Metal Alkoxide Synthesis of Glasses and Glass-Ceramics

1985 ◽  
Vol 57 ◽  
Author(s):  
Charles H. Drummond
Keyword(s):  
Hot Pressing ◽  
Low Temperatures ◽  
Glass Formation ◽  
Glass Ceramics ◽  
Base Hydrolysis ◽  
Metal Alkoxide ◽  
Metal Alkoxides ◽  
Fine Grained ◽  
Amorphous Powders

AbstractMetal alkoxide syntheses of the general form or can be used to form soluble alkoxides of most metals. Mutual solution of these alkoxides followed by acid or base hydrolysis, drying and calcining results in the formation of fine-grained (<10Å) amorphous powders at low temperatures. Subsequent hot-pressing or calcining leads to densification and/or crystallization. Compositions in the MgO-Al2O3-SiO2 system with ZrO2 contents to 30 mol% are discussed. Also glass formation of transition oxides derived from metal alkoxides of Hf, Zr, Y and Nb in various combinations are presented.

Non-Conventional Route To Glass-Ceramics For Electronic Packaging

1986 ◽  
Vol 73 ◽  
Author(s):  
C. Gensse ◽  
U. Chowdhry
Keyword(s):  
Viscous Flow ◽  
Electronic Packaging ◽  
Low Temperatures ◽  
Glass Ceramics ◽  
Fine Grained ◽  
Amorphous Powders ◽  
Organometallic Precursors

ABSTRACTThis paper describes a non-conventional route to formation of dense glass-ceramics at relatively low temperatures. Organometallic precursors were used to synthesize powders with controlled purity and stoichiometry in the MgO/Al2 O3 /SiO2 system. These amorphous powders sintered by viscous flow to form a dense glass below 1000°C. Further heating resulted in the formation of very fine grained glass-ceramics. Beta-quartz, cordierite, and cordierite-mullite glass-ceramics were obtained with attractive properties for electronic packaging.

Non-Conventional Route to Glass-Ceramics for Electronic Packaging

1986 ◽  
Vol 72 ◽  
Author(s):  
C. Gensse ◽  
U. Chowdhry
Keyword(s):  
Viscous Flow ◽  
Electronic Packaging ◽  
Low Temperatures ◽  
Glass Ceramics ◽  
Fine Grained ◽  
Amorphous Powders ◽  
Organometallic Precursors

AbstractThis paper describes a non-conventional route to formation of dense glass-ceramics at relatively low temperatures. Organometallic precursors were used to synthesize powders with controlled purity and stoichiometry in the MgO/A12O3/SiO2 system. These amorphous powders sintered by viscous flow to form a dense glass below 1000°C. Further heating resulted in the formation of very fine grained glass-ceramics. Beta-quartz, cordierite, and cordierite-mullite glass-ceramics were obtained with attractive properties for electronic packaging.

Fabrication of Nano-MgO Reinforced Fe-Cr-Ni Composites by Reactive Hot Pressing

2009 ◽  
Vol 620-622 ◽  
pp. 551-554 ◽  
Author(s):  
Chang Chen ◽  
Jian Feng Yang ◽  
Ji Qiang Gao ◽  
Cong Yang Chu
Keyword(s):  
Hot Pressing ◽  
Low Temperatures ◽  
Bending Strength ◽  
Exothermic Reaction ◽  
X Ray ◽  
Three Point Bending ◽  
Fine Grained ◽  
In Situ Formation ◽  
Reactive Hot Pressing

The self-propagating combustion reaction 0.741Mg + 0.247Fe2O3 + 0.188Ni + 0.318Cr → 0.741MgO + Fe0.494Ni0.188Cr0.318 was applied to prepare a nano-MgO reinforced Fe-Cr-Ni composite, by reactive hot pressing (RHP) under a condition of 700°C/30MPa/2h. The densification was enabled by the low temperatures produced by the exothermic reaction. According to TG-DTA and X-ray diffractometry (XRD), the highly-exothermic thermite reaction began at about 600°C and the in-situ formation of composites comprised predominantly of (FCC) Cr0.19Fe0.7Ni0.11, (FCC) Fe-Cr, (BCC) MgO and a small quantity of (BCC) MgFe2O4. The Vickers hardness was 3.67GPa, the three-point bending strength was 112.5±10MPa, and the fracture toughness was 3.28 MPa•m1/2. The microstructure of the composite was observed via scanning electron microscopy. This indicated that the distributions of in-situ-formed (BCC) MgO phases (~800 nanometers) were homogeneous into in a matrix of a fine-grained metallic alloy phases that gather together to form agglomerates in the composite.

