Study on Low Temperature Sintering Behaviour of CaO-B2O3-SiO2 Glass Ceramics

2010 ◽  
Vol 150-151 ◽  
pp. 350-353
Author(s):  
Peng Fei Wei ◽  
Hong Qing Zhou ◽  
Hai Kui Zhu ◽  
Bin Dai ◽  
Jie Wang
Keyword(s):  
Low Temperature ◽  
Glass Ceramics ◽  
Sintered Sample ◽  
Sintered Glass ◽  
Powder Characteristics ◽  
Sintering Properties ◽  
Median Particle ◽  
Materials Used ◽  
Sintering Behaviour ◽  
The Relationship

CaO-B2O3-SiO2 glass ceramics were prepared by powders of different particle sizes. The relationship between CBS powder characteristics and structures was studied by XRD and SEM, and the effect of powder characteristics on sintering properties, dielectric properties at 10GHz, thermal properties (CTE) were investigated to obtain low-temperature sintered glass ceramics. The results showed that the median particle size of glass powders reduced, sintered temperature and apparent porosity decreased. But at the same time, bulk density and thermal expansivity increased. The sample with the powders of D50=2.34μm could be sintered at 850 with the density about 2.615g•cm-3 and the water absorption about 0.16%. Having a dielectric constant of 6.16 and a dielectric loss of 1.9×10-3 at 9.98GHz, the sintered sample could satisfy the requirements of the substrate materials used in LTCC in some fields.

The Effect of Different Doping Methods of Sintering Aids on the Barium Titanate Based X7R Ceramics

2007 ◽  
Vol 336-338 ◽  
pp. 83-86 ◽  
Author(s):  
C. Ma ◽  
X.H. Wang ◽  
R.Z. Chen ◽  
Long Tu Li ◽  
Zhi Lun Gui
Keyword(s):  
Rare Earth ◽  
Dielectric Loss ◽  
Barium Titanate ◽  
Low Temperature ◽  
Rare Earth Oxide ◽  
Sintering Aids ◽  
Sintering Properties ◽  
Relationship Of ◽  
The Relationship

The barium titanate based X7R ceramics, which are doped with rare earth oxide, Nb2O5, Co3O4 and ZnO-B2O3, could be sintered at a rather low temperature to satisfy the X7R requirements with good permittivity and dielectric loss. In this paper, different doping methods of sintering aids have been used to prepare X7R BaTiO3 ceramics. Samples were sintered at a low temperature and the relationship of doping methods and sintering properties has been concluded.

Manufacturing Technology of Space Optical Materials

2013 ◽  
Vol 785-786 ◽  
pp. 1018-1021
Author(s):  
Ya Chen
Keyword(s):  
Silicon Carbide ◽  
Low Temperature ◽  
Glass Ceramics ◽  
Performance Comparison ◽  
Manufacturing Technology ◽  
Surface Shape ◽  
Element Analysis ◽  
Shape Precision ◽  
Lightweight Structure ◽  
Materials Used

In this paper, the performance comparison between glass ceramics (Zerodur) and silicon carbide (SiC) which are two kinds of common materials used for space optical reflector is carried out, and several lightweight structure forms are analyzed. The oval plane reflector is applied in ultra-low temperature environment of space, take this kind of reflector as an example, its lightweight structure is optimized by CAD, then through finite element analysis, deformation of the planar lightweight mirror is 0.014λ (rms) in gravity condition, and deformation is 0.002λ (rms) in ultra-low temperature of-150 degrees environment. The actual lightweight processing is controled by the CNC system in a graphical way, and using chemical method to eliminate the stress and micro crack generated during processing, its final surface shape precision reaches 0.022λ (rms). Finally, this paper introduces the manufacture method of novel silicon carbide (SiC), and analyzes the current situation and development trends of the spatial lightweight reflector manufacturing technology.

