特氟龙喷涂前处理除油与喷砂：技术深度解析

在我们讨论了表面处理的原因之后，本文将详细介绍如何操作。表面处理的两大支柱工艺是除油和喷砂。以技术精度执行这些步骤，对于获得高质量、高附着力的涂层来说，是绝无商量余地的。

1. 除油：第一步你不能对一个油腻的部件进行喷砂。这样做并不能去除油污；它只会将油污涂抹在整个表面上，并将其更深地嵌入基材中，从而污染部件和喷砂介质。必须首先去除所有有机污染物。

• 水基清洗： 这是最常见的现代方法。它涉及使用混合了专门碱性洗涤剂的高压热水。部件通过一个多级工业“洗碗机”，进行洗涤、漂洗，如果部件是铁质的（例如碳钢）并且不能立即进行喷砂，通常还会施加一层防锈剂。

• 蒸汽除油： 这是一种高效的传统方法。将部件悬挂在装有沸腾溶剂（历史上使用三氯乙烯或正丙基溴）的槽上方。热的溶剂蒸汽在较冷的部件上冷凝，溶解油污，然后滴回槽中，留下一个完美洁净、干燥的表面。由于环境和健康法规（VOCs）的限制，许多此类溶剂受到严格管制，工厂正在转向更安全的水基系统。

• 热力除油（焚烧）： 对于能够承受高温的部件，或用于去除旧涂层，会使用焚烧炉。焚烧炉在控氧环境中将部件加热至 370-425°C (700-800°F)，热解（烘烤掉）所有有机材料，包括旧油漆、油脂，甚至旧的 PTFE。

2. 喷砂：创建锚定轮廓一旦部件洁净并干燥，我们就可以创建机械轮廓。

• 介质： 磨料的选择至关重要。对于氟聚合物，行业标准是氧化铝。它是一种坚硬、有棱角且耐用的磨料，能在金属上切割出侵蚀性的、锋利的齿状轮廓。这就是我们希望涂层“咬入”的表面。我们不使用玻璃珠；玻璃是一种喷丸介质，它会锤击表面，使其孔隙闭合，变得更光滑，这与我们的目标完全相反。

• 过程： 经压缩空气将氧化铝以高压 (80-100 PSI) 喷射出去。对部件进行喷砂，直至达到“白金属”光洁度 (SSPC-SP5)——这是一个 100% 没有任何可见氧化皮、铁锈和污染物的表面，呈现出均匀、明亮的灰色。

• 结果（轮廓）： 喷砂会产生表面粗糙度，或称“轮廓”，以密尔（千分之一英寸）为单位进行测量。大多数氟聚合物系统要求 1.5 到 3.0 密尔的轮廓。如果轮廓太浅，涂层将没有足够的抓地力。如果太深，涂层可能不够厚，无法覆盖最高的“峰”，导致锈点和过早失效。这个轮廓是我们为每项工作测量和记录的一项规格。

Degreasing and Grit Blasting: A Technical Deep Dive

Following our discussion on the why of surface preparation, this article details the how. The two pillar processes of preparation are degreasing and grit blasting. Executing these steps with technical precision is non-negotiable for a high-quality, adhesive coating.

1. Degreasing: The First StepYou cannot grit blast a greasy part. Doing so will not remove the oil; it will merely smear it across the surface and embed it deeper into the substrate, contaminating both the part and the blasting media. All organic contaminants must be removed first.

• Aqueous Cleaning: This is the most common modern method. It involves using hot, high-pressure water mixed with specialized alkaline detergents. The parts are run through a multi-stage industrial "dishwasher" that washes, rinses, and often applies a rust inhibitor if the parts are ferrous (e.g., carbon steel) and cannot be blasted immediately.

• Vapor Degreasing: This is a highly effective, older method. The part is suspended in a tank above a sump of boiling solvent (historically, trichloroethylene or n-propyl bromide). The hot solvent vapor condenses on the cooler part, dissolving oils and dripping back into the sump, leaving a perfectly clean, dry surface. Due to environmental and health regulations (VOCs), many of these solvents are heavily restricted, and shops are moving to safer aqueous systems.

• Thermal Degreasing (Burn-Off): For parts that can withstand high heat, or for stripping old coatings, a burn-off oven is used. The oven heats the parts to 370-425°C (700-800°F) in a controlled-oxygen environment, pyrolyzing (baking off) all organic materials, including old paint, grease, and even old PTFE.

2. Grit Blasting: Creating the Anchor ProfileOnce the part is clean and dry, we create the mechanical profile.

• The Media: The choice of abrasive is critical. For fluoropolymers, the industry standard is Aluminum Oxide. It is a hard, angular, and durable abrasive that cuts an aggressive, sharp-toothed profile into the metal. This is what we want for the coating to "bite" into. We do not use glass beads; glass is a peening media that hammers the surface, closing its pores and making it smoother, which is the exact opposite of our goal.

• The Process: The aluminum oxide is propelled at high pressure (80-100 PSI) using compressed air. The part is blasted until a "white metal" finish (SSPC-SP5) is achieved—a surface that is 100% free of all visible scale, rust, and contaminants, appearing as a uniform, bright grey.

• The Result (Profile): The blasting creates a surface roughness, or "profile," which is measured in mils (thousandths of an inch). Most fluoropolymer systems require a profile of 1.5 to 3.0 mils. If the profile is too shallow, the coating won't have enough to grip. If it's too deep, the coating may not be thick enough to cover the highest "peaks," leading to rust spots and premature failure. This profile is a specification that we measure and log for every job.