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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Internal Residual Stresses in Sintered and Commercial Low Expansion Li2O-Al2O3-SiO2 Glass-Ceramics

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Serbena, Francisco C. [1] ; Soares, Viviane Oliveira [2] ; Peitl, Oscar [2] ; Pinto, Haroldo [3] ; Muccillo, Reginaldo [4] ; Zanotto, Edgar D. [2]
Total Authors: 6
[1] State Univ Ponta Grossa UEPG, Dept Phys, BR-84030900 Ponta Grossa, PR - Brazil
[2] Fed Univ Sao Carlos UFSCar, Vitreous Mat Lab LaMaV, Dept Mat Engn DEMa, BR-13565905 Sao Carlos, SP - Brazil
[3] Univ Sao Paulo USP, Dept Mat Aeronaut & Automot Engn, Engn Sch Sao Carlos EESC, BR-13566590 Sao Carlos, SP - Brazil
[4] Ctr Sci & Technol Mat Energy & Nucl Res Inst IPE, BR-05508900 Sao Paulo - Brazil
Total Affiliations: 4
Document type: Journal article
Source: Journal of the American Ceramic Society; v. 94, n. 4, p. 1206-1214, APR 2011.
Web of Science Citations: 30

We performed Synchrotron X-ray diffraction (XRD) analyses of internal residual stresses in monolithic samples of a newly developed Li(2)O-Al(2)O(3)-SiO(2) (LAS) glass-ceramic produced by sintering and in a commercial LAS glass-ceramic, CERAN (R), produced by the traditional crystal nucleation and growth treatments. The elastic constants were measured by instrumented indentation and a pulse-echo technique. The thermal expansion coefficient of virgilite was determined by high temperature XRD and dilatometry. The c-axis contracts with the increasing temperature whereas the a-axis does not vary significantly. Microcracking of the microstructure affects the thermal expansion coefficients measured by dilatometry and thermal expansion hysteresis is observed for the sintered glass-ceramic as well as for CERAN (R). The measured internal stress is quite low for both glass-ceramics and can be explained by theoretical modeling if the high volume fraction of the crystalline phase (virgilite) is considered. Using a modified Green model, the calculated critical (glass) island diameter for spontaneous cracking agreed with experimental observations. The experimental data collected also allowed the calculation of the critical crystal grain diameters for grain-boundary microcracking due to the anisotropy of thermal expansion of virgilite and for microcracking in the residual glass phase surrounding the virgilite particles. All these parameters are important for the successful microstructural design of sintered glass-ceramics. (AU)

FAPESP's process: 07/08179-9 - Kinetic processes in glasses and glass ceramics
Grantee:Edgar Dutra Zanotto
Support type: Research Projects - Thematic Grants
FAPESP's process: 05/53241-9 - Study of intergranular phenomena in ceramic materials
Grantee:Reginaldo Muccillo
Support type: Research Projects - Thematic Grants