Gate Valve Industrial gate valves are wildly used in all type of industrial pipelines, such as power stataion, petrochemical, natual gas,water treatment ect. Pressure Seal Gate Valve, Bolt Bonnet Gate Valve, High Pressure Gate Valve and API 602 Gate Valve with ASME & DIN & EN & GOST standard are commonly used by customer. Industrial gate valve we provided can cover size from 1/2 inch to 40 inch(DN15-DN1000) matching pressure from class 150 to class 3650(PN10-PN70 0) which are suitable for operating in the working media temperature from -196℃ to 693℃, as well as material in carbon steel, stainless steel, alloy steel and duplex steel in casting material or forging material. Gate Valve,Parallel Slide Gate Valve,Forged Gate Valve,Bw Gate Valve Yongjia South Trading Co.,Ltd , https://www.n-lvalve.com
Recent Advances in Phosphating Technology Before Painting
Improving quality, reducing costs, saving energy, and protecting the environment have always been key goals in materials pretreatment processes. In recent years, Japan has introduced a low-temperature, low-residue phosphating solution that reduces both process temperature and phosphating sludge. Significant progress has been made in nitrite-free phosphating solutions, which are now widely studied and applied.
The use of promoters in phosphating solutions can accelerate the reaction, reduce hydrogen interference, and control sludge formation. Traditionally, sodium nitrite was used as an accelerator. However, it decomposes easily, requiring frequent addition and monitoring. During the phosphating process, small amounts of toxic nitrous acid may form, potentially damaging steel sheets and causing serious line failures. Nitrite can also react with amines to produce carcinogenic nitrosamines, prompting efforts to develop safer alternatives. Currently, three main types of accelerators are used in production lines:
(1) Â Â Â Â Â Â
Hydrogen peroxide (H₂O₂) is a common promoter. It reacts to form water, making it non-toxic, safe, and environmentally friendly. It doesn’t accumulate in the system or emit harmful gases, making it ideal for eco-friendly applications. However, its stability is poor, and it requires strict control, so only a few lines use it in practice.
(2) Â Â Â Â Â Â
Hydroxylamine-based compounds (HA) are often used as in-solution promoters. They don’t need separate addition during the process, making them easy to manage. However, HA can degrade in the bath, releasing ammonia, which requires neutralization with alkali. HA is expensive and rare, and although it can be replaced by HAS (hydroxyamino sulfonate), high sulfate levels from HAS may reduce coating corrosion resistance. This type is mainly used in high-volume immersion systems.
(3) Â Â Â Â Â Â
Nickel-free phosphating has become a major research focus. Nickel was once a critical component in phosphating solutions, especially in zinc-nickel ternary systems, due to its ability to enhance corrosion resistance and speed up reactions. However, nickel is toxic and accumulative, and many countries, including Germany, strictly limit its concentration in wastewater to below 0.2–0.5 ppm. As a result, researchers have developed nickel-free solutions using copper or cobalt instead. These are already used in home appliances like refrigerators and washing machines but lack sufficient corrosion resistance for automotive applications. Recently, new nickel- and cobalt-free phosphating solutions have been developed, offering excellent anti-corrosion performance suitable for cars. They work well on cold-rolled steel, electrogalvanized, and aluminum sheets, though adhesion on hot-dip galvanized sheets remains an issue.
(4) Â Â Â Â Â Â
To reduce vehicle weight, aluminum and even all-aluminum bodies are increasingly replacing traditional steel and galvanized steel. Lighter materials like magnesium and plastic are also being tested, and corresponding pre-treatment solutions are already available. The application of pre-phosphated steel is becoming more widespread across industries.
     Â
[This article is edited and compiled by Xianghe Phosphate Division. If you wish to reprint it, please cite the source via a link. Thank you!]
Article tags: Phosphating Solution http:// 】
**Word count: 576**