J. Fedchak, J. Scherschligt, S. Avdiaj, D. Barker, S. Eckel, B. Bowers, Scott OConnell, Perry A. Henderson
{"title":"Outgassing rate comparison of seven geometrically similar vacuum chambers of different materials and heat treatments","authors":"J. Fedchak, J. Scherschligt, S. Avdiaj, D. Barker, S. Eckel, B. Bowers, Scott OConnell, Perry A. Henderson","doi":"10.1116/6.0000657","DOIUrl":null,"url":null,"abstract":"We have measured the water and hydrogen outgassing rates of seven vacuum chambers of identical geometry but constructed of different materials and heat treatments. Chambers of five different materials were tested: 304L, 316L, and 316LN stainless steels; titanium; and aluminum. In addition, chambers constructed of 316L and 316LN stainless steel were subjected to a vacuum-fire process, where they were heated to approximately 950 °C for 24 hours while under vacuum. These latter two chambers are designated as 316L-XHV and 316LN-XHV. Because all the chambers were of identical geometry and made by the same manufacturer, a relative comparison of the outgassing rates among these chambers can be made. Water outgassing rates were measured as a function of time using the throughput technique. The water outgassing results for the 316L, 316LN, 316L-XHV, 316LN-XHV were all similar, but lower than those of 304L by a factor of 3 to 5 lower at 10,000 s. The water outgassing results for Ti and Al chambers were closer to that of 304L, Ti being slightly lower. Hydrogen outgassing rates were measured using the rate-of-rise method and performed after a low-temperature bake of 125 °C to 150 °C for a minimum of 72 hours. The Ti, Al, 316L-XHV, and 316LN-XHV chambers all have ultra-low specific outgassing rates below 1.0E-11 Pa L s-1 cm-2 and are a factor of 100 or better than the 304L chamber. The 304L, 316L, and 316LN chambers with no vacuum-fire heat treatment have larger hydrogen outgassing rates than the other chambers, with determined specific outgassing rates ranging between 4.0E-11 Pa L s-1 cm-2 and 8.0E-11 Pa L s-1 cm-2. We conclude that Ti, Al, 316L-XHV, and 316LN-XHV have hydrogen outgassing rates that make them excellent choices for ultra-high vacuum (UHV) and extreme-high vacuum (XHV) applications, the choice depending on cost and other material properties.","PeriodicalId":8423,"journal":{"name":"arXiv: Applied Physics","volume":"31 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2020-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"7","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"arXiv: Applied Physics","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1116/6.0000657","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 7
Abstract
We have measured the water and hydrogen outgassing rates of seven vacuum chambers of identical geometry but constructed of different materials and heat treatments. Chambers of five different materials were tested: 304L, 316L, and 316LN stainless steels; titanium; and aluminum. In addition, chambers constructed of 316L and 316LN stainless steel were subjected to a vacuum-fire process, where they were heated to approximately 950 °C for 24 hours while under vacuum. These latter two chambers are designated as 316L-XHV and 316LN-XHV. Because all the chambers were of identical geometry and made by the same manufacturer, a relative comparison of the outgassing rates among these chambers can be made. Water outgassing rates were measured as a function of time using the throughput technique. The water outgassing results for the 316L, 316LN, 316L-XHV, 316LN-XHV were all similar, but lower than those of 304L by a factor of 3 to 5 lower at 10,000 s. The water outgassing results for Ti and Al chambers were closer to that of 304L, Ti being slightly lower. Hydrogen outgassing rates were measured using the rate-of-rise method and performed after a low-temperature bake of 125 °C to 150 °C for a minimum of 72 hours. The Ti, Al, 316L-XHV, and 316LN-XHV chambers all have ultra-low specific outgassing rates below 1.0E-11 Pa L s-1 cm-2 and are a factor of 100 or better than the 304L chamber. The 304L, 316L, and 316LN chambers with no vacuum-fire heat treatment have larger hydrogen outgassing rates than the other chambers, with determined specific outgassing rates ranging between 4.0E-11 Pa L s-1 cm-2 and 8.0E-11 Pa L s-1 cm-2. We conclude that Ti, Al, 316L-XHV, and 316LN-XHV have hydrogen outgassing rates that make them excellent choices for ultra-high vacuum (UHV) and extreme-high vacuum (XHV) applications, the choice depending on cost and other material properties.
我们测量了七个几何形状相同但材料和热处理方式不同的真空室的水和氢放气率。测试了五种不同材料的腔室:304L, 316L和316LN不锈钢;钛;和铝。此外,由316L和316LN不锈钢制成的腔室经受真空火处理,在真空下加热到大约950°C 24小时。后两个室被指定为316L-XHV和316LN-XHV。由于所有的腔室都是相同的几何形状,由同一制造商制造,因此可以对这些腔室的放气速率进行相对比较。利用通量技术测量出水率作为时间的函数。316L、316LN、316L- xhv、316LN- xhv的脱气结果相似,但在10000 s时比304L的脱气结果低3 ~ 5倍。Ti和Al气室的放水结果与304L气室的放水结果接近,Ti气室的放水结果略低。在125°C至150°C的低温烘烤至少72小时后,使用上升速率法测量氢气放气率。Ti、Al、316L-XHV和316LN-XHV气室都具有低于1.0E-11 Pa L s-1 cm-2的超低比放气率,比304L气室低100倍或更好。没有真空火热处理的304L、316L和316LN燃烧室比其他燃烧室有更大的氢气放气速率,确定的比放气速率在4.0E-11 Pa L s-1 cm-2和8.0E-11 Pa L s-1 cm-2之间。我们得出的结论是,Ti, Al, 316L-XHV和316LN-XHV具有氢气放气率,使其成为超高真空(UHV)和极高真空(XHV)应用的绝佳选择,选择取决于成本和其他材料性能。