# Application ofβ-Wollastonite on Bulk Density and Ignition Loss of Clay-Based Ceramic Materials

Authors: Chirotaw Getem Zenebe
Journal: Advances in Materials Science and Engineering
 (2022)

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## Abstract

This work focuses on the effect ofβ-wollastonite percentage with different particle sizes on the bulk density and weight loss of clay-based ceramics. The ceramic bodies were prepared by mixing clay with a synthesized β-wollastonite (5%, 15%, and 25%) using a solid slip casting method. The clay (75 µm) and β-wollastonite (63, 75, and 125 µm) were mixed and fired at 950°C, 1000°C, and 1050°C of firing temperatures. The fabricated ceramic material exhibited a maximum bulk density of 2.35 g/cm3 on 25% content of β-wollastonite, 63 µm particle size of β-wollastonite, and 1050°C of firing temperature. However, a minimum bulk density of 1.87 g/cm3 was found on 25% content of β-wollastonite, 125 µm particle size of β-wollastonite, and 950°C firing temperature. A minimum of 2.32% ignition loss was recorded on a ceramic specimen that contained 25% of β-wollastonite with a particle size of 125 µm and fired at 950°C of firing temperature. In contrast, a maximum of 4.37% ignition loss was observed at a ceramic body made up of 5% of β-wollastonite content with 63 µm particle sizes and fired at 1050°C. In general, the result shows that the firing temperature, the particle size of β–wollastonite, and the addition of β–wollastonite have a great effect on the bulk density and ignition loss of the clay ceramic materials.


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## Body

## 1. Introduction

Ceramic materials are mainly made of clays and/or other inorganic raw materials and are important construction materials employed in most construction sectors. Ceramics are made by starting with the raw material, grinding and combining it, and then usually shaping it at room temperature. After that, it is dried and finally fired at a temperature high enough to impart the necessary qualities [1]. The completed ceramic material’s quality and cost are influenced by the raw materials composition, fire cycle [2], mixing ratios [3, 4], and raw material particle size [5]. Because of technological advancement and market movements, the ceramic sector may be a dynamic one with a complex picture of products and operations [6]. This technological evolution has directly entailed raw material formulations. For this study, the ceramic material specimens were made up of clay and synthesized β-Wollastonite.The term “clay” is typically used to refer to all sedimentary rocks that have been compressed more or less and are the result of changes in fundamental rocks. These rocks are primarily composed of “clayey minerals” of the micronic dimension. Minerals with a clay foundation make up the majority of ceramic bodies; their percentage typically ranges from 40 to 60%. In addition to the main oxides involved in the body’s consolidation mechanism during burning, they also supply plasticity and workability in the green state, as well as fluxes and sintering aids [7, 8]. For the features of ceramics, clays made of pyrophyllite, talc, kaolinite, and montmorillonite are necessary [9]. Clay minerals are among the maximum ample minerals on Earth and are of substantial interest due to their low cost [10]. Natural clay deposits are the primary source of materials for light structural ceramics with good mechanical qualities including low shrinkage and heat transmission [11].β-Wollastonite (βCaSiO3) is a naturally occurring form of calcium silicate with acicular crystal addiction [12]. Naturally, calcium silicate has two polymorphic forms as follows: wollastonite, low-temperature phase β-wollastonite and pseudowollastonite, high-temperature phase α-wollastonite [13]. Wollastonite is most frequently encountered as an impure limestone that has undergone thermal metamorphism, but it can also form when silicon is present as a result of metamorphism in contact with altered calcareous sediments or contamination in the encroaching igneous rock [14]. The β-wollastonite mineral phase is produced at lower temperatures and the phase transition temperature to α-wollastonite is more than 1125°C [15].β-Wollastonite is an extremely interesting but little-studied material that has a combination of properties, such as lack of volatile constituents, fluxing characteristics, low dielectric constant, low dielectric loss, thermal stability, low thermal expansion, low loss on ignition and low thermal conductivity, hence is used in ceramic fabrication, medical material for artificial bones and dental roots, high-frequency insulator, filler material in resins and plastics, paper, civil construction, ceramic glazes, metallurgy, paint, and frictional products [16–19].Ethiopia’s geological formation revealed nothing aboutβ-wollastonite. Ethiopian ceramic and paint factories import β-wollastonite from overseas international locations [20]. To make the most of available resources, past research concentrated on creating β-wollastonite from rice husk and limestone. It was identified using Fourier transform infrared spectroscopy (FTIR) which is also used as a reinforcing filler in the production of ceramic tiles. The results showed that there was a considerable effect on the linear shrinkage, water absorption, acid resistance, and compressive strength of ceramic tile [21]. The present work intends to apply the synthesized β-wollastonite to investigate its effect on the ignition weight loss and bulk density of clay ceramic materials.


## 2. Materials and Methods

### 2.1. Materials

The raw materials wereβ-wollastonite and clay. β-Wollastonite was synthesized and characterized in previous work [21]. Clay was obtained from Kalu Woreda, South Wollo, Ethiopia. Disk mill and ultracentrifugal were used to mill clay and β-wollastonite. Fourier transforms infrared spectrometer was used for the qualitative characterization of surface functional groups present in the clay mineral. Likewise, sieves were used to sieve clay and β-wollastonite. The compactor was used for compacting a green body during casting into a rectangular mold. A digital balance and a standard ruler were used to weigh and measure green body dimensions and ceramic materials, respectively. An electric oven was used for drying clay and green body samples. The electric furnace was used for firing the green body, to transform into ceramic materials.


### 2.2. Methods

#### 2.2.1. Determination of Organic Matter (SOM) and Carbonate Mineral Content (CMC) of Clay

The loss on ignition method was used to examine the clay sample to measure the SOM and CMC (and indirectly of organic and inorganic carbon). The production of pores and cracks in ceramic materials during burning is attributed to the soil’s organic matter and carbonate mineral concentration, which has been extensively measured using the loss on ignition method. The soil sample was sieved using a 2 mm sieve after being air dried. Following overnight oven drying at 105°C, the sample was cooled in a desiccator and weighed (W1). It was then burned at 550°C for 4 hours in an electric furnace, cooled, and weighed (W2) before being burned at 950°C for 12 hours (W3) [22, 23].(1)SOM=W1−W2W1×100,(2)CMC=W2−W3W1×100.


