Influence of calcined halloysite on technological & mechanical properties of wall tile body

Abstract

The effect of adding 0.1, 0.3, 0.6, 1.0 wt.% halloysite clay, which calcined at 600, 800, 1000 and 1200°C, to the standard wall tile slurry was studied. Wet milled halloysite was sieved with different sizes to examine the halloysite grain size effect. The granulated samples were pressed by applying a pressure of 30 MPa using a hydraulic press and made ready for sintering at 1150°C for 30 minutes. Detailed technological, mechanical and microstructural characterization studies were done on sintered samples. Compared to standard wall tile, almost all the halloysite added samples displayed similar technological properties but higher green and fired strength values. The produced sample with adding 0.6% halloysite (at 600°C calcined) by weight showed a higher firing strength with 28.75 MPa value than the minimum requirement (17.75 MPa). Observation of needlelike microstructure in the porcelain body led to establishing a simple relationship between the interlocking effects of thin needlelike mullite grains and increasing strength values. This study has shown that the addition of calcined halloysite may be an alternative to produce a thinner section wall tile product.

Advanced Monitoring and Conservation Strategies for Wall Paintings Impacted by Microbiological Degradation and Clay Minerals at Al-Qurna, Thebes West Bank (Luxor)

“…This property can lead to cracking and flaking of the wall paintings via applying a considerable pressure on the structure of Esna shale, limestone and clay mortars bearing wall paintings affecting the stability of the Theban tombs. Illite-smectite mixed layers may show intermediate swelling behavior and Vermiculite has also a medium shrink-swell capacity, but it can still cause some degree of cracking and flaking of the wall paintings while halloysite has a low shrinkswell capacity [61,62]. However, the fine particle size and high plasticity of halloysite can affect the texture and appearance of the wall paintings.…”

Halloysite-TiO2 Nanocomposites for Water Treatment: A Review

“…After heat treatment at 600, 800, and 1000 °C, in all halloysite samples, quartz is observed in pristine form, and the halloysite crystalline phase is converted into an amorphous phase through dihydroxylation [37]. Finally, when the temperature reaches 1200 °C, recrystallization occurs, and the mullite diffraction peak (ICDD # 015-0776) appears next to the quartz peak (Figure 4b) [28,38].…”

“…Upon calcination at 600 °C, halloysite is dehydroxylated and metahalloysite is formed, leading to the disappearance of the O-H stretch bands of the internal hydroxyl groups and internal surface hydroxyl groups (3622 cm −1 and 3697 cm −1 , respectively). The peaks at 999.76 cm −1 , 906.67 cm −1 , and 748.43 cm −1 correspond to Si-O stretching and O-H deformation vibration of the internal hydroxyl groups [20,38,[40][41][42][43]. In practice, HNTs are considered promising nanomaterials due to their biocompatibility, non-toxicity, good dispersion, and large SSA, which improves their performance [33].…”