The Library
The fabrication and microstructural evolution, at elevated temperatures, of syalon ceramics
Tools
Tools
Tools
Winder, Stephen Morley (1985) The fabrication and microstructural evolution, at elevated temperatures, of syalon ceramics. PhD thesis, University of Warwick.
|
PDF
WRAP_Theses_Winder_1985.pdf - Submitted Version - Requires a PDF viewer. Download (9Mb) | Preview |
Official URL: http://webcat.warwick.ac.uk/record=b1445861~S15
Abstract
A number of experimental grade Syalon Ceramics, pressureless sintered materials prepared from the system Y-Si-Al-O-N, were prepared at Lucas-Cookson Syalon Ltd. (Birmingham). Different series of ceramics were composed with of α-Si3N4 powder provided by different manufacturers, and each series contained alloys of varying (effective) AIN content.
Microstructural characterisation of selected alloys was completed using the techniques of optical microscopy, x-ray diffractometry, electron microscopy with x-ray microanalysis, and energy loss spectroscopy. For 'as-sintered' ceramics, the results Indicate a trend in microstructural parameters with (effective) AIN content, such that the mean Al2O3 substitution level in the βSi6-zAlzOzN8-z (major) phase, and the N/O ratio of the inter-β (minor) glassy phase, both increase with Increased AIN addition. A linear relationship between increasing (Y + 0) content in the 'as mixed' alloy composition and increasing glass volume fraction in the microstructure, formed under given sintering conditions, was demonstrated.
Passive oxidation occurred during heat-treatment in air, in the temperature range 1100-1500°C, and formation of β-Y2Si2O7, crystals on the scale surface was noted.
Two crystalline phases, Y3Al5O12 (YAG) and α, (yttrium disilicate), were produced during devitrification of the intergranular phase, in the temperature interval 1100-1500°C. The volume ratio Y3Al5012 : Y2Si2O7, in the heat-treated microstructures, was found to increase as heat-treatment temperature and glass nitrogen content Increased.
Creep tests were performed in the temperature range 1100-1300°C and enhanced creep resistance was demonstrated for materials of lower intergranular phase content, in which nitrogen levels are higher. Morphological changes occurring in the sub-surface and bulk of the ceramics, due to oxidation and crystallisation reactions, were found to cause a time dependent transient in creep behaviour.
| Item Type: | Thesis (PhD) | ||||
|---|---|---|---|---|---|
| Subjects: | Q Science > QC Physics T Technology > TA Engineering (General). Civil engineering (General) |
||||
| Library of Congress Subject Headings (LCSH): | Ceramic materials., Ceramics -- Research, Ceramic materials -- Heat treatment | ||||
| Official Date: | September 1985 | ||||
| Dates: |
|
||||
| Institution: | University of Warwick | ||||
| Theses Department: | Department of Physics | ||||
| Thesis Type: | PhD | ||||
| Publication Status: | Unpublished | ||||
| Supervisor(s)/Advisor: | Lewis, M. H. (Mike H.) | ||||
| Sponsors: | Lucas Cookson Syalon Limited | ||||
| Format of File: | |||||
| Extent: | vi, 145, [9] leaves : illustrations, charts | ||||
| Language: | eng |
Request changes or add full text files to a record
Repository staff actions (login required)
 |
View Item |
Downloads
Downloads per month over past year
