SEMINAR

 

The State Key Lab of

High Performance Ceramics and Superfine Microstructure

 

 中国科学院上海硅酸盐研究所高性能陶瓷和超微结构国家重点实验室

 

 

 

 

 

 

 

Ductile deformation and fracture behaviour in alumina/silicon carbide nanocomposites

 

 

 

Speaker

 

Dr Houzheng Wu

 

Department of Materials, Loughborough University

 

 

 

 

联系人：张国军研究员

 

 

Abstract

 

Ductile deformation and fracture behaviour in alumina/silicon carbide nanocomposites

 

It has been noticed that, compared to the monolithic alumina ceramics with the same grain size, alumina polycrystals containing small fractions (typically 1-5vol%) of tens to hundreds nanometers of silicon carbide particles (widely called alumina/silicon carbide nanocomposites) are able to show significant increments in strength. Any increase in strength, however, is not accompanied by a corresponding increase in fracture toughness. It has therefore been proposed that the surface properties of alumina/silicon carbide nanocomposites are the key to their enhanced strength. In the past years, we have studied the near surface damage (ductile deformation and micro-fracture) of alumina/silicon carbide nanocomposites using various characterizing techniques, such as TEM, FIB, fluorescence spectroscopy, grazing-incidence X-ray powder diffraction, and Hertzian indentation. It has been demonstrated that dislocations are dominant deformation features in the nanocomposites while twins are prevalent in monolithic alumina in ductile regions after pseudo-static compressive loading. The difference in ductile deformation, and fracture mode, leads to a significant difference in residual compression in the near-surface and a transition in fracture mode on ground or worn surfaces. In this talk, I am going to summarise the research outcomes generated from different characterisation techniques, and to speculate the potential benefits of ceramic nanocomposites.

 

 

 

Dr Houzheng Wu

 

Education

1999 – 2002 　　  D. Phil. (in Material Science)

Department of Materials, University of Oxford, UK

1984 – 1987 　　  M. Phil. (in Material Science & Engineering)

Department of Materials Science & Engineering, Tianjin University, China

1980 – 1984 　　  B. Eng. (in Ceramics)

Department of Chemistry & Chemical Engineering, Hunan University, China

 

Professional History

11/2006 – present	Senior Lecturer	Department of Materials, Loughborough University
01/2003 – 10/2006	Senior Lecturer	Schoolof Engineering, Coventry University
06/1998 -  01/2003	Research Fellow	Department of Materials, Oxford University
10/1997 – 06/1998	Professor	Schoolof Mats. Sci. & Eng., Tianjin University
09/1996 – 09/1997	Sino-British Fellowship	Department of Materials, Oxford University
10/1994 - 09/1997	Associate Professor	Dept. of Mats. Sci. & Eng. Tianjin University
10/1990 - 09/1994	Lecturer	Dept. of Mats. Sci. & Eng. Tianjin University
07/1987 - 09/1990	Assistant Professor	Dept. of Mats. Sci. & Eng. Tianjin University

 

Research Interests

·　　　 Carbon fibre and nano-fibre reinforced ceramic composites – manufacture technology, performance engineering, application technology

·　　　 Ceramic nanocomposites – performance understanding

·　　　 Material microstructure and property characterisation

·　　  Processing technology for ceramic-based materials from powder synthesis to high temperature densification..

 

Research Grants Obtained as PI/CoI

·　　　　 2009-2012 “Sustainable surface engineered carbon fibre reinforced ceramic composites friction materials (SmrFace) funded by TSB, and cooperated with 5 companies in Britain.

·　　　　 2009-2012 “Understanding and improving ceramic armour materials” funded by EPSRC, and cooperated with Oxford University

·　　　　 2007-2010 “Extended life and innovative recycling of carbon waste for friction applications” funded by DTI/EPSRC, and cooperated with 8 companies in Britain.

·　　　　 2009-2010 “Development of ferritic steels for fusion blanket applications” funded by the Royal Society.

·　　　　 2006 “Nucleation and annealing kinetics of the monoclinic phase in the near surface of yttria-stabilized zirconia”, funded by the European Synchrotron Radiation Facility.

·　　　　 2005 “Lifetime Assessment and Improvement of Zirconia Ceramic Human Prosthetic-Experimental Method with ESRF Beam”, funded by the European Synchrotron Radiation Facility.

·　　　　 2005 “Metallurgic Investigation of Failed Transportation Turbochargers”, funded by Bombardier Transportation UK.

·　　　　  2004 “Failure Analysis of Mini-Ceramic Igniters”, funded by Hamworth Heating Ltd, UK.

·　　　　 1998-2000 “Direct Bonding of Ceramics”, funded by MOE^*, Key Fundamental Research Programme (in China).

·　　　　 1998-1999 “Ceramic Ink for Ink-Jet-Print Rapid Prototyping”, funded by NSFC^& (in China).

·　　　　 1996-1998 “Y₂O₃-MgO-ZrO₂ and CeO₂-MgO-ZrO₂ Phase Diagram and Kinetics of Phase Formation”, funded by NSFC^* (in China).

·　　　　 1991-1995 "Development of Refractory Fine-Grain PSZ Ceramics", funded by MOST “863" High-Tech Plan (in China).

·　　　　 1991-1995 "Development of Manufacture Technologies for Ceramic Cylinder Liners of High Pressure Pump for Oil Industry", funded by MOST^£ “8.5”Plan (in China).

·　　　　 1991-1995 "Development of Manufacture Technologies for Cylinder Liners with PSZ Ceramics for Diesel Engine", funded by MOST “8.5”Plan (in China).

 

Research Experience in Other Projects

·　　　　 2006-2009 “The Evaluation of Sonochemical Techniques for Sustainable Surface Modification in Electronic Manufacturing”, funded by IeMRC.

·　　　　 2004 – 2005 “Laser Application in Material Processing” funded by ERDF,

·　　　　 2001-2002 “Development of Growth Processes for HTS Thin Films for Microwave Applications”, funded by EPSRC.

·　　　　 1998-2001 “Strengthening Mechanisms in Oxide Ceramic Nanocomposites”, funded by EPSRC.

·　　　　 Jun. 1995-Sept. 1995 “Sol-gel Synthesis High Purity and Ultrafine Mullite Powder”, funded by ANSTO^%.

·　　　　 1987-1990 "Ceramic Material Selection and Manufacture Technologies for the Fabrication of Ceramic Cylinder Liners, Top Plates for Diesel Engine and Valve Seats for 492QA Gasoline Engine", funded by MOST “7.5 ”Plan (in China)

·　　　　 1987-1988 "Heat Treatment of Ceramics", funded by NSFC (in China).

 

* MOE: Ministry of Education, China. ^& NSFC: National Science Foundation of China

^% ANSTO: Australia Nuclear Science & Technology Organisation. ^£ MOST: Ministry of Science & Technology, China