| Summary: | 碩士 === 國立臺灣大學 === 材料科學與工程學研究所 === 90 === Vacuum and Hydrogen have mostly been used to sinter stainless steels in order to get good corrosion resistance. However, nitrogen-containing atmospheres are the most widely used ones used in the industry due to economic reasons. The objective of this study was thus to improve corrosion resistance through reheating and fast cooling of the compacts sintered in N2-75H2, N2-15H2 and N2.
The results show that when N2-75H2, N2-15H2 and N2 are used as sintered atmospheres, the corrosion resistance is poorer than that using H2. The corrosion resistance deteriorates as the amount of N2 increases. But, all these compacts could still provide satisfactory results when they are cooling-zone cooled with an average cooling rate of 57℃/min between 500-800℃. This shows that stainless steels can still be sintered in NH3 as long as the cooling rate is fast enough to prevent the formation of chromium nitride (Cr2N). The pitting potential was also found to be improved by increasing the amount of nitrogen dissolved.
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