Anorthite ceramics: grog and clay selection for lowering the sintering temperature

ABSTRACT

A research investigation was conducted on two variables that are indicative of plastic raw materials based on kaolin vs. interstratified illite-smectite clay and a non-plastic admixture including grog (quartz vs. alumina) during the sintering process of an anorthite porcelain body beginning at 950°C, up to the sintering temperature. A correlation was found between the mineralogical composition and various parameters of the fired bodies. A purely anorthic sintered body can be produced using interstratified illite-smectite clay with quartz as a grog, which has the lowest coefficient of linear thermal expansion in the temperature range of 30°C to 700°C and highest bending strength – modulus of rupture of sintered body. When alumina is present in the raw material mixture, the coefficient of linear thermal expansion is lower due to the absence of the SiO₂ phases. Quartz in combination with interstratified illite-smectite clay significantly reduces the sintering temperature through the formation of an amorphous melt up to the sintering temperature.

HIGHLIGHTS

Summary of novel conclusions

• Utilization of interstratified illite/smectite clay as a raw material

• Utilization of quartz and alumina as grogs

• Crystallization of anorthite bodies fired at 950°C

• Alumina used as a grog lowered the coefficient of linear thermal expansion.

• Quartz used as a grog lowered the required sintering temperature

KEYWORDS:

• Anorthite ceramics
• mineralogical composition
• sintering temperature
• coefficient of linear thermal expansion
• bending strength

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The data presented in this paper are available upon request from the corresponding author.

Additional information

Funding

This work was supported by the Czech Science Foundation under [Grant No. 20-01536S] “Controlled modification of mineralogical composition of ceramic body for improvement of its utility properties” and Brno University of Technology specific university research under [Grant No. FAST-J-22-7955].