5. Waveguide Flanges
5. 波导凸缘
The three concerns for waveguide flanges are to ensure maximum transfer of electromagnetic energy across the flange interface to prevent RF leakage from the interface, and to maintain pressurization of the waveguide. Conductive elastomeric gaskets provide both an electrical and a seal function. For flat cover flanges, a die-cut sheet gasket (CHO-SEAL 1239 material), incorporating expanded metal reinforcement to control gasket creep into the waveguide opening, provides an excellent seal. Raised lips around the gasket cut-out improve the power handling and pressure sealing capability of the gasket. Choke flanges are best sealed with molded circular D-Section gaskets, and contact flanges with molded rectangular D-gaskets in a suitable groove (both in CHOSEAL 1212 material).
波导凸缘的三个考虑因素是确保在凸缘接面上最大限度地传递电磁能，以防止界面发生 RF 泄漏和保持波导凸缘的压力。导电橡胶垫片同时具有导电和密封功能。对于平盖凸缘，模切垫片（CHO-SEAL 1239 材料）配合防止垫片蠕变至波导开洞内的网眼金属板使用，可提供极佳的密封性能。垫片切边周围的突边可提高垫片的处理功率和压力密封能力。波导管阻波凸缘使用 D 型截面的模制环形垫片可达到最佳的密封效果，带模制矩形 D 型垫片，其中模制的 D 型垫片在适当的开槽内与凸缘接触（二者均为 1212 材料）。
The peak power handling capabilities of waveguide flanges are limited primarily by misalignment and sharp edges of flanges and/or gaskets. Average power handling is limited by the heating effects caused by contact resistance of the flange-gasket interface (“junction resistance”).
波导凸缘的峰值功率处理能力主要受凸缘和（或）垫片对齐性和利边的影响。凸缘的平均功率处理能力的主要限制因素是凸缘－垫片界面接触电阻导致的热效应（“接合电阻”）。
CORROSION
腐蚀
All metals are subject to corrosion. That is, metal has an innate tendency to react either chemically or electrochemically with its environment to form a compound which is stable in the environment.
所有金属材料均会发生腐蚀。也就是说，金属具有固有的易于周围环境发生化学或电化学反应，形成稳定化合物的特点。
Most electronic packages must be designed for one of four general environments:
绝大多数的电子仪器组件必须针对以下四种常见环境中的一种进行设计：
Class A. Controlled Environment
A类 受控环境
Temperature and humidity are controlled. General indoor, habitable exposure.
温度和湿度均在控制下。一般为室内环境，暴露于可居住环境中。
Class B. Uncontrolled Environment
B类 非受控环境
Temperature and humidity are not controlled. Exposed to humidities of 100 percent with occasional wetting. Outdoor exposure or exposure in uncontrolled warehouses.
温度和湿度均不在控制下。接触 100% 湿度，有时会受潮。暴露于室外或环境不受控制的仓库中。
Table 1: Minimum Finish Requirements
表1：表面最低要求
Minimum Finish Requirements for Structural Metals 结构金属件的最低表面要求
Metal 金属 ENVIRONMENT 环境
Class A A类 Class B B 类 Class C C类
Carbon and Alloy Steel
碳钢和合金钢 0.0003 in. cadmium plate
0.0003 英寸镀铬
0.0005 in. zinc plate
0.0005 英寸镀锌
0.0003 in. tin
0.0003 英寸镀锡 0.0005 in. zinc plate
0.0005 英寸镀锌
0.001 in. zinc
0.001 英寸镀锌
0.0005 in. tin
0.0005 英寸镀锡 0.003 in. nickel
0.003 英寸镀镍
0.001 in. tin
0.001 英寸镀锡
华译网上海翻译公司曾经翻译过大量有关碳钢和合金钢资料文件，Beijing Chinese Subtitling Translation Service Agency has translated many technical documents about Carbon and Alloy Steel.
Corrosion-Resistant Steels
耐腐蚀钢 No finish required
不需要表面处理 No finish required;
不需要表面处理；
0.0005 in. nickel to prevent tarrnish
0.0005 厚镀镍，用于防止表面生锈 No finish required;
不需要表面处理；
0.001 in. nickel to prevent tarnish
0.001 厚镀镍，用于防止表面生锈
Aluminum 2000 & 7000 series
2000 和7000 系列铝 Chromate conversion coat (MIL-DTL-5541F, Type I, Class 3)
铬酸盐转化涂层（MIL-DTL-5541F， I 型， 3 类） Chromate conversion coat (MIL – DTL - 5541F, Type I, Class 3) plus conductive expoxy or urethane
铬酸盐转化涂层（MIL-DTL-5541F， I 型， 3 类）加上导电环氧或聚氨脂层 0.001 in. tin
0.001 英寸镀锡
Aluminum 3000, 5000, 6000 series and clad
3000、5000、6000 系列铝材和包铝材料 No finish required, unless shielding requirements are high (see above)
不需要表面处理，除非屏蔽要求较高时（见上） Chromate conversion coat
铬酸盐转化涂层 Chromate conversion coat plush conductive epoxy or urethane
铬酸盐转化涂层加上导电环氧或聚氨脂层
Copper and Copper Alloys
铜和铜合金 0.0003 in. tin
0.0003 英寸镀锡 0.0005 in. tin
0.0005 英寸镀锡 0.003 in. nickel
0.003 英寸镀镍
0.001 in. tin
0.001 英寸镀锡
Magnesium 镁 0.0003 in. tin
0.0003 英寸镀锡 0.0005 in. tin
0.0005 英寸镀锡 0.001 in. tin
0.001 英寸镀锡
Class C. Marine Environment
C 类 海上环境
Shipboard exposure or land exposure within two miles of salt water where conditions of Class A are not met.
甲板上使用或在靠近盐水两英里以内的陆地上使用，同时，不满足 A 类环境中要求的条件。
Class D. Space Environment
D 类，太空环境
Exposure to high vacuum and high radiation.
暴露于高真空度和高辐射中。
FINISHES
表面处理
Table 1 shows the minimum finish necessary to arrest chemical corrosion and provide an electrically conductive surface for the common metals of construction. Only the Class A, B, and C environments are shown in the table because the space environment is not a corrosive one (i.e., metals are not generally affected by the space environment).
表1 中规定了为防止化学腐蚀和提供导电性表面，普通金属结构所需的表面处理做法（最低要求）。表中仅包含 A 类、B 类和 C 类环境 B，因为太空环境不属于腐蚀性环境（即金属在太空环境中一般不会受到影响）。
Some metals require finishing because they chemically corrode. These are listed in Table 1, and should be finished in accordance with the table. To select a proper finish for metals not given in Table 1, refer to the material groupings of Table 2. Adjacent groups in Table 2 are compatible. Another excellent source of information on corrosion-compatible finishes for EMI shielded flanges is ARP 1481, developed and published by SAE’s Committee AE-4 (Electromagnetic Compatibility).
有些金属因为易发生化学腐蚀，需要做表面处理。这些金属均列于表 1 中，应按表中规定对其做表面处理。对于未在表 1 中列出的金属，请按表 2 中的金属分类，选择最适合的表面处理方法。表 2 中相邻金属分类是相容的。您还可以参考 SAE 委员会 AE-4（电磁兼容性）发布的 ARP 1481 资料，在该资料中，包含了 EMI 屏蔽凸缘防腐蚀表面做法的相关内容。 |
