真空冷喷涂LiNi_(0.33)Co_(0.33)Mn_(0.33)O_2涂层颗粒沉积行为研究

真空冷喷涂是一种基于室温及真空条件下超细陶瓷粉末粒子的撞击破碎实现涂层沉积的方法。目前,真空冷喷涂技术已经在微电子器件,金属防护以及新能源领域展现了良好的应用前景。本研究将目光转向锂离子电池,基于真空冷喷涂技术,在氧化铝基体上制备了锂离子电池LiNi_(0.33)Co_(0.33)Mn_(0.33)O_2(NMC)三元材料正极涂层,使用扫面电子显微镜(SEM)观察了NMC涂层的表面及截面微观形貌,使用X射线衍射(XRD)对涂层的相结构进行了测试,使用3D激光显微镜表征了涂层的表面粗糙度,系统研究了载气流量、喷涂距离、喷涂次数等沉积条件对NMC涂层微观形貌及粒子沉积行为的影响。结果表明,在真空冷喷涂NMC涂层中可以观察到明显颗粒破碎沉积现象,涂层结构致密。NMC粉末颗粒沉积方式受气流量、喷涂距离、喷涂次数等沉积条件的影响,载气流量的提高会提高粒子撞击速度,从而提高涂层沉积速率,但过高的气流量会导致粒子发生冲蚀,在涂层表面留下凹坑,致使涂层粗糙度增大。喷涂距离过大会导致NMC颗粒撞击速度减小,粒子破碎不充分,涂层呈现出类似团聚粉末堆积的疏松结构。喷涂次数影响涂层厚度,在合适的沉积参数条件下,可以通过调整喷涂次数实现涂层厚度的线性调控。

Study and performance test of 10 kW molten carbonate fuel cell power generation system

The use of high-temperature fuel cells as a power technology can improve the efficiency of electricity generation and achieve near-zero emissions of carbon dioxide.This work explores the performance of a 10 kW high-temperature molten carbonate fuel cell.The key materials of a single cell were characterized and analyzed using X-ray diffraction and scanning electron microscopy.The results show that the pore size of the key electrode material is 6.5 lm and the matrix material is a-LiAlO_(2).Experimentally,the open circuit voltage of the single cell was found to be 1.23 V.The current density was greater than 100 mA/cm^(2)at an operating voltage of 0.7 V.The 10 kW fuel cell stack comprised 80 single fuel cells with a total area of 2000 cm^(2)and achieved an open circuit voltage of greater than 85 V.The fuel cell stack power and current density could reach 11.7 kW and 104.5 mA/cm2 at an operating voltage of 56 V.The influence and long-term stable operation of the stack were also analyzed and discussed.The successful operation of a 10 kW high-temperature fuel cell promotes the large-scale use of fuel cells and provides a research basis for future investigations of fuel cell capacity enhancement and distributed generation in China.

A methylammonium iodide healing method for CH_(3)NH_(3)PbI_(3) perovskite solar cells with high fill factor over 80%

Repressing the thermal decomposition during the process of heat treatment plays an indispensable part in the preparation of perovskite films.Here,a methylammonium iodide healing method was applied to prevent the volatilization of the organic component inside the perovskite structure during the heat treatment.High-quality CH_(3)NH_(3)PbI_(3) film with a much larger grain size over 800 nm was successfully fabricated via this healing method.Besides,the absorption and photoluminescence intensity were also both improved.Finally,the best power conversion efficiency of 18.89%with a fill factor over 80%was realized in an n-i-p configuration while possessing outstanding stability.This work suggests that methylammonium iodide healing method is a reliable way to promote crystal growth and improve the photovoltaic performance and humidity stability of the CH_(3)NH_(3)PbI_(3) solar cells.

The emerging roles of lysine-specific demethylase 4A in cancer:Implications in tumorigenesis and therapeutic opportunities

Lysine-specific demethylase 4 A(KDM4A,also named JMJD2A,KIA0677,or JHDM3A)is a demethylase that can remove methyl groups from histones H3K9me2/3,H3K36me2/3,and H1.4K26me2/me3.Accumulating evidence suggests that KDM4A is not only involved in body homeostasis(such as cell proliferation,migration and differentiation,and tissue development)but also associated with multiple human diseases,especially cancers.Recently,an increasing number of studies have shown that pharmacological inhibition of KDM4A significantly attenuates tumor progression in vitro and in vivo in a range of solid tumors and acute myeloid leukemia.Although there are several reviews on the roles of the KDM4 subfamily in cancer development and therapy,all of them only briefly introduce the roles of KDM4A in cancer without systematically summarizing the specific mechanisms of KDM4A in various physiological and pathological processes,especially in tumorigenesis,which greatly limits advances in the understanding of the roles of KDM4A in a variety of cancers,discovering targeted selective KDM4A inhibitors,and exploring the adaptive profiles of KDM4A antagonists.Herein,we present the structure and functions of KDM4A,simply outline the functions of KDM4A in homeostasis and non-cancer diseases,summarize the role of KDM4A and its distinct target genes in the development of a variety of cancers,systematically classify KDM4A inhibitors,summarize the difficulties encountered in the research of KDM4A and the discovery of related drugs,and provide the corresponding solutions,which would contribute to understanding the recent research trends on KDM4A and advancing the progression of KDM4A as a drug target in cancer therapy.

