Hits:Updated:2016-08-04 14:08:17【Print】
| All along, the portion of the workpiece to corrosion of household electrical appliances if a higher demand, the relatively common solution before the metal coating treatment process using a chemical and electrochemical phosphate chemical conversion coating (formed by the reaction of this process referred to phosphate, phosphate conversion film called phosphating film formation), which, after coating and protection appliances and other metal products together to ensure that does not occur within 10 years or more time to wear rust and other issues. Although the phosphate anti-corrosion performance is very good, but it also creates a lot of problems, such as high energy consumption, serious pollution, harmful heavy metals, waste water treatment more difficult, easy and pipe wall slagging and other issues . As technology advances and the continuous improvement of environmental requirements, more environmentally friendly metal surface treatment process before being developed on a global scale, the current research in this area focused on new technology and completely non-toxic and environmentally friendly phosphate phosphorus abandon recipe two aspects. Phosphate and nontoxic technology development process Phosphate processing technology, the earliest reliable records are British Charles Ross obtained the patent in 1869, has been more than a century. Development of phosphate treatment process can be divided into the following phases: Before World War I, the basic stage of phosphating process, the completion of this period a number of fundamental discoveries, mainly in the United Kingdom. Between the first World War II, large-scale industrial application stage, when the center of the development process of the transfer of phosphate from the United Kingdom to the United States. During this period, the United States T.W.Coslet zinc, zinc oxide or zinc phosphate salt dissolved in phosphate made the first zinc phosphating solution. This research greatly promoted the development of phosphating process. Research and development of Parker antirust company Parco Power (Parker powder) formulated phosphating solution, phosphating treatment time will be shortened to one hour, 1929 Bonderizing turn phosphating time was shortened to 10 minutes in 1934, phosphate processing technology has made revolution of development, that will be used phosphating solution is sprayed onto the workpiece methods. During World War II, new uses phase phosphating process, mainly in Germany. After World War II, phosphating process of steady development and improvement stage, phosphating technology rarely have a breakthrough. Phosphating treatment during this period important improvements are: low temperature phosphating, various methods of controlling phosphate coating film is heavy, continuous strip high-speed phosphating (processing time of only 5 seconds). 1990s, foreign environment-friendly paint pre-treatment technology has become a hot industry research. Since the phosphate treatment process toxic, heavily polluted mainly nitrite, heavy metals Ni2 +, Cr6 +, Mn2 + plasma. Therefore, research in this area has focused on looking for alternatives to these substances, divided into nitrite-phosphate and nickel-free phosphate. However, the director of the Hefei Metal Surface Engineering Technology Research Center, Liu Wanqing said that this process is environmentally friendly, non-toxic phosphate phosphate in the original system, "circle", while reducing the phosphating process of toxic and hazardous substances, but not from fundamentally solve the problem. Haikai Mittel Chemicals Co., Ltd. (Chemetall), the official also said that the development direction of the metal surface pre-treatment process should not only reduce toxic and hazardous substances, and should solve the pollution problem phosphide fundamentally. Development of alternative technologies phosphide Chemetall official said: "In the past 60 years, two metal ions zinc and nickel phosphide core, increasingly stringent environmental policies and increasing nickel and zinc raw material prices, become drivers of the development of suitable alternatives people first nanoparticles, zirconium, titanium compound monomers, polymers and other metal ions and between assessed and finally decided to develop a new alternative phosphate conversion coating, this should be phosphate-free alternatives and other traditional heavy metal ions or subject to RoHS restrictions and other rules of metal ions contained in the ion concentration of each treatment process are less than the current zinc phosphate process, thereby saving energy and water, to meet the pre-treatment industry performance requirements of today, not the weight of the film more than the traditional zinc phosphate film, in the range of 20 ~ 200mgm2. " |
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