6, the use of anti-cavitation materials Different materials have a very significant difference in cavitation resistance. There are many factors that affect the anti-erosion ability of materials. Generally, materials with high hardness and high elasticity are more resistant to erosion. Foreign recommended low-carbon chromium-nickel alloy steel, such as 13Cr4N as cavitation in the work of hydraulic machinery, has good resistance to erosion. Zhengzhou Machinery Research Institute of Chen Yan conducted a comparison of the anti-cavitation properties of different materials ("Hot Processing Technology" 2000), the results are as follows Material HT200 QT400-15 QT600-3 ZG230-450 ZG310-570 Weight Loss mg 961.4 737.1 481.1 241 155 Test Time h 15 Material ZG40Cr ZG20SiMn ZG1Cr18Ni9Ti ZG0Cr13Ni4Mo ZG0Cr13Ni6Mo Weight loss mg 139.9 122.2 71.5 40.2 25.2 Test time h 15 30 Information provided by Zhu Xu-ren from Changsha Water Pump Factory, whose materials and cavitation loss are shown in the following table. Materials HT200 QT600-3 ZG310-570 18-8 Weight Loss 148.3 76.5 33 16.3 It is effective to use cavitation-resistant materials when cavitation can not be avoided. Such as: Lingcheng pumping station on the 7 # and 10 # units, the impeller room will be replaced by the original cast steel stainless steel, running a few years did not actually find the damage marks. Wuding gate station will be cast iron QT42-10, increased service life of more than 2 times. Jietai pumping station with cast iron and copper contrast, copper impeller anti-cavitation effect is obvious. 7, the impeller protective layer on the impeller coating method is more common, non-metallic coating epoxy resin, nylon powder, polyurethane and so on. The method of surfacing the alloy or sprayed alloy on the surface of the flow channel has also obtained certain effect on the cavitation destruction, such as stainless steel electrode surfacing method, stainless steel inlaid repairing method and alloy powder spray welding. Compare several methods for non-metals and alloys, including stainless steel. Non-metallic coating economy, but should be strictly controlled the operation of its process to prevent the coating off phenomenon. The use of alloy powder spray good but costly, and some places may not be able to proceed. Such as: a pump station using metal alloy powder spray welding blade, and achieved good anti-cavitation effect, the service life can be extended. China Great Wall Aluminum Company Hao Baishun Hl pump impeller cavitation erosion coating applied research. Dazhuang Zhuang Duanzhuang pumping station pumping station serious cavitation, the use of soft ceramic composite repair 4 years 4000h water inspection found no cavitation damage. Wang Songchen, Songliao Committee of the Ministry of Water Resources, Metallurgical Reservoir Administration, introduced the application of TS216 wear-resisting agent in the anti-cavitation of turbine runner. Lianyungang Water Supply Company Ma Aidong laser cladding method of cast iron and cast steel processing, the anti-cavitation performance were spray processing 1.3 and 1.5 times. 8, trim blade head trim impeller head to reduce the flow rate of leaf imports, reduce impeller import crowding, improve pump anti-cavitation capacity is effective. Practice has proved that despite the thinning of imported leaves, impeller life is often longer in the cavitation environment. General trim the impeller head is thinning the back of the blade head, near the impeller repair some more front cover. 2001 Changsha Pump Plant on the flow rate of 5040m3 / h, lift 17.5m pump dressing (while laryngeal dressing), the test found that the NPS decreased by about 0.5.
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