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1
Content available remote Przygotowanie i charakterystyka kompozytowego materiału izolacyjnego nano-MgO/polipropylen do budowy linii przesyłowych prądu stałego ultrawysokiego napięcia
Kang Xuefu, Pei Xudong, An Jianzhen, Liang Daping, Ling Shuqi, Wang Yuping
Przemysł Chemiczny
|
2024
|
T. 103, nr 1
97--103
PL
Nanocząstki MgO (nano-MgO) zostały przygotowane przez wspomagane mikrofalowo kalcynowanie Mg(OH)₂ i wykorzystane do modyfikacji właściwości matrycy polipropylenowej (PP) (zawartość nanocząstek do 2% mas.). Dodatek nano-MgO do matrycy PP zawierającej kopolimer etylen/octan winylu spowodował wzrost jej rezystywności objętościowej z 1,73∙10¹⁴ Ωm do 2,85∙10¹⁴ Ωm, ale miał tylko niewielki wpływ na natężenie pola przebicia materiału. Dodatek nano-MgO spowodował również poprawę makroskopowych właściwości elektrycznych materiałów w porównaniu z czystymi próbkami PP. Po dodaniu 0,5% mas. nano-MgO gęstość ładunku przestrzennego kompozytu PP pozostała niezmieniona na poziomie 0,81 C/m² , a gdy zawartość nano-MgO wynosiła 1% mas., gęstość ładunku przestrzennego była najniższa. Wytrzymałość na rozciąganie i wydłużenie przy zerwaniu kompozytowych materiałów izolacyjnych nano-MgO/PP były nieco niższe niż w przypadku czystego PP, ale ogólny spadek nie był znaczący. Badanie właściwości mechanicznych potwierdziło możliwość zastosowania kompozytowych materiałów izolacyjnych nano-MgO/PP w praktyce przemysłowej.
EN
Nano-MgO particles were prepd. by microwave-assisted calcining Mg(OH)₂ and used for modifying properties of the polypropylene (PP) matrix (nano-MgO content up to 2% by mass). The addn. of nano-MgO to the ethylene/vinyl acetate copolymer-cong. PP matrix, resulted in an increase its volume resistivity form 1.73·10¹⁴ Ωm up to 2.85·10¹⁴ Ωm but had only a small impact on the breakdown field strength of the material. The addn. of nano-MgO resulted also in improving the macroscopic elec. properties of the materials when compared with pure PP samples. When 0.5% by mass nano-MgO was added, the space charge d. of PP composite remained unchanged at 0.81 C/m² , and when the content of nano-MgO was 1% by mass, the space charge density was the lowest. The tensile strength and elongation at break of nano-MgO/PP composite insulation materials were slightly lower than that of pure PP, but the overall decline was not significant. The study on mechanical properties conformed the applicability of the nano-MgO/PP composite insulating materials in the industrial practice.
2
Content available A new chemical mechanical slurry for polishing yttrium aluminium garnet material with magnesium oxide, sodium metasilicate pentahydrate and zirconium dioxide abrasive particles
Duc Le Anh, Hieu Pham Minh, Quang Nguyen Minh
Journal of Machine Engineering
|
2023
|
Vol. 23, No. 2
174--185
EN
This work provided a new chemical-mechanical polishing mixture with MgO, sodium metasilicate pentahydrate, ZrO2 abrasive particles, and deionized water. With chemical-mechanical slurry (CMS) proposed for polishing yttrium aluminum oxide (Y3Al5O12) the surface reaction layer formed with significantly reduced hardness compared to other Y3Al5O12 materials, these products combine with MgO to form montmorillonites (3MgO–Al2O3–3SiO2–3Y2O3–5Al2O3). With this formation, the surface layer of Y3Al5O12 material becomes soft and is easily removed by ZrO2 abrasive particles under the influence of mechanical polishing, resulting in superfine surfaces generated from the proposed CMS model. The experimental results show that the surface quality with CMS proposed gives the surface quality with Ra = 0.471 nm along with the material removal rate 31 (nm/min). Surface quality is improved by 71% along with a superior material removal rate (increased by 287%) compared to silica slurry. The results show excellent polishing ability from CMS proposed for polishing Y3Al5O12 materials.
