溶胶凝胶水热法制备耐高温、隔热增强钙掺杂二氧化硅气凝胶

doi:10.15541/jim20250113

摘要/Abstract

摘要：

二氧化硅气凝胶因低密度、低导热系数和良好的高温稳定性, 广泛应用于高温隔热领域, 但由于其固有的材料特性, 当工作温度超过600 ℃, 其孔结构将逐渐塌缩, 从而使隔热性能大幅度衰减, 同时在高温下红外辐射的遮蔽效果也较差。本研究旨在探讨通过钙掺杂提高二氧化硅气凝胶的高温稳定性及红外遮蔽能力。以水玻璃和无水氯化钙为前驱体, 以三甲基氯硅烷(TMCS)为疏水改性剂, 通过溶胶-凝胶、水热和常压干燥(APD)技术制备了耐高温的钙掺杂二氧化硅气凝胶(CSA)粉体。研究了前驱体中Ca/Si摩尔比和水热条件(温度和pH)对CSA结晶特性、微观形貌和孔结构的影响。结果表明, 在400~1000 ℃范围内, Ca/Si摩尔比和水热处理对CSA的微观结构和耐热性有显著影响。1000 ℃烧结的样品具有较高的比表面积(100.1 m²/g)和孔容(0.8705 cm³/g), 表明CSA具有良好的耐高温性能。温度高达600 ℃的单面隔热测试表明, Ca/Si摩尔比为1的样品隔热性能最好, 冷表面温度为450 ℃, 比纯二氧化硅气凝胶低27 ℃。

关键词: 二氧化硅气凝胶, 钙掺杂, 耐高温性, 水热, 常压干燥

Abstract:

Silica aerogel has broad applications in the field of high-temperature thermal insulation due to its low density, low thermal conductivity and high stability. However, its thermal insulation performance deteriorates significantly at elevated temperatures exceeding 600 ℃, primarily due to the collapse of pore structure. Meanwhile, the shielding capacity of SiO₂ aerogel to the infrared radiation at high temperature is rather low due to the intrinsic properties of SiO₂. Herein, a strategy for improving the high-temperature stability and infrared shielding properties of SiO₂ aerogel via Ca doping was explored. Calcium-doped silica aerogel (CSA) powders were prepared by Sol-Gel, hydrothermal, and ambient pressure drying (APD) techniques using water glass and anhydrous calcium chloride as precursors and trimethylchlorosilane as a hydrophobic modifier. The effects of Ca/Si molar ratio in the precursor and hydrothermal conditions (temperature and pH) on the crystalline properties, microscopic morphology and pore structure of CSAs were investigated. The results show that the Ca/Si molar ratio and hydrothermal treatment have significant effects on the microstructure and heat resistance of CSAs in the temperature range of 400-1000 ℃. The samples sintered at 1000 ℃ have a high specific surface area of 100.1 m²/g and a pore volume of 0.8705 cm³/g, indicating that the CSA has good heat resistance. One-side insulation tests at temperatures up to 600 ℃ show that the sample with a Ca/Si molar ratio of 1.0 has the best insulation performance, with a cold surface temperature of 450 ℃, which is 27 ℃ lower than that of the pure silica aerogel.

Key words: silica aerogel, calcium doping, high-temperature resistance, hydrothermal, ambient pressure drying

中图分类号:

TQ424

李浩, 齐源, 高相东, 张星星, 王金敏. 溶胶凝胶水热法制备耐高温、隔热增强钙掺杂二氧化硅气凝胶[J]. 无机材料学报, 2026, 41(2): 262-272.

LI Hao, QI Yuan, GAO Xiangdong, ZHANG Xingxing, WANG Jinmin. High Temperature Resistant Calcium-doped Silica Aerogels with Enhanced Thermal Insulation via Sol-Gel Hydrothermal Route[J]. Journal of Inorganic Materials, 2026, 41(2): 262-272.

图/表 14

Fig. 1 Schematic illustration of the preparation process of hydrothermal CSA (HCSA) by the Sol-Gel, hydrothermal and APD method

Table 1 Experimental parameters of the aerogel powders

Sample	Ca/Si molar ratio	Temperature/℃	pH^*
PSA	0	-	-
HPSA	0	180	5-6
CSA-0.4	0.4	-	5-6
HCSA-0.4	0.4	120	5-6
	0.4	140	5-6
	0.4	160	5-6
	0.4	180	5-6
	0.4	200	5-6
HCSA-0.6	0.6	180	5-6
HCSA-0.8	0.8	180	5-6
HCSA-1.0	1.0	180	5-6
	1.0	180	7-8
	1.0	180	9-10
	1.0	180	12-13
HCSA-1.2	1.2	180	5-6
HCSA-1.5	1.5	180	5-6

Fig. 2 Packing densities of different samples (a) PSA and CSA-0.4 under different hydrothermal conditions; (b) HCSA-0.4 at different hydrothermal temperatures and HCSA-1.0 at different hydrothermal pH; (c, d) HCSA sintered at different temperatures for 2 h

Fig. 3 XRD patterns of the PSA, HPSA, CSA-1.0, and HCSA-1.0 samples

Fig. 4 (a-d) SEM images of (a) PSA, (b) HPSA, (c) CSA-1.0, and (d) HCSA-1.0; (e) Elemental mappings and (f) EDS spectrum of HCSA-1.0

Fig. 5 (a) TEM image, (b) SAED pattern and (c) HRTEM image of the as-prepared HCSA-1.0; (d) TEM image, (e) SAED pattern and (f) HRTEM image of HCSA-1.0 sintered at 1000 ℃ for 2 h

Fig. 6 Pore structure of HCSA-1.0 sintered at different temperatures (a) Adsorption-desorption isotherms; (b) Pore size distributions (evaluated from desorption isotherm); (c) Specific surface area and pore volume; (d) Average pore size

Fig. 7 SEM images of HCSA-1.0 samples sintered at (a) 400, (b) 600, (c) 800, and (d) 1000 ℃

Fig. 8 TG-DSC curves of (a) PSA and (b) HCSA-1.0

Fig. 9 (a) Flat heating furnace test device; (b) Schematic diagram of a home-made device for measuring thermal insulation properties; (c) Plots of temperature variation of the flat heating furnace test; (d) Specific extinction coefficients of PSA and HCSA-1.0 in infrared band Colorful figures are available on website

Fig. S1 Low resolution SEM image used for EDS mapping test

Fig. S2 Photographs of PSA (a) and HCSA-1.0 (b) samples calcined at 1000 ℃

Fig. S3 TEM images of HCSA-1.0 calcined at 1000 ℃ (a) Fringe of a large particle; (b) A small particle

Fig. S4 XRD patterns of HCSA-1.0 sintered at different temperatures

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