Casting due to the special nature of the manufacturing process, the surface of the casting is easy to corrosion, rust and difficult to deal with, if not pay attention to, not only the poor anti-corrosion ability of the workpiece is not good, decorative, which many enterprises in the casting higher the corrosion resistance requirements, according to the casting different working conditions, low temperature oxidation, phosphate processing and other special anti-rust treatment requirements of the casting (cast iron, cast steel).

　　Here is HH902 low temperature oxidation products on the cast iron as the focus, a brief introduction the several castings rust, and related products.

　　Of HH902 low temperature oxidation of steel products Iron Castings

　　Cast iron requirements for black surface treatment on the rise. Due to the high temperature alkaline black oxide process of casting, the appearance was reddish brown or red soil, can not meet the requirements of manufacturers. Temperature oxidation process, the surface appearance, low cost, does not affect the accuracy of the workpiece, good corrosion resistance, etc., and welcomed by the users.

　　And general steel, cast iron temperature oxidation process both similarities, but also has its own characteristics, the main difference is that the pre-treatment phase.

　　Process: before treatment consists of three phases; room temperature blackening process; post-processing

　　1.1 Pre-treatment:

　　Generally include degreasing and rust activation, two processes, pre-treatment is good or bad is the key to the success of low temperature oxidation, degreasing sure to thoroughly is, surfactants moderate (ie exposing fresh metal surface, without producing corrosion). For castings should pay attention to the following three points:

　　(1) using the method of mechanical descaling. Such as: tumbling, sand blasting, polishing, grinding and so on. Some castings are processed by this method, water cleaning, blackened or other anti-rust treatment.

　　(2) First soaked with clean water or cleaning. Cleaning (immersion), chemical degreasing rust in the workpiece before, the first workpiece, one workpiece can be washed again, the water enriched by the porosity of the surface of the workpiece is, to facilitate cleaning after the chemical treatment.

　　(3) degreasing rust activation. As more casting surface porosity, contamination, especially oil, are difficult to remove, not handled the entire anti-rust treatment impact, not achieve the desired purpose, including iron, copper, aluminum and its alloys castings.

　　Degreasing method. Such as: chemical degreasing, mechanical degreasing, baking degreasing, ultrasonic degreasing, electrolytic and organic solvent degreasing. The to rust activation Usually hydrochloric acid, treated with a solution or dilute sulfuric acid (15-20%) in the temperature treatment.

　　Such products the: HH922A excellent degreasing properties at room temperature, as well as the role of the activation surface, easy to clean, no rust casting or zinc alloy die castings in the 50 ~ 65 ℃ HH922A working fluid for 5 to 15 minutes, washed without pickling directly into the black slot, without pickling room temperature blackening, will help to improve the environment and improve work efficiency. HH942 both, rust, activation of the surface of a variety of effects, and can inhibit the acid mist and improve working conditions, less prone to corrosion helps to overcome the cast iron is easy due to excessive corrosion and ash hanging phenomenon.

　　1.2 room temperature blackening

　　Cast iron can be transferred by the pre-treatment, washed sufficiently low temperature oxidation process.

　　Black cast iron at room temperature blackening agent and 5 to 6 times diluted with water to the working fluid, the pH value of 2 to 2.5, the processing time is generally 1 to 3 minutes, gray cast iron, ductile iron, black and rapid containing high-alloy cast iron black slowly. Black mixed with the workpiece move several times, depending on the workpiece surface black film evenly.

　　Room temperature blackening member after removal from the bath, a chemical reaction of the surface layer did not get the final completion of the chemical reaction continues, the role of oxygen in the air, i.e. "aftereffect" phenomenon. Time up to 24 hours or more (in addition to the high-temperature cooking oil), this process can improve the strength of the conversion coating adhesion and uniformity. The workpiece in the bath time is not too long, black film on the surface uniformity prevail. This can reduce the consumption of black liquor, improve product quality, reduce production costs.

　　1.3 post-processing

　　By the black cast iron pieces treated its corrosion resistance and appearance, good or bad depends on the post-processing, iron casting loose their organizations must be thoroughly rinsed black, the acidic residue in the pore to be released, to avoid The darkening membrane erosion, so that the workpiece yellow. Post-processing The main purpose is to pore sealing of the surface of the workpiece, thereby enhancing the ability to the workpiece resist rust, such products: HH912 chromium passivation solution, the water-soluble sealer series, the HH932 dehydration rust oil. Practice has proved that they are very good accessory products low temperature oxidation process. Can select the appropriate method based on the requirements and conditions of the workpiece for processing, to achieve the purpose of that meets the requirements, but also reduce costs.

　　Cast iron temperature oxidation process is a lowest cost, the operation is relatively simple black casting surface treatment method. The process can be endowed pure elegant black appearance of cast iron, cast iron rust, so as to enhance the value of the product. Therefore, we believe that the process can be widely used on cast iron treated with preservatives, but also in the production practice continuous improvement and innovation.

　　2, HH932 dehydration application of the anti-rust oil

　　HH932 rust oil dehydration its strong dehydration and stain resistance, and has been widely applied to anti-corrosion treatment of metal materials and mechanical parts, in addition to its as Gao Wen Falan, room temperature blackening, the ultimate means of phosphate processing, can also be directly used for the surface of the metal and machined parts between processes sealed surface rust. Particularly suitable because it has a good sweat conversion, dehydration rust resistance, the surface of the loose tissue, pores larger and blind holes, deep hole shape complicated workpieces, such as cast iron (steel), copper, cast aluminum, powder metallurgy, etc. corrosion preventive treatment. Casting Machinery Factory in Changsha year in exports of other parts of Europe, malleable iron and Gwangyang, Changsha, Seiki change gear classes, are parts after machining, directly immersed dehydration rust oil, anti-rust performance to meet the surface of the product. requirements.

　　Anti-rust treatment, cast iron step

　　For those who need to process conversion and short-term storage of the workpiece, the rust is generally 1 to 2 months or so, is not oil-soaked workpiece, you can use a short period of anti-rust products. Such as the HH983 long-term protection of water, it is not only played a rust process also eliminates the trouble degreasing after, while maintaining the workpiece is clean, easy to store, just before the workpiece to be oil-rust, anti-rust after the end of the period for removal of rust layer, the temperature in the available alkaline water-based cleaning agent to clean, more convenient.

　　Casting phosphate treatment (cast iron, cast steel)

　　4.1 directly in the casting surface brushing, wiping or spraying phosphate treatment.

　　Not easy for those larger soak be the casting of the phosphate treatment, can use this process to deal with, such as a large transformer enclosure, outdoor wrought iron parts, machine tools sitting at the end of the wild large steel components. Phosphate solution directly brushing the surface of the workpiece, after drying the surface of the substrate with a solid layer of converting phosphate coating, antirust he not only itself, but also with matching finish compatibility, combined with strong. Just before brushing to the workpiece surface sediment, dust, oil and rust obvious clean.