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Abstract: Silicon-based ceramics and aluminum nitride (Si/AlN) were fabricated by pyrolysis of polysilazane (PSZ) coated AlN at 1600 °C in air, Ar, N2 and NH3 atmospheres. The results from XRD, XPS and SEM/EDS revealed the existence of crystalline phase of Si-based ceramics on AlN particles including SiO2 in Si/AlNair, SiC whisker in Si/AlNAr, SiC whisker/Si3N4 grain in Si/AlNN2, and Si3N4 ceramics in Si/AlNNH3. It was found that the thermal conductivity of silicone rubber filled with Si/AlN hybrid fillers which were fabricated in Ar and NH3, was improved. This might be due to the existence of nanoscale SiC whiskers and a thermal conductive layer of Si3N4 on Si/AlNAr and Si/AlNNH3 surface, respectively. Thus, it can be suggested that Si/AlN hybrid fillers, especially for the case of Si/AlN(Ar and NH3), can be applicable to use as thermally conductive fillers. This work may have found to be an alternative way to improve thermal conductivity, but more work needs to be done to really achieve significant improvement. [Copyright &y& Elsevier]

Highlights: [•] Surface modification of AlN by ceramic coating method. [•] A good compatibility between amorphous SiOC ceramic film coated AlN and silicone rubber composite. [•] Effect of the morphology of PSZ and SiOC films as intermediate layer on the thermal conductivity of the composite. [ABSTRACT FROM AUTHOR]

In this study, we used a LUMiSizer® analytical centrifuge to determine the particle dispersions and size distributions of organic/inorganic composite coatings. The centrifuge was capable of recording both the measure space and time-resolved extinction profiles (STEP™-Technology) for up to 12 samples simultaneously, making it a powerful tool for the characterization and quality control of coatings. While the variation of the light extinction curves after centrifugal segregation provided a qualitative description, a rigorous formulation can provide detailed quantitative characterization. The technique used in this study allowed demixing to be accelerated and direct quantification of the dispersibility of the coatings. Because the dispersants and binders stabilized the organic/inorganic composite coatings, the dispersibility strongly depended on their concentration. The dispersibility of the coatings increased upon increasing the dispersant concentration and decreasing the concentration of the binder. Furthermore, the inorganic particles exhibited good dispersibility, without large degrees of aggregation, in the coating dispersions. We also used the LUMiSizer® to determine the particle size distribution and shelf life of coatings; the results were comparable with those obtained using dynamic light scattering, scanning electron microscope and zeta potential analysis. [ABSTRACT FROM AUTHOR]