3
Content available Mesoporous magnesium oxide xerogels : synthesis and structural characteristics
Malinowski Janusz, Pudło Wojciech
Prace Naukowe Instytutu Inżynierii Chemicznej Polskiej Akademii Nauk
|
2021
|
nr 25
33--43
EN
The paper presents the results of a study on the synthesis of magnesium oxide xerogels. In the synthesis, the sol-gel method was used, in which magnesium methoxide was applied as a magnesium precursor. The obtained magnesium hydroxide was subjected to the thermal dehydration process to obtain magnesium oxide particles. The influence of xylene addition during magnesium methoxide hydrolysis on the structure of the magnesium hydroxide and oxide was investigated.
PL
W pracy przedstawiono wyniki badań nad syntezą cząstek kserożeli tlenku magnezu. W procesie syntezy zastosowano metodę zol-żel, w której wykorzystano metanolan magnezu jako prekursor tlenku magnezu. Otrzymany wodorotlenek magnezu poddano procesowi termicznej dehydratacji w celu otrzymania tlenku magnezu. Zbadano wpływ dodatku ksylenu na strukturę wodorotlenku i tlenku magnezu.
4
Content available remote CVD synthesis of graphene nanoplates on MgO support
Jugade R M, Sharma S., Gokhale S
Materials Science Poland
|
2014
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Vol. 32, No. 2
243--246
EN
Synthesis of graphene directly on MgO has been carried out and the structural properties of the obtained material have been investigated. Few-layered graphene was produced by simple thermal decomposition of methane over MgO powder at 950 °C in a CVD reactor. The samples were purified by 10 N HNO3 treatment, and studied by TEM, Raman spectroscopy, EDAX and SEM. TEM clearly indicated the formation of graphene. EDAX showed that the purified sample contained only carbon and no traces of MgO. The characteristic Raman features of graphene were also seen as D-band at 1316 cm-1, G-band at 1602 cm-1, and a small 2D-band at 2700 cm-1 in the Raman spectra. The strong D-band suggests that the graphene possess large number of boundary defects. The small 2D-band indicates the formation of few-layered graphene.
5
Content available Physico-chemical and dispersive characterisation of magnesium oxides precipitated from the Mg(NO3)2 and MgSO4 solutions
Pilarska A., Paukszta D., Ciesielczyk F., Jesionowsk T.
Polish Journal of Chemical Technology
|
2010
|
Vol. 12, nr 2
52-56
EN
An attempt was made to synthesise magnesium oxide of a high degree of dispersion permitting its use as adsorbent or catalyst. The synthesis method proposed was precipitation with the use of magnesium nitrate or magnesium sulfate. The influence of temperature, the mode and the rate of dosing, the concentration and the ratio of the reagents on the properties of the final product was analysed. Magnesium oxides were obtained by thermal decomposition of magnesium hydroxides and subjected to thorough analysis. The results permitted selection of the reaction systems ensuring synthesis of the final products of the desired properties.
6
Content available Tlenek magnezu – metoda oznaczania
Gawęda E.
Podstawy i Metody Oceny Środowiska Pracy
|
2010
|
Nr 1 (63)
221--226
PL
Metodę stosuje się do oznaczania tlenku magnezu, jak również magnezu metalicznego oraz innych związków magnezu w przeliczeniu na tlenek magnezu (MgO) w powietrzu na stanowiskach pracy. Metoda polega na przepuszczeniu badanego powietrza przez filtr membranowy, mineralizacji próbki na gorąco z zastosowaniem stężonego kwasu azotowego i sporządzeniu roztworu do analizy w rozcieńczonym kwasie azotowym. Tlenek magnezu oznacza się w tym roztworze metodą płomieniową absorpcyjnej spektrometrii atomowej jako magnez. Oznaczalność metody wynosi 0,46 mg/m3 (dla objętości powietrza 360 l i krotności rozcieńczenia 40).
