Sintering and microstructural study of mullite prepared from kaolinite and reactive alumina: Effect of MgO and TiO₂

Abstract

Mullite is the most important ceramic materials in the Al 2 O 3-SiO 2 binary system. It is a well-known refractory material and has several industrial applications. Some of the properties of mullite, which make it most useful as a structural and functional ceramic material are high mechanical strength, low thermal conductivity, excellent thermal shock resistance, stability to high temperature, and good creep resistance up to 1300°C. 1-2 The beneficial features of mullite ceramic are appropriate high-temperature strength for structural application and outstanding stability in severe chemical environments. These properties draw significant attention and made mullite useful as metal fillers, catalyst supports, radiant burner, heat exchanger, hot blast stove, and torpedo ladles. 3-5 Several techniques were applied to prepare mullite powder as it is not readily available in nature. 5,6 Some sophisticated methods used for mullite powder synthesis are solid-state reaction sintering, combustion, sol-gel, precipitation, hydrothermal, and chemical vapor deposition. 5,7-10 The high costs of the raw materials used in these methods make these processes unsuitable for large-scale production. Some readily available alumino-silicates such as sillimanite, andalusite, and kyanites are widely used for commercial mullite production. 11 Preparation of mullite from kaolinite is an economical way, due to the common occurrence, lower cost, and good availability of this clay mineral. 12-14 The alumina content in clay is much less than the requirement (72 wt%) for stoichiometric mullite formation. During heat treatment of kaolinite; mullite formed along with silica and impurity-containing

Influence of zirconia on the sintering behaviour and mechanical properties of reaction-sintered mullite-based composite ceramics

“…The flexural strength and fracture toughness of the as-sintered ceramics were analyzed with a ceramic bending strength tester (WDW-50, Kaiqiangli, China). The flexural strength was measured by a three-point bending method (Suhasinee et al, 2020). Similarly, the fracture toughness was measured by a single-edge notched beam method (SENB) (Lian et al, 2021a).…”

Effect of Binder Content on Properties of Cordierite-Mullite Porous Ceramics

“…Aluminosilicate-based ceramics had become the research focus of refractory materials because of their high temperature properties [7][8]. In the process of sintering at high temperature, the addition of MgO increased the oxygen vacancy in Al2O3 and promoted the formation of liquid phase, which was conducive to physical transfer, thus promoting the formation of mullitite phase and cordierite phase, promoting the discharge of gas inside the ceramic, and improving the overall densification degree of the sample [9][10][11][12][13]. Cordierite has poor mechanical properties and was not easy to prepare by solid phase sintering, mullite had good mechanical properties, and cordierite and mullite had good thermal expansion matching and good chemical compatibility with silicon carbide [14].…”

Development of Mullite- Carbon Refractory Ceramic Composite From Locally Sourced Materials

“…The objective of the research was to examine the impact of introducing silicon carbide and varying sintering temperatures on the phase development within a ceramic composite composed of kaolin and graphite. Behera & Bhattacharyya (2020), conducted a study on the sintering and microstructural analysis of mullite, which was synthesized using kaolinite and reactive alumina with the addition of MgO and TiO2. The researchers examined the effect of these additives on phase creation, microstructural evolution, densification, and mechanical strength of the resulting mullite ceramic.…”