Indian Journal of Engineering & Materials Sciences Vol. 22, April 2015, pp. 215-224 An investigation of color development by means of the factorial design in wall tile glazes with ferrochromium fly ash Zahide Bayer Öztürk a *, Burçak Atay b , Münevver Çaki c & Nuran Ay d a Metallurgical and Materials Engineering Department, Nevsehir Hacı Bekta Veli University, 50300, Nevsehir, Turkey b Eczacıbaı Karo Seramik, Bozüyük, Eskisehir, Turkey c Department of Ceramic Arts, Anadolu University, 26470, Eskisehir, Turkey d Department of Materials Science Engineering, Anadolu University, 26555, Eskisehir, Turkey Received 20 September 2013; accepted 25 September 2014 In tile manufacturing; generally different glazes with 1-15 wt% pigment and dye are used to obtain aesthetic properties. It can be said that pigment and dyes are the most expensive raw materials in glaze production due to its high costs limits. Ferrochromium fly ashes are a waste material obtained from the manufacturing of ferrochromium alloy. It mainly consists of chrome, ferric oxides, CaO and also MgO and Al 2 O 3 . This study outlines a novel approach in formulating tile glaze production as coloring agent. With this aim factorial design of experiment is used for defining the main factors on color formation. These factors are calcination temperature of fly ash, amount of fly ash and type of glaze. Ferrochromium fly ash is calcined at 1000, 1100 and 1160°C for 6 h and added at 1-4 wt% to transparent, opaque and matt glaze compositions. Glazed wall tiles were sintered at 1145°C for 30 min. For comparison of the colorimetric parameters (L*, a*, b*) of glazes spectrometer is used. The crystalline phases of the obtained glazed samples and fly ashes which calcined at different temperatures and different type glazes are evaluated by X-ray diffraction and scanning electron microscopy (SEM, EDS), respectively. Different brown tones are observed related to zinc iron chromite spinel crystal structure in glazed wall tiles. The most effective factors are determined by factorial design as amount of fly ash for L* parameter, and glaze type for a*, b* parameters. Keywords: Ceramic tile, Factorial design, Fly ash, Glaze Ceramic tiles are heterogeneous materials, consisting mainly of natural raw materials with wide range in composition. Thus, these products can tolerate the substitution of different types of waste materials rather well, even in high amounts 1 . In recent years, recycling of industrial wastes has gained great attention and became a major challenge for environmental solutions by reducing natural environment pollution as contamination of soil, water and air. The usage of these wastes by incorporation into a productive cycle represents many advantages as providing alternative raw material resource for many industries, reducing production costs and saving energy 2-4 . The earlier studies 5,6 have focused evaluation of huge waste (post-treated incinerator bottom ash) obtained of new ceramics and permitted to establish a better sinter-crystallization ability for new glass formulation. Ferrochromium fly ash is a waste material existing in large scales during production of power plants which includes high amount of Cr 2 O 3 , Fe 2 O 3 and used for cement, brick and ceramic artware industries as a raw material 7,8 . Chromium and iron compounds are well known coloring materials especially in ceramic industry. In ceramic tile production, coloring agents are used at body and glaze alone or with other oxides 9,10 . In this regard, recycling of fly ashes as a raw material for colored ceramic tiles which are mainly manufactured at large scales would be a challenge for ceramic tile industry by reducing cost and providing the recovery of these wastes due to the application of its high amount of chromium and iron ingredients 11,12 . There are many factors affecting the quality and technical performances of processing during production, such as raw material selection, process equipments, etc. in ceramic industry. In order to determine the main factors influencing the characteristics of the product, experimental design methods are used. It is created by mathematical models and used to survey of qualification and determination of output and also its effectiveness. __________ *Corresponding author: (E-mail: z.ozturk@nevsehir.edu.tr)