Large-scale and ultra-low thermal conductivity of ZrO2 fibrofelt/ZrO2-SiO2 aerogels composites for thermal insulation

Gao

et al. 2019

ACS Appl. Nano Mater.

Compared with single-component aerogels, hybrid aerogels with multiple components possess enhanced properties, especially high thermal stabilities. Thermal stability improvement depends on the mixing between the various components. In the present research, a ZrO2/SiO2 hybrid aerogel was representatively chosen to study the mixing behaviors and resultant thermal stabilities. A series of ZrO2/SiO2 hybrid aerogels were synthesized by using different sol–gel parameters to study shrinkage, nanopore collapse, and crystallization behavior upon heat treatment. The sol–gel hybridization of weakly branched ZrO2 and SiO2 clusters was found to provide maximum mixing of ZrO2/SiO2. The highly mixed hybrid aerogel, with a ratio of 86/14 w/w ZrO2/SiO2, showed the best thermal stability. The thermally stable ZrO2/SiO2 hybrid aerogel, after incorporation into a mullite fiber blanket, showed very low thermal conductivities of 0.026 ± 0.001, 0.037 ± 0.001, and 0.058 ± 0.002 W/(m K) at 600, 800, and 1000 °C, respectively. It was suggested that weakly branched ZrO2 and SiO2 clusters preferred to freely tangle with each other during the preparation procedure, achieving the most highly mixed ZrO2/SiO2 hybrid with the maximum synergistic effect. This hybrid strategy may provide pathways in designing other multiple-component hybrid aerogels.

Section: Results and Discussionmentioning

confidence: 73%

Section: Acs Applied Nano Materialsmentioning

confidence: 99%

Thermally Stable Nanoporous ZrO₂/SiO₂ Hybrid Aerogels for Thermal Insulation

Gao

et al. 2019

ACS Appl. Nano Mater.

“…Some augmented methods have been used in order to obtain a better result, such as including ceramic fibers or functional polymers (epoxy, polyurethane and polyethylene) by cross-linking them with the aerogels. As a comparison between organic or inorganic reinforcement, it has been demonstrated that the inorganic reinforcement is obvious and confirmed as having potential due to its supportive stability behavior at high temperature [91].…”

Section: Zirconium Diboride/silicon Carbide (Zrb 2 /Sic) Compositesmentioning

confidence: 95%

Ceramic Composite Materials Obtained by Electron-Beam Physical Vapor Deposition Used as Thermal Barriers in the Aerospace Industry

et al. 2020

This paper is focused on the basic properties of ceramic composite materials used as thermal barrier coatings in the aerospace industry like SiC, ZrC, ZrB 2 etc., and summarizes some principal properties for thermal barrier coatings. Although the aerospace industry is mainly based on metallic materials, a more attractive approach is represented by ceramic materials that are often more resistant to corrosion, oxidation and wear having at the same time suitable thermal properties. It is known that the space environment presents extreme conditions that challenge aerospace scientists, but simultaneously, presents opportunities to produce materials that behave almost ideally in this environment. Used even today, metal-matrix composites (MMCs) have been developed since the beginning of the space era due to their high specific stiffness and low thermal expansion coefficient. These types of composites possess properties such as high-temperature resistance and high strength, and those potential benefits led to the use of MMCs for supreme space system requirements in the late 1980s. Electron beam physical vapor deposition (EB-PVD) is the technology that helps to obtain the composite materials that ultimately have optimal properties for the space environment, and ceramics that broadly meet the requirements for the space industry can be silicon carbide that has been developed as a standard material very quickly, possessing many advantages. One of the most promising ceramics for ultrahigh temperature applications could be zirconium carbide (ZrC) because of its remarkable properties and the competence to form unwilling oxide scales at high temperatures, but at the same time it is known that no material can have all the ideal properties. Another promising material in coating for components used for ultra-high temperature applications as thermal protection systems is zirconium diboride (ZrB 2 ), due to its high melting point, high thermal conductivities, and relatively low density. Some composite ceramic materials like carbon-carbon fiber reinforced SiC, SiC-SiC, ZrC-SiC, ZrB 2 -SiC, etc., possessing low thermal conductivities have been used as thermal barrier coating (TBC) materials to increase turbine inlet temperatures since the 1960s. With increasing engine efficiency, they can reduce metal surface temperatures and prolong the lifetime of the hot sections of aero-engines and land-based turbines.

ACS Appl. Mater. Interfaces

“…The evaporation system can be meticulously optimized by reducing heat loss due to conduction, convection, and radiation . The yttria-stabilized zirconia (YSZ) has the advantages of light weight, high mechanical vibration resistance, excellent chemical stability, and ultralow thermal conductivity, − which makes it ideal for thermal management in the harsh marine environment . However, most of the reported evaporators can only effectively work on sunny days, and it has been extremely challenging to improve the evaporation efficiency of the evaporator .…”

Section: Introductionmentioning

confidence: 99%

Interface Engineering of a Ti₄O₇ Nanofibrous Membrane for Efficient Solar-Driven Evaporation

Qiu

Kong

et al. 2022

Solar-driven interfacial evaporation provides a feasible and sustainable way to solve the fresh water shortage using abundant solar energy and has recently attracted considerable attention. However, it has been limited by the evaporation rate and solar-heat conversion efficiency of the current materials. Herein, a novel Ti 4 O 7 membrane with synergetic photothermal and electrothermal effects was developed using a straightforward in situ approach. Based on interface engineering, the interface between the surface of the membrane and water was hydrophobically modified, and a thermal insulation layer was added to the bottom of the membrane. The optimized self-floating membrane with excellent sunlight absorbability and conductivity achieved a remarkably high evaporation rate of 7.51 kg m −2 h −1 with a voltage of 3 V as compensation under one-sun irradiation (1 kW m −2 ). Moreover, the bilayered membrane displayed efficient salt ion rejection, and the collected water can meet the World Health Organization (WHO) standard required for potable water.