The zinc phosphate coating is produced by a chemical reaction between iron on the surface of the ferrous metal and the oxidizing salts present in the black oxide solution. These oxidizing salts include penetrators, catalysts, activators and patented additives that participate in the chemical reaction. The resulting zinc phosphate of this chemical reaction is the formation of black iron oxide, magnetite, on the surface of the coated metal. Zinc phosphate has a range of unique properties and benefits that can be applied to different industries.
The process of forming black iron oxide in ferrous metals and other types of materials is often called black oxide. The black oxide process is a chemical conversion coating for ferrous materials, stainless steel, copper and copper alloys, zinc, powder metals and zillases. This process has been done to resist corrosion, improve appearance and minimize light reflection. Black oxide coatings are usually applied to resist mild corrosion and appearance.
To blacken ferrous materials, they must be placed in a patented blackening solution bath containing sodium hydroxide, nitrates and nitrites. The patented black pastry is not applied when applying hot zinc phosphate to stainless steel parts. For example, the zinc phosphate coating process transforms the exterior of stainless steel, steel and ferrous metal alloys by improving corrosion resistance. Specialized coatings also enable the production of protective zinc phosphates in copper and zinc alloy outdoors.
Cold black oxide, also known as black oxide at room temperature, is applied at a temperature of 20–30 ° C (68–86 ° F). It is not an oxide conversion coating, but rather a deposited copper and selenium compound. Cold black oxide offers higher productivity and is suitable for internal blackening. This coating produces a color similar to that of oxide conversion, but tends to rub easily and offers less wear resistance. The application of oil, wax or varnish increases the resistance to corrosion together with heat and average temperature. An application for the cold black oxide process would be in steel architectural tools and finishes .
And when applied to the 300 and 400 series, and precipitate hardened the 17-4 PH stainless steel alloys, it can be used in cast iron and low carbon soft steel. It is this process that complies with the military specification MIL-DTL-13924D Class 4 and resists wear. Zinc phosphate or blackening is a conversion layer for ferrous materials, stainless steel, copper and copper alloys, zinc, powder metals and zillases. It is used to resist light corrosion, to be in appearance and to minimize light reflection.
The use of zinc phosphate coatings is common in combination with treatments that use oil, clear wax or even acrylic to further improve the corrosion resistance of a part. Black Oxide is a conversion coating process created by a chemical reaction with oxidants and metal to form an integral protective surface. Application to ferroalloys and metals starts when oxidizing salts react with iron magnetite, the “black oxide” of iron.
Peters’ black oxide process is alkaline in nature and supports ferrous metals, tool steel and powdered metals. The appearance of black oxide is an attractive black surface that adds light corrosion resistance and minimizes light reflection. Black oxide, also known as black, is the conversion of the top layer of a chemical treatment ferrom material. Treating bras with a black oxide coating not only adds a clean and pleasant black look, but can also add a layer of light of corrosion and wear resistance. To achieve maximum corrosion resistance, black oxide can be waxed or greased to add an extra protective layer. The wax coating can overshadow the color of the treatment, but offers the best resistance.
The solution used is generally a hot bath of sodium hydroxide, nitrates and nitrites at 286 degrees F, with periodic water added according to a controlled method. It is possible to create similar effects at different temperatures, but the results and their effectiveness will vary. For example, a “hot” oxide process will yield very effective results that are consistent. Alternatively, the cold oxide process will tend to show color variations and can cause the black finish to rub. Therefore, it is the most desirable “hot” black oxide process and meets military, car and other specifications. For example, when applying hot black oxide to stainless steel, a solution of caustic, oxidizing and sulfur salts is used.
The hot process provides a deep black finish and delivers superior cold immersion processing results used by some finalizers. The process of hot black oxide was also approved by most industrial and military applications. Mid-South Metallurgical offers a black oxide process that meets or exceeds all government specifications, including MIL-DTL-13924D for Class 1 layers of black oxide. Black Oxide is a coating made by immersing metal parts in a specially formulated solution at specific temperatures. The chemical reaction that occurs during this process creates magnetite on the surface of the parts.
