| 1. |
- Joshi, S. V., et al.
(författare)
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Plasma spraying of biologically derived hydroxyapatite on implantable materials
- 1993
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Ingår i: Journal of Materials Science: Materials in Medicine. - : Kluwer Academic Publishers. ; 4:3, s. 251-255
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Tidskriftsartikel (refereegranskat)abstract
- Plasma spraying of hydroxyapatite (HA) coatings on human implants is considered to provide a promising means of enhancing their biocompatibility and improving tissue growth. This paper briefly describes a method of extracting HA powder from a biological source, namely human teeth. The physical and chemical characteristics of the derived powder are studied and the suitability of this powder for plasma spraying applications is ascertained. The deposited coatings are found to retain the chemistry characteristic of the apatite. Typical results of metallographic and scanning electron microscopy (SEM) studies and hardness measurements on the sprayed HA coatings are presented. © 1993 Chapman & Hall.
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| 2. |
- Chatterjee, M., et al.
(författare)
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Thermal barrier coatings from sol-gel-derived spray-grade Y2O3-ZrO2 microspheres
- 1993
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Ingår i: Journal of Materials Science. - : Kluwer Academic Publishers. ; 28:10, s. 2803-2807
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Tidskriftsartikel (refereegranskat)abstract
- For the development of ceramic thermal barrier coatings, spray-grade yttria-stabilized zirconia microspheres were prepared by the sol-gel technique. Oxide microspheres were obtained by calcination of the corresponding gel spheres at 1000 °C. Scanning electron microscopic and optical microscopic observations revealed the material thus obtained to have a predominantly spherical morphology and the requisite size distribution (5-50 μm). The dense, calcined microspheres showed good flowability. X-ray diffraction studies indicated the presence of the tetragonal polymorph of ZrO2 as the major phase, in addition to about 14% monoclinic ZrO2. The plasma-sprayed YSZ coatings made from the sol-gel-derived microspheres showed a further decrease in the monoclinic ZrO2 content (6%). The coatings survived 40-50 thermal cycles (30 min at 1200 °C followed by a water quench), indicating good thermal shock resistance. © 1993 Chapman & Hall.
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| 3. |
- Das, D. K., et al.
(författare)
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Scratch adhesion testing of plasma-sprayed yttria-stabilized zirconia coatings
- 1991
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Ingår i: Surface and Coatings Technology. ; 46:3, s. 331-345
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Tidskriftsartikel (refereegranskat)abstract
- The suitability of scratch adhesion testing, usually used for determining the critical load for thin hard coatings like TiC and TiN, in characterizing plasma-sprayed yttria-stabilized zirconia coatings is demonstrated. The effects of loading rate and scratching speed on the critical load of these sprayed coatings were studied. Although some peculiarities in acoustic signal-load plot were observed at high values of loading rate and scratching speed, it was found that these intrinsic parameters, at low and medium values, do not have any prominent effect on the critical load. © 1991.
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| 4. |
- Joshi, S. V., et al.
(författare)
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On the thermal cycling life of plasma-sprayed yttria-stabilized zirconia coatings
- 1993
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Ingår i: Surface and Coatings Technology. ; 56:3, s. 215-224
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Tidskriftsartikel (refereegranskat)abstract
- The influence of various factors on the thermal shock resistance of plasma-sprayed yttria-stabilized zirconia (YSZ) coatings was investigated. The coatings, formed using different spraying conditions, were repeatedly exposed to a thermal cycle involving a 30 minute heating period at 1200°C followed by a water quench during this study. The results suggest that, for any given YSZ powder, there exists an optimum plasma arc current for obtaining coatings that best endure such severe temperature cycling conditions. Other coating variables, such as spray distance and powder feed rate, are also observed to effect coating durability. Furthermore, the YSZ overlayer thickness and the bond coat material employed are found to be important coating life determining factors. © 1993.
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| 5. |
- Joshi, S. V., et al.
(författare)
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Plasma spraying of an indigenous yttria stabilized zirconia powder prepared by the sol-gel technique
- 1993
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Ingår i: Bulletin of Materials Science. - : Springer India. ; 16:1, s. 19-28
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Tidskriftsartikel (refereegranskat)abstract
- An indigenous sol-gel derived yttria-partially stabilized zirconia (Y-PSZ) powder has been characterized and its suitability for plasma spraying applications evaluated. The powder, determined to have about 5·1% yttria content, predominantly consisted of spherical particles with an average equivalent particle diameter close to 25 μm. Furthermore, it was found that the powder did not contain any particles >50 μm, which is considered the ideal upper size limit for spray-grade ceramic powders in order to ensure complete melting during spraying. The sol-gel produced powder exhibited good flow characteristics and the plasma sprayed coatings developed using this powder were also found to have excellent thermal shock resistance. The corresponding results obtained using an imported Y-PSZ powder are also presented for the purpose of comparison. © 1993 Indian Academy of Sciences.
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