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American Journal of  
Chemistry and Pharmacy (AJCP)

A Summarized Review of  Refractory Materials and Their Chemical Components
S. Kamara1*

Volume 4 Issue 1, Year 2025
ISSN: 2834-0116 (Online)

DOI: https://doi.org/10.54536/ajcp.v4i1.5789
https://journals.e-palli.com/home/index.php/ajcp

Article Information ABSTRACT

Received: July 20, 2025
Accepted: August 25, 2025
Published: September 29, 2025

Refractories are non-metallic ceramic materials capable of  withstanding temperatures higher 
than 1500 °C, where the refractoriness is defined by the pyrometric cone equivalent. Silica 
fume and fly ash are used in industries as cost-effective raw materials to fabricate refractory 
composites. Mullite ceramic (3Al2O3·2SiO2) is a widely used engineering ceramic material 
with high strength and high creep resistance at high temperatures, low thermal expansion co-
efficient, and thermal stability. Cordierite ceramics (Mg2Al4Si5O18) can be used as the carrier 
of  environmental catalysts because of  their low coefficient of  thermal expansion and stable 
structure. Therefore, it is an important way to reduce the generation of  waste pollutants 
(Silica fume, fly ash, etc.), reflecting the basic idea of  the transformation of  solid waste into 
valuable products. The components of  refractory materials are discussed alongside their 
utilizations, properties, and characteristics.

Keywords
Cordierite, Fly Ash, Kaolin, 
Mullite, Refractory, Silica Fume, 
Sintering

1 Department of  Chemical Engineering, School of  Water and Environment, Chang’an University, Xi’an 710054, China
* Corresponding author’s e-mail: ksaidu2013@gmail.com

INTRODUCTION
The development of  metals, polymers, and ceramic 
materials has significantly contributed to the progress 
of  human civilization. The emergence of  metals 
and ceramics is historically interconnected. The high 
temperatures involved in metallurgical processes lead 
to the development of  suitable refractories of  molten 
metal containers. These refractory materials are non-
metallic with suitable physical and chemical properties 
used for components of  systems that are exposed to 
high temperatures of  above 538 °C (Chandra & Sarkar, 
2019; Dana et al., 2014; Nwannenna et al., 2015). The 
properties of  these refractory materials remain unaltered 
at elevated temperatures of  sustained operations. 
Refractory ceramic materials are classified into chemical 
nature (acid, basic, neutral), implementation method 
(shaped and unshaped), manufacturing method (sintered 
or fused), and porosity of  the material (porous and 
dense) depending on the physicochemical nature of  the 
starting materials (silica, aluminosilicate, magnesia, etc.) 
utilized in the manufacturing process (Biswas et al., 2020; 
Sarkar, 2023). These materials are resistant to heat when 
exposed to different degrees of  mechanical stress and 
strain, corrosion from liquids and gases, and mechanical 
abrasion at high temperatures. The scarcity of  basic 
refractory materials imported from Europe during World 
War II brought about the development of  aluminosilicate 
refractories associated closely with the development of  
bauxite-based refractories in North America (Garbers-
Craig, 2008; Sengupta, 2020).
The advancement of  aluminosilicate refractory materials 
from bauxite began in North America when there was 
a shortage of  refractory materials in Europe during 
the second world war. The overall consumption and 
utilization of  refractories are a result of  the sustained 

development of  starting materials and processing 
technology in the refractory industry. In recent times, 
aluminosilicate refractories are mainly produced in 
developing countries and imported to developed 
nations.  The knowledge obtained from the results of  
experimental research in materials science is essential for 
use in the fields of  engineering and technology in modern 
days. The anticipation of  industrial engineers to develop 
materials that have the advantage to resist high operating 
conditions began with the commencement of  ceramics, 
polymers, refractories, etc. The fabrication of  these latest 
materials has the purpose to produce good and reliable 
products with easy processing and low-cost operation 
(Bramsiepe et al., 2012; Jandyal et al., 2022; Zhong, 2021). 
Refractory ceramics are suitable for use in furnace linings 
or melting pots due to their ability to withstand physical 
and chemical conditions at high temperatures in metal 
casting industries and other applications with critical 
thermochemical properties. The properties of  these 
materials are contingent on the properties of  the starting 
reagents and formulations (chemical and mineralogical 
composition, particle size, and shape distribution), 
forming process, and sintering temperature (Colomban, 
2020; Danninger et al., 2017; Kamara et al., 2025; Mohd 
Mortar et al., 2022; Sun et al., 2024; Ulusoy, 2023).
The fabrication of  different types of  refractory ceramic 
materials is dependent upon the starting materials utilized 
and the stoichiometric processing parameters (Kamara, 
2025; Kamara et al., 2020; Nanda et al., 2023; Shackelford 
& Doremus, 2008). Studies on silica and alumina-
containing compounds show that mullite (3Al2O3.2SiO2) 
mineral phase is one of  the most outstanding refractory 
ceramics (Hossain & Roy, 2020; Vakalova et al., 2004) due 
to a combination of  such distinct properties as elevated 
melting point (1800°C), low thermal expansion coefficient, 



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excellent mechanical and thermal shock resistance, chemical 
stability, etc., making it useful in many applications from 
refractories to electronic substrates (Kamara et al., 2025; 
Kamara et al., 2020). The significant amounts of  silica (SiO2) 
and alumina oxides (Al2O3) in clay minerals make clay 
material a suitable low-cost natural raw material to fabricate 
mullite refractory ceramics. The SiO2/Al2O3 ratio in the clay 
material is low and therefore requires the addition of  suitable 
stoichiometric compositions to produce the major mullite 
phase (Zhang et al., 2022).
In recent decades, concerns about environmental issues 
have grown around the world, particularly in the field of  
education and researchers have now given much attention 
to sustainable methods aimed at recycling inorganic 
waste (Debrah et al., 2021; Townsend, 2011). They are 
coarse-grain ceramics having a microstructure that 
consists of  large grains joined by fine materials (Lan et 
al., 2016).  The major starting materials used to fabricate 
refractories are the oxides of  silicon, aluminum, etc. 
Nitrides, borides, silicates, graphite, etc, are some non-
oxide refractories (Guanghui, 2024). As stated earlier, the 
choice of  refractories by engineers is solely based on the 
operational conditions to which they are being exposed. 
For instance, at extreme temperatures zirconia can be 
utilized to withstand such conditions. Also, silicon carbide 
and carbon are employed for such applications but they 
should be used in the absence of  oxygen because of  their 
oxidative properties. Refractories are a special form of  
ceramic materials which mainly differs from any normal 
ceramic because their coarse grain structure is joined by 
larger grog particles made of  fine intermediate materials 
(bonding). The qualities of  refractories depend on their 
physical, chemical, mineralogical, and thermal properties 
(Sengupta, 2020; Yurkov, 2015). Refractories are normally 
made based on process parameters (temperature profile, 
mode of  operation, and operating atmosphere), expected 
quality characteristics, and best techniques for engineering 
application so that the final physical, chemical, and 
thermal properties are compatible with the application 
(Chandra & Sarkar, 2019).   Refractories are expensive, 
and any failure in the refractories results in a great loss of  
production time, equipment, and sometimes the product 
itself  (Chandra & Sarkar, 2019; Horckmans et al., 2019; 
Yurkov, 2015). The energy consumed and the quality of  
the product is also determined by the type of  refractory 
involved. The main objective of  this work is to review 
the components of  refractory material that provide the 
basis for its suitability in the production of  engineering 
materials. It is therefore very significant to produce 
suitable refractory materials for a particular application. 
The suitability of  a refractory material does not imply 
durability but rather the balance between the initial cost 
and its performance. This balance is never achieved but 
is continuously moving as a result of  the introduction of  
new processes or new types of  refractories.

