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Journal ArticleDOI

Electrocomposite coating of partially stabilized zirconia dispersed in a nickel matrix

01 Jan 1992-Journal of Materials Science Letters (Kluwer Academic Publishers)-Vol. 11, Iss: 8, pp 449-451
About: This article is published in Journal of Materials Science Letters.The article was published on 1992-01-01. It has received 5 citations till now. The article focuses on the topics: Coating & Cubic zirconia.
Citations
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Journal ArticleDOI
TL;DR: In this article, Ni-Co-ZrO2 nano-composites are electrodeposited from sulphamate electrolyte and a comparison is made with Ni-ZRO2 in terms of structure and properties.
Abstract: Ni-Co-ZrO2 nano-composites are electrodeposited from sulphamate electrolyte and a comparison is made with Ni-ZrO2 in terms of structure and properties. The Co content in the coatings is in the range of 10-80wt%. The deposition conditions like current density, pH are optimized in terms of microhardness and amounts of ZrO2 incorporated. The micro- hardness studies revealed that the maximum hardness is exhibited by Ni-28Co-2ZrO2 composite. The FESEM study showed a change in morphology from polyhedral to ridge with increase in Co content from 10 to 80wt%. A change in crystal structure from fcc to hcp is also seen. The effect of annealing treatment in terms of microhardness is studied by subjecting the com- posite electroforms to 800℃. The Co rich composite exhibited better stability compared to Ni rich composites. Ni-28Co-2ZrO2 composite exhibited better immersion corrosion resistance while, Ni-ZrO2 composite displayed better elec- trochemical corrosion resistance. The wear studies showed that Ni-10Co-2ZrO2, Ni-28Co-2ZrO2 composites showed better resistance. Thus, it is seen that the coatings can be tailored to suit various applications.

35 citations

Journal ArticleDOI
TL;DR: In this paper, a sediment electrodeposition technique has been successfully used to prepare Ni + PSZ gradient coatings with a compositional gradient, and the micro structure and composition of the coating have been studied by scanning electron microscopy and electron probe microanalysis.
Abstract: A sediment electrodeposition technique has been successfully used to prepare Ni + PSZ gradient coatings with a compositional gradient. The micro structure and composition of the coating have been studied by scanning electron microscopy and electron probe microanalysis. The variation of the hardness, elastic modulus, residual stress, thermal expansion coefficient and thermal conductivity of the coatings with various components is also discussed. Thermal fatigue tests demonstrate that Ni + PSZ gradient coatings improve the resistance to thermal shock by eliminating the mismatch with the substrate.

21 citations

Journal ArticleDOI
TL;DR: In this article, an economical composite coating with high thermal stability was developed by using Yttria stabilised zirconia, a commonly used high temperature material and alumina (YZA) reinforced in various NiCo alloy matrices through electrodeposition.
Abstract: The aim is to develop an economical composite coating with high thermal stability. Ni–Co alloys are found to possess better thermal, physical and mechanical properties compared to Ni. Also, oxide particles as distributed phase can impart better thermal stability. Hence, particulates of composite Yttria stabilised zirconia, a commonly used high temperature material and alumina (YZA) were reinforced in various Ni–Co alloy matrices through electrodeposition. The influence of YZA on the microhardness, tribology and corrosion behaviour of Ni–Co alloys with Co contents of 0 wt.%, 17 wt.%, 38 wt.% and 85 wt.% was evaluated. Optical and Scanning Electron Microscopy (SEM) confirmed the presence of YZA particles and Energy Dispersive X-ray Analysis (EDX) revealed the composition. Tribology testing showed that composite containing 38 wt.% Co displayed better wear resistance. It was found from the immersion corrosion studies that Ni–17Co–YZA coating displayed improved corrosion resistance. Thermal stability studies showed that Ni–85Co–YZA coating retained its microhardness at temperatures of 600 °C. Thus, these coatings can be tailored for various applications by varying the cobalt content.

16 citations

Journal ArticleDOI
Bin Jiang1, Binshi Xu, Shiyun Dong, Yu Yi1, Peidao Ding1 
TL;DR: In this article, the microstructure, annealing and load on contact fatigue behavior of nano-ZrO 2 /Ni EBP coating was investigated, and the contact fatigue behaviors of the nano-XRO 2/Ni composite coatings were compared.
Abstract: Nano-ZrO 2 /Ni composite coatings were prepared through co-depositing nano-ZrO 2 particles and pure nickel by electro-brush plating (EBP). By analyzing the effects of microstructure, annealing and load on contact fatigue life, the contact fatigue behavior of the nano-ZrO 2 /Ni EBP coating was investigated. Furthermore, the contact fatigue behaviors of the nano-ZrO 2 /Ni EBP coating and the nickel EBP coating were compared. The results show that the nano-ZrO 2 particles in the as-deposited nano-ZrO 2 /Ni EBP coating were partially conglomerated, and the microstructure of the annealed nano-ZrO 2 /Ni EBP coating was finer. Under the as-deposited condition, the contact fatigue life of the nano-ZrO 2 /Ni EBP coating was much lower than that of the nickel EBP coating. After the annealing process, the contact fatigue life of the nano-ZrO 2 /Ni EBP coating was greatly increased and much higher than that of the nickel EBP coating. The scanning electron microscope (SEM) images of the fatigue fracture zones and the transmission electron microscope (TEM) images of microstructure of the deformation layer show that the annealing could improve the ductility of the nano-ZrO 2 /Ni EBP coating, and the nano-ZrO 2 particles could restrain the propagation of the fatigue cracks, which contributed to the enhancement of the contact fatigue properties of the nano-ZrO 2 /Ni EBP coating.

