silicon oxygen
Recently Published Documents


TOTAL DOCUMENTS

292
(FIVE YEARS 33)

H-INDEX

39
(FIVE YEARS 2)

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 657
Author(s):  
Lishun Chen ◽  
Yuting Long ◽  
Mingkai Zhou ◽  
Huaide Wang

In this work, more than 70 wt % of ferromanganese slag (containing 40 wt % CaO) was used to synthesize high-calcium, CaO-MgO-Al2O3-SiO2 (CMAS) glass ceramics. The effect of SiO2/CaO on the structure, crystallization behavior and microstructure of high-calcium, CMAS, slag glass ceramics was studied by IR, NMR, DSC, XRD and SEM. The results showed that in the high-calcium, CMAS glass ceramics, the main existing forms of silicon–oxygen tetrahedra (Qn) were Q0 and Q1. With the increase in the SiO2/CaO, Qn changed from Q0 and Q1 (main units) to Q1 (main units) and Q2, and then to Q1 and Q2 (main units). The polymerization degree of Qn changed from low to high, making the glass more stable, which led to the increase in crystallization temperature and the decrease in crystallization kinetic constant (k) and frequency factor (υ). At the same time, the change in the Qn structure resulted in a gradual change to the main crystal, from akermanite to diopside–wollastonite.


2022 ◽  
Vol 8 ◽  
Author(s):  
Yuan Jia ◽  
Yuxin Zou ◽  
Xinmei Zou ◽  
Yaoting Jiang ◽  
Fangyuan Li ◽  
...  

In this study, we investigated the impact of aluminium ion (Al3+) incorporation on the microstructure and the phase transformation of the magnesium silicate hydrate system. The magnesium silicate hydrate system with aluminium was prepared by mixing magnesium oxide and silica fume with different aluminium ion contents (the Al/Si molar ratios of 0.01, 0.02, 0.05, 0.1, 0.2) at room temperature. The high degree of polymerization of the magnesium silicate hydrate phases resulted in the limited incorporation of aluminium in the structure of magnesium silicate hydrate. The silicon-oxygen tetrahedra sites of magnesium silicate hydrate layers, however, were unable to substitute for silicon sites through inverted silicon-oxygen linkages. The increase in aluminium ion content raised the degree of polymerization of the magnesium silicate hydrate phases from 0.84 to 0.92. A solid solution was formed from residual aluminum-amorphous phases such as hydroxyl-aluminum and magnesium silicate hydrate phases. X-ray diffraction (XRD), field emission scanning electron microscope (F-SEM), and 29Si and 27Al MAS NMR data showed that the addition of Al3+ promotes the hydration process of MgO and has an obvious effect on the appearance of M-S-H gel. The gel with low aluminum content is fluffy, while the gel with high aluminum content has irregular flakes. The amount of Al3+ that enters the M-S-H gel increased with the increase of Al3+ content, but there was a threshold: the highest Al/Si molar ratio of M-S-H gel can be maintained at about 0.006.


2021 ◽  
Vol 25 (11) ◽  
pp. 36-41
Author(s):  
D.V. Bespolitov ◽  
N.A. Konovalova ◽  
O.N. Dabizha ◽  
P.P. Pankov ◽  
E.A. Rush

The possibility of utilization of inactive fly ash in road concrete compositions by bringing of ash into a non-equilibrium condition with increased reactivity by mechanical activation in a vibration eraser is investigated. It was revealed that the optimal content of binder and fly ash in samples of soil concrete was 8 and 10 wt. %, respectively. It is shown that, due to mechanical activation, the specific surface area of fly ash increases by 2 times, dehydration and carbonization occur and silicon is replaced by aluminum in silicon-oxygen tetrahedra. It has been established that an increase of the content of crystalline carbonate phases is the reason for an increase in the strength of ground concrete. It is determined that the introduction of mechanoactivated fly ash into the composition of soil concretes contributes to increasing their physical and mechanical characteristics to the maximum strength grade M100. This indicates the competitiveness of ground concrete and the possibility of direct use of inactive fly ash in road construction.


Catalysts ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 879
Author(s):  
Emily I. Sparkes ◽  
Chisom S. Egedeuzu ◽  
Billie Lias ◽  
Rehana Sung ◽  
Stephanie A. Caslin ◽  
...  

Silicatein-α (Silα), a hydrolytic enzyme derived from siliceous marine sponges, is one of the few enzymes in nature capable of catalysing the metathesis of silicon–oxygen bonds. It is therefore of interest as a possible biocatalyst for the synthesis of organosiloxanes. To further investigate the substrate scope of this enzyme, a series of condensation reactions with a variety of phenols and aliphatic alcohols were carried out. In general, it was observed that Silα demonstrated a preference for phenols, though the conversions were relatively modest in most cases. In the two pairs of chiral alcohols that were investigated, it was found that the enzyme displayed a preference for the silylation of the S-enantiomers. Additionally, the enzyme’s tolerance to a range of solvents was tested. Silα had the highest level of substrate conversion in the nonpolar solvents n-octane and toluene, although the inclusion of up to 20% of 1,4-dioxane was tolerated. These results suggest that Silα is a potential candidate for directed evolution toward future application as a robust and selective biocatalyst for organosiloxane chemistry.