#### 2.2.2. Fourier Transforms Infrared Spectroscopy (FTIR)

To pinpoint the important functional groups of the clay material, FTIR spectroscopy equipment is used. It examines a sample using infrared light, a range of frequencies below the visible spectrum. To make the pellets, 100 mg of KBr were combined with 1 mg (or 63µm) of the sample. The FTIR spectra were captured with a resolution of 4 cm-1 and an ordinate unit of transmittance throughout a wavenumber range of 4000–400 cm-1 (percent) [24].


#### 2.2.3. X-Ray Diffraction (XRD)

For the investigation of crystal materials and atomic spacing at a fixed wavelength (λ) and varied orientations (θ), XRD is a technique. The β-wollastonite sample was ground to a particle size of < 63 µm, and XRD patterns were captured at room temperature using a powder X-ray diffractometer. Cu-Kα1 (λ = 1.540593 Å) was used as the radiation source, and the X-ray patterns were obtained by feeding the X-ray generator 40 kV and 40 mA. A 400 second scanning period was used to observe spectra with steps of 0.052° from 0 to 60° [25].


#### 2.2.4. Determination of Weight Loss ofβ-Wollastonite

Ten grams of driedβ-wollastonite was sintered at 950°C for 2 hours in an electrical furnace. The weight loss of the sample due to thermal decomposition is the difference between the sample’s initial weight and its weight following firing. It is expressed as a percentage based on the weight of the sample before firing or after firing.(3)Weight  loss=Dried Weight−firied WeightDried Weight×100.


#### 2.2.5. Manufacturing of Ceramic Sample

Clay was separated manually from its impurities and soaked in water for 3 days and washed to take away undesirable matters. Then, it was dried overnight in an oven at 105°C and then added to the disk mill then handover to the ultracentrifugal mill. The powdered clay was then passed through a sieve with a nominal aperture of 75µm (Figure 1(a)) whereas the β-wollastonite was sieved in three different sieves with nominal apertures of 63 µm, 75 µm, and 125 µm. β-wollastonite was mixed with clay in three different weight proportions of 5%, 15%, and 25% (Figure 1(b)). Following vigorous mixing until the mixture was easy to work with by hand, tap water (10% by mass) was added to the mixture and left to stand for 16 hours. The mixtures were cast into rectangular (120 × 65 × 8 mm3) formwork (mold) (Figure 1(c)) and compacted by applied uniform pressure (20 MPa). The green bodies formed were then covered and kept in the cabinet for two days in open-air to slowly lose their moisture content. After that, the green bodies were opened and then dried at 105°C in an oven for twenty-four hours. The dried bodies were loaded into the furnace and heated at 5°C/min until 250°C and held at this temperature for half an hour. Then, the temperature was gradually increased to 950°C, 1000°C, and 1050°C at a heating rate of 10°C/min and allowed for an hour to make sure complete firing. The ceramic materials were then allowed to cool in the furnace to room temperature as shown in Figure 1(d).Figure 1
Manufacturing of ceramic materials: (a) clay, (b) mixture of clay andβ-wollastonite, (c) formwork (mold), and (d) ceramic materials.


#### 2.2.6. Determination of Bulk Density (BD)

The ceramic material’s bulk volume and burned weight were divided to determine its bulk density (BD). Using the ceramic body’s dimensions after firing, the bulk volume was estimated. The formula is given by (4) [26].(4)BDg/cm3=Fired WeightgBulk Volumecm3.


#### 2.2.7. Determination of Loss on Ignition (LOI)

The ignition of each of the volatile components yielded the LOI. Equation (5) is used to determine the LOI, which is the difference between the material’s dried weight (DW) and its weight after firing (FW).(5)LOI%=Dw−FwDw×100.


## 2.1. Materials

The raw materials wereβ-wollastonite and clay. β-Wollastonite was synthesized and characterized in previous work [21]. Clay was obtained from Kalu Woreda, South Wollo, Ethiopia. Disk mill and ultracentrifugal were used to mill clay and β-wollastonite. Fourier transforms infrared spectrometer was used for the qualitative characterization of surface functional groups present in the clay mineral. Likewise, sieves were used to sieve clay and β-wollastonite. The compactor was used for compacting a green body during casting into a rectangular mold. A digital balance and a standard ruler were used to weigh and measure green body dimensions and ceramic materials, respectively. An electric oven was used for drying clay and green body samples. The electric furnace was used for firing the green body, to transform into ceramic materials.


## 2.2. Methods

### 2.2.1. Determination of Organic Matter (SOM) and Carbonate Mineral Content (CMC) of Clay

The loss on ignition method was used to examine the clay sample to measure the SOM and CMC (and indirectly of organic and inorganic carbon). The production of pores and cracks in ceramic materials during burning is attributed to the soil’s organic matter and carbonate mineral concentration, which has been extensively measured using the loss on ignition method. The soil sample was sieved using a 2 mm sieve after being air dried. Following overnight oven drying at 105°C, the sample was cooled in a desiccator and weighed (W1). It was then burned at 550°C for 4 hours in an electric furnace, cooled, and weighed (W2) before being burned at 950°C for 12 hours (W3) [22, 23].(1)SOM=W1−W2W1×100,(2)CMC=W2−W3W1×100.


### 2.2.2. Fourier Transforms Infrared Spectroscopy (FTIR)

To pinpoint the important functional groups of the clay material, FTIR spectroscopy equipment is used. It examines a sample using infrared light, a range of frequencies below the visible spectrum. To make the pellets, 100 mg of KBr were combined with 1 mg (or 63µm) of the sample. The FTIR spectra were captured with a resolution of 4 cm-1 and an ordinate unit of transmittance throughout a wavenumber range of 4000–400 cm-1 (percent) [24].


### 2.2.3. X-Ray Diffraction (XRD)

For the investigation of crystal materials and atomic spacing at a fixed wavelength (λ) and varied orientations (θ), XRD is a technique. The β-wollastonite sample was ground to a particle size of < 63 µm, and XRD patterns were captured at room temperature using a powder X-ray diffractometer. Cu-Kα1 (λ = 1.540593 Å) was used as the radiation source, and the X-ray patterns were obtained by feeding the X-ray generator 40 kV and 40 mA. A 400 second scanning period was used to observe spectra with steps of 0.052° from 0 to 60° [25].


### 2.2.4. Determination of Weight Loss ofβ-Wollastonite

Ten grams of driedβ-wollastonite was sintered at 950°C for 2 hours in an electrical furnace. The weight loss of the sample due to thermal decomposition is the difference between the sample’s initial weight and its weight following firing. It is expressed as a percentage based on the weight of the sample before firing or after firing.(3)Weight  loss=Dried Weight−firied WeightDried Weight×100.


