Microstructure development of Al2O3–13wt.%TiO2 plasma sprayed coatings derived from nanocrystalline powders

Goberman, Daniel; Sohn, Yong Ho; Shaw, Leon L.; Jordan, Eric H.; Gell, Maurice

doi:10.1016/s1359-6454(01)00414-1

Cited by 222 publications

(149 citation statements)

References 12 publications

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“…Microcracks and micropores around partially melted and unmelted particles of the initial material were detected on the thin section of the coating sample obtained from the nanoagglomerate powder. This type of microstructure was also described in [4,10,11]. The porosity of the coating was measured.…”

Section: Resultsmentioning

confidence: 96%

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Investigation of deformation behavior and fracture of ceramic coatings by the acoustic emission method

Klyatskina

Salvador

Segovia

et al. 2017

J. Mach. Manuf. Reliab.

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Abstract-The use of protective coatings on components of machines and mechanisms provides the greatest economic benefit at the lowest additional cost. Plasma spraying is one of the most productive, technologically advanced, and efficient methods of producing these coatings. The results of investigations of structures, mechanical properties, and fracture surfaces of ceramic wear resistant coatings produced by plasma spraying have been presented. DOI: 10.3103/S1052618817020078Intensive economic development and its efficiency increase are largely determined by the use of new technological processes. Advanced technologies based on major basic studies (laser, plasma, and powder metallurgy, self-propagating high-temperature synthesis, etc.) make a significant contribution to the development of special engineering.It is impossible to produce machinery and equipment for operation under extreme conditions (large dynamic loads, aggressive media, erosive and abrasive wear, etc.) is impossible without using special coatings. Special coatings are used to save high-alloy materials and to harden surfaces in order to give them special properties, such as protection from exposure to high temperatures, thermal erosion wear, neutron fluxes and radio emissions, abrasive wear, and the restoration of the geometric dimensions of the surface of worn-out details [12].The protective coating material is determined based on the conditions of its use. In the case of oxidecontaining materials (ZrO 2 -Y 2 O 3 and Al 2 O 3 -TiO 2 ), one of the main limiting factors of their use is low plasticity, as a result of which they fracture (due to cracking, delamination, or loss of material) [3].Coating strength is an important characteristic that determines the performance of products. Low strength can be caused by the physical nature of the coating structure consisting of separate relatively weakly bound particles and layers, porosities, and lack of volume coupling during the formation. Cohesive and adhesive strengths of welding regions is low as a consequence of defects in their structure. In addition, low adhesive strength is often caused by the difference in types of connections between the base material and the coating.In view of the above-mentioned, a need arises for standard special tests for the evaluation of the mechanical properties of ceramic coatings. One such method would be to use acoustic emission together with bending tests to investigate the phenomenon of the emergence of sound waves during the deformation of solids. Acoustic emissions are associated with the radiation of stress waves generated in the solid during deformation as result of discrete dynamic processes, such as the occurrence of macro-and microcracks during operation, which, as is known, are accompanied by the release of energy [4,5]. This method makes it possible to investigate the mechanisms of the fracture of materials, namely, the high sensitivity of the acoustic emission method makes it possible to determine the defectology type, which includes the size and number of...

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Section: Resultsmentioning

confidence: 96%

“…Each point corresponds to the number of signals (or their amplitude) detected during the sample bending. Each signal with an amplitude above 40 dB means that the coating is subjected to some microdefect under the stresses that act on it [11].…”

Section: Resultsmentioning

confidence: 99%

Investigation of deformation behavior and fracture of ceramic coatings by the acoustic emission method

Klyatskina

Salvador

Segovia

et al. 2017

J. Mach. Manuf. Reliab.

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“…Nanostructured (Al 2 O 3 -13 wt pct TiO 2 ) powders with mean diameters of 50 and 70 nm, respectively, were blended by Goberman et al [20] to produce a powder mixture. The mixed powders were then ''reconstituted'' to form agglomerates (40 to 70 lm).…”

Section: Drawing Down and Dispersion Of Fine Carbon Particlesmentioning

confidence: 99%

“…In effect, this means that at least the infiltration start pressure given by Eq. [20] must be sustained throughout the passage of the aluminum through the entire width of the graphite filter medium.…”

Section: Melt Decarbonizationmentioning

confidence: 99%

“…Molina et al [27] give the latter as 2.3 ± 0.2 MPa for Al-12 wt pct Si at 680°C, which, using Eq. [20] to correct for the surface tensions involved, translates into 1.68 ± 0.2 or Al at 2160°C. Thus, the allowance for the overall pressure drop must be (0.92) + (1.88) = 2.8 MPa; accordingly, if the exit pressure from the filter medium must be greater than the pressure for first infiltration, the pressurization to be exerted by the compressed argon admitted to the unit = (2.8 + 1.88) = 4.68 MPa.…”

Section: Melt Decarbonizationmentioning

confidence: 99%

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Conceptual Design for Lower-Energy Primary Aluminum

Warner

2008

Metall Mater Trans B

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Operating parameters have been identified such that slag melts typical of other carbothermic aluminum processes are thermodynamically unstable. This facilitates the direct reaction of carbon in carbon-saturated aluminum with alumina under dispersed-contact high-intensity conditions. A conceptual design for one million tonnes per annum (1 Mtpa) aluminum production from Bayer alumina is developed. Freestanding graphite reactors and an ancillary plant encapsulated by inert gas are totally unconstrained within refractory-lined shells. Electrical conductive heating and melt circulation in closed loops, employing a 10 vol pct dispersion of fine carbon particles in aluminum (slurry), transports sensible heat to a single pressurized metalproducing reactor (MPR) to satisfy the endothermicity. In the proposed plant, an MPR at 0.28 MPa (2.8 bar) and 2433 K (2160°C) with a hearth 2-m-wide · 190-m-long leads the melt via a barometric leg back to essentially atmospheric pressure, for further in-line processing. The impeller-stirred assimilation of fine carbon particles is followed by multistage gas-lift pumping to provide a 5.4-m total head, as required by two parallel straight-line melt-conductive heaters 1 m in diameter · 226 m in length. Overall energy-consumption figures 28.7 pct lower than today's more recently installed Hall-Heroult electrolytic plants are predicted, with 51.3 pct less purchased electricity, supplemented with 1.10 times the stoichiometric elemental carbon.

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Coatings and Protection of Structural Ceramics

Basu

Balani

2011

Advanced Structural Ceramics

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Microstructure development of Al2O3–13wt.%TiO2 plasma sprayed coatings derived from nanocrystalline powders

Cited by 222 publications

References 12 publications

Investigation of deformation behavior and fracture of ceramic coatings by the acoustic emission method

Investigation of deformation behavior and fracture of ceramic coatings by the acoustic emission method

Conceptual Design for Lower-Energy Primary Aluminum

Coatings and Protection of Structural Ceramics

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