Creep Failure and Damage Mechanism of Inconel 718 Alloy at 800–900 °C

Kai Chen,Jianxin Dong,Zhihao Yao 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.5

The creep behavior and damage mechanisms of 718 alloys were investigated at 800–900 °C in air. The fracturemorphology and microstructure evolution were observed by optical, scanning and transmission electron microscope. Besides,the creep damage tolerance (λ) and creep strain evolution curve were also calculated. The results showed that the creep curvesof 718 alloys at 800 or 850 °C consisted of primary and tertiary stages, while the steady-state region became apparent at900 °C. The apparent creep activation energy of 718 alloy was in the range from 446.3 to 491.8 kJ/mol. The alloy presentedductile fracture at 800 °C due to the nucleation, growth and linkage of creep voids. However, the failure of alloys at 850 or900 °C presented necking to a point due to the microstructure degradation. Further investigations showed the softening ofmaterials and the loss of mechanical performance could be mainly attributed to the coarsening or decrease of strengtheningprecipitates. Above 850 °C, it was found that γ′ phases would dissolve into matrix and stress promoted the re-dissolution ofγ′ phases or led to the break of δ phases. Moreover, the creep strain evolution curves indicated that 718 alloys kept a relativestable state at 800–900 °C when the strain fraction was below 1.

Elevated thyroid hormones caused by high concentrate diets participate in hepatic metabolic disorders in dairy cows

Chen Qu,Wu Chen,Yao Zhihao,Cai Liuping,Ni Yingdong,Mao Shengyong 아세아·태평양축산학회 2022 Animal Bioscience Vol.35 No.8

Objective: High concentrate diets are widely used to satisfy high-yielding dairy cows; however, long-term feeding of high concentrate diets can cause subacute ruminal acidosis (SARA). The endocrine disturbance is one of the important reasons for metabolic disorders caused by SARA. However, there is no current report about thyroid hormones involved in liver metabolic disorders induced by a high concentrate diet. Methods: In this study, 12 mid-lactating dairy cows were randomly assigned to HC (high concentrate) group (60% concentrate of dry matter, n = 6) and LC (low concentrate) group (40% concentrate of dry matter, n = 6). All cows were slaughtered on the 21st day, and the samples of blood and liver were collected to analyze the blood biochemistry, histological changes, thyroid hormones, and the expression of genes and proteins. Results: Compared with LC group, HC group showed decreased serum triglyceride, free fatty acid, total cholesterol, low-density lipoprotein cholesterol, increased hepatic glycogen, and glucose. For glucose metabolism, the gene and protein expression of glucose-6- phosphatase and phosphoenolpyruvate carboxykinase 1 in the liver were significantly up-regulated in HC group. For lipid metabolism, the expression of sterol regulatory element-binding protein 1, long-chain acyl-CoA synthetase 1, and fatty acid synthase in the liver was decreased in HC group, whereas carnitine palmitoyltransferase 1α and peroxisome proliferator activated receptor α were increased. Serum triiodothyronine, thyroxin, free triiodothyronine (FT3), and hepatic FT3 increased in HC group, accompanied by increased expression of thyroid hormone receptor (THR) in the liver. Conclusion: Taken together, thyroid hormones may increase hepatic gluconeogenesis, β-oxidation and reduce fatty acid synthesis through the THR pathway to participate in the metabolic disorders caused by a high concentrate diet. Objective: High concentrate diets are widely used to satisfy high-yielding dairy cows; however, long-term feeding of high concentrate diets can cause subacute ruminal acidosis (SARA). The endocrine disturbance is one of the important reasons for metabolic disorders caused by SARA. However, there is no current report about thyroid hormones involved in liver metabolic disorders induced by a high concentrate diet.Methods: In this study, 12 mid-lactating dairy cows were randomly assigned to HC (high concentrate) group (60% concentrate of dry matter, n = 6) and LC (low concentrate) group (40% concentrate of dry matter, n = 6). All cows were slaughtered on the 21st day, and the samples of blood and liver were collected to analyze the blood biochemistry, histological changes, thyroid hormones, and the expression of genes and proteins.Results: Compared with LC group, HC group showed decreased serum triglyceride, free fatty acid, total cholesterol, low-density lipoprotein cholesterol, increased hepatic glycogen, and glucose. For glucose metabolism, the gene and protein expression of glucose-6-phosphatase and phosphoenolpyruvate carboxykinase 1 in the liver were significantly up-regulated in HC group. For lipid metabolism, the expression of sterol regulatory element-binding protein 1, long-chain acyl-CoA synthetase 1, and fatty acid synthase in the liver was decreased in HC group, whereas carnitine palmitoyltransferase 1α and peroxisome proliferator activated receptor α were increased. Serum triiodothyronine, thyroxin, free triiodothyronine (FT3), and hepatic FT3 increased in HC group, accompanied by increased expression of thyroid hormone receptor (THR) in the liver.Conclusion: Taken together, thyroid hormones may increase hepatic gluconeogenesis, β-oxidation and reduce fatty acid synthesis through the THR pathway to participate in the metabolic disorders caused by a high concentrate diet.

