Technical Research About Resistance Reduction And Anti-Cavitation Composite Coating Suitable For Pumping

The waste of energy and resources in industrial production will seriously restrict the sustainable development of society.The pump is the main energy-consuming equipment in industrial and agricultural production in China,and is widely used in all aspects of production and life.In this paper,Faced with the problem of reduced pump efficiency and reduced service life,which due to cavitation,corrosion and erosion damage during pump operation.A polyurethane elastomer material protection scheme with excellent cavitation resistance is proposed to reduce the cavitation,corrosion and erosion damage of the pump inner wall substrate,and improve the service life and operating efficiency of the pump.In combination with the current laws and regulations on the environmental protection requirements of coatings,through coating system design,resin screening,formulation and process research and performance evaluation,a composite coating system with high adhesion solvent-free iron red epoxy anticorrosive primer,high toughness solvent-free intermediate transition layer and drag reduction synergistic anti-cavitation polyurethane elastomer topcoat was developed.Firstly,the preparation and properties of high adhesion solvent-free iron red epoxy anticorrosive primer were studied.The epoxy resin and epoxy resin curing agent types were screened by the evaluation of the basic mechanical properties,drawing adhesion and viscosity of the coating.A J51 type epoxy resin and a WH-31 epoxy resin curing agent excellent in performance are preferred,and the viscosity is low,and air spray application can be employed.The epoxy resin coating is toughened by using a reactive diluent.When the mass ratio of the reactive diluent SM80 to the epoxy resin is 1:7,the prepared coating on the carbon steel plate have a drawing adhesion is 14.47 MPa,and flexibility up to 1mm.Based on this,an iron red epoxy primer coating formulation was designed and tested for performance.The results show that the prepared undercoat has excellent anti-corrosion and bonding properties.The drawing adhesion to the carbon steel plate is 11.5 MPa.When the time of neutral salt spray test is 1000hours,the surface is not blistering or rusting,and one-way diffusion at the scratch is less than2mm.Secondly,the preparation and process of solvent-free high toughness intermediate transition layer were studied.In order to achieve good adhesion between the transition intermediate layer and the epoxy resin primer layer and the polyurethane elastomer surface coating,two transition intermediate layer resin schemes were designed.One is the epoxy resin prepolymer modified epoxy resin,which are cured by the epoxy resin curing agent,and the second is to prepare a high toughness polyurethane resin by crosslinking a trifunctional HDI trimer with a polyurethane amine polyamine chain extender.The test results show that the MDI type polyurethane prepolymer with an isocyanate content of 11.33%modified J51 type epoxy resin,and make hydroxyl group to react 40%.The composite coating has a peel strength of 8.05kN·m^-1,but the failure mode is that the intermediate transition layer and the top coat are peeled off.When a polyurethane resin is prepared by using a trifunctional HDI trimer and a diamine chain extender,the mass ratio of DMTDA:PM100 in the chain extender is between 0.45and0.64,and the ratio of the amount of isocyanate to active hydrogen is 1.04:1¹.2:1,the composite coating peel strength is greater than 20 kN·m^-1,and the damage form is the elastic coating itself tearing.The results of the construction process of various coatings of the composite coating system show that:iron red epoxy primer,when using D6630 curing agent,it needs to be cured at 25°C for 24 h,when using WH-31 curing agent,it needs to be cured at30°C for 24 h.The intermediate paint coating needs to be cured after curing at room temperature for about 4 hours,and the effect of the two components of the intermediate paint is 1.28:1,and the peeling strength can reach 20 kN·m^-1 or more.Finally,the preparation and properties of the anti-cavitation solvent-free polyurethane elastomer surface coating with drag reduction and synergistic effect were studied.The results show that the polyurethane elastomer material with a soft segment ratio of 38.3⁴5.1%has higher tensile strength,up to 35Mpa.When the rotational drag reduction tester rotates at300r/min and 400r/min?ie,the line speeds are 3.14m/s and 4.19m/s?,the ratio of soft and hard segments of the coating is 0.706,the thickness of the coating is between 500?m and 700?m,and the flexibility factor is 24²8.The coating has high drag reduction efficiency.Polyurethane elastomer material with a soft segment ratio of 44.5%,no visible microscopic damage within168h of continuous cavitation test,no macroscopic damage visible to the naked eye within 240h.