ISSN:
1662-8985
Quelle:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Thema:
Maschinenbau
Notizen:
Polycondensations (condensation polymerization) are stepwise reactions betweenbifunctional or polyfunctional compoents, with elimination of simple molecules such as water oralcohol and the formation of macromolecular substances. Polyborate ester , formed by this process,gives ceramic materials during pyrolysis. Polymer pyrolysis offers an attractive alternative to thetypical high temperature powder processing approach in the fabrication of high-performanceceramics. This approach might also prove to be useful in the fabrication of fibers, coatings, andcomposites. It is within this framework that the present study was undertaken; its aim is thepreparation of boron-containing oligomeric precursors which gives boron nitride afterpyrolysis. The precursor was synthesized by the condensation reaction between boric acidand urea (or other N-containing reactive multifunctional compounds). The oligomeric precursorand its pyrolysed products were thoroughly characterized by elemental analysis, IR, NMR,XRD, Thermal Analysis and Transmission Electron Microscopy(TEM). The elemental analysisresults of the oligomer are---- C-13.40%, H-5.97%, N-32.44% and B-17.09%. X-ray diffractionand TEM studies showed that boron nitride obtained from this system possess tetragonal structure
Materialart:
Digitale Medien
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/40/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.29-30.199.pdf
Permalink