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Old 09-06-2009, 05:55 PM
Brian Gingras
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SiC elements do break down in contact with glass. I went to High Density elements 2 years ago as a result of aging after 9 months. We have seen zero aging now for 2 years after going to HD SiC elements. The downside of SiC is also that it becomes brittle at 1200F. We found this to be a problem recently when we had 3 elements within 6 months break at exactly the same spot. All 3 were determined to be a result of prolonged exposure to 1200F. We had idled the furnace at 1700 for a wekk at a time when this happened and the breaks were at the point where it was estimated to be 1200 degrees. Without the cycle of charging and blowing and the 1200 point changing it literally cut the elements at 7" from the end each time. Each element only broke when we fired back up and within a minute of running at full power you could hear a sizzle and pop and the SiC litterally melted at the break point.
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