scholarly journals Augsti poraina oksīdu keramika

2018 ◽  
Vol 35 ◽  
pp. 86-111
Author(s):  
Visvaldis Švinka ◽  
Ruta Švinka
Keyword(s):  
High Temperature ◽  
Thermal Shock ◽  
Raw Materials ◽  
Porous Alumina ◽  
Slip Casting ◽  
Carbon Oxide ◽  
Porous Ceramics ◽  
Basic Medium ◽  
Oxide Systems ◽  
Synthesis Conditions

Silikātu materiālu institūtā kopš 2004. g. tiek veikti pētījumi par augsttemperatūras augsti porainu oksīdu keramiku, kas iegūta ar koncentrētas oksīdu pulveru suspensijas liešanas paņēmienu. Poru veidošanās notiek ķīmiskas reakcijas ceļā starp metāliska alumīnija pulveri un ūdeni bāziskā vidē, kur suspensijas pH ir 9,5–10,8. Tādā veidā netiek emitēts CO2, kas parasti notiek, iegūstot keramikas materiālus ar paaugstinātu porainību.Laikā kopš 2007. g. sintezēti materiāli un veikti pētījumi vairākās augsttemperatūras oksīdu sistēmās: cirkonija oksīdu saturošā (promocijas darbs, G. Buļa, Cirkonija oksīdu saturoša augsttemperatūras putu keramika, 2008. g.), korunda- mullīta sistēmā (promocijas darbs, L. Mahņicka-Goremikina, Sintēzes apstākļu un leģējošu piedevu ietekme uz porainas augsttemperatūras oksīdu keramikas īpašībām un struktūru, 2015. g.), alumīnija oksīda sistēmā ar dažādām piedevām (promocijas darbs, I. Zaķe-Tiļuga. Mullītu veidojošu piedevu ietekme uz porainas alumīnija oksīda keramikas īpašībām, 2015. g.; nepabeigts promocijas darbs A. Butlers, Karstumizturīga filtrējoša keramika; maģistra darbs, J. Bobrovika, Augsti poraina siltumizolējoša kordierīta keramika). Pētītie materiāli paredzēti, lai izmantotu tos kā siltumizolējošus materiālus dažādām augsttemperatūras siltuma ierīcēm un arī karstumizturīgiem filtriem.Highly Porous Oxide CeramicsInvestigations of highly porous high temperature ceramic produced by slip casting from concentrated suspensions of raw materials were carried out in the Institute of Silicate Materials since 2004. Pores form due to chemical reaction of metallic aluminium powder with water in basic medium with pH 9.5–10.8. Using this method emission of carbon oxide that usually accompanies fabrication of porous ceramics is avoided. The following investigations in high temperature oxide systems have been carried out since 2007:zirconia containing materials – promotion work by Gerda Bula “Zircon oxide containing high temperature foam ceramic”, 2008;corundum–mullite materials – promotion work by Ludmila Mahnicka- Goremikina “Influence of synthesis conditions and additives on the structure and properties of porous high temperature ceramics”, 2015;alumina materials with various additives – promotion work by Ieva Zake-Tiluga “The effect of mullite-forming additives on the properties of porous alumina ceramics”, 2015;titania containing corundum–mullite materials;cordierite ceramic materials.The goals of these investigations were to obtain of high temperature insulating materials and ceramic filters for filtration of hot and aggressive liquids. Properties of ceramics, such as dependence of thermal conductivity on the temperature and thermal shock durability, were determined.Keywords: aluminium oxide, zirconium oxide, titanium oxide, kaolin, talcum, cordierite, nanopowders, thermal insulation, thermal shock resistance.

scholarly journals Alumina ceramics prepared with new pore-forming agents

2008 ◽  
Vol 2 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Zuzana Zivcová ◽  
Eva Gregorová ◽  
Willi Pabst
Keyword(s):  
Thermal Analysis ◽  
Porous Alumina ◽  
Slip Casting ◽  
Porous Ceramics ◽  
Rice Starch ◽  
Alumina Ceramics ◽  
Poppy Seed ◽  
Biological Origin ◽  
Filtration Membranes ◽  
Wide Range

