Fluorine‐Free White Glass‐Ceramic Enamels From Uzbek Mineral Feedstocks
Shohrukh Naimov, Mastura Aripova, Odiljon Abdurakhmonov, Bakhram Ruzibayev, Zaynobiddin Matkarimov, Eldor Ruzmatov, Farrukh Erkinov, Nurbek Rakhimov, Sherzod Abdurakhmonov, Utkirjon Sharopov, Salohiddin RamazanovABSTRACT
This study presents the development of fluorine‐free white glass‐ceramic enamel coatings from locally available Uzbek mineral raw materials, including quartz sand, clay shale, boron‐ and phosphorus‐containing glass‐forming components. The enamel frits were designed in the SiO 2 –Al 2 O 3 –Na 2 O–K 2 O–B 2 O 3 –TiO 2 –P 2 O 5 multicomponent system by optimizing the contents of the principal glass‐network‐forming oxides (SiO 2 , B 2 O 3 , TiO 2 , and P 2 O 5 ) while keeping the modifier content constant. After application to DC04EK steel substrates, the coatings were produced by a two‐stage firing process. Their phase composition, microstructure, chemical bonding, optical behavior, and functional performance were comprehensively investigated using XRD, SEM–EDS, FTIR, UV–Vis spectroscopy, and standard mechanical and chemical resistance tests. The optimized compositions exhibited high whiteness values of up to 88.9%, excellent chemical resistance (Class AA), strong adhesion to the steel substrate, and good thermal‐cycling stability. XRD confirmed the crystallization of rutile‐type TiO 2 , while FTIR analysis confirmed the presence of a borosilicate glass network and SEM–EDS mapping demonstrated homogeneous elemental distribution within the enamel matrix. The coatings satisfied the requirements of ISO 28722:2008, confirming their suitability for practical application in household steel products. These results demonstrate that locally sourced mineral feedstocks can serve as a sustainable and cost‐effective basis for the production of high‐performance white glass‐ceramic enamel coatings.