14 citations

References
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Journal ArticleDOI
TL;DR: In this article, the size effects introduced by surface phenomena concurrent with the phase transformation were investigated. And the authors showed that these surface phenomena not only introduce a size-dependent energy term into the total free-energy change, but also reduce the strain energy associated with the transformation, which can result in a transformation at a temperature where the chemical free energy change is less than the unrelieved strain energy.
Abstract: The thermodynamics of the constrained phase transformation is presented with particular reference to size effects introduced by surface phenomena concurrent with the transformation, e.g., the formation of solid-solid surfaces (twins, etc.) and solid-vapour surfaces (microcracks). It is shown that these surface phenomena not only introduce a size-dependent energy term into the total free-energy change, but also reduce the strain energy associated with the transformation, which can result in a transformation at a temperature where ¦ΔGc¦, the chemical free energy change, is less thanUse, the unrelieved strain energy associated with the constrained transformation. The results of this analysis lead to a phase diagram representation that includes the size of the transforming inclusion. This diagram can be used to define the critical inclusion size required to prevent the transformation and/or to obtain the transformation, but avoid one or more of the concurrent surface phenomena.

601 citations

Journal ArticleDOI
J. Wang1, R. Stevens1
TL;DR: In the previous decade, a considerable amount of work has been done on the alumina-zirconia composite system with a particular emphasis on improving the mechanical properties utilizing the recognized toughening mechanisms as discussed by the authors.
Abstract: In the previous decade, a considerable amount of work has been done on the alumina-zirconia ceramic composite system with a particular emphasis on improving the mechanical properties utilizing the recognized toughening mechanisms. Zirconia-toughened aluminas (ZTA) can be regarded as a new generation of toughened ceramics; for example, a toughness of >12 MPa m0.5 has been obtained, compared with 3 MPa m0.5 for commercial alumina ceramics. The fracture strength of ZTA is also greatly in excess of that for alumina. The mechanical properties of ZTA are critically dependent on their microstructures, which can be designed in terms of specific applications and controlled by means of powder preparation and densification processes. This review also includes details of the possible future development of ZTA; these are expected to involve the development and measurement of the mechanical properties for high-temperature engineering applications.

370 citations

Journal ArticleDOI
TL;DR: In this article, the authors studied the deformation of tetragonal zirconia polycrystals by inducing volumetric and shear deformation under compression and bending between the burst temperature of martensite (monoclinic) formation (Mb) and burst temperature (Ab) of austenite (tetragonal) formation and found that yield stress has a strong, positive pressure and temperature sensitivity but is strain-rate sensitive only in the last stage of deformation.
Abstract: Transformation plasticity in CeO2-stabilized tetragonal zirconia polycrystals due to the tetragonal-to-monoclinic transformation was studied by inducing volumetric and shear deformation under compression and bending between the burst temperature of martensite (monoclinic) formation (Mb) and the burst temperature of austenite (tetragonal) formation (Ab). The stress-strain curve features a load drop, a perfect plastic regime, and an extended strain-hardening regime before the exhaustion of transformation. Macroscopic shear bands formed in the perfect plastic regime. The yield stress has a strong, positive pressure and temperature sensitivity but is strain-rate sensitive only in the last stage of deformation. These results are rationalized in terms of stress assistance to the transformation which, in a homogeneous tetragonal polycrystal, may propagate autocatalytically. Autocatalysis can be impeded by a second phase, such as monoclinic ZrO2 or Al2O3, and is suppressed at higher temperature. Flow localization is found to precede and precipitate crack formation. As a result, the actual fracture energy is much less than the total plastic work. The implications of stress-assisted, autocatalytic transformation on strength and toughness are explored.

187 citations

Journal ArticleDOI
TL;DR: In this paper, a method for applying zirconia barrier coatings using a solgel method is described, and the coatings of 8 wt % yttria-stabilized ZIRconia are applied by spin coating a solution containing zirconsium alkoxides and yttrium acetate on to stainless steel substrates.
Abstract: A method for applying zirconia barrier coatings using a sol-gel method is described. The coatings of 8 wt % yttria-stabilized zirconia are applied by spin coating a solution containing zirconium alkoxides and yttrium acetate on to stainless steel substrates. Crystallization of the films was observed for thermal treatments in the range 750 to 1050° C. Excellent adhesion at the interface, due to significant coating-substrate interfacial reactions, indicates that this sol-gel route is a feasible method for applying zirconia coatings.

145 citations

Journal ArticleDOI
TL;DR: In this article, an equation for a nonlinear calibration curve of volume fraction vs integrated intensity ratio is presented for monoclinic-stabilized cubic ZrO2 systems containing YO1.5, CaO, and MgO.
Abstract: An equation for a nonlinear calibration curve of volume fraction vs integrated intensity ratio is presented for monoclinic-stabilized cubic ZrO2 systems containing YO1.5, CaO, and MgO. A parameter in the equation was evaluated theoretically and is given for a range of cubic solid solution compositions.

113 citations