Porcelain is a non-porous, vitrified ceramic material characterized by a white, fine-grained, and often semi-transparent body. Its superior toughness, strength, and translucency compared to other ceramic types are primarily attributed to the vitrification process and the formation of mullite phases within the body. Fly ash is a by-product collected by electrostatic precipitators in coal-fired power plants. Due to its rich elemental composition and often alkaline nature, fly ash is commonly utilized as an additive in the production of various ceramic materials. In this study, the effects of fly ash from different thermal power plants—Çatalağzı-Zonguldak (ÇAT), Çayırhan-Ankara (ÇAY), Kangal-Sivas (KAN), and Afşin-Elbistan A (AFŞ)—on the properties of porcelain bodies were investigated. To this end, commercial porcelain bodies were modified by incorporating 0%, 15%, and 30% fly ash by weight into the compositions. The powder mixtures were homogenized by ball milling at 75 rpm for 24 hours and then shaped via uniaxial dry pressing at 100 MPa. The pressed samples were subsequently fired at temperatures ranging from 1050 °C to 1150 °C for 1 hour. Comprehensive analyses were conducted on the resulting porcelain bodies, including microstructural evaluation (SEM), phase analysis (XRD), mechanical testing (three-point bending), and assessments of various physical properties such as color, linear shrinkage, water absorption, apparent porosity, and bulk density. Among the tested samples, the composition containing 15 wt.% ÇAT fly ash and fired at 1150 °C exhibited the best performance, with a compressive strength of 20.58 MPa and a water absorption rate below 0.5%. The results suggest that selected fly ash types can enhance porcelain properties while supporting waste valorization.

Keywords: Porcelain, Fly ash, Ceramic properties, Waste valorization, Sintering behavior.