LITERATURE REVIEW
Refractories are non-metallic ceramic materials capable 

of  withstanding temperatures higher than 1500 ◦C, where 
the refractoriness is defined by the pyrometric cone 
equivalent. Most modern refractories are based on one 
or more non-metallic oxides, which can be divided into 
basic and non-basic refractories. All basic products are 
based on either calcium oxide (CaO) or MgO, whereas 
non-basic materials are based on Al2O3, silicon dioxide 
(SiO2), or zirconium oxide (ZrO2). This is a fundamental 
differentiation, as the correct refractory material is always 
based on the basicity of  the medium in contact with the 
lining. Refractory materials are both economically and 
socially strategic materials as they enable the production 
of  other crucial products, including steel, non-ferrous 
metals, cement clinker, lime, glass, and many others. They 
are designed to operate at high temperatures, temperature 
gradients, and under severe chemical and mechanical 
loadings.
The main raw materials used in the production of  
refractories are: the oxides of  silicon, aluminum, 
magnesium, calcium, and zirconium, and some non-
oxide refractories like carbides, nitrides, borides, silicates 
and graphite. The main types include fire-clay bricks, 
castables, ceramic fiber, and insulating bricks that are 
made in varying combinations and shapes for diverse 
applications. The value of  refractories is not judged by 
the cost of  the material itself, but by the nature of  the 
job and/or its performance in a particular situation. 
Atmosphere, temperature, and the materials in contact 
are some of  the operating factors that determine the 
composition of  refractory materials.
Refractories are utilized by the metallurgy industry in 
the internal linings of  furnaces, kilns, reactors, and other 
vessels for holding and transporting metal and slag. In 
non-metallurgical industries, the refractories are mostly 
installed on fired heaters, hydrogen reformers, ammonia 
primary and secondary reformers, cracking furnaces, 
incinerators, utility boilers, catalytic cracking units, coke 
calciner, sulfur furnaces, air heaters, ducting, stacks, etc. 
The majority of  these listed equipment operates under 
high pressure, and operating temperature can vary from 
very low to very high (approximately 900°F to 2900°F). 
The refractory materials are therefore needed to withstand 
temperatures and above these temperatures.
Important properties of  refractories are: chemical 
composition, bulk density, apparent porosity, apparent 
specific gravity, and strength at atmospheric temperatures. 
These properties are often among those which are used as 
‘control points’ in the manufacturing and quality control 
process. The chemical composition serves as a basic for 
classification of  refractories and the density, porosity and 
strength is influenced by many other factors. Among 
these are type and quality of  the raw materials, the size 
and fit of  the particles, moisture content at the time of  
pressing, pressure at mould, temperature, duration of  
firing and the rate of  cooling.
Some of  the important characteristics of  refractories 
include melting point, size and dimensional stability, 
porosity, bulk density, cold crushing strength, pyrometric 



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cone equivalent (PCE), refractoriness under load, 
creep at high temperature, volume expansion stability 
and shrinkage at high temperature, reversible thermal 
expansion, thermal conductivity, etc. Refractory materials 
are characterized as ceramic materials, exposed during 
their use to high temperatures, and often to other extreme 
chemical and physical exposures that limit their operation 
life. The intensive use of  refractories in steelmaking plants 
is due to the properties these compounds exhibit such 
as high starting melting point, high structural strength at 
high temperatures and in highly corrosive environments, 
and an intensive stability in temperature variations. What 
is common for refractory materials in terms of  not only 
various applications but also their material and structural 
nature is described by a set of  properties of  refractory 
materials.
Previous use of  refractories, particularly aluminum 
oxide (Al2O3) and magnesium oxide (MgO), has exposed 
challenges in terms of  corrosion mainly due to the 
formation of  cobalt aluminates (CoAl2O4) using Al2O3 
as a refractory material and lithium diffusion within the 
crucible walls using MgO. Corrosion, generally defined 
as the chemical attack on refractory material by a liquid 
phase such as slag, metal or alloy, occurs when the melt 
infiltrates the refractory matrix, creating capillaries that 
weaken the material’s mechanical strength. During this 
process, the fine grain of  the refractory is washed out 
leaving the coarse grain exposed. This process occurs 
due to the chemical reaction between the liquid slag and 
solid refractory phases. It continues until the saturation 
point of  the slag or the metal bath occurs through the 
refractory material. Such issues can lead to contamination 
of  the input material and significantly impact refractory 
stability and reusability. Furthermore, diffusion-related 
constraints can hinder lithium removal rates, thereby 
diminishing the overall process efficiency.

MATERIALS AND METHODS
Several articles related to refractory technology were 
downloaded from various online publishing sources, 
of  which 53 topically related papers were selected and 
systematically reviewed. The work was summarized 
based on the research objectives, which focuses on the 
components of  refractory materials.

Classification of  Refractory Refractories
They are categorized based on their chemical composition 
and chemical properties.