Microstructural development of Si3N4–SiC–Y2O3 ceramics derived from polymeric precursors

1998 ◽  
Vol 13 (2) ◽  
pp. 353-361 ◽  
Author(s):  
Yuji Iwamoto ◽  
Ko-ichi Kikuta ◽  
Shin-ichi Hirano
Keyword(s):  
Heat Treatment ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Hot Pressing ◽  
Microstructural Development ◽  
Polymeric Precursors ◽  
Fine Grained ◽  
Chemically Modified ◽  
Amorphous Powders

[Si–Y–O–C–N] amorphous powders were synthesized by the pyrolysis at 1000 °C in N2 of chemically modified perhydropolysilazane using n-decyl alcohol and yttrium tri-methoxide. [Si–Y–O–C–N] amorphous powders yielded a unique fibrous microstructure by heat treatment in N2 at 1800 °C. The fibrous microstructure was composed of β–Si3N4 whiskers of submicron in diameter and more than 10 μm in length. Fully dense Si3N4 –SiC–Y2O3 ceramics were also fabricated by heat treatment at 1800 °C followed by powder-vehicle hot pressing at 1700 °C. After these two-step processings, [Si–Y–O–C–N] amorphous powders yielded a unique fine-grained microstructure composed of submicron grains with high aspect ratio.

Low-temperature fabrication of Al 2 O 3 -ZrO 2 (Y 2 O 3 ) nanocomposites through hot pressing of amorphous powders

2016 ◽  
Vol 42 (13) ◽  
pp. 15065-15071 ◽  
Author(s):  
Xiaojing Xu ◽  
Xiqing Xu ◽  
Jiachen Liu ◽  
Wenhu Hong ◽  
Haiyan Du ◽  
...  
Keyword(s):  
Low Temperature ◽  
Hot Pressing ◽  
Amorphous Powders

scholarly journals Use of Fine-Grained Heat-Strengthened Steels to Increase the Operation Qualities of Bunker Capacities from Thin-Walled Galvanized Profiles

2021 ◽  
pp. 84-93
Author(s):  
Y. I. Hezentsvei ◽  
D. O. Bannikov
Keyword(s):  
Low Temperatures ◽  
High Strength Steels ◽  
High Strength ◽  
Numerical Calculations ◽  
Structural Scheme ◽  
Plan View ◽  
Fine Grained ◽  
Steel Sheets ◽  
Stiffening Ribs ◽  
Corrugated Sheets

Purpose. The work is aimed to study the use efficiency of fine-grained heat-strengthened steels (mainly 10G2FB) for steel bunker capacities. At the same time, the structural scheme of such a structure using corrugated steel sheets is considered as the main variant. Methodology. To achieve this purpose, a series of numerical calculations was carried out for a steel bunker capacity of a pyramidal-prismatic type with overall dimensions in plan view of 6×5.2 m and a total height of 4.5 m. The capacity was designed for complicated working conditions, in particular, increased loads, including long-term dynamic ones. The potential possibility of operating the container under conditions of high or low temperatures was also taken into account. At the same time, both the traditional structural scheme of a bunker capacity with horizontal stiffening ribs and the developed structural scheme based on corrugated steel sheets were analyzed. The calculations were carried out by the finite element method based on the SCAD for Windows project complex. Findings. Based on the results of the analysis and comparison of the data obtained in numerical calculations, it was found that the use of fine-grained heat-strengthened high-strength steels (for example, steel 10G2FB) for bunker capacities, both the traditional structural scheme with stiffening ribs and the developed structural scheme based on corrugated sheets, allows reducing material consumption by about 30% in both cases. At the same time, due to the good performance of fine-grained heat-strengthened steel 10G2FB, both at high and at low temperatures, it can be effectively used for steel bunker capacities that work in difficult conditions. Originality. The possibility and efficiency of the use of fine-grained, heat-strengthened high-strength steels for the construction of a steel bunker capacity is estimated. At the same time, such an estimation was given not only for structures of the traditional structural scheme with horizontal stiffening ribs, but also for bunkers with a developed structural scheme based on corrugated sheets. Practical value. From a practical point of view, quantitative parameters of the stress-strain state were obtained during investigations of various design variants for a steel bunker capacity. The data are presented in a compact form that is easy to evaluate and compare. They allow us to state about the improvement of the operation characteristics of capacities and the potential reduction of the risks of their failures and accidents during operation.

