Wyniki wyszukiwania - Biblioteka Nauki

1

Fabrication of highly-transparent Er:CaF2 ceramics by hot-pressing technique

100%

Zhou W. B. , Cai F. F. , Zhi G. L. , Mei B. C.

Materials Science Poland

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2014

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tom Vol. 32, No. 3

358--363

EN

Highly-transparent trivalent erbium ion doped calcium fluoride (5 mol % Er:CaF2) ceramics were fabricated by a hotpressing (HP) method using high-purity Er:CaF2 nanoparticles, which were synthesized by co-precipitation method. The mean grain size of the nanoparticles was about 24.7 nm. The nanoparticles were sintered at 600 respectively, for 30 min under a uniaxial pressure of 30 MPa and vacuum of 10-3 Pa with 1 mol % lithium fluoride (LiF) as sintering additive. The 5 mol % Er:CaF2 ceramics sintered at 800 C exhibits high density and pore-free microstructure with an average grain size of about 8 μm. The optical transmittance of the transparent ceramics is close to 85 % at visible and nearinfrared wavelengths. The strong and broad absorptions peaks corresponding to characteristic absorption of trivalent erbium ions make the ceramics a potential candidate for infrared and upconversion laser operating.

2

Production of synthetic fluorspar from waste calcium fluoride slurry

88%

Kowalski Z. , Paszek A.

Polish Journal of Environmental Studies

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1999

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tom 08

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nr 2

3

Otrzymywanie ceramiki przezroczystej z CaF2 z wykorzystaniem techniki Hot Isostatic Pressing-HIP

75%

Perkowski K. , Gizowska M. , Zalewska M. , Kobus I. , Konopka G. , Osuchowski M. , Witosławska I.

Szkło i Ceramika

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2016

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tom R. 67, nr 4

19--23

PL

W niniejszej publikacji przedstawiono badania dotyczące otrzymywania przezroczystej ceramiki z fluorku wapnia. W pracy zastosowano dwa rodzaje proszku CaF2, które zostały scharakteryzowane pod względem składu fazowego metodą XRD, morfologii przy użyciu elektronowego mikroskopu skaningowego, wielkości cząstek, a także pod względem stabilności termicznej metodą DTA-TG do 600ºC w atmosferze powietrza syntetycznego. Pierwszy z proszków firmy Sigma-Aldrich charakteryzował się średnim rozmiarem cząstek/aglomeratów Dv50 na poziomie 20,3 μm, natomiast proszek firmy ABCR odznaczał się większym/szerszym rozkładem cząstek, a Dv50 wynosiła 8,9 μm. Oba proszki wykazują silną aglomerację, co zostało potwierdzone w trakcie badań za pomocą SEM. Rentgenowska analiza fazowa wykazała obecność fazy regularnej w przypadku obu proszków. Badanie termograwimetryczne wykazało dla drobniejszego proszku fluorku wapnia (firmy ABCR) obecność zanieczyszczenia, które zostało zanalizowane jako pozostałość węgla po syntezie. Oba surowce były spiekane w zakresie temperatur 900–1350ºC w atmosferze argonu lub próżni. Dodatkowo próbki były dogęszczane w wysokotemperaturowej prasie izostatycznej przy ciśnieniu argonu wynoszącym 2000 barów i temperaturze 1300ºC. W artykule przedstawiono rezultaty badań przewodnictwa cieplnego materiału domieszkowanego (2%at. Yb), jak i nie domieszkowanego fluorku wapnia. W pracy przedstawiono widma fluorescencyjne próbek CaF2 domieszkowanych fluorkiem iterbu w ilości 2% at.