Chemical Composition
Silica refractories are fabricated in the form of  quartz 
and it is composed of  92% of  SiO2. The iron and steel 
industries extensively utilize SiO2 refractories due to their 
outstanding resistance to thermal shock. The raw materials 
for this class of  refractories are high-grade rocks and fly 
ash. Fireclay refractories are formed by heating a particular 
type of  clay and it comprises less than 78% of  SiO2 
and 44% of  Al2O3. They are cost-effective and popular 

industrial materials. Alumina refractories are also made of  
Al2O3 and SiO2 with a minimum of  50% Al2O3. They are 
subdivided into seven different percentages such as 50% 
Al2O3, 60% Al2O3, 70%Al2O3, 80%Al2O3, 85%Al2O3, 
90% Al2O3, and 99% Al2O3. Magnesia refractories have 
magnesium oxide (MgO) and their principal sources 
are brines, seawater, and sintered and fused magnesia 
with magnesia-carbon refractory identified as the most 
important. Dolomite refractories comprise MgO and 
CaO as their main components. These refractories are 
fabricated from sintered dolomite. Magnesia-chrome 
refractories mainly consist of  MgO and chromium oxide 
(Cr2O3). They are named magnesia chrome or chrome-
magnesite depending on the percentages of  MgO and 
Cr2O3 present in the refractory. About 15% to 35% Cr2O3 
and 42% to 50% of  MgO are contained in magnesite 
chrome while magnesite-chromite has about 60% MgO 
and 8% to 18% of  Cr2O3. They are utilized to construct 
critical parts of  high-temperature furnaces due to their 
abilities to withstand corrosive slags and gases and their 
high refractoriness. Magnesite-chrome has better-spalling 
resistance than chrome-magnesite refractories in some 
cases. Silicon carbide refractories are manufactured 
from silicon carbide (SiC) obtained by reacting silica and 
carbon in an electric furnace at a high temperature of  
over 25000 °C. Zirconia refractories have zirconium oxide 
(ZrO2) as their principal component and are utilized as 
high-temperature construction materials. Nozzles, gates, 
crucibles, furnace liners, and kilns, etc., are cast at high 
temperatures greater than 1900°C from these class of  
refractories. It is a suitable insulating material due to its 
lower thermal conductivity at high temperatures, and they 
do not react with liquid metals. Carbon refractories have 
carbon as the principal component, existing in the form 
of  graphite or semi-graphite. They can resist the action 
of  slags and have high thermal stability.

Chemical Reactivity 
There are several typical chemical reactivities of  
refractories based on the chemical reactivity of  their 
constituent substances.
Acidic refractories contain silica and alumina, which tend 
to react with basic slags. They are resistant to acid slags and 
are therefore utilized in an acidic environment and slags. 
Basic refractories constitute calcium oxide, magnesia 
refractories, dolomite refractories, magnesia-chrome 
refractories, etc. They react with acidic slags but are 
resistant to alkaline (basic) slags, specks of  dust, and 
fumes at extreme temperatures. Steel manufacturers make 
use of  this class of  refractory to construct furnace linings 
in an alkaline medium. 
Neutral refractories are chemically stable in both acidic 
and basic media and can be utilized in acidic or basic 
environments and slags. Carbon graphite (most inert), 
chromite refractories, and alumina are typical examples 
of  these refractories, among which graphite is the least 
reactive and is suitably utilized in metallurgical furnaces 
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Special refractories include pure alumina, sialons (Si-Al-
O-N), beryllia (BeO), zirconia, boron nitride, spinel, etc. 
They are costly refractory materials that are fabricated 
using pure synthetic (fused/sintered) suitable production 
parameters and conditions. They have especially used 
refractories in the construction of  crucibles, research and 
development purposes, etc. where the cost of  a refractory 
is not considered. 

Cordierite (2MgO. 2Al2O3. 5SiO2) and Mullite 
(3Al2O3. 2SiO2)
These are technologically popular aluminosilicate 
refractory materials due to their suitable properties 
(thermal shock resistance, low thermal conductivity, 
creep resistance, low thermal expansion, elevated thermal 
and chemical stabilities, etc.) for various engineering 
purposes. Their raw materials are easily obtainable 
at cheap prices. The low production costs of  these 
materials influenced their potential use as an alternative 
material to alumina. They are used in welding shapes, 
electrical insulators, furnace liners, etc. The high thermal 
coefficient of  expansion of  mullite renders it a suitable 
refractory utilized to ameliorate the thermal operational 
problems encountered at the silicon-substrate overlap 
of  integrated circuit devices (Fahlman, 2023; Rahman 
et al., 2014). What is normally done in this case is to 
decrease the thermal expansion coefficient to equalize 
the thermal coefficient of  silicon by adding cordierite 
as a second phase, since it has a low thermal expansion 
coefficient. A cordierite-mullite refractory composite is 
superior to mullite refractory because of  the high thermal 
conductivity of  the former (mullite). An adequate liquid 
phase is formed between 1290-1550oC to form a density. 
Another important factor to note is that both mullite and 
cordierite co-exist in thermal equilibrium, which means 
mullite can exist in the cordierite phase and cordierite 
can exist in thermal equilibrium with the mullite phase. 
Cordierite-mullite composite ceramics were fabricated 
from commercially available cordierite and mullite 
powders (Xu et al., 2017) in which the mullite content 
in the composite was about 65% (Xu et al., 2017). The 
electrical conductivity of  the composite was studied 
based on the influence on porosity, mullite glass phase, 
and grain size. The composition of  refractory composite 
renders them suitable for thermal expansion behavior.
The consequence of  starting materials on the morphology 
of  mullite crystals in the composite refractories 
(cordierite-mullite), and was observed the morphology of  

the mullite crystals became different contingent on the 
type and source of  aluminum utilized in the fabrication of  
the composite refractories (Chermat et al., 2025; Sun et al., 
2022). It was revealed that alumina-sol mixtures give rise 
to acicular grains while Al(OH)3 powder mixtures show 
the appearance of  angular or granular mullite mixtures. 
A lower mullitization temperature of  a composite made 
with alumina sol shows better reactivity and dispersibility 
than those with Al(OH)3 powder. Cordierite and mullite 
powders obtained from commercial vendors have been 
used by Phatthamon Kiattisaksophon and Sukdiphon 
Thiansem as raw materials in different ratios of  up to 
100 wt% (Kiattisaksophon & Thiansem, 2008). The raw 
material was combined, mixed, processed, and taken 
to a ball grinding mill for composite formation. The 
samples were then sintered at temperatures between 
1250 and 1400 at an interval of  50°C.  The samples 
were heated at extreme temperatures and cooled down 
to room temperature to study their thermal actions 
to measure the thermal expansion coefficient. It was 
learned from the thermal behavior of  the samples that 
the fabricated cordierite-mullite composite showed good 
physical and chemical properties at 70:30 wt% sintered 
at 1400°C. The fabricated cordierite-mullite composite 
also shows improved densification of  cordierite and 
mullite structures, thermal shock resistance, pore size 
variation, bulk density, and apparent low porosity. The 
crack and microstructural characteristics suitably attract 
the utilization of  cordierite-mullite composite in the swift 
firing of  porcelain whiteware. One significant concern 
pointed out by the refractory industries is the thermal 
shock degeneration of  commercial refractories that 
results in to decrease in stiffness, mechanical strength, 
and degradation when subjected to high industrial 
thermal conditions. The use of  high-quality starting 
reagents ignited the cost of  refractory composites in 
the market. Considerations are now made for the use of  
non-destructive testing to determine damages caused by 
thermal shocks. The thermal degeneration of  commercial 
refractory composites was investigated by (Boccaccini 
et al., 2008; Cioangher et al., 2024; Flores-Jacobo et al., 
2023) exposed to harsh industrial thermal conditions 
by comparing the degenerated curves acquired from the 
non-destructive testing, e.g. comparing images acquired 
from ultrasonic velocity testing (UPVT)  with those 
secured from measuring the flexural strength and fracture 
toughness by three-point bending test and chevron 
notched method, respectively.