EN
This method is based on stopping magnesium oxide on a membrane filter, mineralizing the sample with concentrated nitric acid and preparing the solution for analysis. Magnesium oxide in the solution is determined with flame atomic absorption spectrophotometry, as magnesium. The determination limit of this method is 0.46 mg/m3.
7
Catalytic Transfer Hydrogenation of Cycloalkanones on MgO. Vapour and Liquid Phase Modes of Reaction
Gliński M.
Polish Journal of Chemistry
|
2009
|
Vol. 83, nr 2
187-194
EN
The reactivity of a series of cycloalkanones of the general formula (CH2)nCO, where n = 4, 5, 6, 7, 11 and 14 in the transfer hydrogenation reaction over magnesium oxide as the catalyst, either in vapour or liquid phase (VP or LP) has been studied. In the VP mode of reaction the activity of MgO treated with triethylamine, water, phenol or benzoic acid in the reduction of cyclopentanone by propan-2-ol has been determined. A strongly diminished or residual activity of MgO has been observed after the catalyst's treatment with phenol or benzoic acid, respectively. The occurence of side reactions of cyclopentanone in the LP mode of reaction resulted in high conversions of the ketone (up to 91%), very low yields of cyclopentanol (I) (be low 6%) and very high yields of 2-cyclo pentylidene-cyclopentanone (II) (greater than 80%).
8
Content available remote Wpływ wybranych dodatków na hydratację tlenku magnezu
Wojsa J.
Materiały Ceramiczne
|
2009
|
T. 61, nr 4
273-277
PL
Przedstawiono znaczenie hydratacji w technologii i w wybranych obszarach stosowania materiałów zasadowych. Zaprezentowano podstawowe dane dotyczące statyki i kinetyki reakcji, metody przeciwdziałania hydratacji tlenku magnezu oraz najczęściej stosowane sposoby ilościowego opisu jej efektów. Eksperymentalnie potwierdzono chemiczną inertność spineli MgAI2O4 i MgCr2O4 w warunkach hydratacji bezciśnieniowej. Zbadano wpływ czterech glikoli na hydratację MgO stwierdzając, że ich skuteczność jako inhibitorów hydratacji rośnie w sekwencji od glikolu mono-etylenowego do propylenowego. Przedstawiono wpływ soli dwusodowej EDTA na hydratację MgO oraz zweryfikowano dane literaturowe odnośnie sposobu ograniczania hydratacji poprzez wprowadzenie silikonu. Wyniki nie potwierdziły oczekiwań. Wykazano, że wolny tlenek magnezu w koklinkierze MgO-SnO2 nie ulega hydratacji, co stanowi pewną nowość poznawczą i technologiczną. Zbadano wpływ pH wodnych roztworów na hydratację MgO i uzyskano wyniki pozostające w dobrej zgodności z wynikającymi z teorii. Stwierdzono, że zmiany pH roztworów wydają się być skutecznym sposobem zwiększania stopnia hydratacji, a efektu jej ograniczania należy raczej oczekiwać wprowadzając wybrane substancje organiczne adsorbowane na powierzchni ziaren MgO, z uwzględnieniem specyfiki danej technologii.
