主讲人：潘伟教授【清华大学教授，博士生导师，世界陶瓷科学院院士，清华大学校务委员会委员，新型陶瓷与精细工艺国家重点实验室主任】

时间：2018年6月20日上午10:00

地点：工学二号馆202会议室

潘伟教授简介：

潘伟，清华大学教授，博士生导师，世界陶瓷科学院院士，清华大学校务委员会委员，新型陶瓷与精细工艺国家重点实验室主任。中国硅酸盐学会常务理事，中国硅酸盐学会特种陶瓷分会常务副理事长兼秘书长，国际梯度功能材料顾问委员会理事，亚洲－澳州陶瓷联盟理事长。担任过第六至第十九届全国特种陶瓷学术年会秘书长、组委会主席，第一至第九届中国国际高性能陶瓷材料学术会议组委会主席，第7届国际梯度功能材料学术会议主席，第五届国际陶瓷大会组委会主席。研究领域为热障涂层陶瓷材料，透明陶瓷，电纺丝法制备纳米纤维和功能器件，固态离子导体材料，轻质超硬材料、精密陶瓷部件制备技术。

报告内容简介：

Defect Engineering in Development of Low Thermal Conductivity Materials

Wei Pan

State Key Lab of New Ceramics and Fine Processing, School of materials science and engineering,

Tsinghua University,Beijing, China

panw@mail.tsinghua.edu.cn

Increasing thermal efficiency and lower emissions require gas turbine designers to further increase the combustion temperature that leads to the high temperature components such ascombustion chambers, blade and vanes surfaces face more rigorous conditions. Therefore, there is urgent demand to develop new ceramic coatings with even lower thermal conductivity, higher stability and durability than currently used thermal barrier coatings coating on the surface of high temperature alloy components.

Defect engineering has attracted much attention in seeking better low thermal conductivitymaterials since lattice defects play a crucial role in phonon scattering and thermal conductivity reduction. Oxygen vacancies and substitutions are proven to be the most effective, while the accompanying lattice distortion is also of great importance. In thistalk, recent advances of reducing the thermal conductivity of potential thermal barrier coating materials by defect engineering are comprehensively reviewed. Effects of the mass and size mismatch between the defects and the host lattice are quantitatively estimated and unconventional thermal conductivity reduction caused by the lattice distortions is alsointroduced. Finally, challenges and potential opportunities are briefly assessed to further minimize the thermal conductivity ofthermal barrier coatings materials in the future.

In this presentation,effects of macro defects on the heat transfer in porous ceramics are also talked including the characterization method as well as modeling.

References

[1] Wan CL,W. Pan, Xu Q, Qin YX, Wang JD, Qu ZX, Fang MH, Effect of point defects on the thermal transport properties of (La_xGd_1-x)₂Zr₂O₇ : Experiment and theoretical model.Phys. Rev. B 74, 144109-1~9 (2006).

[2] Wan CL, Qu ZX, He H, Luan D,W. Pan, Ultralow thermal conductivity in highly anion-defective aluminates,Phys. Rev. Lett. 101, 085901 (2008).

[3] J. Feng, C. Wan, B. Xiao, R. Zhou, W. Pan, D. R. Clarke, Calculation of the thermal conductivity of R₂SrAl₂O₇ (R = La, Nd, Sm, Eu, Gd, Dy),Phy. Rew. B,84, 024302 (2011)

[4] ZX Qu, Taylor Sparks, W. Pan, and David R. Clarke, Thermal conductivity of the gadolinium calcium silicate apatites: Effect of different point defect types,Acta Mater. 59 (2011) 3841–3850.

[5] CL Wan, W Zhang, YF Wang, ZX Qu, AB Du, RF Wu, W. Pan, Glasslike thermal conductivity in ytterbium doped lanthanum zirconate pyrochlore,Acta Mater. 58 (2010) 6166– 6172.

[6] XR Ren, W Pan,Mechanicalproperties ofhightemperaturedegradedyttriastabilizedzirconia,Acta Mater.69 (2014) 397–406.

[7] J. Feng, B. Xiao, R. Zhou, W. Pan, Anisotropy in elasticity and thermal conductivityof monazite-type REPO₄ (RE = La, Ce, Nd, Sm, Eu and Gd) from first-principles calculations,Acta Mater. 61 (2013) 7364–7383

[8] M Zhao, W. Pan, Effect of lattice defects on thermal conductivity of Ti-doped, Y₂O₃-stabilized ZrO₂,Acta Mater. 61 (2013) 5496–5503.

[9] CL Wan, ZX Qu, AB Du,W. Pan, Influence of B site substituent Ti on structure and thermophysical properties of A₂B₂O₇-type pyrochlore Gd₂Zr₂O₇,Acta Mater., 57 (2009) 4782–4789.

[10] ZX Qu, CL Wan,W. Pan, Thermophysical properties of rare-earth stannates: Effect of Pyrochlore Structure, Acta Mater. 60 (2012) 2939–294