Application of thermally sprayed coatings of the type WC/CoCr in reverse osmosis processes for seawater desalination

Abstract

Seawater desalination based on the reverse osmosis process requires a variety of hydraulic systems. The material concepts of these hydraulic systems are designed to reliably resist the corrosive properties of seawater and brine as well as the tribological loads. Strong tribological loads typically occur during the start-up and shutdown of multi-stage high-pressure pumps. Thermally sprayed coatings can be used to increase the wear resistance and also the tribological properties of bearings. Also in pressure exchangers for energy recovery, high tribological loads occur on the surfaces of rotors which operate with a clearance gap of 40-100 mm. Today, thermally sprayed coatings are used for the surface protection of these rotors. To resist the various tribological loads, the material pairs are optimized for each case. Thermally sprayed coatings with high surface hardness have proven to be particularly successful. A coating system, based on a CoCr matrix, has been developed especially for these applications.

Laser Shock Peening of Duplex Stainless Steel in Comparison with Other Methods of Surface Treatment

“…2, the highest surface hardness enhancement, up to about 300% or higher, was achieved by thermal spray coating of WC-based ceramic particles 6,30 or plasma nitriding. 7,8,31 For WC particles coating, various matrix compositions were attempted, for example, 50(WC + 12Co)-balanceNi9Cr2Si3.5Fe2B0.5C and 83WC-17Co, 30 86WC-1 0 C o -4 C r a n d 5 0 W c -5 0 N i -C r-B -S i , 3 2 9 0 W C 1 0 C o , 86WC10Co4Cr, 83WC13Co4Cr, 6 and it was shown that the matrix composition was critical in determining the properties of coated layer. Direct injection of WC particles into a laser remelted layer was also tried.…”

Control logic and strategy for emergency condition of piston type energy recovery device

“…2 [22,23]. The flow diagram of the stand is similar to the actual RO system and owns feed-water pump (Grundfos, CR32-3-2), high pressure pump (Danfoss, PAH80), booster pump (Sulzer, ZF50-3315) and FS-ERD (in the red box).…”

Studies on several key problems of water hydraulic vane pump

“…The friction pair is ceramics -metal combinations. Thermally sprayed WC/CoCr type coatings were proved to meet wear and corrosion requirements in seawater situation (Dwars et al, 2008;Zhao et al, 2008).…”