Phase separation in sol gel-derived ceramic films of silica-zirconia, alumina-zirconia, and titania-zirconia system

Author(s):  
J. Tong ◽  
L. Eyring

There is increasing interest in composites containing zirconia because of their high strength, fracture toughness, and its great influence on the chemical durability in glass. For the zirconia-silica system, monolithic glasses, fibers and coatings have been obtained. There is currently a great interest in designing zirconia-toughened alumina including exploration of the processing methods and the toughening mechanism.The possibility of forming nanocrystal composites by a phase separation method has been investigated in three systems: zirconia-alumina, zirconia-silica and zirconia-titania using HREM. The morphological observations initially suggest that the formation of nanocrystal composites by a phase separation method is possible in the zirconia-alumina and zirconia-silica systems, but impossible in the zirconia-titania system. The separation-produced grain size in silica-zirconia system is around 5 nm and is more uniform than that in the alumina-zirconia system in which the sizes of the small polyhedron grains are around 10 nm. In the titania-zirconia system, there is no obvious separation as was observed in die alumina-zirconia and silica-zirconia system.

2017 ◽  
Vol 622 ◽  
pp. 11-16
Author(s):  
Triin Kangur ◽  
Valter Kiisk ◽  
Ardi Loot ◽  
Martin Timusk ◽  
Martin Järvekülg

2012 ◽  
Vol 24 (3) ◽  
pp. 783-792 ◽  
Author(s):  
Paula Reemann ◽  
Triin Kangur ◽  
Martin Pook ◽  
Madis Paalo ◽  
Liis Nurmis ◽  
...  

1990 ◽  
Vol 180 ◽  
Author(s):  
Y. Tsurita ◽  
K. Wada

ABSTRACTA new method for preparation of porous mixed oxide with SiO2 -ZrO2 -Na2O composition was investigated by heating the sol-gel derived SiO2 microsphere gel in the presence of ZrOCl2 and NaCI. Surface of the -products was composed of sponge-like structure, similar to the porous glasses manufactured by the phase separation method. Their pore volumes ranged from 1.0 to 1.5 cc/g(pore radius 100–lO00Å) and their pore distributions were sharp, with peak tops of about 450–600Å in radius.


Author(s):  
D.M. Vanderwalker

Aluminum-lithium alloys have a low density and high strength to weight ratio. They are being developed for the aerospace industry.The high strength of Al-Li can be attributed to precipitation hardening. Unfortunately when aged, Al-Li aquires a low ductility and fracture toughness. The precipitate in Al-Li is part of a sequence SSSS → Al3Li → AlLi A description of the phases may be found in reference 1 . This paper is primarily concerned with the Al3Li phase. The addition of Zr to Al-Li is being explored to find the optimum in properties. Zirconium improves fracture toughness and inhibits recrystallization. This study is a comparision between two Al-Li-Zr alloys differing in Zr concentration.Al-2.99Li-0.17Zr(alloy A) and Al-2.99Li-0.67Zr (alloy B) were solutionized for one hour at 500oc followed by a water quench. The specimens were then aged at 150°C for 16 or 40 hours. The foils were punched into 3mm discs. The specimens were electropolished with a 1/3 nitric acid 2/3 methanol solution. The transmission electron microscopy was conducted on the JEM 200CX microscope.


2000 ◽  
Vol 628 ◽  
Author(s):  
Kazuki Nakanishi ◽  
Souichi Kumon ◽  
Kazuyuki Hirao ◽  
Hiroshi Jinnai

ABSTRACTMacroporous silicate thick films were prepared by a sol-gel dip-coating method accompanied by the phase separation using methyl-trimethoxysilane (MTMS), nitric acid and dimethylformamide (DMF) as starting components. The morphology of the film varied to a large extent depending on the time elapsed after the hydrolysis until the dipping of the coating solution. On a glass substrate, the films prepared by early dipping had inhomogeneous submicrometer-sized pores on the surface of the film. At increased reaction times, relatively narrow sized isolated macropores were observed and their size gradually decreased with the increase of reaction time. On a polyester substrate, in contrast, micrometer-sized isolated spherical gel domains were homogeneously deposited by earlier dippings. With an increase of reaction time, the volume fraction of the gel phase increased, then the morphology of the coating transformed into co-continuous gel domains and macropores, and finally inverted into the continuous gel domains with isolated macropores. The overall morphological variation with the reaction time was explained in terms of the phase separation and the structure freezing by the forced gelation, both of which were induced by the evaporation of methanol during the dipping operation.


2018 ◽  
Vol 60 (11) ◽  
pp. 1077-1083 ◽  
Author(s):  
Zhaoming Zhou ◽  
Xishui Guo ◽  
Tiejun Lin ◽  
Desen Mao

Alloy Digest ◽  
1994 ◽  
Vol 43 (11) ◽  

Abstract CARLSON ALLOYS C600 AND C600 ESR have excellent mechanical properties from sub-zero to elevated temperatures with excellent resistance to oxidation at high temperatures. It is a solid-solution alloy that can be hardened only by cold working. High strength at temperature is combined with good workability. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as forming, heat treating, and machining. Filing Code: Ni-470. Producer or source: G.O. Carlson Inc.


Alloy Digest ◽  
1994 ◽  
Vol 43 (1) ◽  

Abstract INCONEL ALLOY 725 is an age-hardenable alloy that displays high strength along with excellent ductility and toughness. Its corrosion resistance is comparable to alloy 625. Good flattening properties are exhibited in age-hardened tubing. This datasheet provides information on composition, physical properties, hardness, tensile properties, and shear strength as well as fracture toughness. It also includes information on corrosion resistance as well as heat treating and machining. Filing Code: Ni-445. Producer or source: Inco Alloys International Inc.


Alloy Digest ◽  
1963 ◽  
Vol 12 (6) ◽  

Abstract DURANICKEL Alloy 301 is a wrought, age-hardenable nickel alloy having high strength, high corrosion and heat resistance. It is recommended for springs, diaphrams, bearings, pump and valve parts. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness and fatigue. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ni-83. Producer or source: The International Nickel Company Inc..


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