EN
The importance of hydration in technology and in selected application areas of basic materials was shown. The thermodynamic and kinetic data of the reaction were presented. Methods of counteracting the hydration of free magnesium oxide in basic materials and the most frequently applied methods of quantitative evaluation of the effects of MgO hydration were discussed. Basing on the investigations, the chemical inertness of MgAI2O4 and MgCr2O4 spinels in the non-pressure hydration conditions was proved. The effect of four glycols on MgO hydration was analysed and it has been proved, that intensity of the reaction decreased in sequence from mono-ethylene to propylene glycol. The effect of disodium salt of EDTA on MgO hydration was described. The literature reports were experimentally verified with a negative result, regarding the limitation of MgO hydration by the introduction of silicon. The chemical inertness of free MgO in the MgO-SnO2 coclinker nas been proved, contrary to the well known magnesite-chromite materials. The effect of pH of the electrolyte water solutions on MgO hydration was explored and the results seemed to be in a good accordance with theoretical expectations. It was concluded, that the solution pH change seems to be an effective way for increasing the hydration degree, while the opposite effect should be sought through adsorption of selected organic substances, taking into consideration a specific character of the given technology.
9
Content available Dye-sensitized solar cells based on sno2 nanorod and surface treatment with MG(II) film
Bai J., Murakami K.
Journal of Automation Mobile Robotics and Intelligent Systems
|
2009
|
Vol. 3, No. 4
69-71
EN
Homocentrically grown SnO2 nanorods were synthesized by a hydrothermal method, whose diameter and length are around 20 nm and 100-200 nm, respectively. The photovoltaic properties of dye-sensitized SnO and MgO-treated SnO2 films were investigated. A light-to-electricity conversion yield of 0.8% was achieved by applying the nanorods as a thin film layer for the dye-sensitized solar cells. Treatment with MgO on SnO2 surface improves the photovoltage, fill factor and cell efficiency owing to preventing a recombination of the electrons injected into SnO with acceptors in the electrolyte.
10
Content available remote Rola MgO i CaO w oczyszczaniu atmosfery ziemskiej z freonów
Karski S., Gołuchowska J., Szynkowska M., Witońska I.
Przemysł Chemiczny
|
2005
|
T. 84, nr 3
171-174
PL
Dokonano analizy zanieczyszczeń obecnych w troposferze ziemskiej oraz podano przyczynę absorpcji promieniowania przez obecne w troposferze tlenki wapnia i magnezu. Przedstawiono także najważniejsze mechanizmy przebiegu reakcji fotochemicznych związane z fotogenerowaniem chemicznie reaktywnej pary elektron– dziura oraz z powstawaniem na powierzchni tlenków aktywnych centrów reakcyjnych, którymi są jony niektórych metali przejściowych na niskim stopniu utlenienia.
EN
A review covering the troposphere as a natural photocatalytic reactor, photocatalytic reaction mechanisms, MgO and CaO as absorbers of 300–400-nm radiation, which give rise to mobile electron–mobile hole pairs and destroy freons by photoadsorption.
11
Content available remote Ceramic hydration with expansion. The structure and reaction of water layers on magnesium oxide. A cyclic cluster study
Bredow T., Heidberg B., Littmann K., Jug K.
Materials Science Poland
|
2005
|
Vol. 23, No. 2
501--508
EN
MgO hydration is an expansive process. It is used in cement to compensate for shrinkage, but it can be harmful at higher concentrations. In this quantum-chemical study, the first steps of the hydration of MgO have been explored. The semiempirical MO method MSINDO with the cyclic cluster model, including long-range electrostatic interactions, has been applied to investigate water adsorption on the ( 001) surface of MgO. Both molecular adsorption and dissociative adsorption have been found to occur. The latter is stabilized by hydrogen bonding from neighbouring water molecules and surface oxygen. Several energy minima exist for the experimentally low temperature p( 3 x 2) monolayer H2O observed on the MgO ( 001) surface which consists of a mixture of dissociated and molecular water. One third of the water molecules were dissociated, which is consistent with previous DFT studies. A stable fully hydroxylated MgO ( 001) surface with OH bridging two Mg ions and the hydrogen bound to the surface oxygen was discovered. This structure appears to promote the expansive, topotactic nucleation of brucite on the MgO (001) surface.
12
Content available remote Powstawanie węglowodorów w materiałach nieorganicznych
Malinowski S.
