Chemical tempering of porcelain tiles

Abstract This work presents an innovative approach for strengthening porcelain tiles via chemical tempering, which consists in replacing cations with smaller ionic radius by similar cations with larger ionic radius. Na-containing porcelain tiles were immersed into molten KNO 3 bath. A concentration profile of Na and K in the cross section of porcelain tiles to a depth of 200 µm from the surface confirmed the ion exchange. Compressive stresses on the material surface were produced, leading to flexural strength of up to 54.5 MPa (~74% increase) after chemical tempering at 360 °C during 5.5 h.