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11/14 Seminar Speech

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Speaker:陳光 博士、楊穎 博士
Topic:

Polysynthetic Twinned TiAl Single Crystals for High Temperature Applications(陳光博士)、

High Energy Density PZT-based Piezoelectric Ceramics and the Application in Small Rotational Wind Energy Harvesters(楊穎博士)

 

  

Speaker:陳光 博士、楊穎 博士
Organization:

陳光 博士:南京理工學材料院士
楊穎 博士 :南京航空航天大學

Topic:

陳光 博士:Polysynthetic Twinned TiAl Single Crystals for High Temperature Applications
楊穎 博士:High Energy Density PZT-based Piezoelectric Ceramics and the Application in Small Rotational Wind Energy Harvesters

Date: 10:10 , 2016.11.14
Location:Room B03,College of Engineering

Resume:

陳光教授簡介:
陳光,工學博士,二級教授,博士生導師。南京理工大學材料評價與設計教育部工程研究中心主任、金屬納米材料與技術聯合實驗室主任,教學名師。江蘇省有突出貢獻中青年專家、中青年科技領軍人才、第六屆"十大優秀專利發明人"、第十二屆"江蘇省優秀科技工作者",中國發明協會第九屆"發明創業獎•人物獎"獲得者。
作為第一主研人主持完成的成果中,榮獲教育部技術發明一等獎1項、江蘇省科技一等獎2項、中國產學研合作創新成果獎1項、中國專利優秀獎1項、省部級科技進步二等獎 4 項、三等獎 1 項、國家發明專利近百項(含受理),公開發表學術論文 200 餘篇,出版《金屬玻璃及其複合材料》、《非平衡凝固新型金屬材料》、《新材料概論》等。
楊穎教授簡介:
楊穎,理學博士,南京航空航太大學航空宇航學院、機械結構力學及控制國家重點實驗室教授、博士生導師。
長期從事大功率壓電材料、新型功能材料、壓電器件等方面的研究。擔任Energy Harvesting and Systems副主編和國際協調人,是International Workshop on Piezoelectric materials and Application in Actuators(壓電材料及其在作動器上的應用國際研討會 ),Energy Harvesting Workshop(能量收集國際研討會)兩個國際研討會的常設組織委員會委員。已發表SCI收錄論文50餘篇,授權發明專利20餘項。

Abstract:

Polysynthetic Twinned TiAl single crystals for high-temperature applications *

G. Chen1, Y. B. Peng1, G. Zheng1, Z. X. Qi1, M. Z. Wang1, H. C. Yu2, C. L. Dong2 and C. T. Liu3
1Engineering Research Center of Materials Behavior and Design, Ministry of Education, Nanjing University of Science and Technology, Nanjing 210094, China. 2Aviation Key Laboratory of Science and Technology on Materials Testing and Evaluation, Science and Technology on Advanced High Temperature Structural Materials Laboratory, Beijing Key Laboratory of Aeronautical Materials Testing and Evaluation, Beijing Institute of Aeronautical Materials, Beijing 100095, China. 3Centre for Advanced Structural Materials, Department of Mechanical and Biomedical Engineering, CSE, City University of Hong Kong, Hong Kong, China. e-mail: Email住址會使用灌水程式保護機制。你需要啟動Javascript才能觀看它 ; Email住址會使用灌水程式保護機制。你需要啟動Javascript才能觀看它

 

TiAl alloys are lightweight, show decent corrosion resistance and have good mechanical properties at elevated temperatures, making them appealing for high-temperature applications. However, polysynthetic twinned TiAl single crystals fabricated by crystal-seeding methods face substantial challenges, and their service temperatures cannot be raised further. Here we report that Ti-45Al-8Nb single crystals with controlled lamellar orientations can be fabricated by directional solidification without the use of complex seeding methods. Samples with 0° lamellar orientation exhibit an average room temperature tensile ductility of 6.9 % and a yield strength of 708 MPa, with a failure strength of 978 MPa due to the formation of extensive nanotwins during plastic deformation. At 900℃ yield strength remains high at 637 Mpa, with 8.1 % ductility and superior creep resistance. Thus, this TiAl single-crystal alloy could provide expanded opportunities for higher-temperature applications, such as in aeronautics and aerospace.

*Chen, G. et al. Nature Mater. 15, 876–881 (2016).

 

Design and Optimization of Small Rotational Piezoelectric Wind Energy Harvesters for Different Load Types and Working Conditions
YANG, Ying*
State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, P. O. Box 359, 29 Yudao Street, Nanjing 210094, China
* Email住址會使用灌水程式保護機制。你需要啟動Javascript才能觀看它

In the future, smart devices are expected to operate autonomously and will be self-powering, self-sensing utilizing ambient sources. With the enormous development in low-power sensors, a self-contained electrical system will be used in practical applications. At the same time, many studies have demonstrated that vibrational energy could be present in the ambient environment. In particular, the vibrational energy produced by combining the mechanical structure and wind energy has been paid more attention recently because wind flow provides a constant source of mechanical energy and this energy can be easily harvested.
This talk will introduce several different small rotational piezoelectric wind energy harvesters which have been designed in recent years. Firstly, a piezoelectric bimorph cantilever polygon with horizontal shaft has been designed and impact-induced resonance proposed to enable effective excitation of the piezoelectric cantilevers' vibration modes and obtain optimum deformation, which enhances the mechanical/electrical energy transformation to improve the output power. And then a vertical shaft wind energy harvester has been proposed as an optimized version of the former one. This vertical shaft Darrieus-type windmill may rotate easily in any wind direction and will have a higher mechanical to electrical energy conversion efficiency. The followed design is a bending rod piezoelectric energy harvester, which is deliberately designed for the extremely high wind speed situation. These small scale piezoelectric wind energy harvesters have been designed, optimized and tested. The output power goes from hundreds microwatts to hundreds milliwatts for different designs. The generated electricity can be stored in a supercapacitor and be used to power small electronic devices or wireless sensor nodes placed in remote locations. In the end, a new composition of high energy density piezoelectric ceramics xPb(Zr0.5Ti0.5)O3-yPb(Zn1/3Nb2/3)O3-(1-x-y)Pb(Ni1/3Nb2/3)O3 (xPZT- yPZN- (1-x-y) PNN) with high d33*g33 value will be introduced.