问:我们在粉末前的浸入式磷酸铁工艺中一直难以获得良好的覆盖, resulting in several reworks and off-spec parts. This issue arose about the same time our supplier switched to a stearate-based lube, so I believe we need to reassess our cleaning process, but not sure where to start.

A. 磷酸铁化学和其他预处理方法旨在为成品零件或表面提供增强的物理和性能. 这些应用应用于各个行业-从汽车和航空航天到建筑, firearms, and others — to improve the durability and reliability of the product in the field. While a few factors influence the efficacy of the phosphate coating, 充分的清洁和表面准备是确保涂层均匀应用和有效粘附的关键.

任何表面制备的主要目的是确保基质完全没有有机和无机污染，否则解决任何阻碍磷酸盐应用发展或质量的特性. Organic contaminants are characterized as carbon-based molecules; this includes natural and synthetic oils, pre-existing rust inhibitors, machining and metalworking fluids, 蜡, lubricants, and more. Inorganic contaminants are another form of surface imperfection and a common inhibitor to effective coatings; these include mill and heat-treat scale, base metal surface oxidation (corrosion/rust), and smut. 有针对性地去除所有存在的污染物是成功的表面制备和磷酸盐涂层的关键方面.

清洁和表面准备可以通过机械，化学或通过两者的组合来实现. Mechanical methods can include blasting and wire brushing, and while these are effective techniques, they are often not practical or cost-effective at scale for many applications. 化学应用使用溶剂或水性产品，通过批量或连续循环进行大规模加工和制备零件.

Aqueous cleaners are vast and varied in formulations and functions, often designed with a focus on specific applications or purposes. Typically, the first level of classification or segregation would be based on the cleaner’s primary builder(s); consequently, this translates to its relative acidity/alkalinity as well:

  • Acid-based cleaners are formulated using mineral and organic acids, resulting in pH levels <6. 这些 cleaners are commonly, but not exclusively, used in non-ferrous substrate applications and are highly effective in de-rusting, deoxidizing, and descaling various inorganic contaminants.
  • Neutral to mildly alkaline cleaners can be made with a host of builder chemistries, including phosphates, 胺, and silicates. 这些 cleaners can range in pH from roughly 6.5 to 10.5 and are generally multi-metal safe.
  • Caustic cleaners utilize sodium and/or potassium hydroxide and have pH levels >11; these are often very effective in cleaning ferrous substrates and are commonly used before phosphate coatings. 在正确的操作条件下，这些产品还可以有效地防锈表面氧化.

In addition to these builders, 水性清洁剂具有一系列的特殊成分，以解决各种污染物. Organic soils generally have low-to-no solubility in water, 因此，水清洗应用使用表面活性剂包来增加其溶解度并将其从基质中去除. Caustic cleaners can also facilitate the chemical reaction of saponification, 较大的有机分子(土壤)被分解成脂肪酸盐或肥皂. Additionally, cleaners can use several other agents to offer properties such as chelation, sequestration, mild corrosion protection, brightening, and more.

Beyond the chemical makeup of the cleaner, 三个重要的操作参数对清洁器的性能起着至关重要的作用:时间, temperature, and concentration. 这些参数是平衡澳门威尼斯人网上赌场需求和限制的直接变量. 磷酸盐浴通常使用碱基清洁剂，因为基材通常是亚铁，而碱基清洁剂往往是最坚固的. 浸泡时间通常在5-10分钟的范围内，但可以根据需要延长. Temperature is also quite variable, with operating ranges from 150°F up to 200°F; temperatures at the top of that range can be required for more tenacious materials such as stearate lubes and polymeric compounds. 最后, 浓度也会影响效率和活性——浸入式清洗剂通常运行在5-10% v/v，但对于存在腐蚀或广泛污染的应用，可以运行在高达20% v/v. Modifying any of these parameters can improve the cleaning performance and, 反过来, improve the phosphate’s crystal formation, coverage, and adhesion properties.

其他值得评估的方面包括清洁操作的设置和维护. Immersion cleaners can be either emulsifying or oil-splitting. 乳化清洗剂是桶式加工零件的理想选择，直到表面活性剂容量饱和后才能发挥作用. Conversely, 油裂解清洗剂是首选的冲压件和在应用中，相当多的有机污染物被去除. 相对于零件几何形状的夹具也会影响清洗机的性能，因为凹陷区域和凹陷需要充分的溶液接触和冲洗作用. 主动过滤的清洁溶液，确保浴缸不会变得过饱和与土壤. 最后, bath maintenance is undoubtedly something that should not be overlooked. Daily checks for temperature, concentration titrations, 清洁解决方案的目视检查可确保根据澳门威尼斯人网上赌场的规格始终如一地处理工作. 对清洁浴池的日常操作进行明智的护理，可以减少定期维护，因为浴池质量保持在规范范围内, leading to few bath dumps and tank cleanouts. 这些, among others, 在评估和排除清洁器问题时，是否需要了解所有影响因素.

考虑清洁澳门威尼斯人网上赌场的整体并理解有效的变量对于评估和排除任何清洁问题至关重要. Each application is unique, from the equipment being used, to the part’s substrate and geometry, to the contaminants needing to be addressed. 经常, a minor adjustment in the operating parameters or fixturing can address the issue; other times, with more substantial changes, you may need to consider alternative chemistries better suited to your application. 如有疑问，请向您的化学品供应商咨询故障排除指导和产品输入.