### 2.2.5. Manufacturing of Ceramic Sample

Clay was separated manually from its impurities and soaked in water for 3 days and washed to take away undesirable matters. Then, it was dried overnight in an oven at 105°C and then added to the disk mill then handover to the ultracentrifugal mill. The powdered clay was then passed through a sieve with a nominal aperture of 75µm (Figure 1(a)) whereas the β-wollastonite was sieved in three different sieves with nominal apertures of 63 µm, 75 µm, and 125 µm. β-wollastonite was mixed with clay in three different weight proportions of 5%, 15%, and 25% (Figure 1(b)). Following vigorous mixing until the mixture was easy to work with by hand, tap water (10% by mass) was added to the mixture and left to stand for 16 hours. The mixtures were cast into rectangular (120 × 65 × 8 mm3) formwork (mold) (Figure 1(c)) and compacted by applied uniform pressure (20 MPa). The green bodies formed were then covered and kept in the cabinet for two days in open-air to slowly lose their moisture content. After that, the green bodies were opened and then dried at 105°C in an oven for twenty-four hours. The dried bodies were loaded into the furnace and heated at 5°C/min until 250°C and held at this temperature for half an hour. Then, the temperature was gradually increased to 950°C, 1000°C, and 1050°C at a heating rate of 10°C/min and allowed for an hour to make sure complete firing. The ceramic materials were then allowed to cool in the furnace to room temperature as shown in Figure 1(d).Figure 1
Manufacturing of ceramic materials: (a) clay, (b) mixture of clay andβ-wollastonite, (c) formwork (mold), and (d) ceramic materials.


### 2.2.6. Determination of Bulk Density (BD)

The ceramic material’s bulk volume and burned weight were divided to determine its bulk density (BD). Using the ceramic body’s dimensions after firing, the bulk volume was estimated. The formula is given by (4) [26].(4)BDg/cm3=Fired WeightgBulk Volumecm3.


### 2.2.7. Determination of Loss on Ignition (LOI)

The ignition of each of the volatile components yielded the LOI. Equation (5) is used to determine the LOI, which is the difference between the material’s dried weight (DW) and its weight after firing (FW).(5)LOI%=Dw−FwDw×100.


## 2.2.1. Determination of Organic Matter (SOM) and Carbonate Mineral Content (CMC) of Clay

The loss on ignition method was used to examine the clay sample to measure the SOM and CMC (and indirectly of organic and inorganic carbon). The production of pores and cracks in ceramic materials during burning is attributed to the soil’s organic matter and carbonate mineral concentration, which has been extensively measured using the loss on ignition method. The soil sample was sieved using a 2 mm sieve after being air dried. Following overnight oven drying at 105°C, the sample was cooled in a desiccator and weighed (W1). It was then burned at 550°C for 4 hours in an electric furnace, cooled, and weighed (W2) before being burned at 950°C for 12 hours (W3) [22, 23].(1)SOM=W1−W2W1×100,(2)CMC=W2−W3W1×100.


## 2.2.2. Fourier Transforms Infrared Spectroscopy (FTIR)

To pinpoint the important functional groups of the clay material, FTIR spectroscopy equipment is used. It examines a sample using infrared light, a range of frequencies below the visible spectrum. To make the pellets, 100 mg of KBr were combined with 1 mg (or 63µm) of the sample. The FTIR spectra were captured with a resolution of 4 cm-1 and an ordinate unit of transmittance throughout a wavenumber range of 4000–400 cm-1 (percent) [24].


## 2.2.3. X-Ray Diffraction (XRD)

For the investigation of crystal materials and atomic spacing at a fixed wavelength (λ) and varied orientations (θ), XRD is a technique. The β-wollastonite sample was ground to a particle size of < 63 µm, and XRD patterns were captured at room temperature using a powder X-ray diffractometer. Cu-Kα1 (λ = 1.540593 Å) was used as the radiation source, and the X-ray patterns were obtained by feeding the X-ray generator 40 kV and 40 mA. A 400 second scanning period was used to observe spectra with steps of 0.052° from 0 to 60° [25].


## 2.2.4. Determination of Weight Loss ofβ-Wollastonite

Ten grams of driedβ-wollastonite was sintered at 950°C for 2 hours in an electrical furnace. The weight loss of the sample due to thermal decomposition is the difference between the sample’s initial weight and its weight following firing. It is expressed as a percentage based on the weight of the sample before firing or after firing.(3)Weight  loss=Dried Weight−firied WeightDried Weight×100.


## 2.2.5. Manufacturing of Ceramic Sample

Clay was separated manually from its impurities and soaked in water for 3 days and washed to take away undesirable matters. Then, it was dried overnight in an oven at 105°C and then added to the disk mill then handover to the ultracentrifugal mill. The powdered clay was then passed through a sieve with a nominal aperture of 75µm (Figure 1(a)) whereas the β-wollastonite was sieved in three different sieves with nominal apertures of 63 µm, 75 µm, and 125 µm. β-wollastonite was mixed with clay in three different weight proportions of 5%, 15%, and 25% (Figure 1(b)). Following vigorous mixing until the mixture was easy to work with by hand, tap water (10% by mass) was added to the mixture and left to stand for 16 hours. The mixtures were cast into rectangular (120 × 65 × 8 mm3) formwork (mold) (Figure 1(c)) and compacted by applied uniform pressure (20 MPa). The green bodies formed were then covered and kept in the cabinet for two days in open-air to slowly lose their moisture content. After that, the green bodies were opened and then dried at 105°C in an oven for twenty-four hours. The dried bodies were loaded into the furnace and heated at 5°C/min until 250°C and held at this temperature for half an hour. Then, the temperature was gradually increased to 950°C, 1000°C, and 1050°C at a heating rate of 10°C/min and allowed for an hour to make sure complete firing. The ceramic materials were then allowed to cool in the furnace to room temperature as shown in Figure 1(d).Figure 1
Manufacturing of ceramic materials: (a) clay, (b) mixture of clay andβ-wollastonite, (c) formwork (mold), and (d) ceramic materials.


## 2.2.6. Determination of Bulk Density (BD)

The ceramic material’s bulk volume and burned weight were divided to determine its bulk density (BD). Using the ceramic body’s dimensions after firing, the bulk volume was estimated. The formula is given by (4) [26].(4)BDg/cm3=Fired WeightgBulk Volumecm3.


## 2.2.7. Determination of Loss on Ignition (LOI)

The ignition of each of the volatile components yielded the LOI. Equation (5) is used to determine the LOI, which is the difference between the material’s dried weight (DW) and its weight after firing (FW).(5)LOI%=Dw−FwDw×100.


