scholarly journals Effects of Aging Time on The Formation of Calcium Carbonate Polymorphs

2018 ◽  
pp. 227-236
Author(s):  
Özlem DOĞAN
Keyword(s):  
Calcium Carbonate ◽  
Aging Time ◽  
Effects Of Aging ◽  
Calcium Carbonate Polymorphs

CALCIUM CARBONATE POLYMORPHS IN FISH OTOLITHS: TOWARDS UNDERSTANDING ONTOGENETIC, ENVIRONMENTAL, AND PHYLOGENETIC CONTROLS

2018 ◽  
Author(s):  
Bryan C. Chakoumakos ◽  
◽  
Brenda M. Pracheil ◽  
R. Seth Wood ◽  
Alison Loeppky ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Fish Otoliths ◽  
Calcium Carbonate Polymorphs

Effects of Aging on the Solubility of Palladium

1995 ◽  
Vol 412 ◽  
Author(s):  
C. Oda ◽  
H. Yoshikawa ◽  
M. Yui
Keyword(s):  
Aqueous Solution ◽  
Aging Time ◽  
Room Temperature ◽  
High Level Waste ◽  
Anaerobic Conditions ◽  
Dilute Aqueous Solution ◽  
Waste Repository ◽  
Ph Range ◽  
Effects Of Aging ◽  
High Level

AbstractPalladium solubility was measured in a dilute aqueous solution at room temperature in the pH range from 3 to 13 under anaerobic conditions. Crystalline Pd metal was clearly visible and the concentration of palladium in solution decreased gradually with aging time. The palladium concentrations in solution were less than 9.4×10-10M in the pH range from 4 to 10 and increased to 10-7M in the pH range greater than 10. This study suggests that palladium concentrations in certain high-level waste repository environments may be limited by Pd metal and may be less than 10-9M.

scholarly journals Effect of Thermal Aging on the Mechanical Properties of High Tenacity Polyester Yarn

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1666
Author(s):  
Tsegaye Sh. Lemmi ◽  
Marcin Barburski ◽  
Adam Kabziński ◽  
Krzysztof Frukacz
Keyword(s):  
Mechanical Properties ◽  
Structural Change ◽  
Aging Time ◽  
Thermal Aging ◽  
Temperature Influence ◽  
Polyester Yarn ◽  
Textile Materials ◽  
Conveyor Belts ◽  
Effects Of Aging ◽  
Vulcanization Process

Textile materials produced from a high tenacity industrial polyester fiber are most widely used in the mechanical rubber goods industry to reinforce conveyor belts, tire cords, and hoses. Reinforcement of textile rubber undergoes a vulcanization process to adhere the textile materials with the rubber and to enhance the physio-mechanical properties of the product. The vulcanization process has an influence on the textile material being used as a reinforcement. In this work, the effects of aging temperature and time on the high tenacity polyester yarn’s mechanical and surface structural properties were investigated. An experiment was carried out on a pre-activated high tenacity polyester yarn of different linear densities, by aging the yarn specimens under various aging temperatures of 140, 160, 200, and 220 °C for six, twelve, and thirty-five minutes of aging time. The tensile properties and surface structural change in the yarns pre- and post-aging were studied. The investigation illustrates that aging time and temperature influence the surface structure of the fiber, tenacity, and elongation properties of the yarn. Compared to unaged yarn, an almost five times higher percentage of elongation was obtained for the samples aged at 220 °C for 6 min, while the lowest tenacity was obtained for the sample subjected to aging under 220 °C for 35 min.

Flotation behavior and mechanism of calcium carbonate polymorphs with sodium oleate as collector

2021 ◽  
pp. 117040
Author(s):  
Jingzhong Kuang ◽  
Xiaoyuan Wang ◽  
Mingming Yu ◽  
Weiquan Yuan ◽  
Zheyu Huang ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Sodium Oleate ◽  
Flotation Behavior ◽  
Calcium Carbonate Polymorphs

scholarly journals Luminescence reveals variations in local structural order of calcium carbonate polymorphs formed by different mechanisms

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Michael B. Toffolo ◽  
Giulia Ricci ◽  
Luisa Caneve ◽  
Ifat Kaplan-Ashiri
Keyword(s):  
Infrared Spectroscopy ◽  
Calcium Carbonate ◽  
Construction Materials ◽  
Reference Database ◽  
Formation Processes ◽  
X Ray Diffraction ◽  
Structural Order ◽  
Lime Plaster ◽  
Calcium Carbonate Polymorphs

