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61.
《Ceramics International》2021,47(18):25520-25530
(Ti0·8Mo0.2)3AlC2 solid solutions were successfully synthesized from Ti, Al, TiC, and Mo powders using the in situ hot-pressing sintering method. The tribological properties of (Ti0·8Mo0.2)3AlC2 and the reference Ti3AlC2 in the temperature range 25–800 °C were evaluated in ambient air with the counterpart of Al2O3 balls. The results show that (Ti0·8Mo0.2)3AlC2 has improved lubricating properties and wear resistance above 400 °C compared with Ti3AlC2. This can be contributed to the formation of tribo-oxidation films containing MoO3 and MoO3-x. Structural characterization of the tribo-oxidation films was conducted using SEM, EDS, Raman spectroscopy, and XPS to evaluate the effect of Mo doping on the wear mechanisms of Ti3AlC2 in detail. 相似文献
62.
为了对实际信号进行监测,设计了以W77E58微控制器为核心的多路数据采集系统,介绍了系统总体结构,阐明了模拟量采集的硬件和软件设计方法,给出了具体的电路图和软件程序,经实际测试表明,该系统具有采集精度高、功耗低、抗干扰能力强、通用性好的特点。 相似文献
63.
Ke Chen Youhu Chen Jianning Zhang Yujie Song Xiaobing Zhou Mian Li Xiaomeng Fan Jie Zhou Qing Huang 《Ceramics International》2021,47(6):7582-7587
Medium- and high-entropy alloys or ceramics for tuning the physicochemical properties of materials by the combination of multiple principal elements have received much interest. Herein, a medium-entropy (Ti, Zr, Hf)2SC phase was synthesized attributing to the structural and chemical diversity of MAX phases. The crystal structure of (Ti, Zr, Hf)2SC was determined by the Rietveld refinement of XRD, SEM, and atom-resolved TEM along with EDS elemental analysis. Phase evolution of X-ray diffraction patterns and TG/DSC curves were employed to reveal the synthesis mechanism of (Ti, Zr, Hf)2SC from 2TiC–Zr–ZrC-2HfH2-3.2FeS reactant system. The Vicker's hardness and the electrical resistivity of (Ti, Zr, Hf)2SC were found higher than those of Ti2SC, but the thermal conductivity of (Ti, Zr, Hf)2SC was lower. 相似文献
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66.
Tailoring Magnetic Properties of MAX Phases,a Theoretical Investigation of (Cr2Ti)AlC2 and Cr2AlC 下载免费PDF全文
Jiemin Wang Zhimou Liu Haibin Zhang Jingyang Wang 《Journal of the American Ceramic Society》2016,99(10):3371-3375
(Cr2Ti)AlC2 is a newly discovered MAX phase with ordered occupations of Ti and Cr atoms on M sites. The Cr‐containing MAX phase is expected showing magnetic property, which provides functional applications in spintronics and as self‐monitoring smart coating. The magnetic states of (Cr2Ti)AlC2 are predicted by GGA and GGA + U methods and compared to those of Cr2AlC. The ground states are predicted as FM or AFM‐XX configurations depending on the calculation methods. Analysis of the electronic structure shows that the magnetic moments mainly originate from the net spins of Cr 3d valence electrons, whereas the contribution of other atoms is negligible. The calculated magnetic moments of Cr atoms in (Cr2Ti)AlC2 are higher than those in Cr2AlC due to the larger distance between the out‐plane Cr atoms separated by the intercalated nonmagnetic Ti–C slab. This work provides an insight on tailoring magnetic properties of MAX phases by modifying the crystal structure. 相似文献
67.