## 3. Results and Discussion

### 3.1. Weight Loss ofβ-Wollastonite

The weight loss ofβ-wollastonite was determined by sintering at 950°C for 2 hours in three runs of experiments. The weight of the three samples is weighed before and after ignited. The average weight of the sample after sintered is 9.92 g. Therefore, the average weight loss is 0.8%. This implies the weight loss due to ignition up to 950°C is low. The previous [27] study found that the pure β-wollastonite has a loss on ignition of less than 1%, which reduces gas evolution during firing and attributes it to a smooth surface with diminished pinhole problems. Thus, the result is consistent with the previous works.


### 3.2. Powder X-Ray Diffraction (XRD)

Figure2 illustrates the results of an XRD investigation into the phase-formation behavior of β-wollastonite throughout the impregnation and calcination processes. With only a little quantity of amorphous phase, it appears that nearly all peaks were connected to triclinic-β-wollastonite, which had the highest relative intensity (98.8%) at a diffraction angle of 2θ equal to 34.5° (d = 2.6 Å). According to XRD data at 2θ, the peak temperatures for β-wollastonite are 16.56°, 18.3°, 29.1°, 31.2°, 32.51°, 33.01°, 34.5°, 41.62°, 45.93°, 47.63°, and 51.22°. The XRD pattern found by Obeid [19], in which the highest peak was noted at 2θ equal to 33.05°, supports this conclusion [19].Figure 2
X-ray diffraction ofβ-wollastonite.


### 3.3. Soil Organic Matter (SOM) and Carbonate Mineral Content (CMC)

Clay sample SOM and CMC determinations were carried out. Clay soil has an average SOM and CMC of 11.4% and 0.5%, respectively. The results revealed that the clay contains little carbonate and organic materials. According to Stefanie A. Mayer [28], organic matter starts to burn at temperatures of around 200°C and burns out completely at around 550°C (Stefanie [28], while the majority of carbonate minerals are destroyed at temperatures of 950°C [29, 30].


### 3.4. FTIR Spectra Analysis of Clay

The major functional groups present in the clay mineral were identified by the FTIR spectra as shown in Figure3. Region 3800–3000 cm-1 (O-H stretching region) identified kaolinite associated with octahedral stretch vibrations from OH [31]. The absorption band at 3620 cm-1, is attributed to water molecules weakly hydrogen-bonded to the AlAl-OH and stretching vibrations. The H-O-H symmetric stretching vibration (broadband at 3434 cm–1) and the O-H bending vibration (band at 1637 cm–1) were observed, respectively. The peak observed at 1033 cm-1 and 789 cm-1 are attributed to the Si-O symmetric vibrational stretching. The other peaks observed at 540 and 468 cm-1 are assigned to Si-O-Al (octahedral Al) and Si-O-Si bending vibrations, respectively [32].Figure 3
FTIR spectra of clay.


### 3.5. Effect of Operating Conditions

Twenty-seven groups of specimens containing different combinations of clay andβ-wollastonite and particle sizes were fired according to three different firing temperatures. Then, the bulk density and loss on ignition of the ceramic bodies were determined. To investigate the effect of β-wollastonite content the firing temperature must be kept below 1125°C (changed to α-wollastonite at 1125°C). Additionally, adsorbed and crystalline water must be eliminated in order to produce high-strength ceramic bodies. The volatile components must also be entirely eliminated or broken down. Therefore, 950°C, 1000°C, and 1050°C were chosen as the ceramic bodies’ firing temperatures.


#### 3.5.1. Effect of Operating Conditions on Bulk Density (BD)

The influence of firing temperature (FT), amount ofβ-wollastonite added (AW), and particle size of β-wollastonite (PS) on the BD of ceramic materials were studied. Table 1 below lists the typical bulk densities of the ceramic specimens.Table 1
Average values of BD.
FactorsFT (950°C)FT (1000°C)FT (1050°C)AW (%)AW (%)AW (%)PS (µm)515255152551525631.962.032.082.032.072.082.192.262.35751.911.931.961.992.032.042.112.132.171251.891.881.871.951.931.922.082.052.03Figure4(a) illustrates the effect of firing temperature on the bulk density of ceramic materials. It has been found that the firing temperature increases the bulk density of ceramic material. The bulk densities on average for firing temperatures of 950, 1000, and 1050°C are 1.94, 2, and 2.15 g/cm3, respectively. The pore in green bodies is filled as a result of the grain beginning to develop in the hole part of the bodies when the firing temperature is raised from 950°C to 1050°C, and the bulk densities increased correspondingly. Another study found that the bulk density of ceramic materials increased as the firing temperature increased [33, 34]. The lower temperature was not high enough to encourage densification, which would have substantially closed the pore created during green body casting [35].Figure 4
Effect of FT and AW (a), PS and FT (b), and PS and AW (c) on BD.
(a)(b)(c)As can be seen in Figure4(a), bulk density also varies due to the variation of the amount of β-wollastonite incorporated into ceramic materials. The average bulk density for the addition of 5%, 15%, and 25% of β-wollastonite is 2.01, 2.03, and 2.05 g/cm3, respectively. As the amount of β-wollastonite increased from 5 to 25%, the bulk density of ceramic materials increased since β-wollastonite is denser than clay soils [36]. Previous research showed that ceramic bodies made up of pure clay exhibited a low bulk density (1.64 g/cm3) [37]. The firing temperature and amount of β-wollastonite have no synergetic effect (p>0.05) on the bulk density of ceramic material. However, the bulk density of ceramic materials increases with both firing temperature and the amount of β-wollastonite increases as shown in Figure 4(a).The bulk density of ceramic materials is decreased when the particle size ofβ-wollastonite increased as shown in Figure 4(b). This is due to the fine particles are easy to compact during green ceramic body casting and also have a big tendency of flowability during firing compared to the coarse particles. It is possible to increase the bulk density and decrease the porosity of the ceramic body with the addition of fine particles to larger granule blends. This can be accounted for by the fact that the little particles fill in the voids left by the giant particles without expanding the volume of the entire system [38].The average bulk densities are 2.11, 2.03, and 1.95 g/cm3 for 63, 75, and 125 µm particle sizes of β-wollastonite, respectively. Figure 4(b) also confirms that there is no significant interaction effect (p>0.05) between the firing temperature and the particle size of β-wollastonite on the bulk density of ceramic materials. The bulk density is decreased when the particle size of β-wollastonite increased for each firing temperature. However, the maximum bulk density was recorded for 63 µm particle size of β-wollastonite and 1050°C firing temperature since finer particles are easy to deform (flow) and fill the voids than coarse particles. This finding also suggests that bulk density for ceramic materials fired at high temperatures (1050°C) varies widely.As can be seen in Figure4(c), there is a synergetic effect on the particle size and amount of β-wollastonite added to the bulk density of ceramic materials (p<0.05). When the particle size of β-wollastonite increased (63 to 125 µm) the bulk density decreased by 4.29% (2.06 to 1.97 g/cm3), 7.87% (2.12 to 1.95 g/cm3), and 10.46% (2.17 to 1.94 g/cm3) for 5%, 15% and 25% of the β-wollastonite composition, respectively. The material which contains 25% of β-wollastonite is rapidly decreased than the remaining two concentrations. This implies that the ceramic materials with a 25% concentration of β-wollastonite and with a coarse particle size (125 µm) have the lowest bulk density.