Abstract In nature, calcium carbonate (CaCO3) in the form of calcite and aragonite nucleates through different pathways including geogenic and biogenic processes. It may also occur as pyrogenic lime plaster and laboratory-precipitated crystals. All of these formation processes are conducive to different degrees of local structural order in CaCO3 crystals, with the pyrogenic and precipitated forms being the least ordered. These variations affect the manner in which crystals interact with electromagnetic radiation, and thus formation processes may be tracked using methods such as X-ray diffraction and infrared spectroscopy. Here we show that defects in the crystal structure of CaCO3 may be detected by looking at the luminescence of crystals. Using cathodoluminescence by scanning electron microscopy (SEM-CL) and laser-induced fluorescence (LIF), it is possible to discern different polymorphs and their mechanism of formation. We were thus able to determine that pyrogenic calcite and aragonite exhibit blue luminescence due to the incorporation of distortions in the crystal lattice caused by heat and rapid precipitation, in agreement with infrared spectroscopy assessments of local structural order. These results provide the first detailed reference database of SEM-CL and LIF spectra of CaCO3 standards, and find application in the characterization of optical, archaeological and construction materials.

Effects of Microstructures on the Mechanical Properties of Dilute Al-Si Alloys

2007 ◽  
Vol 345-346 ◽  
pp. 821-824
Author(s):  
Keiyu Nakagawa ◽  
Teruto Kanadani
Keyword(s):  
Fatigue Strength ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Aging Time ◽  
Fracture Elongation ◽  
Micro Cracks ◽  
Hand Fracture ◽  
Stress Cycles ◽  
Effects Of Aging ◽  
The Relationship

In this paper, we investigated effects of aging at 473K on the relationship between microstructure in the vicinity of the grain boundaries and fatigue strength for Al-1.2%Si alloy. Results obtained show the following features. (1) As aging time, tA increase, the tensile strength (σB) and 0.2% proof stress (σ0.2) increase slowly, but gradually decrease after reaching a maximum at around 18 ks. On the other hand, fracture elongation shows an opposite trend, suggesting that at aging times above 18ks, over aging occurs. (2) The fatigue strength lowers with increasing aging time, however, when the aging time is more than 18 ks at 473K, the fatigue strength remains almost the same. (3) When the aging time is more than 6 ks, grain boundary precipitates with a size greater than several 10s of nm are observed. (4) When the aging time is 18 ks, an accumulation of dislocations are observed at the grain boundaries and in the vicinity of grain boundary precipitates, and dislocations increase with the number of stress cycles. (5) When the aging time is more than 6 ks, the fatigue fracture surface is mainly intergranular. These results suggest that reduction of fatigue strength results from propagation of micro-cracks which are initiated at the large precipitates on the grain boundaries.

scholarly journals The effect of different amino acids on spontaneous precipitation of calcium carbonate polymorphs

2018 ◽  
Vol 486 ◽  
pp. 71-81 ◽  
Author(s):  
Lara Štajner ◽  
Jasminka Kontrec ◽  
Branka Njegić Džakula ◽  
Nadica Maltar-Strmečki ◽  
Milivoj Plodinec ◽  
...  
Keyword(s):  
Amino Acids ◽  
Calcium Carbonate ◽  
Calcium Carbonate Polymorphs

X-Ray Diffraction Analysis of the Calcium Carbonate Polymorphs

1970 ◽  
Vol 14 ◽  
pp. 29-37 ◽  
Author(s):  
S. T. Silk ◽  
S. Z. Lewin
Keyword(s):  
Calcium Carbonate ◽  
Size Distributions ◽  
X Ray Diffraction ◽  
Particle Size Distributions ◽  
Ray Method ◽  
X Ray ◽  
Packing Efficiency ◽  
Integrated Intensities ◽  
Packing Effect ◽  
Calcium Carbonate Polymorphs

AbstractIt is shown that the integrated intensities of diffraction lines from calcite and aragonite powders prepared by precipitation vary markedly, due to variations in sample packing efficiency arising from different degrees of polydispersity in the particle size distributions. Since prolonged grinding to equalize initially divergent distributions changes the polymorph composition, the packing effect imposes the principal limitation on the precision of the x-ray method for certain types of calcium carbonate preparations.

Sign in / Sign up

Export Citation Format

Share Document