Microstructure and properties of porous anorthite/mullite whiskers ceramics with high porosity

Abstract

Porous anorthite/mullite whiskers ceramics with high porosity (>91%) and high strength (>0.45 MPa) have been successfully prepared by foam gel‐casting method. Effects of extra mullite whiskers on properties including thermal conductivity and compressive strength at different temperatures were investigated and discussed in terms of microstructure observed through SEM and TEM. The results showed that the addition of extra mullite whiskers in certain content could effectively reduce thermal conductivity, improve the compressive strength both at room and high temperature at same time. When the mullite whiskers content was 20 mol%, the porosity was as high as 91.6 ± 0.19%, the thermal conductivity was low to 0.034 ± 0.003 W/(m·K), and the compressive strength at 1000°C was high to 0.64 ± 0.11 MPa three times to the pure one. Small pores, small grains, and more phase interface or grain boundary caused by the addition of extra mullite whiskers were the main factors for low thermal conductivity. Meanwhile, small pores, closely bonded small grains, and the stable three‐dimension network formed by mullite whiskers helped to improve strength.

Mössbauer study of the black‐glazed Jian bowl in the Song dynasty

“…The SEM images of selected areas on the surface of Jianjian black glaze and the overlay of the major elemental mapping are shown in Figure 3. It can be seen that the distribution of each element on the surface of the sample is relatively uniform and characterized by amorphous glassy silicate 15,16 . In addition, the distribution of Fe elements remains consistent with O, Si, Al, and Ca, indicating that Fe elements are uniformly distributed in the calcium‐aluminum silicates, which corroborates with the XRD results.…”

Fiber reinforced porous (La1/5Nd1/5Sm1/5Gd1/5Yb1/5)2Zr2O7 ceramics with enhanced compressive strength

“…It can be concluded that the as‐prepared YSZ f /(5RE 1/5 ) 2 Zr 2 O 7 PCs showed both the highest compressive strength and lowest thermal conductivity, compared with the sample YSZ f /(3RE 1/5 ) 2 Zr 2 O 7 and sample YSZ f /La 2 Zr 2 O 7 , which can be ascribed to the high‐entropy effect 44–46 . We have also made a contrast of compressive strength versus thermal conductivity, as shown in Figure 5D, to evaluate the merits of the YSZ f /(5RE 1/5 ) 2 Zr 2 O 7 PCs over other porous ceramics reported in the literatures 47–56 . It can be clearly concluded that the as‐prepared YSZ f /(5RE 1/5 ) 2 Zr 2 O 7 PCs exhibited outstanding strength‐to‐thermal conductivity ratio (higher strength and lower thermal conductivity), demonstrating that the YSZ f /(5RE 1/5 ) 2 Zr 2 O 7 PCs can be applied to the field of high‐temperature thermal insulations.…”

“…[44][45][46] We have also made a contrast of compressive strength versus thermal conductivity, as shown in Figure 5D, to evaluate the merits of the YSZ f /(5RE 1/5 ) 2 Zr 2 O 7 PCs over other porous ceramics reported in the literatures. [47][48][49][50][51][52][53][54][55][56] It can be clearly concluded that the as-prepared YSZ f /(5RE 1/5 ) 2 Zr 2 O 7 PCs exhibited outstanding strength-to-thermal conductivity ratio (higher strength and lower thermal conductivity), demonstrating that the YSZ f /(5RE 1/5 ) 2 Zr 2 O 7 PCs can be applied to the field of high-temperature thermal insulations. thermal conductivity performed a slow increasing trend with increased testing temperature.…”

Recent Advances in the Nanomaterials, Design, Fabrication Approaches of Thermoelectric Nanogenerators for Various Applications

“…[ 79–81 ] However, the sputtering process makes it difficult to control the Se content. [ 79,81 ] Thermal evaporation deposition is another facile technique used to fabricate Cu 2 Se thin films with better control over Cu or Se content, but the process requires high temperatures above 1500 K. [ 82 ] By combining both magnetron sputtering and thermal evaporation in a layer‐by‐layer process, Fan et al. [ 70 ] fabricated an α‐phase Cu 2 Se thin film fabricated at room temperature.…”