#### 3.5.2. Effect of Operating Conditions on Loss on Ignition (LOI)

The main and synergetic effect of Firing Temperature (FT), the amount ofβ-wollastonite added (AW), and particle size of β-wollastonite (PS) on the LOI of ceramic materials were investigated. Table 2 contains the average LOI values for ceramic specimens.Table 2
The average value of LOI.
FactorsFT (950°C)FT (1000°C)FT (1050°C)AW (%)AW (%)AW (%)PS (µm)515255152551525633.993.082.634.323.273.074.373.343.1753.973.052.484.253.232.994.33.313.041253.882.972.324.153.22.694.213.252.74Figure5 shows the effect of firing temperature on the LOI of ceramic materials. The average values are 3.15, 3.46, and 3.52% for firing temperatures of 950, 1000, and 1050°C, respectively. The LOI is increased by 9.85% and 1.58% when the firing temperature is raised from 950 to 1000°C and then to 1050°C, respectively. Similar studies showed that the LOI of the ceramic materials rose with the firing temperature [39]. Between the temperature range of 950°C and 1000°C, the highest change in the LOI was observed. This is because the materials’ volatile components, which cause weight loss upon ignition, were either eliminated or destroyed at temperatures below 1000°C. Additionally, most carbonates and organic materials ignite at temperatures below 1000°C [40]. On the other hand, less organic matter could be detected in the materials burned between 1000°C and 1050°C temperatures. Higher temperatures can also drive off structural water from clays and β-wollastonite [39].Figure 5
Effect of FT and AW (a), PS and FT (b), and PS and AW (c) on LOI.
(a)(b)(c)The LOI of ceramic materials is decreased as the quantity ofβ-wollastonite added increases (see Figure 5(a)). Because, the amount of organic matter, inorganic carbon, and miner organic residue existing in the clay is substantially replaced by β-wollastonite. Besides, the LOI of β-wollastonite is low compared to clay. A comparable result has been reported elsewhere [27, 41] that the presence of β-wollastonite decreases the gas exchange during firing which is a low loss on ignition. The average results of the LOI of ceramic materials are 4.16, 3.19, and 2.79% for the addition of 5, 15, and 25% of β-wollastonite. Ceramic bodies prepared from pure clay exhibited high weight loss on ignition (9.7%) [37]. Figure 5(a) also shows the synergetic effect of firing temperature and the amount of β-wollastonite on the LOI of ceramic materials. There is no interaction effect between firing temperature and the addition of β-wollastonite (p>0.05) on the LOI of ceramic materials. When the composition of β-wollastonite increased from 5 to 25% the loss on ignition of ceramic materials decreased by 37.16% (3.95 to 2.48%), 31.21% (4.24 to 2.92%), and 31% (4.29 to 2.96%) for firing temperature of 950°C, 1000°C, and 1050°C, respectively.Figure5(b) shows the effect of particle size of β-wollastonite on the LOI of ceramic materials. It is observed that the LOI is decreased with an increase in particle size of β-wollastonite. The finer particles completely ignited compared to coarse particles due to their greater specific surface area and greater heat exposure [42]. The weight loss due to the gases off during ignition is the main cause of the formation of pores and cracks. The average values are 3.46, 3.4, and 3.27%. Figure 5(b) also shows the interaction effect between the firing temperature and particle size of β-wollastonite on the LOI of ceramic materials (p>0.05). The LOI of ceramic materials shows a small variation between firing temperatures 1000 and 1050°C when the particle size of β-wollastonite increased from 63 to 125 µm. On the other hand, the ceramic material is fired at 950°C has a low LOI. The average values of loss on ignition of ceramic materials for each particle size of β-wollastonite (63, 75, and 125 µm) are 3.24, 3.17, and 3.06%, 3.55, 3.49, and 3.35%, and 3.6, 3.55, and 3.4% for firing temperature of 950°C, 1000°C, and 1050°C, respectively.There is no significant interaction effect between the amount ofβ-wollastonite added and particle size of β-wollastonite (p>0.05) on the LOI as shown in Figure 5(c). The LOI of ceramic materials exhibited a large variation for ceramics made from 25% of β-wollastonite and 125 µm particle size of β-wollastonite. The coarse particle takes more time and energy to complete the ignition process compared to the fine particle. The amount of β-wollastonite increased from 5 to 25% the LOI reduced by 30.57% (4.23 to 2.93), 31.97% (4.17 to 2.84), and 36.62% (4.08 to 2.58) for 63, 75 and 125 µm of particle size of β-wollastonite, respectively.


## 3.1. Weight Loss ofβ-Wollastonite

The weight loss ofβ-wollastonite was determined by sintering at 950°C for 2 hours in three runs of experiments. The weight of the three samples is weighed before and after ignited. The average weight of the sample after sintered is 9.92 g. Therefore, the average weight loss is 0.8%. This implies the weight loss due to ignition up to 950°C is low. The previous [27] study found that the pure β-wollastonite has a loss on ignition of less than 1%, which reduces gas evolution during firing and attributes it to a smooth surface with diminished pinhole problems. Thus, the result is consistent with the previous works.


## 3.2. Powder X-Ray Diffraction (XRD)

Figure2 illustrates the results of an XRD investigation into the phase-formation behavior of β-wollastonite throughout the impregnation and calcination processes. With only a little quantity of amorphous phase, it appears that nearly all peaks were connected to triclinic-β-wollastonite, which had the highest relative intensity (98.8%) at a diffraction angle of 2θ equal to 34.5° (d = 2.6 Å). According to XRD data at 2θ, the peak temperatures for β-wollastonite are 16.56°, 18.3°, 29.1°, 31.2°, 32.51°, 33.01°, 34.5°, 41.62°, 45.93°, 47.63°, and 51.22°. The XRD pattern found by Obeid [19], in which the highest peak was noted at 2θ equal to 33.05°, supports this conclusion [19].Figure 2
X-ray diffraction ofβ-wollastonite.