Porous ceramics have a wide range of applications at all length scales, ranging from filtration membranes and catalyst supports to biomaterials (scaffolds for bone ingrowths) and thermally or acoustically insulating bulk materials or coating layers. Organic pore-forming agents (PFAs) of biological origin can be used to control porosity, pore size and pore shape. This work concerns the characterization and testing of several less common pore-forming agents (lycopodium, coffee, fl our and semolina, poppy seed), which are of potential interest from the viewpoint of size, shape or availability. The performance of these new PFAs is compared to that of starch, which has become a rather popular PFA for ceramics during the last decade. The PFAs investigated in this work are in the size range from 5 ?m (rice starch) to approximately 1 mm (poppy seed), all with more or less isometric shape. The burnout behavior of PFAs is studied by thermal analysis, i.e. thermogravimetry and differential thermal analysis. For the preparation of porous alumina ceramics from alumina suspensions containing PFAs traditional slip casting (into plaster molds) and starch consolidation casting (using metal molds) are used in this work. The resulting microstructures are investigated using optical microscopy, combined with image analysis, as well as other methods (Archimedes method of double-weighing in water, mercury intrusion porosimetry).

Preparation of Porous Lightweight Ceramics and Fibre Joining Materials

2011 ◽  
Vol 415-417 ◽  
pp. 1038-1041 ◽  
Author(s):  
Ying Na Zhao ◽  
Cai Fen Wang ◽  
Jia Chen Liu ◽  
Hai Xu
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Raw Materials ◽  
Low Cost ◽  
Microwave Sintering ◽  
Porous Ceramics ◽  
Temperature Resistance ◽  
Selective Heating ◽  
Fly Ash Cenosphere ◽  
Ceramics Matrix

The high-temperature resistance compression material of lightweight porous ceramics and fiber joining is becoming a kind of promising seal parts in high-temperature industries and aerospace field. A combination of the lightweight mullite matrix porous ceramics and the elastic 3-D silica woven fibre, a novel joining material was studied. The low cost fly ash cenosphere as raw materials, mullite porous ceramics with density 0.92 g/cm3, and the thermal conductivity 0.13 w/m.K, were prepared. Using microwave selective heating properties, designing the interlayer composition, the bonding materials were attained by microwave sintering. The flexural strength of joint materials was about 23 MPa, which was higher than porous ceramics matrix.

scholarly journals Pressureless Sintering of YIG Ceramics from Coprecipitated Nanopowders

2021 ◽  
Vol 7 (5) ◽  
pp. 56
Author(s):  
Yimin Yang ◽  
Xiaoying Li ◽  
Ziyu Liu ◽  
Dianjun Hu ◽  
Xin Liu ◽  
...  
Keyword(s):  
High Temperature ◽  
Calcination Temperature ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Secondary Phase ◽  
Coprecipitation Method ◽  
Pressureless Sintering ◽  
Densification Behavior ◽  
Sintering Process

Nanoparticles prepared by the coprecipitation method were used as raw materials to fabricate Y3Fe5O12 (YIG) ceramics by air pressureless sintering. The synthesized YIG precursor was calcinated at 900–1100 °C for 4 h in air. The influences of the calcination temperature on the phase and morphology of the nanopowders were investigated in detail. The powders calcined at 1000–1100 °C retained the pure YIG phase. YIG ceramics were fabricated by sintering at 1200–1400 °C for 10 h, and its densification behavior was studied. YIG ceramics prepared by air sintering at 1250 °C from powders calcinated at 1000 °C have the highest in-line transmittance in the range of 1000-3000 nm. When the sintering temperature exceeds 1300 °C, the secondary phase appears in the YIG ceramics, which may be due to the loss of oxygen during the high-temperature sintering process, resulting in the conversion of Fe3+ into Fe2+.