High‐Temperature Neutron Diffraction,Raman Spectroscopy,and First‐Principles Calculations of Ti3SnC2 and Ti2SnC 下载免费PDF全文
Grady W. Bentzel Michael Naguib Nina J. Lane Sven C. Vogel Volker Presser Sylvain Dubois Jun Lu Lars Hultman Michel W. Barsoum El'ad N. Caspi 《Journal of the American Ceramic Society》2016,99(7):2233-2242
Herein, we report—for the first time—on the additive‐free bulk synthesis of Ti3SnC2. A detailed experimental study of the structure of the latter together with a secondary phase, Ti2SnC, is presented through the use of X‐ray diffraction (XRD), and high‐resolution transmission microscopy (HRTEM). A previous sample of Ti3SnC2, made using Fe as an additive and Ti2SnC as a secondary phase, was studied by high‐temperature neutron diffraction (HTND) and XRD. The room‐temperature crystallographic parameters of the two MAX phases in the two samples are quite similar. Based on Rietveld analysis of the HTND data, the average linear thermal expansion coefficients of Ti3SnC2 in the a and c directions were found to be 8.5 (2)·10?6 K?1 and 8.9 (1)·10?6 K?1, respectively. The respective values for the Ti2SnC phase are 10.1 (3)·10?6 K?1 and 10.8 (6)·10?6 K?1. Unlike other MAX phases, the atomic displacement parameters of the Sn atoms in Ti3SnC2 are comparable to those of the Ti and C atoms. When the predictions of the atomic displacement parameters obtained from density functional theory are compared to the experimental results, good quantitative agreement is found for the Sn atoms. In the case of the Ti and C atoms, the agreement is more qualitative. We also used first principles to calculate the elastic properties of both Ti2SnC and Ti3SnC2 and their Raman active modes. The latter are compared to experiment and the agreement was found to be good. 相似文献
68.
MAX相材料有作为事故容错燃料(accident tolerant fuel,ATF)包壳材料的潜力,为了全面了解MAX相材料在模拟正常工况下的腐蚀行为,使用基体为Ti3SiC2的MAX相陶瓷管材于400℃/10.3 MPa过热蒸气,360℃/18.6 MPa去离子水、3.5μL/L Li+1000μL/L B溶液和70μL/L Li溶液4种不同的水化学条件中进行腐蚀试验,采用XRD、SEM和FIB/TEM观察分析腐蚀前后样品的显微组织、晶体结构和成分。结果表明,Ti3SiC2管材在4种条件下的腐蚀速率均远高于参比Zr-4合金,腐蚀后主要检测到腐蚀产物TiO2,且其表面疏松多孔,未形成保护性的氧化膜。 相似文献
69.
随着控制技术的发展,控制系统越做越复杂,由单片机构建的控制系统已经由一个单片机组成的系统发展到多个单片机组成的多机控制系统和多个单片机组成的网络系统。在工业监控和民用产品中单片机系统使用的越来越多。随着技术的发展和市场竞争的加剧,生产厂家除了考虑到产品的性能也要考虑到产品成本。Microehip公司的PIC16C57是一款性价比较高的单片机。由该单片机建立起来的系统成本大大降低。本文介绍了一种由PIC16C57单片机建立起来的分级总线型网络系统,系统可以用于工业系统监控和民用楼宇监控系统,该网络系统在硬件和软件上都采取了特别的保护措施,系统具有非常好的稳定性和可靠性。 相似文献
70.
《Journal of the European Ceramic Society》2022,42(8):3415-3426
Herein, a reliable diffusion bonding of Ti3Si(Al)C2 ceramic is achieved by applying Au foil as an interlayer at 650 °C for 30 min with an axial pressure of 20 MPa. This novel method significantly decreases the bonding temperature, which is about 150 °C lower than the lowest bonding temperature from current research to the best of our knowledge. Maximum shear strength of 58 MPa is achieved at 650 °C among the bonding temperature range of 600 °C~800 °C. The microstructure evolution mechanism and the relationship between microstructure and mechanical property are discussed. The facile mutual diffusion of Au with de-intercalated Al and Si from Ti3Si(Al)C2 is considered critical in achieving sound interfacial bonding. 相似文献