## 3.3. Soil Organic Matter (SOM) and Carbonate Mineral Content (CMC)

Clay sample SOM and CMC determinations were carried out. Clay soil has an average SOM and CMC of 11.4% and 0.5%, respectively. The results revealed that the clay contains little carbonate and organic materials. According to Stefanie A. Mayer [28], organic matter starts to burn at temperatures of around 200°C and burns out completely at around 550°C (Stefanie [28], while the majority of carbonate minerals are destroyed at temperatures of 950°C [29, 30].


## 3.4. FTIR Spectra Analysis of Clay

The major functional groups present in the clay mineral were identified by the FTIR spectra as shown in Figure3. Region 3800–3000 cm-1 (O-H stretching region) identified kaolinite associated with octahedral stretch vibrations from OH [31]. The absorption band at 3620 cm-1, is attributed to water molecules weakly hydrogen-bonded to the AlAl-OH and stretching vibrations. The H-O-H symmetric stretching vibration (broadband at 3434 cm–1) and the O-H bending vibration (band at 1637 cm–1) were observed, respectively. The peak observed at 1033 cm-1 and 789 cm-1 are attributed to the Si-O symmetric vibrational stretching. The other peaks observed at 540 and 468 cm-1 are assigned to Si-O-Al (octahedral Al) and Si-O-Si bending vibrations, respectively [32].Figure 3
FTIR spectra of clay.


## 3.5. Effect of Operating Conditions

Twenty-seven groups of specimens containing different combinations of clay andβ-wollastonite and particle sizes were fired according to three different firing temperatures. Then, the bulk density and loss on ignition of the ceramic bodies were determined. To investigate the effect of β-wollastonite content the firing temperature must be kept below 1125°C (changed to α-wollastonite at 1125°C). Additionally, adsorbed and crystalline water must be eliminated in order to produce high-strength ceramic bodies. The volatile components must also be entirely eliminated or broken down. Therefore, 950°C, 1000°C, and 1050°C were chosen as the ceramic bodies’ firing temperatures.


### 3.5.1. Effect of Operating Conditions on Bulk Density (BD)

The influence of firing temperature (FT), amount ofβ-wollastonite added (AW), and particle size of β-wollastonite (PS) on the BD of ceramic materials were studied. Table 1 below lists the typical bulk densities of the ceramic specimens.Table 1
Average values of BD.
FactorsFT (950°C)FT (1000°C)FT (1050°C)AW (%)AW (%)AW (%)PS (µm)515255152551525631.962.032.082.032.072.082.192.262.35751.911.931.961.992.032.042.112.132.171251.891.881.871.951.931.922.082.052.03Figure4(a) illustrates the effect of firing temperature on the bulk density of ceramic materials. It has been found that the firing temperature increases the bulk density of ceramic material. The bulk densities on average for firing temperatures of 950, 1000, and 1050°C are 1.94, 2, and 2.15 g/cm3, respectively. The pore in green bodies is filled as a result of the grain beginning to develop in the hole part of the bodies when the firing temperature is raised from 950°C to 1050°C, and the bulk densities increased correspondingly. Another study found that the bulk density of ceramic materials increased as the firing temperature increased [33, 34]. The lower temperature was not high enough to encourage densification, which would have substantially closed the pore created during green body casting [35].Figure 4
Effect of FT and AW (a), PS and FT (b), and PS and AW (c) on BD.
(a)(b)(c)As can be seen in Figure4(a), bulk density also varies due to the variation of the amount of β-wollastonite incorporated into ceramic materials. The average bulk density for the addition of 5%, 15%, and 25% of β-wollastonite is 2.01, 2.03, and 2.05 g/cm3, respectively. As the amount of β-wollastonite increased from 5 to 25%, the bulk density of ceramic materials increased since β-wollastonite is denser than clay soils [36]. Previous research showed that ceramic bodies made up of pure clay exhibited a low bulk density (1.64 g/cm3) [37]. The firing temperature and amount of β-wollastonite have no synergetic effect (p>0.05) on the bulk density of ceramic material. However, the bulk density of ceramic materials increases with both firing temperature and the amount of β-wollastonite increases as shown in Figure 4(a).The bulk density of ceramic materials is decreased when the particle size ofβ-wollastonite increased as shown in Figure 4(b). This is due to the fine particles are easy to compact during green ceramic body casting and also have a big tendency of flowability during firing compared to the coarse particles. It is possible to increase the bulk density and decrease the porosity of the ceramic body with the addition of fine particles to larger granule blends. This can be accounted for by the fact that the little particles fill in the voids left by the giant particles without expanding the volume of the entire system [38].The average bulk densities are 2.11, 2.03, and 1.95 g/cm3 for 63, 75, and 125 µm particle sizes of β-wollastonite, respectively. Figure 4(b) also confirms that there is no significant interaction effect (p>0.05) between the firing temperature and the particle size of β-wollastonite on the bulk density of ceramic materials. The bulk density is decreased when the particle size of β-wollastonite increased for each firing temperature. However, the maximum bulk density was recorded for 63 µm particle size of β-wollastonite and 1050°C firing temperature since finer particles are easy to deform (flow) and fill the voids than coarse particles. This finding also suggests that bulk density for ceramic materials fired at high temperatures (1050°C) varies widely.As can be seen in Figure4(c), there is a synergetic effect on the particle size and amount of β-wollastonite added to the bulk density of ceramic materials (p<0.05). When the particle size of β-wollastonite increased (63 to 125 µm) the bulk density decreased by 4.29% (2.06 to 1.97 g/cm3), 7.87% (2.12 to 1.95 g/cm3), and 10.46% (2.17 to 1.94 g/cm3) for 5%, 15% and 25% of the β-wollastonite composition, respectively. The material which contains 25% of β-wollastonite is rapidly decreased than the remaining two concentrations. This implies that the ceramic materials with a 25% concentration of β-wollastonite and with a coarse particle size (125 µm) have the lowest bulk density.


