TAN Xiang 1,2, LI Yueming 1,2, SUN Yi 1,2, BAO Yiwang 1,3, WAN Detian 1,3
(1. School of Materials Science and Engineering, Jingdezhen Ceramic Institute, Jingdezhen 333403, Jiangxi, China; 2. China National Light Industry Key Laboratory of Functional Ceramic Materials, Jingdezhen 333403, Jiangxi, China; 3. China Building Materials Academy, Beijing 100024, China)
Abstract: Analytical pure KNO3 is used as molten salt to strengthen building ceramic tiles through low temperature ion exchange. A compressive pre-stress is applied to the surface to enhance the mechanical strength of building ceramic tiles. The effects of crystalline phase, gas phase and glass phase in the ceramics, as well as the ion-exchange time, temperature and Na2O content, on enhancement and K+ distribution in the ceramic tiles have been studied. It is found that K+-Na+ ion-exchange takes place mainly in glass phase, whereas the crystalline phase and gas phase prevent the diffusion of K+. The flexural strength of the ceramic tiles are enhanced effectively after the ion exchange process. With increasing treat time, temperature and content of Na2O, the flexural strength is increased, reaches a maximum point and then decreased. The thickness of the exchange layer is increased with increasing treat time. Meanwhile, the thickness shows a maximum with the content of Na2O. The sample with 2.27 wt.% Na2O has a flexural strength of 128.5 MPa, while the value of the pristine sample is 72 MPa, with an enhancement of 78.5% after reaction at 450 ℃ for 5 h.
Key words: ion-exchange; building ceramic tile; flexural strength; pre-stress