**2.3 Experimental**

242 Ceramic Coatings – Applications in Engineering

flat surfaces with high reflective index. They reflect most of the radiant light and transmit a bit. Simultaneous reflection of light from small parallel surface layers of pigments causes the effect of deepness and brightness, such as exhibited by a pearl [2.2]. Each layer regularly reflects a part of the light and transmits the rest. The transmissible light is again reflected by other layers. Therefore, the manifestation of lustrous and interfering colours are revealed due to reflection from the interface between layers. This phenomenon is observed in natural

Pearlescent pigments are synthesized via two main methods. In the first, single crystals such as BiOCl or polycrystals like TiO2 are considered as bright and light materials due to their special structure. In the second, the pearlescent state is formed through the coating of materials with a high refractive index, (mainly metal oxide) on a transparent substrate like mica. This group is more important because of higher mechanical stability and brightness

One of the most important kinds of these pigments is TiO2 coated mica which due to its high refractive index of TiO2, has high light resistance, low cost, good chemical and heat

However, a new kind of these pigments is gold pearlescent pigment of mica-tin dioxide which is obtained through coating mica platelets by tin dioxide. This chapter section examines mica-tin dioxide and uses muscovite mica as the substrate and is prepared by laying a particle layer of tin dioxide on its surface. Due to the absorption and reflection of light in this layer, the pigment is termed a colouring pearlescent pigment. This pigment is widely used in many fields such as glass, glaze, automotive, plastics,

The main purpose of this study was to prepare pearlescent pigment and to find the optimum values of process parameters which affect its properties using the Taguchi

The Taguchi technique is a powerful tool for the design of high quality systems developed by Taguchi between 1950 to 1960 [2.4-2.6]. It provides a simple, efficient and systematic approach to optimize designs for performance, quality and cost. The methodology is valuable when design parameters are qualitative and discrete. Taguchi parameter design can optimize the performance characteristics through the setting of design parameters and reduce the sensitivity of the system performance to source of variation [2.6-2.7]. This technique is multi-step process, which follow a certain sequence for the experiments to yield an improved understanding of product or process performance. This design of experiments process is made up of three main phases: the planning phase, the conducting phase and analysis interpretation phase. The planning phase is the most important phase and one must give a maximum importance to this phase. The data collected from all the experiments in the set are analysed to determine the effect of various design parameters. This approach is to use a fractional factorial approach and this may be accomplished with the aid of orthogonal arrays. Analysis of variance is a mathematical technique, which is based on a least square approach. The treatment of the experimental results is based on the analysis of average and

pearl, fish scale, pearl body, birds feather, the butterfly wing, etc .

resistance and nontoxicity has many applications in different industries.

[2.3].

cosmetics, etc.

statistical method.

**2.2 Taguchi techniques** 

analysis of variance [2.8-2.9].