Table 1: Physical properties of  cordierite and mullite (Camerucci et al., 2001; da Silva et al., 2019)
Property Cordierite Mullite
Chemical formula 3Al2O3. 2SiO2 2MgO.2Al2O3. 5SiO2

Density 3.03g/cc 2.60 g/cc
Thermal expansion coeff. 4.5- 5.6 (x10-6/ °C) 1.7(x10-6/°C)
Thermal Conductivity 4-6 W/m K (100-1400°C) 3 W/m K (room temp.)
Max. Operating temp. 1725 °C 1371°C



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Mullite has suitable thermal and mechanical properties 
which account for its importance in traditional and 
advanced refractory material. It is not widely distributed in 
nature because of  its high temperature and low pressure. 
Many methods are used to fabricate refractory composite 
materials. The two methods employed to fabricate mullite-
cordierite composite refractory: (1) by a combination 
of  raw material, and (2) by joining of  pre-made mullite 
and cordierite powders (Bilung, 2012). The ground raw 
materials are heated at low temperatures between 550°C 
to 9000C to enhance the densification of  the materials. 
The microstructure, crystalline, dielectric, and mechanical 
properties of  the composite manufactured from the 
various raw materials were analyzed. Crystals were easily 
formed refractory composites made of  finely ground 
precursors than those from aluminum sulfate reagents. 
A composite refractory fabricated from a raw material 
made of  composite materials attains a better density at 
lower temperatures due to the gummy or sticky flow of  
the ceramics. Mechanical properties of  a composite can 
be accounted for from microstructures while strength 
and hardness are correlated to the composition, grain 
size, and porosity. In a solid-state reaction, a refractory 
composite with its desired properties is incompletely 
transformed into another composite having another set 
of  desired properties. The product from this process 
has the benefit of  carrying the advantages of  both the 
starting materials. It is observed from various cordierite-
mullite ceramics that an increase in cordierite causes a 
decrease in the thermal expansion coefficient. Preferably, 
we can keep the percentage of  cordierite-mullite ratio at 
the constant of  70:30%. Shock resistance is supported 

by the cordierite while strength is aided by mullite. The 
existence of  the cordierite reduces the temperature and 
the firing shrinkage (El-Fadaly et al., 2022; Sadik et al., 
2016). (Zemánek et al., 2021) in their work combined 
cordierite and mullite in various proportions either as 
reactants or grog and studied the effect of  the percentage 
of  grog added. Components with 50-70 & grog acquired 
improved mechanical, thermal, and physical properties. 
Table 1 above shows some physical parameters of  
cordierite and mullite.

Ternary Phase Diagrams for Cordierite and Mullite 
A ternary phase diagram is a complex diagram captured 
in a three-dimensional plot in which each side of  the 
plot represents a pure component in the system. Figure 
1 below is the ternary diagram of  the magnesium 
oxide aluminum silicate system. The MgO.Al2O3.SiO2 
system has been studied for so many years through the 
extensive experimental system. The compositions within 
the system are important for many reasons. They are 
important to geologists looking for mineralogical systems 
and also many of  the compounds within the system 
have important applications such as high-temperature 
ceramics and structural ceramics in kilns or ovens. Most 
of  the compositions in the system form transparent 
glass ceramics and from the geologic point of  view, 
they contribute many of  the lower mantle minerals. 
Understanding the melting behavior and crystallization 
part of  the system is therefore important. It is also a great 
test system to see if  we can apply our knowledge to read 
the crystallization part from the liquidus projections. 

Figure 1:  Modified ternary phase diagram of  refractory composites (Dudnik et al., 2014)

Many years of  studies lead to the experimental 
determination of  the system and detailed characterization 
of  the phase stability in melting temperatures. The 
objectives here are to read and interpret all of  the 

information in the diagram and then track some 
solidifications. The three compositions (MgO, Al2O3 
& SiO2) in the diagram are shown in percent weight or 
mass percent and not moles. It is observed that the part 



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where you have the cordierite (2MgO.2Al2O3.5SiO2) 
with blue dotted lines is a little bit congested. Along 
the MgO and SiO2 binary are two compounds which 
are MgO.SiO2 mineral called enstatite and 2MgO.SiO2 is 
known as forsterite. Both of  these compounds do not 
show solubility. Between the MgO and Al2O3 is a well-
known phase called spinel (MgO.Al2O3) which shows 
a very significant solid solution. The compound along 
Al2O3 and SiO2 is mullite (3Al2O3.2SiO2). There are 
two ternary compounds, one is the cordierite mineral 
(2MgO.2Al2O3.5SiO2) which has ceramic applications, 

and immediately below the cordierite mineral is sapphirine 
(4MgO.5Al2O3.2SiO2). Between the spinel (MgO.Al2O3) 
and Al2O3 is a solid solution. A significant amount of  
solid solution is also found around the mullite and the 
cordierite. 

The Structural Chemistry of  Alumina
Aluminum oxide is an oxide obtained from bauxite and 
occurs in mineral corundum alongside some impurities 
from ruby and sapphire(Abyzov, 2019; Giuliani et al., 2020; 
Panasyuk et al., 2019; Simonet et al., 2008). The oxides of  

Figure 2: shows the thermal transformation of  aluminum hydroxides (modified).

Figure 3: (A) Modified corundum structure in alpha-
Al2O3 and (B) Modified octahedral coordination of  
alpha-alumina (Abdelkader & Abdecharif, 2012; Ahmed 
et al., 2021; Khosravi Mardkhe, 2014).

alumina obtained from bauxite with varying particle sizes 
are reactive alumina, low bauxite, calcined alumina, etc. 
They have properties such as particle size, surface area, 
surface reactivity, catalytic properties, etc., which account 
for their structural differences. The illustration in figure 
1 below shows the thermal conversion of  aluminum 
hydroxide into various forms when subjected to heat 
(Castruita et al., 2013; Shirai et al., 2010).
There are many allotropes of  Al2O3, and α-Al2O3 is the 
most stable thermodynamic phase which is formed at 
high temperatures by metastable or transition alumina 
precursors such as γ-alumina, β-alumina, δ-alumina, 
σ-alumina, etc. Aluminum hydroxide thermally 
decomposes to form these metastable phases (Castruita et 
al., 2013; Yang et al., 2024). For instance, heating gibbsite 
(γ-trihydrate; γ-Al(OH)3), boehmite (γ-monohydrate; 
γ-AlOOH), bayerite (α-trihydrate; α-Al(OH)3), and 
diaspore (α-monohydrate; α-AlOOH) convert to various 
crystalline phases when calcined at high temperatures 
(Atanga, 2013). The crystalline form of  alumina is 
hexagonal in structure, as shown below, flocked by 
O2- anions and Al3+ cations (Baronskiy et al., 2022; 
Nestler et al., 2019). The Al atoms are in an octahedral 
arrangement with six oxygen rings as shown in the 
diagram below(Gutierrez & Johansson, 2002; Rustad et 



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al., 2004). The dimensions of  the unit cells in the trigonal 
lattice structure are a = 4.7587 Å, b = 4.7587 Å, and c = 
12.99 Å.

