33
3.5 Sintering
In this work, furnace Box Furnace Fabricated, T
1
= annealed T, R
1
= 5 °C min was used to sinter the coating layer on the stainless steel, ceramic, glass and acrylic substrates.
This process reduces dehydroxylation
3
and increases the crystallization structure of the coating material, which is to focus on the anatase structure. For this purpose coated
specimens were sintered in furnace with an annealing temperature below the melting point of each substrate.
In this research, various sintering temperatures were applied to obtain good mechanical properties for thin film coating. The substrates covered with AgTiO
2
thin films were calcined through annealing treatment in a furnace at 120, 160, 200, 400, 600
°C soaked for 1 hour, within an increasing rate of 5 °Cmin. Only acrylic substrates needs to
undergone a heat treatment at a lower temperature 120 and 160 °C compared to other
substrates due to its low melting temperature. Following this, the substrates were directly cooled down to the room temperature.
The range of temperatures was chosen because 200-600 °C was the value where all crystal anatase were gradually transformed and can be compared to each of their own
variances. At the starting temperature of 200 °C was to predict the beginning of crystal anatase transformation while at 600 °C was the starting of anatase transformation rutile
phase. However, for ceramic, the calcined temperature was only at 600 °C because of its optimum calcinations temperature had been performed onto ceramics. The same reason
was applied for the substrates involved for the deposited AgTiO
2
thin film without the Degussa P25 powder as precursor. The dipping steps for each substrate are defined in the
Table 3.2.
3
Loss of structural hydroxyl -OH ions as water molecules on heating
34
Table 3.2: Total samples and characterized by annealing temperatures
Substrate Layers
Calcined Temperature for AgTiO
2
thin film,
o
C 120
160 200
400 600
316L SS Cleaned surface
5 X
X X
Without degussa 5
X
Glass Cleaned surface
5 X
X X
Without Degussa 5
X Acrylic
Perspex Cleaned surface
5 X
X Without Degussa
5 X
Ceramic Glass 5
X Glazed ceramic
5 X
3.6 Thin film characterization