### 3.5.2. Effect of Operating Conditions on Loss on Ignition (LOI)

The main and synergetic effect of Firing Temperature (FT), the amount ofβ-wollastonite added (AW), and particle size of β-wollastonite (PS) on the LOI of ceramic materials were investigated. Table 2 contains the average LOI values for ceramic specimens.Table 2
The average value of LOI.
FactorsFT (950°C)FT (1000°C)FT (1050°C)AW (%)AW (%)AW (%)PS (µm)515255152551525633.993.082.634.323.273.074.373.343.1753.973.052.484.253.232.994.33.313.041253.882.972.324.153.22.694.213.252.74Figure5 shows the effect of firing temperature on the LOI of ceramic materials. The average values are 3.15, 3.46, and 3.52% for firing temperatures of 950, 1000, and 1050°C, respectively. The LOI is increased by 9.85% and 1.58% when the firing temperature is raised from 950 to 1000°C and then to 1050°C, respectively. Similar studies showed that the LOI of the ceramic materials rose with the firing temperature [39]. Between the temperature range of 950°C and 1000°C, the highest change in the LOI was observed. This is because the materials’ volatile components, which cause weight loss upon ignition, were either eliminated or destroyed at temperatures below 1000°C. Additionally, most carbonates and organic materials ignite at temperatures below 1000°C [40]. On the other hand, less organic matter could be detected in the materials burned between 1000°C and 1050°C temperatures. Higher temperatures can also drive off structural water from clays and β-wollastonite [39].Figure 5
Effect of FT and AW (a), PS and FT (b), and PS and AW (c) on LOI.
(a)(b)(c)The LOI of ceramic materials is decreased as the quantity ofβ-wollastonite added increases (see Figure 5(a)). Because, the amount of organic matter, inorganic carbon, and miner organic residue existing in the clay is substantially replaced by β-wollastonite. Besides, the LOI of β-wollastonite is low compared to clay. A comparable result has been reported elsewhere [27, 41] that the presence of β-wollastonite decreases the gas exchange during firing which is a low loss on ignition. The average results of the LOI of ceramic materials are 4.16, 3.19, and 2.79% for the addition of 5, 15, and 25% of β-wollastonite. Ceramic bodies prepared from pure clay exhibited high weight loss on ignition (9.7%) [37]. Figure 5(a) also shows the synergetic effect of firing temperature and the amount of β-wollastonite on the LOI of ceramic materials. There is no interaction effect between firing temperature and the addition of β-wollastonite (p>0.05) on the LOI of ceramic materials. When the composition of β-wollastonite increased from 5 to 25% the loss on ignition of ceramic materials decreased by 37.16% (3.95 to 2.48%), 31.21% (4.24 to 2.92%), and 31% (4.29 to 2.96%) for firing temperature of 950°C, 1000°C, and 1050°C, respectively.Figure5(b) shows the effect of particle size of β-wollastonite on the LOI of ceramic materials. It is observed that the LOI is decreased with an increase in particle size of β-wollastonite. The finer particles completely ignited compared to coarse particles due to their greater specific surface area and greater heat exposure [42]. The weight loss due to the gases off during ignition is the main cause of the formation of pores and cracks. The average values are 3.46, 3.4, and 3.27%. Figure 5(b) also shows the interaction effect between the firing temperature and particle size of β-wollastonite on the LOI of ceramic materials (p>0.05). The LOI of ceramic materials shows a small variation between firing temperatures 1000 and 1050°C when the particle size of β-wollastonite increased from 63 to 125 µm. On the other hand, the ceramic material is fired at 950°C has a low LOI. The average values of loss on ignition of ceramic materials for each particle size of β-wollastonite (63, 75, and 125 µm) are 3.24, 3.17, and 3.06%, 3.55, 3.49, and 3.35%, and 3.6, 3.55, and 3.4% for firing temperature of 950°C, 1000°C, and 1050°C, respectively.There is no significant interaction effect between the amount ofβ-wollastonite added and particle size of β-wollastonite (p>0.05) on the LOI as shown in Figure 5(c). The LOI of ceramic materials exhibited a large variation for ceramics made from 25% of β-wollastonite and 125 µm particle size of β-wollastonite. The coarse particle takes more time and energy to complete the ignition process compared to the fine particle. The amount of β-wollastonite increased from 5 to 25% the LOI reduced by 30.57% (4.23 to 2.93), 31.97% (4.17 to 2.84), and 36.62% (4.08 to 2.58) for 63, 75 and 125 µm of particle size of β-wollastonite, respectively.


## 3.5.1. Effect of Operating Conditions on Bulk Density (BD)

The influence of firing temperature (FT), amount ofβ-wollastonite added (AW), and particle size of β-wollastonite (PS) on the BD of ceramic materials were studied. Table 1 below lists the typical bulk densities of the ceramic specimens.Table 1
Average values of BD.
FactorsFT (950°C)FT (1000°C)FT (1050°C)AW (%)AW (%)AW (%)PS (µm)515255152551525631.962.032.082.032.072.082.192.262.35751.911.931.961.992.032.042.112.132.171251.891.881.871.951.931.922.082.052.03Figure4(a) illustrates the effect of firing temperature on the bulk density of ceramic materials. It has been found that the firing temperature increases the bulk density of ceramic material. The bulk densities on average for firing temperatures of 950, 1000, and 1050°C are 1.94, 2, and 2.15 g/cm3, respectively. The pore in green bodies is filled as a result of the grain beginning to develop in the hole part of the bodies when the firing temperature is raised from 950°C to 1050°C, and the bulk densities increased correspondingly. Another study found that the bulk density of ceramic materials increased as the firing temperature increased [33, 34]. The lower temperature was not high enough to encourage densification, which would have substantially closed the pore created during green body casting [35].Figure 4
Effect of FT and AW (a), PS and FT (b), and PS and AW (c) on BD.
(a)(b)(c)As can be seen in Figure4(a), bulk density also varies due to the variation of the amount of β-wollastonite incorporated into ceramic materials. The average bulk density for the addition of 5%, 15%, and 25% of β-wollastonite is 2.01, 2.03, and 2.05 g/cm3, respectively. As the amount of β-wollastonite increased from 5 to 25%, the bulk density of ceramic materials increased since β-wollastonite is denser than clay soils [36]. Previous research showed that ceramic bodies made up of pure clay exhibited a low bulk density (1.64 g/cm3) [37]. The firing temperature and amount of β-wollastonite have no synergetic effect (p>0.05) on the bulk density of ceramic material. However, the bulk density of ceramic materials increases with both firing temperature and the amount of β-wollastonite increases as shown in Figure 4(a).The bulk density of ceramic materials is decreased when the particle size ofβ-wollastonite increased as shown in Figure 4(b). This is due to the fine particles are easy to compact during green ceramic body casting and also have a big tendency of flowability during firing compared to the coarse particles. It is possible to increase the bulk density and decrease the porosity of the ceramic body with the addition of fine particles to larger granule blends. This can be accounted for by the fact that the little particles fill in the voids left by the giant particles without expanding the volume of the entire system [38].The average bulk densities are 2.11, 2.03, and 1.95 g/cm3 for 63, 75, and 125 µm particle sizes of β-wollastonite, respectively. Figure 4(b) also confirms that there is no significant interaction effect (p>0.05) between the firing temperature and the particle size of β-wollastonite on the bulk density of ceramic materials. The bulk density is decreased when the particle size of β-wollastonite increased for each firing temperature. However, the maximum bulk density was recorded for 63 µm particle size of β-wollastonite and 1050°C firing temperature since finer particles are easy to deform (flow) and fill the voids than coarse particles. This finding also suggests that bulk density for ceramic materials fired at high temperatures (1050°C) varies widely.As can be seen in Figure4(c), there is a synergetic effect on the particle size and amount of β-wollastonite added to the bulk density of ceramic materials (p<0.05). When the particle size of β-wollastonite increased (63 to 125 µm) the bulk density decreased by 4.29% (2.06 to 1.97 g/cm3), 7.87% (2.12 to 1.95 g/cm3), and 10.46% (2.17 to 1.94 g/cm3) for 5%, 15% and 25% of the β-wollastonite composition, respectively. The material which contains 25% of β-wollastonite is rapidly decreased than the remaining two concentrations. This implies that the ceramic materials with a 25% concentration of β-wollastonite and with a coarse particle size (125 µm) have the lowest bulk density.