Understanding of degradation-resistant behavior of nanostructured thermal barrier coatings with bimodal structure

Nanostructured thermal barrier coatings(TBCs) often provide high degradation resistance, as well as extended lifetime. However, the underlying mechanism has not been fully understood. In this study, the sintering characteristics of nanostructured yttria-stabilized zirconia(YSZ) coatings were investigated,and compared with those of the conventional YSZ coatings. Multiscale characterizations of the changes in microstructures and properties were performed. Results showed that the enhanced high-performance durability was mainly attributed to different sintering mechanisms of lamellar zones and nanozones.Sintering characteristics of the lamellar zones were similar to those of the conventional coatings. Stagesensitive healing of two-dimensional(2 D) pores dominated the sintering behavior of the lamellar zones.However, the differential densification rates between nanozones and lamellar zones of the nanostructured TBCs led to the formation of coarse voids. This counteractive effect, against healing of 2 D pores, was the main factor contributing to the retardation of the performance degradation of bimodal TBCs during thermal exposure. Based on the understanding of the performance-degradation resistance, an outlook towards TBCs with higher performances was presented.

Corrigendum to"Understanding of degradation-resistant behavior of nanostructured thermal barrier coatings with bimodal structure"[J.Mater.Sci.Technol.35(2019)231-238]

The authors regret to inform that(i)a wrong Table 1 was uploaded,and a corrected one was show below;(ii)a reference label is missing in caption of Fig.8(A),and it should be:Fig.8.Interfacial evolution between nanozones and lamellar zones during thermal exposure:(A)as-deposited state[45];(B)20 h;(C)500 h;(iii)a wrong figure was uploaded in Fig.2(A,0 h),and a revised one is shown below.

Dynamic-stiffening-induced aggravated cracking behavior driven by metal-substrate-constraint in a coating/substrate system

Air plasma sprayed thermal barrier coatings(APS-TBCs)saw their wide application in high-temperaturerelated cutting-edge fields.The lamellar structure of APS-TBCs provides a significant advantage on thermal insulation.However,short life span is a major headache for APS-TBCs.This is highly related to the property changes and passive behaviors of the coatings during thermal service.Herein,a finite element model was developed to investigate the dynamic stiffening and substrate constraint on total spallation process.Results show that the stiffening accelerates the crack propagation of APS-TBCs.The driving force for crack propagation,which is characterized by strain energy release rate(SERR),is significantly enlarged.Consequently,the crack starts to propagate when the SERR exceeds the fracture toughness.In addition,the changing trends of SERR and crack propagation features are highly associated with temperatures.A higher temperature corresponds to more significant effect of stiffening on substrate constraint.In brief,temperature-dependent stiffening significantly aggravates the substrate constraint effect on APS-TBCs,which is one of the major causes for the spallation.Given that,lowering stiffening degree is essential to maintain high strain tolerance,and to further extend the life span of APS-TBCs.This understanding contributes to the development of advanced TBCs in future applications.

Efficient and Stable Large-Area Perovskite Solar Cells with Inorganic Perovskite/Carbon Quantum Dot-Graded Heterojunction

This work reports on a compositionally graded heterojunction for photovoltaic application by cooperating fluorine-doped carbon quantum dots(FCQDs in short)into the CsPbI_(2.5)Br_(0.5)inorganic perovskite layer.Using this CsPbI_(2.5)Br_(0.5)/FCQDs graded heterojunction in conjunction with low-temperature-processed carbon electrode,a power conversion efficiency of 13.53%for 1 cm^(2)all-inorganic perovskite solar cell can be achieved at AM 1.5G solar irradiation.To the best of our knowledge,this is one of the highest efficiency reported for carbon electrode based all-inorganic perovskite solar cells so far,and the first report of 1 cm^(2)carbon counter electrode based inorganic perovskite solar cell with PCE exceeding 13%.Moreover,the inorganic perovskite/carbon quantum dot graded heterojunction photovoltaics maintained over 90%of their initial efficiency after thermal aging at 85°for 1056 hours.This conception of constructing inorganic perovskite/FCQDs graded heterojunction offers a feasible pathway to develop efficient and stable photovoltaics for scale-up and practical applications.