Properties of  Al2O3
The typical properties of  alumina are: high hardness, 
chemical inertness, high thermal stability, low coefficient 
of  thermal expansion, good thermal conductivity, good 
wear and abrasion resistance, high corrosion resistance, 
a high melting temperature (2050°C), and its commercial 
availability in different purity ranges and grain sizes, 
makes it attractive for a great variety of  engineering 
application. The suitability of  alumina to resist thermal 
fatigue is related to its geometric arrangement and 
strength, controlled by its thermal properties like thermal 
conductivity and thermal expansion characteristics 
(Czerwinski, 2020; Kamara et al., 2025; Sobczak et al., 
2002; H. Wang et al., 2020).

Applications of  Al2O3 Ceramics
The applications of  alumina ceramics in engineering are 
as follows:

• as a refractory material for the lining of  furnaces 
(Sengupta, 2020; Slovikovskii & Gulyaeva, 2018). 

• as an abrasive material and cutting tool (Hosseini & 
Kishawy, 2014; Toenshoff  & Denkena, 2013) 

• as substrate material for electronic parts and packing 
materials for integrated circuits (e.g. silicon chips, 
electrical insulators, and spark plugs) (Pulugurtha et al., 
2022; Yin et al., 2024) 

• alumina also has widespread applications as a porous 
ceramic and catalyst support (Wang et al., 2022).
The suitability of  alumina for all these applications is due 
to the properties listed in table 2.

Structural Chemistry of  SiO2 
Silica (SiO2) is a compound made of  silicon and oxygen 

Table 2: Mechanical and thermal properties of  alumina (Gudlur et al., 2012; Xie et al., 2011)
Characteristics Measured values
density, [g cm-3] 3.95-4.10
melting point, [°C] 2072
microhardness, [GPa] 20
hardness, [GPa] 9
young’s modulus, [GPa] 260-410
bending strength, [MPa] 150-600
fracture toughness, [MPa m0.5] 4-6
thermal conductivity from 25 °C to 1000 °C, [W m-1 K-1] 30-40
coefficient of  thermal expansion from 20 °C to 1000 °C, *10-6 [K-1] 5.4-9.5

atoms, which occurs in nature as quartz, silica sand, or 
sandstone(Götze, 2012; Pan et al., 2022), and can also be 
obtained from various sources in different forms like silica 
fume, fused silica, colloidal silica, and gel silica (Hyde et 
al., 2016). The reaction in equation 1 below shows the 
formation of  silica from alkoxide.
Si(OR)4 (1) + 2H2O (1) →SiO2 (s)+ 4ROH                            (1)
Efficient nucleation and heterogeneous growth of  the 
amorphous material lead to the fabrication of  stable 
mullite phases. A mullite refractory fabricated from 
amorphous silica is more stable than mullite from 

crystalline silica reagent. The formation of  mullite with 
better microstructure is dependent on the silica precursor, 
the alumina precursor, and processing conditions. 
There are several crystalline forms of  silica, but the 
three major crystalline phases are quartz, tridymite, and 
cristobalite. The low and high-temperature crystalline 
forms or polymorphs are represented as the α-form and 
the β-form. The β-cristobalite is stable at around 1705 
°C and melts at temperatures equal  or equal to 1705 °C 
(Fernandes et al., 2024; Ortiz-Bravo et al., 2022; Wiberg et 
al., 2001).

Table 3: Silica and some properties (Pabst & Gregorová, 2013; Polyakova, 2014)
Form Crystal symmetry Stable range Density (g cm-3)
α-quartz hexagonal < 573 °C 2.65
β-quartz hexagonal 573 °C - 870 °C 2.53
α-tridymite monoclinic metastable 2.36
β-tridymite hexagonal 870 °C - 1470 °C 2.25
α-cristobalite tetragonal metastable 2.32
β-cristobalite tetragonal 1470 °C - 1705 °C 2.20
Silica melt - ≥ 1705 °C -



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Figure 4 represents the stable crystalline phase of  silica 
at extreme temperatures in which each silicon atom 
is bonded to four oxygen atoms to form a tetrahedral 

structure (Norman et al., 2013; Polyakova, 2014; Schnurre 
et al., 2004).
The silica group in the structure constitutes various 

Figure 4: Modified crystal structure of  cristobalite (a high-temperature crystalline form of  silica)(Aleem et al., 2014).

minerals with different structures, symmetries, and 
physical properties but with the same composition. An 
increase in temperature causes a shift in the positions 
of  the atoms in the crystal lattice structure. The bond 
angle between the SiO4 tetrahedra) change from 153° 
(β-quartz) via 180° (β-tridymite) to 151° (β-cristobalite). 
A shift is induced in the bond length of  Si-O, resulting 
in a contraction from 0.161 nm (α-quartz) to 0.158 nm 
(β-cristobalite). A corresponding decrease in density and 
an increase in hardness have been discussed by some 
researchers. Silica is the most significant component of  
mullite, which has many industrial applications.  It has 
a high melting temperature, used to produce molds and 
cores for the production of  metal castings in ferrous 
and non-ferrous industries. It is the main component of  
ceramic products. Silica is used to regulate drying and 
shrinkage; it modifies thermal expansion and improves 
structural and mechanical properties (Hou et al., 2025; 
Tran et al., 2021; J. Wang et al., 2020).

CONCLUSION
Refractories are well-known for their superior engineering 
properties. They involve low production costs due to the 
reasonable source of  raw materials involved. The most 
common and widely used refractory composites are 
cordierite and mullite. They are prepared through various 
methods such as the combustion process, mechanical route, 
sol-gel route, the effect of  pH, etc. These compounds can 
also be studied in a ternary system to understand important 
applications such as those in high-temperature ceramics. 
They are made of  aluminosilicate compounds. 

REFERENCES
Abdelkader, D., & Abdecharif, B. (2012). Peculiarity 

of  the cathodoluminescence of  lpha-alumina 
prepared by calcination of  gibbsite powder or 
generated by oxidation of  a metallic FeCrAl alloy. In 
Cathodoluminescence. IntechOpen. 