Manufacture Technology for Large Lightweight Optical Materials

2014 ◽  
Vol 941-944 ◽  
pp. 623-626
Author(s):  
Ya Chen
Keyword(s):  
Silicon Carbide ◽  
Low Temperature ◽  
Optical Materials ◽  
Glass Ceramics ◽  
Performance Comparison ◽  
Surface Shape ◽  
Element Analysis ◽  
Shape Precision ◽  
Lightweight Structure ◽  
Materials Used

In this paper, the performance comparison between glass ceramics (Zerodur) and silicon carbide (SiC) which are two kinds of common materials used for space optical reflector is carried out, and several lightweight structure forms are analyzed. The oval plane reflector is applied in ultra-low temperature environment of space, take this kind of reflector as an example, its lightweight structure is optimized by CAD, then through finite element analysis, deformation of the planar lightweight mirror is 0.014λ (rms) in gravity condition, and deformation is 0.002λ (rms) in ultra-low temperature of-150 degrees environment. The actual lightweight processing is controled by the CNC system in a graphical way, and using chemical method to eliminate the stress and micro crack generated during processing, its final surface shape precision reaches 0.022λ (rms). Finally, this paper introduces the manufacture method of novel silicon carbide (SiC), and analyzes the current situation and development trends of the spatial lightweight reflector manufacturing technology.

scholarly journals Sintered Glass-Ceramics, Self-Glazed Materials and Foams from Metallurgical Waste Slag

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2263
Author(s):  
Nicolai B. Jordanov ◽  
Ivan Georgiev ◽  
Alexander Karamanov
Keyword(s):  
Glass Ceramics ◽  
Glass Frit ◽  
Heating Rates ◽  
Good Thermal Stability ◽  
Initial Batch ◽  
Sintered Glass ◽  
Glazed Surface ◽  
Heat Treated ◽  
Different Temperatures ◽  
Materials Used

The materials used for the synthesis of parent glass are 70% wt. metallurgical slag and 30% wt. industrial quartz sand. The initial batch is melted at and then quenched in water. The resulting glass frit is milled bellow 75 microns and pressed 1400 °C into “green” samples. In a next stage, they are heat treated at different temperatures with various heating rates and holding times. As a result, it is demonstrated the possibility for production variations, allowing the manufacture of three types of new materials by using the same pressed glass powders. We highlight the flexibility of the synthesis obtaining namely well densified glass-ceramics at about 950 °C, self-glazed glass-ceramics at about 1000 °C or glass-ceramic foams at approximately 1100 °C. The first set of materials is characterized by very well sintered structure combined with reasonable crystallinity; the second one—by smooth self-glazed surface with an attractive appearance and good properties and the third one—by 80–90% closed porosity and very good thermal stability above 1000 °C.

Energy saving technology for sintering of black bricks from high-siliceous clay

MRS Advances ◽  
2020 ◽  
Vol 5 (61) ◽  
pp. 3123-3131
Author(s):  
Mario Flores Nicolas ◽  
Marina Vlasova ◽  
Pedro Antonio Márquez Aguilar ◽  
Mykola Kakazey ◽  
Marcos Mauricio Chávez Cano ◽  
...  
Keyword(s):  
Low Temperature ◽  
Oxygen Deficiency ◽  
Glass Ceramics ◽  
Total Content ◽  
Ceramic Materials ◽  
Ternary Mixtures ◽  
High Porosity ◽  
Reducing Conditions ◽  
Binary And Ternary Mixtures ◽  
Dark Color

AbstractThe low-temperature synthesis of bricks prepared from high-siliceous clays by the method of plastic molding of blanks was used. For the preparation of brick blanks, binary and ternary mixtures of high-siliceous clays, black sand, and bottle glass cullet were used. Gray-black low-porosity and high-porosity ceramics was obtained by sintering under conditions of oxygen deficiency. It has been established that to initiate plastic in mixtures containing high-siliceous clay, it is necessary to add montmorillonite/bentonite additives, carry out low-temperature sintering, and introduce low-melting glass additives with a melting point ranging from 750 to 800 °C. The performed investigations have shown that the sintering of mixtures with a total content of iron oxide of about 5 wt% under reducing conditions at Tsint. = 800°C for 8 h leads to the formation of glass ceramics consisting of quartz, feldspars, and a phase. The main sources of the appearance of a dark color is the formation of [Fe3+O4]4- and [Fe3+O6]9- anions in the composition of the glass phase and feldspars. By changing the contents of clay, sand, and glass in sintering, it is possible to obtain two types of ceramic materials: (a) in the form of building bricks and (b) in the form of porous fillers.

