Influence of nanopowder sintering technology on crack resistance of tetragonal zirconium dioxide

Peculiarities of formation of microstructure in composites based on chemically synthesized zirconium nanopowders obtained by the method of decomposition from fluoride salts were considered. Hydrofluoric acid, concentrated nitric acid, aqueous ammonia solution, metallic zirconium, and polyvinyl alcohol were used. It was established that the reduction of porosity in nanopowders in the sintering process is the main problem in the formation of high-density materials. Analysis of various initial nanopowders, their morphology, and features of sintering by the method of hot pressing with direct transmission of electric current was made. Peculiarities of obtaining the composites based on them with the addition of Al2O3 nanopowders applying the electric sintering method were considered. It was shown that the increase in the content of alumina nano additives leads to an increase in strength and crack resistance of the samples due to simultaneous inhibition of abnormal grain growth and formation of a finer structure with a high content of tetragonal phase. The influence of sintering modes on the formation of the microstructure of zirconium nanopowders has been studied for different contents of alumina additives. Electric current promotes the surface activity of nanopowders and its variable value promotes partial fragmentation of agglomerated grains thus affecting the composite structure. Physical-mechanical properties of the obtained samples, optimal compositions of mixtures, and possibilities of improving some parameters were determined. It was found that nanopowders of zirconium dioxide obtained by the method of decomposition from fluoride salts are quite suitable for the production of composite materials with high physical and mechanical properties. They can compete with imported analogs and enable obtaining of crack resistance of 7.8 MPa·m1/2 and strength of 820 MPa.

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Surface Films on Zircaloy-2 Samples Cracked in Neutral Aqueous NaCl by Stress Corrosion

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100070679 ◽

1973 ◽

Vol 31 ◽

pp. 46-47

Author(s):

R.A. Ploc

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Film Thickness ◽

Stress Corrosion ◽

Zirconium Dioxide ◽

Surface Film ◽

Surface Films ◽

Continuous Layer ◽

Transmission Electron ◽

Product Film

Samples of low-nickel Zircaloy-2 (material MLI-788-see(1)), when anodically polarized in neutral 5 wt% NaCl solutions, were found to be susceptible to pitting and stress corrosion cracking. The SEM revealed that pitting of stressed samples was occurring below a 2000Å thick surface film which behaved differently from normal zirconium dioxide in that it did not display interference colours. Since the initial film thickness was approximately 65Å, attempts were made to examine the product film by transmission electron microscopy to deduce composition and how the corrosion environment could penetrate the continuous layer.

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Effect of Plastic Deformation on Hydrogen Induced Crack Resistance of API X65 Linepipe Steel

Korean Journal of Metals and Materials ◽

10.3365/kjmm.2016.54.4.295 ◽

2016 ◽

Vol 54 (4) ◽

pp. 295-303 ◽

Cited By ~ 4

Author(s):

Kyung-Mox Cho ◽

Joon-Ho Sung ◽

Yun-Kyu Kim ◽

Jong-Geol Moon ◽

Ki-Won Kim ◽

...

Keyword(s):

Plastic Deformation ◽

Crack Resistance ◽

Linepipe Steel

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PLASMA SPRAYING OF COATINGS FROM PARTIALLY STABILIZED ZIRCONIUM DIOXIDE AND NICKEL CERMET ON THE FUEL CELL ELEMENT WITH ACCOUNT FOR PREDICTION

High Temperature Material Processes (An International Quarterly of High-Technology Plasma Processes) ◽

10.1615/hightempmatproc.2015012595 ◽

2013 ◽

Vol 17 (2-3) ◽

pp. 75-89

Author(s):

O. G. Devoino ◽

Vjatcheslav Okovity

Keyword(s):

Fuel Cell ◽

Plasma Spraying ◽

Zirconium Dioxide ◽

Cell Element ◽

Stabilized Zirconium Dioxide

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Complex study of the fracture processes in materials and structures

Industrial laboratory Diagnostics of materials ◽

10.26896/1028-6861-2018-84-11-46-51 ◽

2018 ◽

Vol 84 (11) ◽

pp. 46-51 ◽

Cited By ~ 1

Author(s):

N. A. Makhutov

Keyword(s):

Fracture Mechanics ◽

Crack Resistance ◽

Scientific Basis ◽

Intensity Factors ◽

Nonlinear Fracture Mechanics ◽

Nonlinear Fracture ◽

Linear Fracture ◽

Science Technology ◽

Fracture Processes

The results of comprehensive studies of multifactor processes, mechanisms and criteria for fracture at a variation of the crack-like defect state, loading conditions and mechanical properties of structural materials carried out in the 20th - 21st centuries are presented on the basis of monographic publications and articles published in the journal “Zavodskaya Laboratoriya. Diagnostika Materialov.” Crack resistance of materials and structures has become a key problem of the material science, technology, design, manufacture and service of structures. Fracture mechanics including estimation of the stress-strain and limiting states in a cracks tip formed a scientific basis of the crack resistance analysis Stress intensity factors (linear fracture mechanics) and strain intensity factors (nonlinear fracture mechanics) are accepted as the basic criteria of those states. The basic computational relations for construction of the fracture diagrammes which link the cracks growth with conditions of a static, cyclic, long-term, dynamic loading are presented. Parameters of computational relations are put into correspondence with the features of fracture processes on nano-, micro-, meso- and macrolevels. Prospects of the research and guidelines of further studing crack resistance are discussed.

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