Remaining useful life prediction of circuit breaker operating mechanisms based on wavelet‑enhanced dual‑tree residual networks

Tailong Wu,Yuan Yao,Zhihao Li,Binqiang Chen,Yue Wu,Weifang Sun 전력전자학회 2024 JOURNAL OF POWER ELECTRONICS Vol.24 No.1

The remaining useful life prediction of circuit breaker operating mechanisms is crucial for the condition-based maintenance of national power grids. To realize accurate remaining useful life prediction, a novel wavelet-enhanced dual-tree residual network is proposed in this paper. Through this wavelet transform, the time series is decomposed into two components (high frequency and low frequency). Then the two decomposed components are fed into two lightweight residual neural network structures. By concatenating the dual-tree features, the remaining useful life of a circuit breaker operating mechanism can be predicted. The proposed network is validated using a full-life cycle experiment of the circuit breaker operating mechanism. Results show that the proposed method has good capability when it comes to predicting the remaining useful life of the circuit breaker operating mechanism. Along with application in the construction of smart grids and green energy, it is expected that the proposed method has potential in running state prognostics of circuit breakers.

Fabrication of novel Fe2O3/MXene cathode for heterogeneous electro-Fenton degradation of sulfamethoxazole

Huilai Liu,Minshu Cui,Yao Liu,Defeng Kong,Zhihao Li,Rohan Weerasooriya,Xing Chen 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.125 No.-

Sulfamethoxazole (SMX) is a widely used antibiotic drug in medical applications resulting in its ubiquityin water and wastewater. Most of the treatment processes are inefficient in destroying SMX in water. Theheterogeneous electro-Fenton (EF)process shows promise in the non-selective degradation of antibioticdrugs in water and wastewater. Fe2O3/MXene-x (x is the ferric ion loading) was fabricated on 2DMXene carriers by hydrothermal method. The Fe2O3/MXene-x substrates were characterized by electronmicroscopic, X-ray, and molecular spectroscopic methods. Degradative products of SMX were identifiedby free radical quenching and LC-MS measurements. Electron micrographs show that Fe2O3 particulatesare uniformly distributed on MXene nanosheets. Fe2O3/MXene-x coated graphite was used as a cathodewith titanium anode for in situ generation of H2O2 required to produce free radicals (e.g. OH and O2 – ) todestroy SMX. Three possible SMX degradation routes by the electro-Fenton process were proposed. SMXand intermediates are eventually mineralized as CO2 and H2O. The new electrocatalyst shows reducedmetal ions leaching and good stability in repeated use cycles. This work offers a new electro-Fentonmethod to destroy antibiotic drugs in water and wastewater.