2021 ◽  
Author(s):  
Jie Liu ◽  
Wenqi Jiang ◽  
Ling Sun ◽  
Chun Lv

Abstract Alkali-oxygen one-bath scouring and bleaching process of the flax roving was studied by using a new type of synthesized non-silicon oxygen bleaching stabilizer Poly(acrylic acid) magnesium instead of sodium silicate. Based on the analysis of the effects of single factors such as sodium hydroxide concentration, hydrogen peroxide concentration, temperature, time and the amount of the synthesized non-silicon oxygen bleaching stabilizer poly(acrylic acid) magnesium salt on the performance of the bleached flax roving, including the whiteness, the breaking tenacity, the capillary effect and the weight loss ratio. The optimal process for the application of the stabilizer was determined by orthogonal test, namely, hydrogen peroxide concentration 8.5 g/L, sodium hydroxide concentration 5 g/L, sodium bisulfite 3 g/L, sodium carbonate 3 g/L, the synthesized non-silicon oxygen bleaching stabilizer poly(acrylic acid) magnesium 5.5 g/L, scoured and bleached at 90 ℃ for 60 min, and the bath ratio was 25:1. Compared with the traditional oxygen bleaching stabilizer sodium silicate, it not only has good ability to inhibit the rapid decomposition of hydrogen peroxide, but also has the advantages of higher whiteness, higher capillary effect, good feel and breaking tenacity, and can effectively solve the "silicon scale" problem and improve the quality of flax products.


2021 ◽  
Vol 56 ◽  
pp. 14-22
Author(s):  
Yang Luo ◽  
Tianyu Li ◽  
Hongzhang Zhang ◽  
Ying Yu ◽  
Arshad Hussain ◽  
...  

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 400
Author(s):  
Ying Dai ◽  
Qian Peng ◽  
Kun Liu ◽  
Xuekun Tang ◽  
Muyang Zhou ◽  
...  

An environmentally friendly activation method of peroxymonosulfate (PMS) provides a promising advanced oxidation processes for the degradation of organic wastewater. In this article, chrysotile, extracted from asbestos tailings, was found to be a kind of one-off catalyst relying on hydroxyl groups to activate PMS. Furthermore, the activation performance of the chrysotile had been greatly improved by the mean of calcining at 850 °C (850CC). It is worth mentioning that 850CC could not only realize three effective cycles, but also the mineralization ratio of Rhodamine B (RhB) could be impressively higher than 60%. According to characterization results, it was discovered that the chrysotile had transformed into forsterite with a fibrous morphology after calcination at 850 °C due to the loss of hydroxyl groups and the recombination of silicon, oxygen and magnesium atoms. Besides, the main active species produced by 850CC activating PMS were singlet oxygen and sulfate radicals. Further studies uncovered that PMS was successfully activated by a large number of unsaturated coordination oxygen on 850CC surface, and the activation mechanism was further elucidated. This study provides a new route for the comprehensive utilization of chrysotile and a valuable strategy for the degradation of hazardous organic pollutants in wastewater by PMS activation.


2021 ◽  
Vol 2021 (4) ◽  
pp. 449-453
Author(s):  
B. A. Greenberg ◽  
M. A. Ivanov ◽  
V. P. Pilyugin ◽  
M. S. Pushkin ◽  
T. P. Tolmachev ◽  
...  

2021 ◽  
Vol 316 ◽  
pp. 34-39
Author(s):  
Artem E. Buntin

The paper studies the influence of nanodispersed aluminum and silicon oxides on the structural, physico-chemical and mechanical characteristics of calcium-magnesium bentonite deposits of the Republic of Tatarstan, in order to determine the optimal concentrations of the nanomodifier, and to improve the performance of respective materials. It was found that nanomodification of bentonite increases the strength of samples after firing by more than 1,5 times, the adsorption index by 20–25 %. The optimal concentration of nanoparticles was determined by changing the properties. The methods of Brunauer-Emmett-Teller (BET), x-ray phase analysis and infrared spectroscopy show an increase in the specific surface area, a change in the phase composition of the annealed samples, the intensity and position of the characteristic absorption bands, as well as the chemical bond silicon-oxygen in bentonite, modified by nanoparticles of aluminum and silicon oxides of similar nature.


Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1080
Author(s):  
Karol Zalewski ◽  
Zbigniew Chyłek ◽  
Waldemar A. Trzciński

Polysiloxanes are reviewed for their properties depending on the functionalization of a silicon–oxygen backbone chain. Next, the properties were referred to the requirements that polymers used in plastic/polymer-bonded explosive (PBX)-type explosives must meet. Finally, the current state and prospects for the implementation of polysiloxanes in plastic/polymer-bonded explosive (PBX) formulations are presented.


Sign in / Sign up

Export Citation Format

Share Document