Thermophysical Properties of Kaolin–Zeolite Blends up to 1100 °C

Ján Ondruška,Anton Trník,Tomáš Húlan,Grzegorz Łagód,Štefan Csáki,Alena Struhárová,Ivana Sunitrová

doi:10.3390/cryst11020165

Abstract

In this study, the thermophysical properties such as the thermal expansion, thermal diffusivity and conductivity, and specific heat capacity of ceramic samples made from kaolin and natural zeolite are investigated up to 1100 °C. The samples were prepared from Sedlec kaolin (Czech Republic) and natural zeolite (Nižný Hrabovec, Slovakia). Kaolin was partially replaced with a natural zeolite in the amounts of 10, 20, 30, 40, and 50 mass%. The measurements were performed on cylindrical samples using thermogravimetric analysis, a horizontal pushrod dilatometer, and laser flash apparatus. The results show that zeolite in the samples decreases the values of all studied properties (except thermal expansion), which is positive for bulk density, porosity, thermal diffusivity, and conductivity. It has a negative effect for thermal expansion because shrinkage increases with the zeolite content. Therefore, the optimal amount of zeolite in the sample (according to the studied properties) is 30 mass%.

Highlights

Ceramic production is known as one of the oldest sectors of human activity
The aim of this paper was to estimate the influence of natural zeolite in the kaolin–zeolite samples on their thermophysical properties, such as the thermal expansion, thermal diffusivity and conductivity, and specific heat capacity, during heating up to 1100 ◦ C and to determine the possible usage of natural zeolite in ceramic materials
The chemically bound water is evaporated, and this causes the structure of kaolinite to transform into metakaolinite

Summary

Introduction

Ceramic production is known as one of the oldest sectors of human activity. Traditional ceramics are usually used in the building industry, such as bricks and tiles. The partial substitution of raw materials with waste or new materials can improve the properties of ceramic products and reduce the cost of their production [1]. Many published studies deal with partial substitution of traditional input raw materials for production of ceramics by waste materials such as fly or bottom ash [2,3,4,5,6,7,8,9,10,11,12], waste glass [13,14,15,16], waste calcite [17], etc. Húlan et al [7] determined that a higher Young’s modulus was reached after sintering with a lower amount of fly ash

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