黑色氧化物是将贱金属材料转化为该贱金属材料的氧化物. A prime example would be Fe3O4, which is black iron oxide, otherwise known as magnetite; another is a CuO, 或者一氧化铜. 当化学物质与基础物质反应形成基础主要成分的氧化物时，就会发生这种反应. In the case of stainless steel, not only does it form oxides, but it also forms sulfides of the base materials that tend to be black as well.
一般, “氧化黑色”一词有了更广泛的定义，因为几乎任何在金属基底上产生的无机黑色都可以被称为氧化黑色涂层. That might not necessarily be absolutely true; it could be a deposit, 在室温黑色氧化物的情况下，它将浸入铜，然后形成硒化物或碲化物, which tend to be black compounds on the surface. Some other metals that also could be blackened include zinc, pewter, or aluminum.
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关于黑色氧化物最常被问到的问题之一是涂层的厚度. 一般来说, we refer to it as not affecting the tolerance of the part; in other words, the coatings are so thin that they really don’t affect the tolerance of the part. For hot black oxide 钢, the Fe3O4 type coatings thickness is anywhere from 0.4 to 2.4 microns, and that relates to about 0.00016 to 0.00096 inches; it’s a very thin coating.
Black oxide is used as a functional or decorative coating. A functional black oxide coating is one that’s produced to give a characteristic to the base material; it could be used to enhance the corrosion protection of the base material, 也可能是出于光学目的而影响或改变该部分的吸收率和反射率. Black oxides are also used for anti-galling purposes to modify the friction of meshing parts. 装饰应用更多的是为了美观或在销售点展示零件. 例如, 钢铁上的氧化黑色转化涂层已经在枪械工业中使用了很长时间, 它的用途是增强枪支的耐磨性和耐腐蚀性, but it’s also used for decorative purposes particularly in commemorative type firearms.
下面我们就来看看关于功能性或装饰性黑色氧化涂料的一些常见问题:
For decorative hot black oxide, if I start with a shiny steel part, will the blackened part have a shine as well? What about a dull steel part?
When you look at hot black oxide, they’re not all created equal. It really comes down to the substrate as well. 例如, 钢, the black oxide will typically take on the same level of gloss or polish as the substrate; it doesn’t have a dulling effect. It doesn’t really enhance the brightness, 但是黑色可能会比抛光后的光面材料更亮，更有光泽. In the case of the hot black oxide and steel, it takes on the degree of luster that the base material has. If the part is matte to start with, the black oxide will be matte; if the part is a high-gloss, the black oxide will be high-gloss. For black on copper or black on brass, the black oxide produced always tends to be dull. A unique thing about the black on brass and copper is what is called the ‘nap’ that is present on it; when the part comes out of the blackening solution and is rinsed, it almost looks like it has a velvet appearance. If you rub it, that nap lays down, and the part will be dull. 如果你想要一个有光泽的表面，在暗淡的基材上，或者在产生暗黑色的氧化物上, you’ll have to rely on a subsequent topcoat.
When compared with a blackened steel part, 为什么用于装饰用的黑色不锈钢零件会有更多的钝化, 喷砂面?
That’s very similar to the black on copper; it’s the nature of the black itself. 不锈钢上的黑色是被变黑的特定不锈钢合金成分的氧化物和硫化物的结合. 虽然氧化物——就像钢的情况一样——可能会呈现出基材的光泽，变得明亮, 由于硫化物和氧化物的混合存在，SS的黑色表面趋于暗淡. 不锈钢的黑色总是比基材更暗，或者看起来更暗.
For decorative room temperature black oxide, if I start with a shiny steel part, will the blackened part have a shine as well? What about a dull steel part?
It’s much less frequent to see room temperature black oxides used for decorative purposes. 它们可能被用来提高零件的销路——这可以被认为是装饰性的——但它们很少被使用. Instead, they are used more for functional purposes. Room temperature blacks being really selenides of copper or copper telluride; if someone is using a tellurium-based room- temperature chemistry tend to be dull deposits anyway. They will dull the part, and the black will be duller than the substrate material; it could be enhanced with a topcoat, but they do naturally tend to be duller type finishes. A dull part will remain dull after blackening.
用于功能使用, if I black oxide a steel part, what kind of corrosion protection can I expect from the black oxide coating? What about a blackened stainless steel part?
钢铁上的黑色, 氧化层—磁性磁铁矿Fe3O4涂层—具有一定的防腐蚀作用, particularly if it were to be sealed with an inorganic mil-spec specified seal. Mil-C-13924D用于钢上的黑色氧化物，最初建议之后用铬酸浸. 黑色氧化物-特别是在它之后的铬酸-将提供长达两个小时的耐盐雾性(ASTM B117)，而无需补充面漆. There is so much variability in the corrosion resistance of a given part; it’s alloy dependent, 硬度的依赖, micro structure-dependent, 但更重要的是, the biggest contributor is the subsequent topcoat that is put on it. 钢上的氧化黑色倾向于介于纳米孔和微孔之间，简单地说, 一种像海绵一样的涂层，它比光秃秃的基材本身更能粘合和吸收后续的面漆. 在给定面漆的钢部件上涂上黑色氧化物，它的抗盐雾性是具有相同面漆的基材的两倍, but without the black oxide. 如果你把水置换防腐蚀剂——这可能是最常见的一种缓蚀剂——放在黑色氧化物上, you might get 80 hours on the black oxide, where you’d only get 40 hours on the bare steel substrate itself. 对钢铁, you do get a little bit of corrosion resistance from the oxide coating, but much more due to its ability to absorb the topcoat. 不锈钢黑色——是氧化物和硫化物的混合物或混合物——对零件没有任何防腐增强作用. 换句话说, if you were to salt spray the stainless steel part unblackened, you’d get the same result if you were to salt spray it with a black coating on it. Due to the fact that sulfur is present in the coating, you may actually see that you get slightly less corrosion protection with the black on it. Being a microporous or a nanoporous type coating, the stainless steel black will also absorb a topcoat to a greater extent. 不锈钢材质, it depends on the corrosion resistance of the stainless itself, which is ordinary very high — particularly if it is passivated—or passive before the black. 如果你想提高防腐蚀的能力，而不是你通常用不锈钢得到的, you could use water displacing or a water-soluble oil to do that.
For functional hot black oxide, what temperature range is the functional black oxide coating on a steel part stable?
我的经验是，如果你的钢部件上有黑色的氧化物，而且它没有密封，那就是氧化物, 已经洗过了, no chromate seal and no corrosion inhibitor top coat — and you were to put that in an oven, it should hold up to 700°F before you see any type of discoloration or mottling. When I talk to customers, and they ask that question, I say you could probably go up to 700°F, 但在700华氏度之后, 你会开始看到一些氧化发生，这可能会转化成更多的红锈和斑点.
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