Low thermal conductivity and high porosity ZrC and HfC ceramics prepared by in-situ reduction reaction/partial sintering method for ultrahigh temperature applications

Rigid polyurethane foam (RPUF) is typically prepared by the reaction of an isocyanate, such as methyl diphenyl diisocyanate (MDI) with a polyol blend. During the polymerization reaction, a blowing agent expands the reacting mixture. The finished product is a solid, cellular polymer with a high thermal resistance. RPUF is an outstanding material for different applications. It has many desirable properties such as low thermal conductivity, low density, low water absorption, low moisture permeability, excellent dimensional stability, high strength to weight ratio. So, it is the best insulating material for industrial buildings, cold storages, telecom and defense shelters due to low thermal conductivity, low density, low moisture permeability and high porosity. It works to reduce heating and cooling loss, improving the efficiency of the building envelope. Thus, RPUF insulation in building envelopes brings additional benefits in energy savings, resulting in lower energy bills and protecting the environment by cutting CO2 emissions.

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Green Synthesis of Silk Sericin-Based Silver Nanoparticles

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.415-417.487 ◽

2011 ◽

Vol 415-417 ◽

pp. 487-490 ◽

Cited By ~ 1

Author(s):

Jia Li Ding ◽

Wen Wu

Keyword(s):

Silver Nanoparticles ◽

Green Synthesis ◽

Room Temperature ◽

Reduction Reaction ◽

In Situ Reduction ◽

Silk Sericin ◽

Vis Spectroscopy ◽

Highly Dispersed ◽

Average Size

Green synthesis of silver nanoparticles (AgNPs) using the silk sericin (SS) solution by in situ reduction at room temperature is reported. The effect of pH on the reduction reaction is studied by UV-Vis spectroscopy. The structure of the sericin-based silver nanoparticles is characterized by TEM. According to the TEM images, the average size of the silver nanoparticles is about 16 nm. The silver nanoparticles are highly dispersed and stable in silk sericin solution for monthes.

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Achieving low thermal conductivity in Sr(Zr0.9Yb0.05Gd0.05)O2.95: A suitable material for high temperature applications

Ceramics International ◽

10.1016/j.ceramint.2020.08.040 ◽

2020 ◽

Vol 46 (18) ◽

pp. 28778-28784

Author(s):

Matiullah Khan ◽

Yi Zeng

Keyword(s):

Thermal Conductivity ◽

High Temperature ◽

Low Thermal Conductivity ◽

Suitable Material ◽

Temperature Applications

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Low thermal conductivity boulder with high porosity identified on C-type asteroid (162173) Ryugu

Nature Astronomy ◽

10.1038/s41550-019-0832-x ◽

2019 ◽

Vol 3 (11) ◽

pp. 971-976 ◽

Cited By ~ 31

Author(s):

M. Grott ◽

J. Knollenberg ◽

M. Hamm ◽

K. Ogawa ◽

R. Jaumann ◽

...

Keyword(s):

Thermal Conductivity ◽

High Porosity ◽

Low Thermal Conductivity

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Synthesis and Characterization of Poly(2-acrylamido-2-methyl propyl sulfonic acid-co-2-hydroxyethyl methclate)/ Silver Nanoparticle Composite Hydrogel as Catalysts for the Reduction of 4-Nitrophenol

Materials Science Forum ◽

10.4028/www.scientific.net/msf.809-810.59 ◽

2014 ◽

Vol 809-810 ◽

pp. 59-66

Author(s):

Yun Long Li ◽

Bin Huang Liu ◽

Song Bai Lin

Keyword(s):

Sulfonic Acid ◽

Reduction Method ◽

Catalytic Properties ◽

Reduction Reaction ◽

Composite Hydrogel ◽

Synthesis And Characterization ◽

In Situ Reduction ◽

End Group

A novel kind of AgNPs catalyst was synthesized by in-situ reduction method using poly(2-acrylamido-2-methyl propyl sulfonic acid-co-2-hydroxyethyl methclate) [short as P(AMPS-co-HEMA)] hydrogel as matrices and AgNO3as a metal precursor. The structure of the composite hydrogel was characterized by Scan Electrical Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). The results showed that AgNPs were binded with end group and most of the particles were isolated and uniformly distributed on the P(AMPS-co-HEMA). The catalytic properties in the reduction reaction of 4-nitrophenol(shorted as 4-NP) to 4-aminophenol(shorted as 4-AP) were studied in detail, and the result showed that conversion rate and conversion efficiency attained 97.56% and 0.9671 mmol/g·min when the amount of AgNPs was 9mg, [NaBH4] was 2.0×10−1mol/L, [4-NP] was 2.0×10−2mol/L and the total volume of solution was 50 mL, respectively.

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Development of Porous Tungsten Mud Waste-based Alkali-activated Foams with Low Thermal Conductivity

KnE Engineering ◽

10.18502/keg.v5i5.6927 ◽

2020 ◽

Author(s):

Imed Beghoura ◽

Joao Castro-Gomes

Keyword(s):

Thermal Conductivity ◽

Mining Waste ◽

Foaming Properties ◽

Original Material ◽

Insulation Material ◽

High Porosity ◽

Low Thermal Conductivity ◽

Aluminium Powder ◽

Blowing Agent ◽

Alkali Activated

Aim of this study was to produce alkali-activated foams with low thermal conductivity. Different precursors’ maximum particles sizes of 150μm, 300μm, and 500μm using a blend of 70% tungsten mining waste mud (TWM), 20% grounded waste glass (WG) and 10 % metakaolin (MK) with sodium silicate (SS) and sodium hydroxide (SH) as original material. Aluminium powder (Al) was used as a blowing agent and added first to the dry mix by changing content from 0.1g to 0.5g. Precursors and activators were mixed together to produce a homogeneous mixture, which was placed into a mould (100x200x60 mm3), and cured in the oven at 60∘C for 24 hours. The effect on foaming properties of different precursors maximum particles sizes were studied. The AAFs exhibited 28 day compressive strengths ranging from 2.28 to 16.1 MPa with the different densities from 913 to 1647 kg/m3 achieved through alteration of the foaming content. The thermal conductivity of AAFs was in the range 0.21– 0.33 W/m*K. Open celled hardened of the AAFs with 0.5g Al shows a high porosity of 58% with the mix made with 500μm. Therefore, tungsten mining waste-based alkali-activated foams shows a promise as thermal insulation material in some situations.

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