scholarly journals Sintering Behavior, Thermal Expansion, and Environmental Impacts Accompanying Materials of the Al2O3/ZrO2 System Fabricated via Slip Casting

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3365
Author(s):  
Justyna Zygmuntowicz ◽  
Magdalena Gizowska ◽  
Justyna Tomaszewska ◽  
Paulina Piotrkiewicz ◽  
Radosław Żurowski ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Life Cycle ◽  
Coefficient Of Thermal Expansion ◽  
Raw Materials ◽  
Slip Casting ◽  
Ceramic Materials ◽  
Sintering Behavior ◽  
Environmental Loads ◽  
Practical Applications ◽  
Technical Ceramics

This work focuses on research on obtaining and characterizing Al2O3/ZrO2 materials formed via slip casting method. The main emphasis in the research was placed on environmental aspects and those related to the practical use of ceramic materials. The goal was to analyze the environmental loads associated with the manufacturing of Al2O3/ZrO2 composites, as well as to determine the coefficient of thermal expansion of the obtained materials, classified as technical ceramics. This parameter is crucial in terms of their practical applications in high-temperature working conditions, e.g., as parts of industrial machines. The study reports on the four series of Al2O3/ZrO2 materials differing in the volume content of ZrO2. The sintering process was preceded by thermogravimetric measurements. The fabricated and sintered materials were characterized by dilatometric study, scanning electron microscopy, X-ray diffraction, and stereological analysis. Further, life cycle assessment was supplied. Based on dilatometric tests, it was observed that Al2O3/ZrO2 composites show a higher coefficient of thermal expansion than that resulting from the content of individual phases. The results of the life cycle analysis showed that the environmental loads (carbon footprint) resulting from the acquisition and processing of raw materials necessary for the production of sinters from Al2O3 and ZrO2 are comparable to those associated with the production of plastic products such as polypropylene or polyvinyl chloride.

Colorimetric Optical Thermometry of Host-Sensitized Pr3+-Doped Niobate Phosphors based on Electronic-Rich-Site Strategy

2021 ◽  
Author(s):  
Yao Wang ◽  
Ning Guo ◽  
Yanmei Xin ◽  
Jing Li ◽  
Ruizhuo Ouyang ◽  
...  
Keyword(s):  
High Temperature ◽  
Charge Migration ◽  
Temperature Synthesis ◽  
Synthesis Conditions ◽  
Reducing Atmosphere ◽  
High Temperature Synthesis ◽  
Optical Thermometry

Most praseodymium-doped red-emitting phosphors need high-temperature synthesis conditions with reducing atmosphere. The niobate matrix selected in this paper provides sufficient electron-rich-site environment for praseodymium through charge migration, and praseodymium can...

Scaling Behavior of Superheater Tube Alloys in ASME High Temperature Steam Research Tests at 1100–1500 F

1962 ◽  
Vol 84 (3) ◽  
pp. 223-257 ◽  
Author(s):  
F. Eberle ◽  
C. H. Anderson
Keyword(s):  
High Temperature ◽  
Chemical Composition ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Scaling Behavior ◽  
Effect Of Temperature ◽  
Relative Resistance ◽  
Superheater Tube ◽  
Shock Resistance ◽  
High Temperature Steam

The scales formed on seven ferritic and ten austenitic types of commercial tubing presently in use and of potential future use for superheater service were examined after 6, 12, and 18 months’ exposure to air and to flowing steam of 2000 psi at temperatures of 1100, 1200, 1350, and 1500 F. The effect of temperature and time of exposure on the adherence, thermal-shock resistance, thickness, structure, and chemical composition of the scales was investigated and the relative resistance to scaling of the various alloys evaluated.

Sign in / Sign up

Export Citation Format

Share Document