Effect of micro-cracking on the thermal conductivity and thermal expansion of tialite (Al2TiO5) ceramics

Papitha, Ramanathan; Suresh, M. Buchi; Das, Dibakar; Johnson, Roy

doi:10.2298/pac1303143p

Cited by 21 publications

(13 citation statements)

References 11 publications

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“…As confirmed by the results of this study, cooling strain values decrease with the increase in thermal cycle number under a same temperature change. This situation verified that the thermal strain capability decreases with a notable increase in porosity resulting from micro-cracking and the start of weathering (Papitha et al 2013;Lin 2002). As it was seen from andesite specimens, thermal strain limits can also decrease despite the increase in temperature of ongoing thermal cycle.…”

Section: Discussionsupporting

confidence: 69%

Thermal Shock Effect on Strength Loss Properties of Rock Materials: An Experimental Study on Thermal Fatigue Durability

Komurlu

2019

Doğal Afetler Ve Çevre Dergisi

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Four different types of rock materials from Eastern Black Sea Region of Turkey were investigated to determine their change in porosity as well as the degree of cracking, fracturing, disintegration and strength loss under heating-cooling cycles with variations in temperatures up to 300 C o. Cooling time and thermal strains of the rock specimens were also determined in this study. Totally, sixty rock core samples were tested to evaluate their physico-mechanical and mechanical properties. Thermal cycling was found to lead for increase in the porosity of the rocks, making new cracks, particle disintegration for two types of tested rocks and considerable losses in uniaxial compressive strength values of all the rock materials tested in this study. The purpose of this study is to investigate immediate changes in temperature values rather than step by step heating up to a target temperature. For instance, rock samples were directly put in 250 o C stove from a-50 o C cabin in the last and fifth thermal cycling. After the heating process, specimens were cooled in water and air. This study aims to be a usable reference to establish a thermal change procedure and improve a new testing method for determination of thermal fatigue durability of rock materials.

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Section: Discussionsupporting

confidence: 69%

Thermal Shock Effect on Strength Loss Properties of Rock Materials: An Experimental Study on Thermal Fatigue Durability

Komurlu

2019

Doğal Afetler Ve Çevre Dergisi

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“…First, a high fraction of interphase grain boundaries was formed as the charge carrier separation centers as a result of the new phase formation during the sintering process. Second, the difference in thermal expansion property between alumina and tialite (8 × 10 -6 /°C and 1 × 10 -6 /°C, respectively) [36] induced oxygen vacancies. Such a mechano-chemical effect due to the difference in the thermal expansion coefficient could effectively form oxygen vacancies as a charge compensation of Ti 3+ and Al 3+ formation.…”

Section: Optical Propertiesmentioning

confidence: 99%

Band gap tuning of oxygen vacancy-induced Al2O3-TiO2 ceramics processed by spark plasma sintering

2021

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Optical and photocatalytic applications of Al 2 O 3 and TiO 2 ceramics are limited, especially under visible light, due to their wide bandgap; so, this parameter plays an important and even decisive role in these applications. In the present study, Al 2 O 3 -TiO 2 ball milled powders were sintered by spark plasma sintering (SPS) at 1573 K. The products were characterized using XRD, SEM, UV-Vis and electrochemical methods. The results indicated effective improvement in the light absorbing capability of the composites (up to 95%) under visible light and the decrease of the band gap down to 2.2 eV owing to the increase of oxygen vacancies, which was, in turn, due to the reduced atmosphere of the sintering process. In addition, formation of a new phase (Al 2 TiO 5 ) during sintering greatly affected the absorption of Al 2 O 3 -TiO 2 composites in the visible light region due to the increase in the fraction of the charge carrier separation centers. Photo-luminescence spectroscopy also showed that tialite formation could be effective in improving the charge separation efficiency.

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“…The effects of cracks on the thermal conductivity have been investigated on various materials such as optical coatings [1], graphite materials [2], ceramics [3], thermal barrier coatings [4][5][6], fiber-reinforced composites [7], clay [8] and among others. These studies show that the thermal conductivity of materials decreases with the presence of cracks due to the very low thermal conductivity of air void created by cracks.…”

Section: Introductionmentioning

confidence: 99%

“…These studies show that the thermal conductivity of materials decreases with the presence of cracks due to the very low thermal conductivity of air void created by cracks. The presence of cracks was evidenced by micrograph [3,5], topological sensitivity [9,10] and was quantitatively characterized to interpret the results on thermal conductivity [6]. X-ray micro-tomography can be considered as a powerful tool to monitor the 3D spatial distribution of cracks in materials [11].…”

Section: Introductionmentioning

confidence: 99%

Heat conduction and thermal conductivity of 3D cracked media

Sang

Tang

et al. 2015

International Journal of Heat and Mass Transfer

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International audienceThis study deals with the heat conduction within a medium containing cracks that are assumed to be perfect insulators. Multi-region boundary element approach is employed to obtain a boundary singular integral equation governing the steady state thermal transfer within this medium. This equation presents the temperature field within the whole cracked body as a function of temperature and rate of heat flow on the domain's boundary and temperature discontinuity across the cracks. For the particular case of an infinite domain under far-field condition, the temperature field solution is only a function of the cracks tem-perature's discontinuity. The basic problem of a single crack in an infinite domain is investigated and a closed-form solution is derived for a crack of elliptic plane from this analysis. This solution is the key issue to estimate the effective thermal conductivity of the whole domain by coupling with the classical homogenization schemes. The arbitrary crack form is covered up by using the excluded volume definition. Estimations of effective thermal conductivities stemming from diluted, differential and self-consistent approaches are compared to numerical solution obtained by the finite volume modeling that is available in literature. This comparison shows that the self-consistent scheme is the most appropriate model to estimate the thermal conductivity of materials containing cracks

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Effect of micro-cracking on the thermal conductivity and thermal expansion of tialite (Al2TiO5) ceramics

Cited by 21 publications

References 11 publications

Thermal Shock Effect on Strength Loss Properties of Rock Materials: An Experimental Study on Thermal Fatigue Durability

Thermal Shock Effect on Strength Loss Properties of Rock Materials: An Experimental Study on Thermal Fatigue Durability

Band gap tuning of oxygen vacancy-induced Al2O3-TiO2 ceramics processed by spark plasma sintering

Heat conduction and thermal conductivity of 3D cracked media

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