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Development of a Polymer Based Syntactic Foam for High Temperature Applications

100%

Yazici M., Fahr P., Shukla A., Gunes S., Akay S.

Acta Physica Polonica A

2014

vol. 125

issue 2

526-528

Syntactic foams are one of the most widely used close cell structured foams. They are used in applications for naval, aeronautical, aerospace, civil, industrial, and automotive engineering due to good acoustical attenuation, excellent strength to weight ratio, vibration isolation, and dielectric properties. These foams are fabricated by incorporation of hollow particles in a matrix material. The most preferred matrix materials are polymers. In this study silicone resin (useful temperature range - 53C to 232°C) was selected as a binder material. Glass bubbles were incorporated into the silicone resin at three different mass percentages (10%, 20%, and 30%). The density of the silicone was reduced more than 50% by 30% glass bubble contribution. The foam mechanical properties were investigated in a room temperature and after heat treatment at 500C by quasi-static compression experiments. Microstructural transitions by the temperature raises were examined by using scanning electron microscopy pictures. It was observed that the increase of glass bubble percentage in silicone rubber enhanced the energy absorption properties in the heat treated and room temperature specimens. Plateau stress and densification amount were improved under quasi-static compression load by the glass bubble percentage increase. It can be said that developed syntactic foams can be used in heat resistant, low weight and high compression strength exigencies.

"Ridge" Fermi Surface Study in Metallic (R)Ba_{2}Cu_{3}O_{7-δ} (R = Y, Dy) and in Oxygen Deficient YBa_{2}Cu_{3}O_{7-δ} by Positron Annihilation

86%

Hoffmann L., Manuel Α. A., Barbiellini B., Peter Μ., Shukla A., Walker E.

Acta Physica Polonica A

1995

vol. 88

issue 1

147-161

We present a detailed positron 2D-ACAR measurements study of the "ridge" Fermi surface of (R)Ba_{2}Cu_{3}O_{7-δ} (R = Y, Dy) compared to full-potential linearized augmented plane wave and linear muffin-tin orbital calculations. From different 2D-ACAR projections measured in DyBa_{2}Cu_{3}O_{7-δ}, a 3D model of the momentum density of the ridge was established and is in good agreement with LMTO calculations of YΒa_{2}Cu_{3}O_{7}, confirming the description of the ridge Fermi surface by local density approximation calculations. The ridge is also studied in oxygen deficient YΒa_{2}Cu_{3}O_{7-δ}. With growing δ, the ridge disappears without changing in width. This is consistent with full-potential linearized augmented plane wave calculations of YΒa_{2}Cu_{3}O_{6.5}, and supports the phase separation model of Mesot et al.

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2 Acta Physica Polonica A

1 2014

1 1995

2 Shukla A.

1 Akay S.

1 Barbiellini B.

1 Fahr P.

1 Gunes S.

1 Hoffmann L.

1 Manuel Α. A.

1 Peter Μ.

1 Walker E.

1 Yazici M.

Search results

Development of a Polymer Based Syntactic Foam for High Temperature Applications

"Ridge" Fermi Surface Study in Metallic (R)Ba_{2}Cu_{3}O_{7-δ} (R = Y, Dy) and in Oxygen Deficient YBa_{2}Cu_{3}O_{7-δ} by Positron Annihilation