scholarly journals Influence of thermoactivation on properties of mineral additives in dry mixtures

2021 ◽  
Vol 2124 (1) ◽  
pp. 012003
Author(s):  
V I Loganina ◽  
N N Laskov ◽  
G G Boldyrev
Keyword(s):  
Heat Treatment ◽  
Compressive Strength ◽  
Lewis Acid ◽  
Low Temperatures ◽  
Thermal Activation ◽  
Acid Centers ◽  
Strength In Compression ◽  
Mineral Additives ◽  
Brønsted And Lewis Acid ◽  
Ultimate Strength In Compression

Abstract Information on the effect of thermal activation of silicate and aluminosilicate rocks used as a filler in dry building mixtures on their reactivity of interaction with lime binder is presented. The change in the distribution of acidic Bronsted and Lewis centers on the filler surface as a result of thermal activation is shown. It was found that the number of Bronsted and Lewis acid centers on the surface of fired clays exceeds the number of the same centers on the surface of unbaked clays. The number of adsorption centers at pKa from 0 to 7 and pKa> 13 on the surface of fired diatomite is 2.435 * 10-5 mol/g, and on the surface of unbaked diatomite -1.678 * 10−5 mol/g. The heat treatment of diatomite at low temperatures (2000C and 3000C) does not significantly affect the values of the compressive strength of the mortar. An increase in the firing temperature to 7000C leads to an increase in strength characteristics up to R = 4.38 MPa. However, the greatest effect is achieved when diatomite is fired at a temperature of t = 9000C. The value of the ultimate strength in compression was R = 5.1 MPa.

scholarly journals The crucial roles of guest water in a biocompatible coordination network in the catalytic ring-opening polymerization of cyclic esters: a new mechanistic perspective

2020 ◽  
Vol 11 (12) ◽  
pp. 3345-3354 ◽  
Author(s):  
Sheng-Chun Chen ◽  
Fei-Hang Zhang ◽  
Kun-Lin Huang ◽  
Feng Tian ◽  
Zhi-Hui Zhang ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Cyclic Esters ◽  
Polymerization Mechanism ◽  
Synergistic Catalysis ◽  
Coordination Network ◽  
Coordination Framework ◽  
Acid Centers ◽  
Brønsted And Lewis Acid

A new ring-opening polymerization mechanism is unveiled based on synergistic catalysis involving Brønsted and Lewis acid centers in a coordination framework.

DEWARD

Alloy Digest ◽  
1976 ◽  
Vol 25 (12) ◽  
Keyword(s):  
Heat Treatment ◽  
Fracture Toughness ◽  
Wear Resistance ◽  
Compressive Strength ◽  
Physical Properties ◽  
Heat Treating ◽  
Die Steel ◽  
Satisfactory Performance ◽  
Specialty Steel ◽  
Minimum Distortion

Abstract DEWARD is an oil-hardening, non-deforming, manganese die steel that is characterized by uniformity, good machinability and satisfactory performance in service. Its composition permits a relatively low hardening temperature to give minimum distortion after heat treatment and little danger of cracking. It has good wear resistance and gives excellent results when used for all kinds of intricate tools. This datasheet provides information on composition, physical properties, hardness, elasticity, and compressive strength as well as fracture toughness. It also includes information on forming, heat treating, and machining. Filing Code: TS-310. Producer or source: AL Tech Specialty Steel Corporation.

Determination of the degree of adsorption and the heat of adsorption for 1-butylamine and ammonia on NaHY zeolites

1984 ◽  
Vol 49 (12) ◽  
pp. 2739-2743 ◽  
Author(s):  
Miloslav Křivánek ◽  
Pavel Jírů
Keyword(s):  
Lewis Acid ◽  
Adsorption Isotherms ◽  
Heat Of Adsorption ◽  
Brønsted And Lewis Acid

The degree and heat of adsorption of 1-butylamine and ammonia were measured on samples of NaHY zeolites activated at 400-600°C. The adsorption isotherms and calorimetric curves were compared for the two bases, and the amount of Bronsted and Lewis acid centres was determined from the calorimetric curves.