Wiadomości Chemiczne
|
2004
|
[Z] 58, 5-6
373--402
EN
A series of papers by F. Freund and his collaborators concerning the defect structure of water and/or carbon dioxide doped magnesium oxide is reviewed. The model of defect structure has been used to explain high temperature emission of water vapour, hydrogen and oxygen as well as some hydrocarbons from such preparations. According to the authors similar effects may also occur in the case of CaO or SiO and silicates. The possibility of abiotic formation of hydrocarbons in the earth's crust is discussed.
13
Some properties of MgO and catalytic performance in oxidative coupling of methane
Taniewski M., Kuś S.
Polish Journal of Applied Chemistry
|
2000
|
Vol. 44, nr 4
181-194
EN
The catalytic performance of unpromoted MgO in oxidative coupling of methane to C(2)+ hydrocarbons (OCM) and a controversial question of possible MgO properties/performance relationship were studied. The properties and structure of several MgO samples of different origin (BET surface area and pore size distribution, surface morphology by electron scanning microscopy, phase characteristics by thermo-gravimetry, identification of impurities by AAS) were determined. Tests carried out in the small-scale laboratory unit with silica tubular reactor at 760°C, demonstrated the diversity of catalytic performance of applied MgO samples in OCM C(2) selectivity, in particular). It was shown that the surface area and the structure of MgO were not the main factors responsible for the diversity of catalytic performance. The content or absence of Ca compounds in applied MgO samples appeared to be the main factor. The presence of Ca compounds led to the increase in C(2) selectivity and activity of MgO. Similar effects were achieved by introduction of various alkalies, water, etc. to MgO. It was concluded that the variation in the basicity could be a decisive factor responsible for observed differences between MgO samples regarding their selectivity and activity in OCM.
14
Infrared spectroscopic study of magnesium oxide catalysts doped with sodium ions
Ignaczak W., Jóżwiak W., Szubiakiewicz E., Paryjczak T.
Polish Journal of Chemistry
|
1999
|
vol. 73 nr 4
645-654
EN
Infrared results concerning the surface species in MgO catalysts doped with Na+ ions are presented. Different surface carbonate structures and hydroxyls groups have been found. It was assumed that created carbonate compounds could be involved in decreasing of MgO specific surface area. Sodium carbonate and unidentate carbonate structures may cause elimination and blockage of low coordination sites of MgO surface, being responsible both for hydrogen detachment from CH4 molecules and for oxidation of methyl radicals to carbon oxides - the undesired reactions of oxidative coupling of methane (OCM). It was observed that increasing temperature led to decomposition of surface bicarbonate and unidentate carbonate structures. Some of them are being reconverted to more stable bicarbonate structures. Carbon dioxide and water desorptions result in gradual restoration of low coordinated sites of MgO, corresponding to high selectivity to C2 hydrocarbon formation. Sodium ions may also cause structural changes in MgO lattice. The catalysts were active and selective above 950 K for C2 hydrocarbon formation, although sodium carbonate is sufficiently stable under the conditions of the OCM process.
15
Content available remote Oxygen adsorption on magnesium oxide
Duński H., Jóźwiak. W.K.
Zeszyty Naukowe. Chemia / Politechnika Łódzka
|
1998
|
Z. 46
103-107
EN
The low temperature range adsorption of oxygen on the surface of magnesium oxide was investigated. The temperature-vacuum treatment of MgO above 800K resulted in the appearance of the low coordinated surface magnesium ions, most likely responsible for the relatively strong oxygen adsorption effects.
PL
Przeprowadzono badania niskotemperaturowej adsorpcji tlenu na powierzchni tlenku magnezu stosując metody TPD i EPR. Wysokotemperaturowa kalcynacja (powyżej 800K) MgO w próżni powoduje odsłonięcie niskoskoordynowanych jonów magnezu na powierzchni tlenku odpowiedzialnych za relatywnie silne efekty adsorpcji tlenu.
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