shock resistance
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2021 ◽  
Vol 11 (1) ◽  
pp. 1-56
Author(s):  
Dewei Ni ◽  
Yuan Cheng ◽  
Jiaping Zhang ◽  
Ji-Xuan Liu ◽  
Ji Zou ◽  
...  

AbstractUltra-high temperature ceramics (UHTCs) are generally referred to the carbides, nitrides, and borides of the transition metals, with the Group IVB compounds (Zr & Hf) and TaC as the main focus. The UHTCs are endowed with ultra-high melting points, excellent mechanical properties, and ablation resistance at elevated temperatures. These unique combinations of properties make them promising materials for extremely environmental structural applications in rocket and hypersonic vehicles, particularly nozzles, leading edges, and engine components, etc. In addition to bulk UHTCs, UHTC coatings and fiber reinforced UHTC composites are extensively developed and applied to avoid the intrinsic brittleness and poor thermal shock resistance of bulk ceramics. Recently, highentropy UHTCs are developed rapidly and attract a lot of attention as an emerging direction for ultra-high temperature materials. This review presents the state of the art of processing approaches, microstructure design and properties of UHTCs from bulk materials to composites and coatings, as well as the future directions.


2021 ◽  
Vol 3 (1) ◽  
pp. 041-045
Author(s):  
Dikdik Yuliana ◽  
Hengki Irawan

In the industrial environment, a sight glass acts as a gauge for the fluid level in a pressure vessel. Sight glass must have the following physical properties: clarity (clear enough to view the fluid in the vessel), hardness (not easily broken), thermal shock resistance, and corrosion resistance. A historical investigation of the equipment placed in the High-Pressure Decomposer (HPD) unit of the Urea Plant-X and Plant-Y has a pressure of 17 Bar and a temperature of 124-155oC, yielded an analysis of sight glass degradation in carbamate solution. The sight glass that was installed is soda-lime fused glass. The average is based on the equipment's history.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Karan Singh ◽  
Ekta Kochar ◽  
Prakhar Gahlot ◽  
Karan Bhatt ◽  
Nagaraj Guru Prasad

Abstract Background In insect species like Drosophila melanogaster, evolution of increased resistance or evolution of particular traits under specific environmental conditions can lead to energy trade-offs with other crucial life-history traits. Adaptation to cold stress can, in principle, involve modification of reproductive traits and physiological responses. Reproductive traits carry a substantial cost; and therefore, the evolution of reproductive traits in response to cold stress could potentially lead to trade-offs with other life-history traits. We have successfully selected replicate populations of Drosophila melanogaster for increased resistance to cold shock for over 33 generations. In these populations, the ability to recover from cold shock, mate, and lay fertile eggs 24 h post cold shock is under selection. These populations have evolved a suite of reproductive traits including increased egg viability, male mating ability, and siring ability post cold shock. These populations also show elevated mating rate both with and without cold shock. In the present study, we quantified a suite of life-history related traits in these populations to assess if evolution of cold shock resistance in these populations comes at a cost of other life-history traits. Results To assess life-history cost, we measured egg viability, mating frequency, longevity, lifetime fecundity, adult mortality, larva to adult development time, larvae to adults survival, and body weight in the cold shock selected populations and their controls under two treatments (a) post cold chock and (b) without cold shock. Twenty-four hours post cold shock, the selected population had significantly higher egg viability and mating frequency compared to control populations indicating that they have higher cold shock resistance. Selected populations had significantly longer pre-adult development time compared to their control populations. Females from the selected populations had higher body weight compared to their control populations. However, we did not find any significant difference between the selected and control populations in longevity, lifetime fecundity, adult mortality, larvae to adults survival, and male body weight under the cold chock or no cold shock treatments. Conclusions These findings suggest that cold shock selected populations have evolved higher mating frequency and egg viability. However, there is no apparent life-history associated cost with the evolution of egg viability and reproductive performances under the cold stress condition.


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