EN

The paper presents the research on obtaining a transparent ceramics made from calcium fluoride. The researchers used two types of calcium fluoride powders which were characterized by XRD (phase content), SEM (microstructure), grain size analysis and thermal analysis DTA-TG, with temperature up to 600ºC in atmosphere of synthetic air, so as to define a temperature of decomposition. The raw materials used were different in terms of grain size. Powder (under symbol C1) provided by Sigma-Aldrich has an average grain/agglomerate size Dv 50 at the level of 20,3 μm, whereas powder (under symbol C2) provided by ABCR has a wider range of grain/agglomerate size distribution and Dv 50 was 8,9 μm. A strong tendency to agglomeration was proved by SEM analysis. X-ray phase analysis indicated a cubic phase in case of both powders. Differences between materials were noticed during thermogravimetric analysis, where for powder provided by ABCR some contamination was observed, which was analyzed as residual carbon after synthesis. For the purpose of further research, cylindrical samples were obtained by die-pressing method from both powders and sintered in temperature range of 900–1350ºC, in protective atmosphere of argon or vacuum. Additionally, the samples were densificated by hot isostatic pressing under pressure of 2000 bar of argon and temperature 1300ºC. The results of thermal conductivity and fluoresces spectrum of raw calcium fluoride and doped with ytterbium (2% at.) were shown in this paper.

4

Otrzymywanie fluorku wapnia z kwasu heksafluorokrzemowego w instalacji przemysłowej

75%

Kic B. , Grzmil B. , Burkiewicz A. , Tarnowska A.

Przemysł Chemiczny

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2020

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tom T. 99, nr 1

127--131

PL

Przeprowadzono badania otrzymywania syntetycznego fluorku wapnia o małej zawartości krzemionki (poniżej 2% mas.) z wykorzystaniem kwasu heksafluorokrzemowego z zatężania ekstrakcyjnego kwasu fosforowego. Proces prowadzono w instalacji przemysłowej w Grupie Azoty Zakłady Chemiczne Police SA. Zbadano wpływ takich parametrów procesu, jak stosunek fazy stałej do ciekłej w zawiesinie kredy (45-56:1) oraz stosunek molowy CaCO₃:H₂SiF₆ (Ca:F - w granicach 0,45-0,55), na skład chemiczny uzyskanych produktów. Otrzymano fluoryty, które zawierały 44,70-47,55% mas. Ca, 43,32-46,95% mas. F i 1,79-3,58% mas. SiO₂. Stosunek molowy Ca:F we fluorytach otrzymanych w testach przemysłowych wahał się w zakresie 0,46-0,52, a zawartość CaF₂ wynosiła 89-94% mas.

EN

H₂SiF₆·2H₂O was sepd. from H₃PO₄ prodn. mixt. and treated with chalk to obtain CaF₂ by pptn. F ions at 20°C in presence of 2 com. flocculants. The product of the high purity (94% by mass CaF₂) and low SiO₂ content (1.79% by mass) was obtained at Ca-to-F molar ratio 0.5 and liq. phase mass to a suspended solid chalk ratio equal to 50:1.

5

Experimental composite material modified with calcium fluoride – three-point bending flexural test

63%

Łapińska B. , Podlewska M. , Kleczewska J. , Nowak J. , Szczesio A. , Sokołowski J. , Łukomska-Szymańska M.

Journal of Achievements in Materials and Manufacturing Engineering

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2016

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tom Vol. 74, nr 2

72--77

EN

Purpose: Evaluation of mechanical properties of fluoride-based experimental composite material. Design/methodology/approach: Flexural strength of experimental light-curing composite material (ECM) modified with the addition of calcium fluoride was tested. The composite material was modified with 0.5–5.0 wt% anhydrous calcium fluoride. Mechanical properties were tested after 24-hour storage of specimens in dry or wet conditions. Findings: Flexural strength of ECM modified with 1.5 wt% up to 5.0 wt% CaF2, stored dry, was statistically higher than in wet conditions. Research limitations/implications: The best mechanical properties of flowable experimental composite material modified with CaF2 were obtained when 1.0 wt% CaF2 was added to the composite. Fluoride-based composite materials need further studies to confirm present findings. Also, fluoride ion release and microbiological properties of CaF2modified composite materials should be evaluated. Originality/value: Fluoride-based composite materials are promising research field and would be found desirable dental restorative materials.

6

Experience with a commercial wet-scrubber (Alusuisse) used in unconventional seawater environment

63%

Bilinski H.

