國際交流英語演講

1、Transparent mullite ceramics from diphasic aerogels by microwave and conventional processings Speechmaker：Feng QingfuCatalog Background Experiment Results and discussion Conclusion BackgroundMullite (3Al,O, . 2Si0,) is by far the most widely used ceramic material . high melting point (1850C ) low th

2、ermal expansion coefficient low thermal conductivity excellent thermal-shock resis- tance high strength good creep resistance,etc. BackgroundHense mullite glass-ceramics have been the best and most realistic choice. The sol-gel technique Microwave heating of ceramics A combination of mi- crowave pro

3、cessing with aerogel precursor based on diphasic materials made it possible to achieve trans- parent mullite ceramics in the current study. Experimenta) Synthesis of diphasic mullite precursors b) Sintering c) Characterization Results and discussion Microstructure of diphasic mullite: (a) aerogel an

4、d (b) xerogel. Results and discussion Microstructure of diphasic mullite: (a) aerogel and (b) xerogel. Results and discussion Mullite ceramics sintered by (a) microwave (13OO 10 min) and (b, c, d) conventional (b, c: 1300C 10 min; d: 5 /min to 1320C without holding) methods. Sample (c), made from di

5、phasic xerogel is opaque, while the rest made from aerogel show transparency. Conclusion X-ray diffraction showed that conventionally sintered samples were nearly amor- phous (only a very weak diffraction peaks of - Al2O3, and mullitization had not yet taken place), whereas the microwave-sintered sample was trans- parent and consisted of highly crystalline mullite. The key factor The aerogel o