Abyzov, A. (2019). Aluminum oxide and alumina ceramics 
(review). Part 1. Properties of  Al2O3 and commercial 
production of  dispersed Al2O3. Refractories and 
Industrial Ceramics, 60, 24-32. 

Ahmed, M. I., Jahin, H. S., Dessouki, H. A., & Nassar, M. 
Y. (2021). Synthesis and characterization of  γ-Al2O3 
and α-Al2O3 nanoparticles using a facile, inexpensive 
auto-combustion approach. Egyptian Journal of  
Chemistry, 64(5), 2509-2515. 

Aleem, S. A. E., Heikal, M., & Morsi, W. (2014). Hydration 
characteristic, thermal expansion and microstructure 
of  cement containing nano-silica. Construction and 
Building Materials, 59, 151-160. 

Atanga, V. K. (2013). Processing and properties of  alumina 
reinforced mullite ceramics [Universitätsbibliothek]. 

Baronskiy, M., Tsybulya, S., Kostyukov, A., Zhuzhgov, 
A., & Snytnikov, V. (2022). Structural properties 
investigation of  different alumina polymorphs (η-, γ-, 
χ-, θ-, α-Al2O3) using Cr3+ as a luminescent probe. 
Journal of  Luminescence, 242, 118554. 

Bilung, A. (2012). Synthesis and Characterization of  Cordierite 
and Mullite composite.

Biswas, S., Sarkar, D., Biswas, S., & Sarkar, D. (2020). 
Refractories for Iron and Steel Plant. Introduction to 
Refractories for Iron-and Steelmaking, 1-97. 

Boccaccini, D. N., Cannio, M., Volkov-Husoviæ, 
T., Kamseu, E., Romagnoli, M., Veronesi, P.,…
Boccaccini, A. R. (2008). Service life prediction for 
refractory materials. Journal of  materials science, 43, 
4079-4090. 



Pa
ge

 
45

https://journals.e-palli.com/home/index.php/ajcp

Am. J. Chem. Pharm. 4(1) 37-47, 2025

Bramsiepe, C., Sievers, S., Seifert, T., Stefanidis, G., 
Vlachos, D. G., Schnitzer, H.,…Bruins, M. (2012). 
Low-cost small scale processing technologies for 
production applications in various environments—
Mass produced factories. Chemical Engineering and 
Processing: Process Intensification, 51, 32-52. 

Camerucci, M., Urretavizcaya, G., Castro, M., & Cavalieri, 
A. (2001). Electrical properties and thermal expansion 
of  cordierite and cordierite-mullite materials. Journal 
of  the European Ceramic Society, 21(16), 2917-2923. 

Castruita, G., Perera-Mercado, Y., & Saucedo-Salazar, E. 
(2013). Sol–Gel Aluminum Hydroxides and Their 
Thermal Transformation Studies for the Production 
of  α-Alumina. Journal of  inorganic and organometallic 
polymers and materials, 23, 1145-1152. 

Chandra, K. S., & Sarkar, D. (2019). Refractories and 
failures. In Ceramic Processing (pp. 167-213). CRC Press. 

Chermat, Z., Loucif, K., & Belbali, A. (2025). The Effect 
of  K2CO3 on the SiC Formation by Carbothermal 
Reduction of  Chamotte. Silicon, 17(2), 311-321. 

Cioangher, M., Amarande, L., Stan, G., Nedelcu, 
L., Pasuk, I., Leonat, L.,…Moisescu, M. (2024). 
Hindrances and solutions on the path towards 
adjoined barium titanate–hydroxyapatite ceramics 
with uncompromised piezoelectric and biological 
responses. Ceramics international, 50(17), 29711-29728. 

Colomban, P. (2020). Chemical preparation routes and 
lowering the sintering temperature of  ceramics. 
Ceramics, 3(3), 312-339. 

Czerwinski, F. (2020). Thermal stability of  aluminum 
alloys. Materials, 13(15), 3441. 

da Silva, V. J., de Almeida, E. P., Gonçalves, W. P., da 
Nóbrega, R. B., de Araújo Neves, G., de Lucena Lira, 
H.,…de Lima Santana, L. N. (2019). Mineralogical 
and dielectric properties of  mullite and cordierite 
ceramics produced using wastes. Ceramics international, 
45(4), 4692-4699. 

Dana, K., Sinhamahapatra, S., Tripathi, H. S., & Ghosh, 
A. (2014). Refractories of  alumina-silica system. 
Transactions of  the Indian Ceramic Society, 73(1), 1-13. 

Danninger, H., Calderon, R., & Gierl-Mayer, C. (2017). 
Powder metallurgy and sintered materials. Addit. 
Manuf, 19(4). 

Debrah, J. K., Vidal, D. G., & Dinis, M. A. P. (2021). Raising 
awareness on solid waste management through formal 
education for sustainability: A developing countries 
evidence review. Recycling, 6(1), 6. 

Dudnik, E., Lakiza, S., Tishchenko, Y. S., Ruban, A., 
Red’ko, V., Shevchenko*, A., & Lopato*, L. (2014). 
Phase diagrams of  refractory oxide systems and 
microstructural design of  materials. Powder metallurgy 
and metal ceramics, 53, 303-311. 

El-Fadaly, E. A., Askar, A. S., Aly, M. H., & Ibrahim, 
D. M. (2022). Rheological, physico-mechanical and 
microstructural properties of  porous mullite ceramic 
based on environmental wastes. Boletín de la Sociedad 
Española de Cerámica y Vidrio, 61(2), 121-129. 

Fahlman, B. D. (2023). Semiconductors. In Materials 

Chemistry (pp. 291-405). Springer. 
Fernandes, I. J., Moraes, C. A., Egea, J. R., & Sousa, V. 

C. (2024). Production and characterization of  silica 
materials from rice husk ash by different combustion 
processes. Powder Technology, 436, 119473. 

Flores-Jacobo, A., Aguilar-Reyes, E. A., & León-Patiño, 
C. A. (2023). Effect of  dopants on the physical, 
mechanical, and biological properties of  porous 
scaffolds for bone tissue engineering. Biomedical 
Materials & Devices, 1(1), 234-255. 

Garbers-Craig, A. (2008). Presidential address: How cool 
are refractory materials? Journal of  the Southern African 
Institute of  Mining and Metallurgy, 108(9), 491-506. 

Giuliani, G., Groat, L. A., Fallick, A. E., Pignatelli, I., 
& Pardieu, V. (2020). Ruby deposits: A review and 
geological classification. Minerals, 10(7), 597. 

Götze, J. (2012). Classification, mineralogy and industrial 
potential of  SiO 2 minerals and rocks. Quartz: Deposits, 
mineralogy and analytics, 1-27. 

Guanghui, L. (2024). Refractory Industry in China. In The 
ECPH Encyclopedia of  Mining and Metallurgy (pp. 1781-
1782). Springer. 