Pressure assisted sintering of Al2O3–Y2O3 glass microspheres: sintering conditions, grain size, and mechanical properties of sintered ceramics

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Anna Prnová ◽  
Jana Valúchová ◽  
Monika Michálková ◽  
Beáta Pecušová ◽  
Milan Parchovianský ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Hot Pressing ◽  
Pechini Method ◽  
Sol Gel ◽  
Applied Pressure ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Glass Microspheres ◽  
Amorphous Powders

Abstract Glass microspheres with yttria-alumina eutectic composition (76.8 mol % Al2O3 and 23.2 mol % Y2O3) were prepared by sol-gel Pechini method and flame synthesis with or without subsequent milling. Prepared amorphous powders were studied by X-ray powder diffraction (XRD), particle size analysis (PSA), scanning electron microscopy (SEM) and differential thermal analysis (DTA). Hot pressing (HP), rapid hot pressing (RHP) and spark plasma sintering (SPS) were used to sinter amorphous precursor powders at 1600 °C without holding time (0 min). The preparation process including milling step resulted in amorphous powders with narrower particle size distribution and smaller particle size. All applied pressure assisted sintering techniques resulted in dense bulk samples with fine grained microstructure consisting of irregular α-Al2O3 and Y3Al5O12 (YAG) grains. Milling was beneficial in terms of final microstructure refinement and mechanical properties of sintered materials. A material with the Vickers hardness of HV = (17.1 ± 0.3) GPa and indentation fracture resistance of (4.2 ± 0.2) MPa.m1/2 was prepared from the powder milled for 12 h.

Fabrication of fine-grained α/β Si3N4 by Hot Pressing Flowing Sintering at 1550 °C

2019 ◽  
Vol 45 (11) ◽  
pp. 13958-13963 ◽  
Author(s):  
Bo Wang ◽  
Qiang-Guo Jiang ◽  
Wen-Yong Liu ◽  
Zu-Yun Zhu ◽  
Jie Liu ◽  
...  
Keyword(s):  
Hot Pressing ◽  
Fine Grained

High Temperature Oxidation Behavior of Ti3SiC2 in Air

2005 ◽  
Vol 486-487 ◽  
pp. 97-100
Author(s):  
J.H. Ko ◽  
Sung Sic Hwang ◽  
Sang Whan Park ◽  
Dong Bok Lee
Keyword(s):  
High Temperature ◽  
Hot Pressing ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
Coarse Grained ◽  
Amorphous Sio2 ◽  
Temperature Oxidation ◽  
Fine Grained ◽  
High Temperature Oxidation Behavior ◽  
Tio2 Rutile

Fine-grained and coarse-grained Ti3SiC2 materials were synthesized by hot pressing using TiC0.67 and Si powders as starting materials. The oxidation between 900 and 1100oC in air resulted in the formation of an outer TiO2 (rutile) layer and an inner mixed layer of TiO2 and amorphous SiO2, accompanying the liberation of carbon into the air. Fine-grained Ti3SiC2 displayed better oxidation resistance than coarse-grained one, with activation energies of 376.5~380 kJ/mol for oxidation.

Thick-Film Processing of Pb5Ge3O11-Based Ferroelectric Glass-Ceramics

1995 ◽  
Vol 398 ◽  
Author(s):  
Iván A. Cornejo ◽  
Michael J. Haun
Keyword(s):  
Thick Film ◽  
Glass Ceramic ◽  
Low Temperatures ◽  
Ferroelectric Phase ◽  
Glass Ceramics ◽  
Axis Orientation ◽  
Film Processing ◽  
Processing Techniques

ABSTRACTProcessing techniques were investigated to produce c-axis orientation, or texture, of ferroelectric Pb5Ge3O11-based glass-ceramic compositions during crystallization of amorphous thick-film printed samples from the Pb5Ge3O11-PbTiO3 (PG-PT) and Pb5Ge3O11Pb(Zr1/2Ti1/2)O3 (PG-PZT) systems. In these systems the PG crystallized into a ferroelectric phase, producing a multiple ferroelectric phase composite at low temperatures, PG-PT or PG-PZT. In this way the non-ferroelectric component of traditional ferroelectric glass-ceramics was eliminated.

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