Environment Protection Engineering

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2009

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tom Vol. 35, nr 3

249-257

EN

An experience gained in the closed aluminum smelter in Sibenik (Croatia) is described in order to highlight possible similar problems anywhere in the world, when commercial wet-scrubber, designed for fresh water, is used in an unconventional seawater environment. Lime treatment process was used to remove fluoride as an insoluble calcium fluoride. Wet-scrubbing in real system is compared with that in model system, using the SOLGASWATER program (ERICSSON, 1979) for heterogeneous equilibria. It is shown that chemical modelling can help to control the wet-scrubbing process and thus to avoid the undesirable breaking of pipelines. The removal of fluoride at pH 5.4 in the form of insoluble cryolite, using lime slurry process and seawater in recirculation, is suggested to be an alternative to precipitation of calcium fluoride. Environmental consequences of partial discharging aluminum and fluoride into the marine environment are discussed in comparison with ecosystem response to volcanic aerosol.

7

Analysis of Multicriteria Optimisation in the Decopperisation Process of Flash Smelting Slags

63%

Wędrychowicz M. , Bydalek A. W.

Archives of Foundry Engineering

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2018

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tom Vol. 18, iss. 2

131--136

EN

This article presents results of studies on multicriteria optimisation in the decopperisation process of flash smelting slags coming from the process of decopperisation at the "Głogów II" Copper Smelter. Measurements of viscosity were conducted using a high-temperature viscometer manufactured by Brookfield company. An addition in the form of calcium fluoride has an advantageous influence on decreasing the liquidus temperature of slag, and the effect of decreasing viscosity at the participation of calcium fluoride is significant. A motivation to conduct studies on viscosity of decopperised slags is an optimisation of the process of decopperisation at an improvement of this process parameters, i.e. the time of melt per one production cycle and consumption of electric power in the whole process. The efficiency of optimisation of the process course depends not only on an accepted criterion of the quality of controlling, a type of technological parameters, but also, to large extent, on characteristics and features of these parameters. CaCO3 currently added to the process of decopperisation efficiently decreases viscosity of flash slag, at the same time has influence on an increase of the yield of copper in alloy, but on the other hand, it increases the mass of slag, artificially under representing concentration of this metal. The article is completed with a conclusion of discussed issues, stating that a search for a new technological addition is still necessary.

8

Wpływ rodzaju zasilacza na brykietowanie fluorku wapnia w prasie walcowej

63%

Janewicz A.

Inżynieria i Aparatura Chemiczna

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2006

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tom Nr 4s

72-73

EN

Some experimental results dealing with two types of feeders and their influence on briquetting of waste calcium fluoride in a roll press are shown. To estimate this influence on the process the specific roll force was measured. The effect on briquette quality, i.e. density and shatter (impact) strength is also presented.

9

Wpływ CaF2 na strukturę i własności kompozytów na osnowie stali szybkotnącej

51%

Leżański J.

Rudy i Metale Nieżelazne

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2004

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tom R. 49, nr 4

202-205

PL

Przedstawiono wyniki badań doświadczalnych, mających na celu opracowanie technologii wytwarzania spiekanych kompozytów na osnowie stali szybkotnących, odznaczających się dużą odpornością na zużycie cierne i wysokimi własnościami ślizgowymi. Badano przebieg formowania kompozytów stal szybkotnąca-węglik WC-miedź-fosfor-węgiel-fluorek wapnia oraz strukturę i własności.

EN

Results of experimental studies aimed to develop technology for the fabrication of high-speed steel based sintered composites, characterized by high resistance to frictional wear and high sliding properties, have been presented. The process of forming high-speed steel-carbide WC-copper-phosphorous-carbon-calcium fluoride composites, and their structure and properties, were investigated.

10

Mozliwosci utylizacji odpadowego fluorku wapniowego

51%

Kowalski Z. , Wzorek Z.

Biuletyn. Komitet Inżynierii Środowiska PAN

|

1993

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nr 1

70-76