Gudlur, P., Forness, A., Lentz, J., Radovic, M., & Muliana, 
A. (2012). Thermal and mechanical properties of  Al/
Al2O3 composites at elevated temperatures. Materials 
Science and Engineering: A, 531, 18-27. 

Gutierrez, G., & Johansson, B. (2002). Molecular dynamics 
study of  structural properties of  amorphous Al 2 O 
3. Physical Review B, 65(10), 104202. 

Horckmans, L., Nielsen, P., Dierckx, P., & Ducastel, A. 
(2019). Recycling of  refractory bricks used in basic 
steelmaking: A review. Resources, Conservation and 
Recycling, 140, 297-304. 

Hossain, S. S., & Roy, P. (2020). Sustainable ceramics 
derived from solid wastes: a review. Journal of  Asian 
Ceramic Societies, 8(4), 984-1009. 

Hosseini, A., & Kishawy, H. A. (2014). Cutting tool 
materials and tool wear. In Machining of  titanium alloys 
(pp. 31-56). Springer. 

Hou, T., Liu, X., Ren, J., Xu, X., Lan, D., Zhang, S.,…Wu, 
G. (2025). Mesoporous hollow silica with controlled 
particle size for optimizing dielectric properties 
and coefficient of  thermal expansion of  polyimide 
packaging materials. Journal of  Materials Science & 
Technology, 235, 122-132. 

Hyde, E. D., Seyfaee, A., Neville, F., & Moreno-Atanasio, 
R. (2016). Colloidal silica particle synthesis and future 
industrial manufacturing pathways: a review. Industrial 
& Engineering Chemistry Research, 55(33), 8891-8913. 

Jandyal, A., Chaturvedi, I., Wazir, I., Raina, A., & Haq, 
M. I. U. (2022). 3D printing–A review of  processes, 
materials and applications in industry 4.0. Sustainable 
Operations and Computers, 3, 33-42. 

Kamara, S. (2025). SEM, EDS, FTIR, & XRD 
Characterization of  Cordierite Ceramics Mechanically 
Synthesized from Silica and Kaolin Reinforced with 
Magnesia (MgO). Moroccan Journal of  Chemistry, 13(3), 
J. Chem. 13(13)-1092. 



Pa
ge

 
46

https://journals.e-palli.com/home/index.php/ajcp

Am. J. Chem. Pharm. 4(1) 37-47, 2025

Kamara, S., Ma, Y., Foday Jr, E. H., & Kallon, H. D. S. 
(2025). Synthesis of  mullite ceramics from powdered 
mine tailings reinforced with Al2O3. International 
Journal of  Applied Ceramic Technology, 22(2), e14932. 

Kamara, S., Wang, W., & Ai, C. (2020). Fabrication of  
refractory materials from coal fly ash, commercially 
purified kaolin, and alumina powders. Materials, 
13(15), 3406. 

Khosravi Mardkhe, M. (2014). Facile Synthesis and 
Characterization of  a Thermally Stable Silica-Doped 
Alumina with Tunable Surface Area, Porosity, and 
Acidity. 

Kiattisaksophon, P., & Thiansem, S. (2008). The 
preparation of  cordierite-mullite composite for 
thermal shock resistance material. Chiang Mai J. Sci, 
35(1), 6-10. 

Lan, L., Yu, J., Yang, Z., Li, C., Ren, Z., & Wang, Q. 
(2016). Interfacial microstructure and mechanical 
characterization of  silicon nitride/nickel-base 
superalloy joints by partial transient liquid phase 
bonding. Ceramics international, 42(1), 1633-1639. 

Mohd Mortar, N. A., Abdullah, M. M. A. B., Abdul 
Razak, R., Abd Rahim, S. Z., Aziz, I. H., Nabiałek, 
M.,…Ghazali, M. F. (2022). Geopolymer ceramic 
application: A review on mix design, properties and 
reinforcement enhancement. Materials, 15(21), 7567. 

Nanda, S., Choudhury, A., Chandra, K. S., & Sarkar, D. 
(2023). Raw materials, microstructure, and properties 
of  MgO–C refractories: directions for refractory 
recipe development. Journal of  the European Ceramic 
Society, 43(1), 14-36. 

Nestler, T., Fedotov, S., Leisegang, T., & Meyer, D. C. 
(2019). Towards Al3+ mobility in crystalline solids: 
critical review and analysis. Critical Reviews in Solid State 
and Materials Sciences, 44(4), 298-323. 

Norman, P., Schwartzentruber, T. E., Leverentz, H., Luo, 
S., Meana-Pañeda, R., Paukku, Y., & Truhlar, D. G. 
(2013). The structure of  silica surfaces exposed to 
atomic oxygen. The Journal of  Physical Chemistry C, 
117(18), 9311-9321. 

Nwannenna, O., Apeh, F., Ogunro, A., & Fabiyi, M. (2015). 
Characterization of  Ibamajo, Moye and Nkwo-Alaike 
Fireclays for Use as Refractory Materials in Foundry 
Industry. Chemical and Process Engineering Research, 35. 

Ortiz-Bravo, C. A., Figueroa, S. J., Portela, R., Chagas, C. 
A., Bañares, M. A., & Toniolo, F. S. (2022). Elucidating 
the structure of  the W and Mn sites on the Mn-
Na2WO4/SiO2 catalyst for the oxidative coupling of  
methane (OCM) at real reaction temperatures. Journal 
of  Catalysis, 408, 423-435. 

Pabst, W., & Gregorová, E. (2013). Elastic properties of  
silica polymorphs–a review. Ceramics-Silikáty, 57(3), 
167-184. 

Pan, X., Li, S., Li, Y., Guo, P., Zhao, X., & Cai, Y. (2022). 
Resource, characteristic, purification and application 
of  quartz: A review. Minerals Engineering, 183, 107600. 

Panasyuk, G., Azarova, L., Belan, V., Semenov, E., 
Danchevskaya, M., Voroshilov, I.,…Kharatyan, S. 

Y. (2019). Methods for high-purity aluminum oxide 
production for growth of  leucosapphire crystals. 
Theoretical foundations of  chemical engineering, 53, 596-601. 

Polyakova, I. G. (2014). The main silica phases and some 
of  their properties. Glass: selected properties and 
crystallization. Walter de Gruyter GmbH, 197-268. 

Pulugurtha, M. R., Sharma, H., Pucha, R., Kathaperumal, 
M., & Tummala, R. (2022). Packaging materials in 
high-performance computing applications. Journal of  
the Indian Institute of  Science, 102(1), 461-487. 

Rahman, M., Haider, J., Akter, T., & Hashmi, M. (2014). 
1.02-Techniques for assessing the properties of  
advanced ceramic materials. Comprehensive Materials 
Processing, Hashmi, S., et al., Editors: Elsevier: 
Oxford, 3-34. 

