11.3 PASSIVATION11.3 钝化作用11.3.1 Introduction11.3.1 简介Pharmaceutical equipment and high purity water systems are designed so that product contact surfaces are not reactive, additive, or absorptive so the drug product is not adversely altered. High purity water systems are primarily composed of austenitic stainless steel (SS) materials due to their corrosion resistant and contaminant free properties. Passivation is performed to maximize the metals corrosion resistance. The stainless steel is sulfuric/nitric/hydrofluoric acid pickled at the mill to remove manganese sulfide inclusions, scale, and other impurities or imperfections from the surface of the steel. As the steel is removed from the pickling bath, a thin oxide layer forms immediately over the surface. This oxide layer is what renders the stainless steel passive and non-reactive to corrosion. Any 300 series chromium steels containing 17% or more chromium that has been handled, welded, or worked should be passivated prior to service and suitably cleaned prior to passivation.为了使得药品没有不利变化，在设计制药设备和高纯水系统时，保证它们和产品的接触面是不具有反应性、添加性和吸收性的。考虑到铬镍不锈钢（SS）的抗腐蚀和防污染性，高纯水系统基本上都是由铬镍不锈钢材料构成。钝化作用要做到材料抗腐蚀性的最大程度。不锈钢是将钢浸在硫酸/硝酸/氢氟酸打磨，以去除钢表面的硫化锰类物质、污垢、杂质和缺陷。当从酸浸浴中取出钢时，其表面就会立即形成一层薄薄的氧化物。该氧化物层能使得不锈钢表面不活泼并不具反应性从而不易于腐蚀。300系列的铬钢中，任何系列都含有17或更多的经处理或焊接的铬，这些铬钢在使用前应钝化，并且在钝化前要做适当的清洁。Passivation is the method used to fortify the steel surface by strong oxidizing chemicals such as nitric acid. The acid depletes the steel surface of acid soluble species, leaving the highly reactive chromium on the surface in a compounded oxide form.钝化作用是通过强氧化性的化学试剂如硝酸，来强化钢表面的。酸可减少钢表面的酸可溶性物质，使得表面的高反应性的铬处于复合氧化物形式。11.3.2 Advantages of Passivation11.3.2 钝化作用的优点When SS systems are fabricated, the welding process destroys the existing passive film and compromises the metals ability to ward off the corrosive process. This is particularly applicable in those zones that are either heat affected or have had residues remain in contact with the metal surface for prolonged periods. Passivating then provides a method to restore the integrity of the metals corrosion resistant surfaces that were disturbed. Passivation must be proceeded by a cleaning process.铬镍不锈钢系统建立后，焊接处理会破坏存在的钝化膜，并降低材料抗腐蚀的性能。这尤其会出现在以下地带：受热侵袭的地方或者需延长和材料表面接触时间的残留物存在处。这样，钝化就会修复那些被破坏的抗腐蚀材料表面的完整性。11.3.3 The Chemical Process11.3.3 化学加工Excessive electron depletion of the upper film and an inadequate supply of oxygen (molecular O2) will ensure the formation of surface corrosion products. When this occurs, the chromium (Crn+) separates from the surface and opens the way for oxidation of the iron (Fe) and nickel (Ni), lower in the metal lattice.表面膜的过度电排除以及氧化剂（O2分子）的供应不足会形成表面腐蚀产物。当出现这种情况时候，铬（Crn+）就会和表面分离，将材料筛格下层的铁（Fe）和镍（Ni）暴露氧化。Establishing a passive surface or film on austenitic SS is essential to maximize the corrosion resistance that the metals offer. Passive surfaces on these metals occur naturally when exposed to an oxidizing environment. Sources of oxygen include air, aerated water, and other oxidizing atmospheres. Formation of a substantial uniform oxidized corrosion resistant surface or film is the result of passivation.在铬镍不锈钢表面形成一个钝化的表面或膜是非常重要的，它可以将材料的抗腐蚀性提高到最大。当暴露在氧化的环境下，这些材料会自发形成钝化表面。氧的来源包括：空气、充氧的水以及其他氧化的大气。钝化的结果是形成了经氧化的均匀的抗腐蚀表面或膜。Besides natural occurring passivation, chemical and electro-chemical processes can be used to obtain an anodic oxide film. Nitric acid solution (HNO3), is an oxidizing acid (depletes electron from the metal surface) which erodes the metal. This initial reaction or oxidation resists further chemical reaction on the metal surface. Metals that have such a state are called passive and the phenomenon itself is called passivity.除了自发形成的钝化外，化学和电化学加工都可用于形成氧化物膜。硝酸溶液（HNO3）是氧化性酸（去除材料表面的电子），它可以腐蚀材料。初始的反应或氧化可以抵制材料表面再进行化学反应。处于这种状态的材料被称为“经钝化的”，这种现象的本身被称为“钝化性”。The chromium oxide film thickness typically ranges from 0.5-5.0 nm, averaging 2.0-3.0 nm. The chrome to iron ratio measured in atomic percent within the chromium oxide should be at least one with ratios of two or more being optimal.铬氧化物膜的厚度范围通常是0.5-5.0 nm，平均在2.0-3.0 nm。铬氧化物中的铬和铁的原子百分数比例至少是1:2（或2以上）。11.3.4 Passivation Procedures11.3.4 钝化操作Numerous procedures are available for passivating; they share the commonality of consisting of four main steps which are:钝化操作有很多种，但它们有共同的主要步骤：1) Wash (Solvent Degreasing) 洗（去油溶剂）2) Water Rinse 水冲洗3) Acid Wash (Passivation Step) 酸洗（钝化步骤）4) Final Water Rinse 最终的水洗Proper preparation of the metal surface to obtain a uniform non-defective passive film mandates metal surface be completely clean and void of any organic or inorganic soils, free iron metallic contaminant, or corrosive products.为了形成均一的、无缺陷的钝化膜就要对材料表面进行预处理，这就要求材料表面应是完全的清洁，并且没有任何有机或无机污物、自由金属离子污染物，或腐蚀产物。The First Step (Degreasing) of the procedure is designed to remove dirt, dust, oil and grease. A water-soluble detergent is used to accomplish this, or a solvent.第一步（去油）：去除污垢、灰