Gebirgswaldpflege – es kommt auf den Standort an | Mountain silviculture – it all depends on the site

2001 ◽  
Vol 152 (5) ◽  
pp. 169-176 ◽  
Author(s):  
Monika Frehner
Keyword(s):  
Nature Conservation ◽  
Low Temperature ◽  
Tree Species ◽  
Forest Stand ◽  
Ground Vegetation ◽  
Mountain Forests ◽  
Research Projects ◽  
Snow Mould ◽  
The Relationship ◽  
Protection Forests

The article shows that knowledge of the site of a particular forest stand, together with research results and experience, can provide information that is important for the cultivation of mountain forests, including knowledge of the composition of the tree species and the structure and growth capacity of natural forest. Furthermore, certain sites can, thus, be characterized by factors that influence restocking, such as snow mould,lush ground vegetation or low temperature. The guidelines«minimale Pflegemassnahmen» – «Minimal tending of protection forests» (WASSER und FREHNER, 1996) are based on this principle. For individual sites, warnings about natural dangers such as rock fall or statements concerning nature conservation can be made (e.g., the occurrence of tree species, suitability as a biotope for Capercaille). In conclusion, two research projects on the relationship between site and natural dangers will be presented.

scholarly journals Correlation between Defects and Technical Wear of Materials Used in Traditional Construction

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2482
Author(s):  
Jarosław Konior ◽  
Mariusz Rejment
Keyword(s):  
Residential Buildings ◽  
Descriptive Analysis ◽  
Technical Condition ◽  
Water Penetration ◽  
Major Drawback ◽  
Wear Process ◽  
Materials Used ◽  
Traditional Construction ◽  
The Relationship ◽  
Measurable Property

The degree of technical wear of old buildings, which are made of basic materials (cement, concrete, steel, timber, plaster, brick) using traditional technology, is expressed by the size and intensity of damage to their elements. The topic of the research concerns old residential buildings from the turn of the 19th and 20th centuries, which are located in the downtown district of Wroclaw, Poland. The descriptive analysis and the analysis of the definitions of defects that occur in the elements of residential buildings, which were performed as random analyzes, do not allow defects to be considered as measurable variables at a level of visual investigation. The major drawback of the method that is used by experts when assessing the technical condition of civil engineering buildings is that it does not numerically express the magnitude (strength) of the defects. Therefore, an attempt was made to numerically express the relationship (if such a relationship exists) between the occurred defects of buildings and the extent of their technical wear process. When calculating the strength of this relationship, the method of determining the point biserial correlation coefficient for the measurable property and the dichotomous property was used. It was found that the direction of the relation is right-hand for all the tested building elements, but the strength of the correlation between the detected defects and technical wear shows a considerable span and depends on the conditions of the apartment house’s maintenance. As a rule, damage caused by water penetration and moisture penetration always shows correlations of at least moderate strength.

scholarly journals Influence of Preaging Temperature on the Indentation Strength of 3Y-TZP Aged in Ambient Atmosphere

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2767
Author(s):  
Ki-Won Jeong ◽  
Jung-Suk Han ◽  
Gi-Uk Yang ◽  
Dae-Joon Kim
Keyword(s):  
Residual Stress ◽  
Phase Transformation ◽  
Low Temperature ◽  
Compressive Residual Stress ◽  
Yttria Stabilized Zirconia ◽  
Ambient Atmosphere ◽  
Aged Specimen ◽  
Stabilized Zirconia ◽  
M Phase ◽  
The Relationship

Yttria-stabilized zirconia (3Y-TZP) containing 0.25% Al2O3, which is resistant to low temperature degradation (LTD), was aged for 10 h at 130–220 °C in air. The aged specimens were subsequently indented at loads ranging from 9.8 to 490 N using a Vickers indenter. The influence of preaging temperature on the biaxial strength of the specimens was investigated to elucidate the relationship between the extent of LTD and the strength of zirconia restorations that underwent LTD. The indented strength of the specimens increased as the preaging temperature was increased higher than 160 °C, which was accompanied by extensive t-ZrO2 (t) to m-ZrO2 (m) and c-ZrO2 (c) to r-ZrO2 (r) phase transformations. The influence of preaging temperature on the indented strength was rationalized by the residual stresses raised by the t→m transformation and the reversal of tensile residual stress on the aged specimen surface due to the indentation. The results suggested that the longevity of restorations would not be deteriorated if the aged restorations retain compressive residual stress on the surface, which corresponds to the extent of t→m phase transformation less than 52% in ambient environment.

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