Rustad, J. R., Loring, J. S., & Casey, W. H. (2004). Oxygen-
exchange pathways in aluminum polyoxocations. 
Geochimica et Cosmochimica Acta, 68(14), 3011-3017. 

Sadik, C., Moudden, O., El Bouari, A., & El Amrani, I.-E. 
(2016). Review on the elaboration and characterization 
of  ceramics refractories based on magnesite and 
dolomite. Journal of  Asian Ceramic Societies, 4(3), 219-233. 

Sarkar, R. (2023). Refractory technology: fundamentals and 
applications. CRC Press. 

Schnurre, S., Gröbner, J., & Schmid-Fetzer, R. (2004). 
Thermodynamics and phase stability in the Si–O 
system. Journal of  Non-Crystalline Solids, 336(1), 1-25. 

Sengupta, P. (2020). Refractories for the chemical industries. 
Springer. 

Shackelford, J. F., & Doremus, R. H. (2008). Ceramic and 
glass materials. Structure, Properties and Processing. 

Shirai, T., Watanabe, H., Fuji, M., & Takahashi, M. (2010). 
Structural properties and surface characteristics 
on aluminum oxide powders Nagoya Institute of  
Technology]. 

Simonet, C., Fritsch, E., & Lasnier, B. (2008). A 
classification of  gem corundum deposits aimed 
towards gem exploration. Ore Geology Reviews, 34(1-2), 
127-133. 

Slovikovskii, V., & Gulyaeva, A. (2018). Creation of  
high-efficiency promising refractory materials and 
constructions for the lining of  metallurgical units. 
Refractories and Industrial Ceramics, 58, 475-480. 

Sobczak, J., Sobczak, N., Darlak, P., Slawinski, Z., Asthana, 
R., & Rohatgi, P. (2002). Thermal fatigue resistance 
of  discontinuously reinforced cast aluminum-
matrix composites. Journal of  materials engineering and 
performance, 11, 595-602. 

Sun, Y., Cai, J., Xu, L., Ma, X., & Pan, J. (2024). Mechanical 
and environmental performance of  engineered 
geopolymer composites incorporating ternary solid 
waste. Journal of  Cleaner Production, 441, 141065. 

Sun, Z., Yu, J., Zhao, H., Sang, S., & Zhang, H. (2022). 
Effects of  partial substitution of  calcium alumino-
titanate on the properties and microstructure of  
mullite–cordierite composites. Ceramics international, 
48(24), 36056-36065. 

Toenshoff, H. K., & Denkena, B. (2013). Basics of  cutting 



Pa
ge

 
47

https://journals.e-palli.com/home/index.php/ajcp

Am. J. Chem. Pharm. 4(1) 37-47, 2025

and abrasive processes. 
Townsend, T. G. (2011). Environmental issues and 

management strategies for waste electronic and 
electrical equipment. Journal of  the Air & Waste 
Management Association, 61(6), 587-610. 

Tran, N. P., Gunasekara, C., Law, D. W., Houshyar, S., 
Setunge, S., & Cwirzen, A. (2021). A critical review 
on drying shrinkage mitigation strategies in cement-
based materials. Journal of  Building Engineering, 38, 
102210. 

Ulusoy, U. (2023). A review of  particle shape effects on 
material properties for various engineering applications: 
from macro to nanoscale. Minerals, 13(1), 91. 

Vakalova, T., Pogrebenkov, V., Ivanchenkov, A., & 
Alekseev, E. (2004). Effect of  topaz on the synthesis 
of  mullite in mixtures of  kaolinite and alumina. 
Refractories and Industrial Ceramics, 45, 416-420. 

Wang, H., Li, L., Wei, X., Hou, X., Li, M., Wu, X.,…
Yu, J. (2020). Combining alumina particles with 
three-dimensional alumina foam for high thermally 
conductive epoxy composites. ACS Applied Polymer 
Materials, 3(1), 216-225. 

Wang, J., Cheng, Y., Yuan, L., Xu, D., Du, P., Hou, P.,…
Wang, Y. (2020). Effect of  nano-silica on chemical 
and volume shrinkage of  cement-based composites. 
Construction and Building Materials, 247, 118529. 

Wang, Y., Ma, B., Ulbricht, M., Dong, Y., & Zhao, X. 
(2022). Progress in alumina ceramic membranes 
for water purification: status and prospects. Water 
Research, 226, 119173. 

Wiberg, N., Niedermayer, W., Nöth, H., Knizek, J., 
Ponikwar, W., Polborn, K.,…Baum, G. (2001). 
Disupersilylsilane R* 2, Disupersilyldisilane R* 2XSi–
SiX3 und Tetrasupersilyltetrasilane R* 2XSi–SiX2–

SiX2–SiXR* 2. Zeitschrift für anorganische und allgemeine 
Chemie, 627(4), 594-606. 

Xie, Z., Xue, W., Chen, H., & Huang, Y. (2011). Mechanical 
and thermal properties of  99% and 92% alumina at 
cryogenic temperatures. Ceramics international, 37(7), 
2165-2168. 

Xu, X., Zhang, Y., Wu, J., Hu, C., & Tang, Z. (2017). 
Preparation and performance study of  cordierite/
mullite composite ceramics for solar thermal energy 
storage. International Journal of  Applied Ceramic 
Technology, 14(2), 162-172. 

Yang, Z., Liu, G., Qi, T., Zhou, Q., Peng, Z., Shen, L.,…Li, 
X. (2024). Bayerite in aluminum hydroxide effecting 
the thermal decomposition pathways and reducing 
density of  α-Al2O3. Journal of  Alloys and Compounds, 
1004, 175884. 

Yin, L., Cheng, R., Ding, J., Jiang, J., Hou, Y., Feng, X.,…
He, J. (2024). Two-dimensional semiconductors and 
transistors for future integrated circuits. ACS nano, 
18(11), 7739-7768. 

Yurkov, A. (2015). Refractories for aluminium. Switzerland, 245-249. 
Zemánek, D., Lang, K., Tvrdík, L., Všianský, D., 

Nevřivová, L., Štursa, P.,…Dvořák, K. (2021). 
Development and properties of  new mullite based 
refractory grog. Materials, 14(4), 779. 

Zhang, B., Yu, T., Guo, H., Chen, J., Liu, Y., & Yuan, 
P. (2022). Effect of  the SiO2/Al2O3 molar ratio on 
the microstructure and properties of  clay-based 
geopolymers: a comparative study of  kaolinite-based 
and halloysite-based geopolymers. Clays and Clay 
Minerals, 70(6), 882-902. 

Zhong, Z.-W. (2021). Processes for environmentally 
friendly and/or cost-effective manufacturing. Materials 
and Manufacturing Processes, 36(9), 987-1009. 


