crucible method at a temperature of 1580 °C with an exposure time of 8 hours were carried out. It has been established that, glass «E» and basalt impregnate refractories, moreover for samples with the developed optimal composition the impregnation depth was the smallest in comparison with samples of other compositions. The corrosion mechanism has been established, which consists in the penetration of glass «E» and basalt melts into refractory with further dissolution of corundum grains in them. Sintered Cr2O3 and solid solutions based on it in the composition of samples prevent corrosion, reducing the interaction area of melts with corundum grains, and when exposed to basalt melt, also forming spinelid with its components, which slows down further penetration of melt into refractory structure, thereby reducing its corrosive effect on the refractory. Based on the obtained results, a technology of a new domestic type of product (alumina-chromia-zirconium silicate refractories with 60 % Cr2O3 content manufactured by semi-dry pressing method) was developed.

scholarly journals Effect study of an amount of active alumina addition on the properties of alumina refractories with a complex additive of chromium oxide and zirconium dioxide

2020 ◽  
Vol 120 ◽  
pp. 3-11
Author(s):  
I. G. Shulik ◽  
T. G. Galchenko ◽  
E. B. Protsak ◽  
L. V. Belik
Keyword(s):  
Chromium Oxide ◽  
Zirconium Dioxide ◽  
Effect Study ◽  
Pressing Method ◽  
Complex Additive ◽  
Active Alumina ◽  
Cold Crushing Strength ◽  
Dry Pressing ◽  
Alumina Addition ◽  
Carbon Black Production

An effect of active alumina amount introduced into a batch (7.5 - 22.0 %) on the properties of alumina samples containing a complex additive of chromium oxide (10 %) and zirconium dioxide (3 %) was studied. The optimal amount of introduced active alumina (12.5 %) was established, which ensures the production of samples fired at a temperature of 1580 ºС, with the lowest open porosity (18.2 %), the highest apparent density (3.25 g/cm3) and the highest cold crushing strength (117 N/mm2), refractoriness under a load of 0.2 N/mm2 > 1700 ºС, thermal shock resistance (in the mode of 1300 ºС — water) not less than 7 thermal cycles.The results of carried out studies were used in the development of production technology of domestic refractory products based on fused corundum, α-form alumina, active alumina, containing the complex addition of chromium oxide and zirconium dioxide, by semi-dry pressing method. These refractory products characterized by high properties and intended for service at a temperature of 1850 ºС in the combustion chamber of carbon black production reactors.The use of these refractories in the lining of above mentioned high-temperature industrial units will allow to increase a duration of their operation due to an increase in the refractory durability in service, as well as to save material and energy resources associated with a relining of the reactors.

Chapter 26 A Mechanistic Description of Granule Deformation and Breakage

2007 ◽  
pp. 1055-1120 ◽  
Author(s):  
Yuen Sin Cheong ◽  
Chirangano Mangwandi ◽  
Jinsheng Fu ◽  
Michael J. Adams ◽  
Michael J. Hounslow ◽  
...  
Keyword(s):  
Granule Deformation
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