The fluorphlogopite mica, because of its purity, has high body resistivity (1000 times higher than natural mica) and can be safely used at the temperature up to 1100°C. Natural mica, due to its impurity, has unstable electric performance, especially at high temperature and high frequency. When above 500°C, it will gradually lose the characteristics of original because of dehydration.
Performance of Vacuum Deflation
The vacuum deflation of fluorphlogopite mica is low, and only the absorbed gases such as O2 , N2 and Ar are detected by a mass spectrograph. As no vapor of H2O is emitted, it is recommendable as electric vacuum insulant with the vacuum components’ service life greatly prolonged.
The natural mica gives off H2O and other volatiles, hence large vacuum deflation, 2000 times higher than fluorphlogopite mica at 900°C.
Fluorphlogopite mica is not inclined to distortion and can bear big stress, tension and compression.
Fluorphlogopite mica has superior thermal stability. It can be used up to 1100℃ with its thickness almost unchanged, and will decompose gradually at 1200℃. Its melting or crystallization temperature is (1350±5)℃.
Natural mica, as containing (OH) -, tends to be agravic at 200℃, and begins to decompose above 450℃ while thickening, severely agravic above 600°C and almost completely decomposing at 900°C. Therefore, the use of natural mica is restricted. Synthetic mica is therefore recommended for high temperature applications up to 1100 ℃. It can also work in sub-zero temperatures to - 100 ℃.
Fluorphlogopite mica, because of its small impurity, it has good photopenetrativity from ultraviolet to infrared. Ultraviolet almost cannot penetrate natural mica, but can penetrate fluorphlogopite mica by nearly 0.2 microns. The natural mica has a distinct absorption peak at 2.75 microns, while fluorphlogopite mica has not, which is an important indication that fluorine replaces hydroxyl. So we can conclude that fluorphlogopite mica is a sort of good euphotic material from ultraviolet (0.2 microns) to infrared (4.5 microns).
|Photopenetrativity of fluorphlogopite mica
|in UV and visual range
||in IR range
Fluorphlogopite mica will not react with common acid and alkali solutions, neither will it with water. For that reason, it will not become layered, dirty and disrupted. It will almost remain its original clarity and transparence after being washed by water (either acid or alkali) of high temperature and high pressure for a long time (2-3 years).
Natural mica will become buff and hydrated after being washed by heated and pressurized water or overheated vapor for months. As a result, it becomes much less transparent and layered, dirty, even nontransparent and disrupted. Even long term immersion in hydrochloric or sulfuric acid is not a problem.