ESR investigation of MoSi2 powders used as reactive fillers in polymer-derived ceramics

✍ Scribed by B. Hahn; S. Walter; R. Weissmann; P. Greil

• Book ID: 103967553
• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 311 KB
• Volume: 115
• Category: Article
• ISSN: 0927-7757
• DOI: 10.1016/0927-7757(96)03660-6

✦ Synopsis

An electron spin resonance (ESR) and thermal rheology study is carried out on novel ceramic composites made by pyrolysis of polysiloxane MoSi2 mixtures, which show potential for high temperature applications with their excellent oxidation stability and creep resistance up to 1500 C, but for which injection moulding of the precursor mixture is strongly affected by catalytic effects of MoSi2 on the crosslinking reaction of the polymer phase. ESR showed that the surface of MoSi2 was oxidized during grinding, resulting in an active oxide layer of SiO2 and Mo,O.~. with Mo s+ centres. The Mo s+ signal is correlated with the MoSi2 grain size and the lowering of the thermosetting temperature. Both the Mo s+ signal and the catalytic effect can be suppressed by remo\mg this mixed oxide laver with dilute acids.