## 3.5.2. Effect of Operating Conditions on Loss on Ignition (LOI)

The main and synergetic effect of Firing Temperature (FT), the amount ofβ-wollastonite added (AW), and particle size of β-wollastonite (PS) on the LOI of ceramic materials were investigated. Table 2 contains the average LOI values for ceramic specimens.Table 2
The average value of LOI.
FactorsFT (950°C)FT (1000°C)FT (1050°C)AW (%)AW (%)AW (%)PS (µm)515255152551525633.993.082.634.323.273.074.373.343.1753.973.052.484.253.232.994.33.313.041253.882.972.324.153.22.694.213.252.74Figure5 shows the effect of firing temperature on the LOI of ceramic materials. The average values are 3.15, 3.46, and 3.52% for firing temperatures of 950, 1000, and 1050°C, respectively. The LOI is increased by 9.85% and 1.58% when the firing temperature is raised from 950 to 1000°C and then to 1050°C, respectively. Similar studies showed that the LOI of the ceramic materials rose with the firing temperature [39]. Between the temperature range of 950°C and 1000°C, the highest change in the LOI was observed. This is because the materials’ volatile components, which cause weight loss upon ignition, were either eliminated or destroyed at temperatures below 1000°C. Additionally, most carbonates and organic materials ignite at temperatures below 1000°C [40]. On the other hand, less organic matter could be detected in the materials burned between 1000°C and 1050°C temperatures. Higher temperatures can also drive off structural water from clays and β-wollastonite [39].Figure 5
Effect of FT and AW (a), PS and FT (b), and PS and AW (c) on LOI.
(a)(b)(c)The LOI of ceramic materials is decreased as the quantity ofβ-wollastonite added increases (see Figure 5(a)). Because, the amount of organic matter, inorganic carbon, and miner organic residue existing in the clay is substantially replaced by β-wollastonite. Besides, the LOI of β-wollastonite is low compared to clay. A comparable result has been reported elsewhere [27, 41] that the presence of β-wollastonite decreases the gas exchange during firing which is a low loss on ignition. The average results of the LOI of ceramic materials are 4.16, 3.19, and 2.79% for the addition of 5, 15, and 25% of β-wollastonite. Ceramic bodies prepared from pure clay exhibited high weight loss on ignition (9.7%) [37]. Figure 5(a) also shows the synergetic effect of firing temperature and the amount of β-wollastonite on the LOI of ceramic materials. There is no interaction effect between firing temperature and the addition of β-wollastonite (p>0.05) on the LOI of ceramic materials. When the composition of β-wollastonite increased from 5 to 25% the loss on ignition of ceramic materials decreased by 37.16% (3.95 to 2.48%), 31.21% (4.24 to 2.92%), and 31% (4.29 to 2.96%) for firing temperature of 950°C, 1000°C, and 1050°C, respectively.Figure5(b) shows the effect of particle size of β-wollastonite on the LOI of ceramic materials. It is observed that the LOI is decreased with an increase in particle size of β-wollastonite. The finer particles completely ignited compared to coarse particles due to their greater specific surface area and greater heat exposure [42]. The weight loss due to the gases off during ignition is the main cause of the formation of pores and cracks. The average values are 3.46, 3.4, and 3.27%. Figure 5(b) also shows the interaction effect between the firing temperature and particle size of β-wollastonite on the LOI of ceramic materials (p>0.05). The LOI of ceramic materials shows a small variation between firing temperatures 1000 and 1050°C when the particle size of β-wollastonite increased from 63 to 125 µm. On the other hand, the ceramic material is fired at 950°C has a low LOI. The average values of loss on ignition of ceramic materials for each particle size of β-wollastonite (63, 75, and 125 µm) are 3.24, 3.17, and 3.06%, 3.55, 3.49, and 3.35%, and 3.6, 3.55, and 3.4% for firing temperature of 950°C, 1000°C, and 1050°C, respectively.There is no significant interaction effect between the amount ofβ-wollastonite added and particle size of β-wollastonite (p>0.05) on the LOI as shown in Figure 5(c). The LOI of ceramic materials exhibited a large variation for ceramics made from 25% of β-wollastonite and 125 µm particle size of β-wollastonite. The coarse particle takes more time and energy to complete the ignition process compared to the fine particle. The amount of β-wollastonite increased from 5 to 25% the LOI reduced by 30.57% (4.23 to 2.93), 31.97% (4.17 to 2.84), and 36.62% (4.08 to 2.58) for 63, 75 and 125 µm of particle size of β-wollastonite, respectively.


## 4. Conclusion

The bulk density and loss on ignition of ceramic materials were increased with firing temperature. However, both bulk density and loss on ignition of ceramic materials were decreased when the particle size ofβ-wollastonite increased. Similarly, the bulk density of ceramic materials is increased with the composition of β-wollastonite. The loss on ignition of ceramic materials is decreased when the amount of β-wollastonite increased. In general, it was observed that firing temperature, particle size, and percentage of β-wollastonite have an important effect on the quality of the ceramic materials.



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*Source: 3555999-2022-09-23.xml*