The Study On The Relationship Between CAS Glass-ceramics Composition And Residual Stress

Recently, there are many researches on decorated glass-ceramics for building at home and abroad, and the main crystal phase of that is β-wollastonite. These researches cove crystallization, composition, technics, properties and so forth. With the development of CAS glass-ceramic industry, there are some intractable problems in the industry process, such as deformation and failure, which troubles the production, and leads higher cost and increases the danger in service. The residual stress in CAS glass-ceramics is the main reason for these phenomena. Unlike the normal glass, the CAS glass-ceramics, a heterogeneous composite material, consists of β -wollastonite crystal phase and glass phase. There are differences in some aspects between them, such as coefficient of thermal expansion, transition temperature, mechanical properties, microstructure, and so on, especially in the case of being heated, which inevitably induce residual stress in glass-ceramics. Though it is very valuable to study residual stress in glass-ceramics, the work in the field is not enough.Because of good elastoplasticity, mechanical properties and machinability in metal, and sophisticate elastopasticity theory, research on residual stress in metal or metal film has had a magnificent achievement. But, to the inorganic non-metal material, few reports about residual stress can be seen in the world, not to mention in-depth research. On the other hand, how to control and reduce the residual stress to minimize the breakage caused by residual stress is an important problem must be solved.So the role of measurement of residual stress is being highlighted. Now the typical means to measure residual stress are polariscope, X-ray diffraction, neutron diffraction, ultrasonic and so on. Considering the properties of CAS glass-ceramics, in this study, X-ray diffraction method on residual stresses measurement was used. Then modern testing means were used to test the properties and structure of CAS glass-ceramics, including XRD, FUR and SEM, which was useful for elucidating what influence the residual stress in CAS glass-ceramics. And the result of this research, combined with industry production, can help us to know the residual stress in other glass-ceramics and boost the invention of new glass-ceramics.In this study, we utilized the X radial incidence produced from cathode radial tube, and took the space between crystals as measurement of strain. When the stresses produced, the space between crystals changed and the diffraction peak moved during Bragg diffraction. The magnitude of movement is related to the stresses. Thus we can calculate the stress value. The test was carried out on the X-ray diffraction testinginstrument named D/Max-III A produced from RIGAKU Company of Japan.The results showed that increasing of the CaO content led to decrease initially, and then increase, and increasing of the Al2O3 content led to lower residual stress. So the optional content for CaO is from 16wt% to 18wt% and the optional content for Al2O3 is from 6wt% to 8wt%.Thanks for the financial support by National Science Foundation (50272043)!...