On the nature of framework Brønsted and Lewis acid sites in ZSM-5

Zeolites ◽  
1997 ◽  
Vol 19 (4) ◽  
pp. 288-296 ◽  
Author(s):  
G.L. Woolery ◽  
G.H. Kuehl ◽  
H.C. Timken ◽  
A.W. Chester ◽  
J.C. Vartuli
Keyword(s):  
Lewis Acid ◽  
Acid Sites ◽  
Lewis Acid Sites ◽  
Brønsted And Lewis Acid

The Impact of Heat Treatment on Pyrophyllite Structure and Acid-Soluble Properties

2011 ◽  
Vol 366 ◽  
pp. 326-329 ◽  
Author(s):  
Jun Jun Wu ◽  
Hai Feng Chen ◽  
Shi Jiang Zhao ◽  
Bin Li
Keyword(s):  
Heat Treatment ◽  
Thermal Activation ◽  
Acid Leaching ◽  
Basic Structure ◽  
Hydrochloric Acid Concentration ◽  
Activation Temperature ◽  
Different Temperatures ◽  
Ft Ir ◽  
Heat Activation ◽  
The Impact

This paper studied the influence of heat treatment on the pyrophyllite structure and acid-soluble properties of alumina. Qualitative tests had been performed in studying pyrophyllite crystal at different temperatures by XRD, TG-DTA, FT-IR and quantitative analysis of Al2O3. The quantitative titration method studied the dissolve characteristics of the different heat treatment samples in different acid conditions, and then a numerical simulation was done. The results showed that at temperatures below 480 °C, the pyrophyllite did not change the basic structure. 480~700 °C dehydroxylation reaction occurred, and the structure water of pyrophyllite is removed, and then turned into partial pyrophyllite. Dissolution experiments showed that after thermal activation the behavior of alumina in acid the dissolution was different, which was affected by hydrochloric acid concentration, heat activation temperature and acid leaching time. When the calcinations temperature was 700 °C, the dissolution amount of alumina was largest. These works could provide some theoretical basis for further application of pyrophyllite research.

scholarly journals Characteristics of Black Ginseng (Panax ginseng C.A. Mayer) Production Using Ginseng Stored at Low Temperature after Harvest

Metabolites ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 98
Author(s):  
Hyo Bin Oh ◽  
Ji Won Lee ◽  
Da Eun Lee ◽  
Soo Chang Na ◽  
Da Eun Jeong ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Low Temperature ◽  
Panax Ginseng ◽  
Low Temperatures ◽  
Sugar Content ◽  
Base Material ◽  
Free Sugar ◽  
Drying Process ◽  
Heat Treated ◽  
Black Ginseng

Ginseng processing often involves multiple drying and heat treatments. Ginseng is typically processed within one week of harvesting or is stored at low temperatures to prevent spoilage. Black ginseng (BG) is manufactured by repeating the heat treatment and drying process of ginseng several times. We compared the suitability of low-temperature stored ginseng (SG) and harvested ginseng (HG) as the components for black ginseng production. SG and HG were processed into black ginseng and the appearance change, free sugar content, and benzo[a]pyrene (BAP) content were observed. Appearance observations showed the SG to be suitable in terms of quality when heat-treated at a temperature of 95 ℃ or higher. The BAP content of the SG increased significantly as the steaming process was repeated. A maximum BAP concentration of 5.31 ± 1.12 μg/kg was measured in SG steamed from 2 to 5 times, making it unsuitable for processing into BG. SG and HG showed similar trends in the content of sucrose, fructose, and glucose during steaming. This study aimed to facilitate the proper choice of base material to improve the safety of black ginseng by limiting BAP production during processing.

ENDOR study of anthraquinone paramagnetic complexes with Lewis acid centers of aluminium oxide

1991 ◽  
Vol 2 (4) ◽  
pp. 675-681 ◽  
Author(s):  
E. V. Lunina ◽  
G. L. Markaryan ◽  
A. V. Fionov ◽  
A. V. Astashkin ◽  
R. I. Samoilova ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Aluminium Oxide ◽  
Acid Centers ◽  
Paramagnetic Complexes
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