Journal of the American Ceramic Sociery-Morscher Vol. 80. No 8 1200c Fracture Surface PBNS 5.8kV×1.egk3e 700c 1 mm Fig. 10. (a) Longitudinal length of minicomposite that ruptured after 36 h at 1200oC, where the hot-zone section of the minicomposite is indicated by the 1200C" marking,(b)a high ication FESEM micrograph of an opened matrix crack. The experiments on Hi-Nicalon minicomposites were per- formed in the summer months(June-September), which meant .The National Weather Service in Cleveland, OH is at Hopkins International that the atmosphere was very hu The experiments that were performed on the Nic-BN minicomposites were in No- outside air and is often at negative pressure. For the air-conditioning system that wa vember and December, i.e with lower ambient humidity. Dat lat outsId that was obtained from the National weather Service2 enabled an approximation of the water content in the air. The water estimates of hur that were used to determine the water pressure of the atmo- sphere in the laboratory; they are considered to be conservativeThe experiments on Hi-Nicalon minicomposites were per￾formed in the summer months (June–September), which meant that the atmosphere was very humid. The experiments that were performed on the Nic-BN minicomposites were in No￾vember and December, i.e., with lower ambient humidity. Data that was obtained from the National Weather Service29 enabled an approximation of the water content in the air.‡‡ The water ‡‡The National Weather Service in Cleveland, OH is at Hopkins International Airport, which is <0.5 mi. from where the experiments were performed. The air￾handling system in the building where the experiments were performed takes in all outside air and is often at negative pressure. For the air-conditioning system that was in place at the time of the experiments, the humidity in the building was estimated to be the same as that outside for a relative humidity of #60%. For relative outside humidities of 60%–100%, the inside humidity would be 60%–80%. These are the estimates of humidity that were used to determine the water pressure of the atmo￾sphere in the laboratory; they are considered to be conservative. Fig. 10. (a) Longitudinal length of minicomposite that ruptured after 36 h at 1200°C, where the hot-zone section of the minicomposite is indicated by the ‘‘1200C’’ marking; (b) a higher-magnification FESEM micrograph of an opened matrix crack. 2038 Journal of the American Ceramic Society—Morscher Vol. 80, No. 8