%0 Journal Article %T Evolution of structural features and mechanical properties during the conversion of poly[(methylamino)borazine] fibers into boron nitride fibers %+ Laboratoire des Multimatériaux et Interfaces (LMI) %A Bernard, Samuel %A Ayadi, Khaled %A Berthet, Marie-Paule %A Chassagneux, Fernand %A Cornu, David %A Letoffe, Jean-Marie %A Miele, Philippe %< avec comité de lecture %@ 0022-4596 %J Journal of Solid State Chemistry %I Elsevier %V 177 %N 6 %P 1803-1810 %8 2004-06 %D 2004 %R 10.1016/j.jssc.2004.01.004 %K Boron nitride %K Ceramic fiber %K Preceramic polymer %K Polymer-to-ceramic conversion %K Ceramization %K Crystallization %Z Chemical Sciences %Z Chemical Sciences/Material chemistry %Z Engineering Sciences [physics]Journal articles %X Poly[(methylamino)borazine] (PolyMAB) green fibers of a mean diameter of 15 μm have been pyrolyzed under ammonia up to 1000°C and heat treated under nitrogen up to 2000°C to prepare boron nitride (BN) fibers. During the polymer-to-ceramic conversion, the mechanical properties of the green fibers increase within the 25–400°C temperature range owing to the formation of a preceramic material and remain almost constant up to 1000°C. Both the crystallinity and the mechanical properties slightly increase within the 1000–1400°C range, in association with the consolidation of the fused-B3N3 basal planes. A rapid increase in tensile strength (σR) and elastic modulus (Young's modulus E) is observed in relation with crystallization of the BN phase for fibers treated between 1400°C and 1800°C. At 2000°C, “meso-hexagonal” BN fibers of 7.5 μm in diameter are finally obtained, displaying values of σR=1.480 GPa and E=365 GPa. The obtention of both high mechanical properties and fine diameter for the as-prepared BN fibers is a consequence of the stretching of the green fibers on a spool which is used during their conversion into ceramic. %G English %L hal-02617050 %U https://cnrs.hal.science/hal-02617050 %~ CNRS %~ UNIV-LYON1 %~ LMI %~ INC-CNRS %~ UDL %~ UNIV-LYON %~ TEST2-HALCNRS