Black oxide is the conversion of a base metal material to an oxide of that base metal material. 最典型的例子就是Fe3O4, 什么是黑色的氧化铁, otherwise known as magnetite; another is a CuO, or copper monoxide. It occurs when the chemicals react with a base material to form an oxide of the base’s primary constituent. 在不锈钢的情况下, 它不仅形成氧化物, 但它也会形成基材的硫化物，这些硫化物往往也是黑色的.
Generally, the term ‘black oxide’ has taken on a bigger definition in that almost any inorganic black produced on a metal substrate could be referred to as a black oxide coating. That might not necessarily be absolutely true; it could be a deposit, and — in the case of room temperature black oxide — it is putting down an immersion copper and then subsequently forming either selenides or tellurides, 哪些是表面上的黑色化合物. 其他一些金属也可以变黑，包括锌、锡和铝.
One of the most commonly asked questions in regards to black oxide is the thickness of the coating. Generally speaking, we refer to it as not affecting the tolerance of the part; in other words, 涂层很薄，不会影响零件的公差. 对于钢上的热黑氧化物，Fe3O4型涂层的厚度从0.4 to 2.4微米，这和0有关.00016 to 0.00096 inches; it’s a very thin coating.
黑色氧化物用作功能性或装饰性涂层. 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, or it could be for optical purposes to affect or alter the absorptivity and the reflectivity of the part. 黑色氧化物也用于防磨损目的，以改变啮合部件的摩擦. Decorative applications are more for aesthetic appeal or for the presentation of the part at point-of-sale. For example, black oxide conversion coating on steel has been used in the firearms industry for a very long time, and it’s used for a functional purpose to enhance both the abrasion resistance and the corrosion resistance of the firearm, 但它也用于装饰目的，特别是在纪念型枪支上.
Let’s take a look at some common questions that have been asked regarding functional or decorative black oxide coatings:
用于装饰用热黑氧化物, 如果我从闪亮的钢制部件开始, 变黑的部分也会有光泽吗? 钝钢部件怎么样?
当你观察热黑氧化物时，它们并不都是一样的. 这也取决于底物. For instance, on steel, the black oxide will typically take on the same level of gloss or polish as the substrate; it doesn’t have a dulling effect. 它并不能真正提高亮度, but the black may appear brighter — of a higher luster — than the bare material that is polished. 在热黑氧化物和钢的情况下, 它具有基材所具有的光泽程度. 如果零件是哑光开始, the black oxide will be matte; if the part is a high-gloss, 黑色氧化物将是高光泽的. 对于镀黑铜或镀黑黄铜，所产生的黑色氧化物往往是暗淡的. 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, 它看起来几乎像天鹅绒一样. 如果你摩擦它，那部分就会变钝. On substrates that are dull — or for oxides that produce a dull black —if you want a glossy finish, 你将不得不依靠随后的面漆.
当与黑钢部件相比, why does a blackened stainless- steel part for decorative hot black oxide possess more of a dull, matte finish?
That’s very similar to the black on copper; it’s the nature of the black itself. Black on stainless steel is a combination of oxides and sulfides of the alloying constituents of the particular stainless steel that’s being blackened. Although oxides — as in the case of steel — might take on the luster of the substrate and could be bright, the black finish on SS tends to be duller because of the presence of the sulfides mixed with the oxides. The stainless-steel black will always be duller — or take on a duller appearance — than the base material.
用于装饰室温氧化黑色, 如果我从闪亮的钢制部件开始, 变黑的部分也会有光泽吗? 钝钢部件怎么样?
很少看到室温下的黑色氧化物用于装饰目的. They might be used to enhance the salability of the part — which could be conceived as decorative — but they are rarely used. 相反，它们更多地用于功能性目的. 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. 他们会使零件变钝, and the black will be duller than the substrate material; it could be enhanced with a topcoat, 但它们确实自然倾向于暗哑型饰面. 暗淡的部分在涂黑后仍然暗淡.
For function use, 如果我黑氧化一个钢部件, 黑色氧化物涂层能起到什么样的防腐作用呢? 黑色的不锈钢部件呢?
With black on steel, the oxide coating —the magnetic magnetite Fe3O4 coating— will give a certain degree of corrosion protection, 特别是如果它是密封的无机军事规格指定的密封. Mil-C-13924D for black oxide on steel and had originally recommended chromic acid dip afterward. The black oxide — particularly with chromic acid after it —will give up to two hours of salt spray resistance (ASTM B117) without a supplemental topcoat. There is so much variability in the corrosion resistance of a given part; it’s alloy dependent, hardness dependent, 微structure-dependent, but more importantly, 最大的贡献者是随后涂在上面的面漆. Black oxide on steel tends to be somewhere between nanoporous and microporous and is simplistically stated, a coating that acts as a sponge and will bond and absorb subsequent topcoats to a much greater extent than the bare substrate itself. With black oxide on a steel part — with a given topcoat — it could give twice the salt spray resistance than the substrate with the same top coat, 但是没有黑色氧化物. If you were to put water displacing corrosion preventive —which is probably the most common type corrosion inhibitor— on a black oxide, 你可以用80个小时处理黑色氧化物, 你只能在光秃秃的钢板上工作40个小时. For steel, 你可以从氧化物涂层中获得一点抗腐蚀能力, 但更多的是由于它吸收面漆的能力. Stainless steel black — being a blend or a mixture of oxides and sulfides —does not impart any corrosion protection enhancement to the part. In other words, 如果你用盐雾使不锈钢部分变黑, 如果你在上面涂上一层黑色的盐雾，你也会得到同样的结果. 由于硫存在于涂层中, 你可能会发现黑色的防腐蚀效果会稍微差一些. 为微孔或纳米孔型涂层, 不锈钢黑色也会更大程度地吸收面漆. With stainless steel, 这取决于不锈钢本身的耐腐蚀性, 哪一个是普通的非常高，特别是如果它是钝化的，或者在黑色之前是钝化的. If you want to enhance the corrosion protection above and beyond what you’d ordinarily get with stainless steel, 你可以用水来代替或者用水溶性油来代替.
用于功能性热黑氧化物, 在什么温度范围内功能黑色氧化物涂层在钢件上是稳定的?
My experience is if you have black oxide on a steel part and it’s not sealed — it’s just the oxide, it’s been rinsed, 没有铬酸盐密封，没有防腐蚀涂层，你要把它放在烤箱里, 在你看到任何类型的变色或斑驳之前，它应该保持在700华氏度. 当我和顾客交谈时, 他们问了这个问题, 我说你可以把温度调到华氏700度, but after 700°F, you’re going to start to see some oxidation occurring that may be a conversion back to more of red rust and maybe spots.
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