Spectroscopic studies on U(VI) incorporation into CaCO3: Effects of aging time and U(VI) concentration

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.

Download Full-text

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

Materials ◽

10.3390/ma14071666 ◽

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.

Download Full-text

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

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.345-346.821 ◽

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.

Download Full-text