Consistensy Among Measured Thermal Conductivity, Diffusivity and Spesific Heat Capasity of Pyroceram 9606
Penulis: Akira Ono, Tetsuya Baba, Tsuyoshi Matsumoto and M. M. SuliyantiRound Robin measurements managed by ASTM Subcommittee C-14.91 (Glass standard Reference Material) are under way to establish a new standard reference material for thermal conductivity measurement at a medium conductivity level like glasses and ceramics. Test sample, Pyroceram 9606 made by Corning Glass works, were distributed to the participating institutes. National Research Laboratory of Metrology (NRLM) received six lots of Pyroceram in two different sizes. We made thermal diffusivity measurements by the laser flash method, thermal conductivity measurements by the radiative heat exchange method, specific heat capacity measurements by the differential scanning calorimetry (DSC), and density measurements. The correlation equation of thermal diffusivities for eight specimens from two different lots is given by Eq. (1)in the temperature range from 300K to 1,200K with a estimated accuracy of 3%. The thermal diffusivity differed from lot to lot by less than 1% in most of the temperature range with a maximum difference of 1.4% at 400K. The correlation equation of thermal conductivity for a specimen is given by Eq. (2) in the temperature range from 30oC to100oC with an estimated accuracy of 2.5%. The specific heat capacity measurements were performed for three Pyroceram specimens with a sapphire specimen as a reference material. Figure 1 shows measured specific heat capacity with a correlation equation. The correlation equation is given by Eq.(3) in the temperature range from 27oC to 112oC with an estimated accuracy of 3%. Specific heat capacities at 500C and 1000C are list in table 1 together with literature values. The differences among those are less than 1%. The density measured at room temperature is given by Eq.(5) with an estimated accuracy of 0.5%. Table 2 list the density value with literature values. The differences among those are less than 0.4%. The thermal conductivity, thermal diffusivity, specific heat capacity and density are generally related to each other as expressed by Eq.(6). A consistency check was made among the measurement data according to Eq.(6) in the temperature range between 300C and 1000C. Figure 2 shows a comparison of thermal conductivities directly measured and derived from the thermal diffusivity, specific heat capacity and density. The thermal conductivity values differed each other by 3.5% at 300C and by 2.8% at 1000C. Those two data are consistent with each other within the accuracy level of measurement. Figure 2 also shows the thermal conductivities of Pyroceram 9606 recommended in 1966 and 1988. Both recommended values were greater than the present one by up to 4%. Taking into account the accuracy levels of recommended values (5% for recommended value in 1966 and 2.8% for that in 1988) and that of the present measurements, those data are not inconsistent with each other. However the difference between the present data and the recommended values may be significant.
The 13th Japan Symphosium on Thermophysical Properties, 1992
ISSN / ISBN / IBSN : mari004
DOI: Maria Margaretha Suliyanti
No. Arsip : LIPI-92002