CN-121975416-A - Preparation method of shearing reinforced polyurethane composite coating for erosion resistance

CN121975416ACN 121975416 ACN121975416 ACN 121975416ACN-121975416-A

Abstract

The invention discloses a preparation method of a shearing reinforced polyurethane composite coating for erosion resistance. The preparation method takes polyurethane as a matrix material, and is prepared by adding shear hardening gel obtained by polymerization reaction of hydroxyl-terminated polydimethylsiloxane and boric acid as an additive, and blending and polymerizing. The composite coating introduces dynamic boron-oxygen bonds, so that the mechanical property of the composite coating changes and responds in a transient state along with the self-adaptive change of the impact condition of the sand-containing water flow particles. Under low-speed impact, the composite coating is buffered by means of viscoelasticity and molecular chain segment movement to buffer energy consumption and relieve erosion, and under high-speed impact, the toughness is kept through the elastic chain segment, and the modulus is suddenly increased by means of the shearing hardening effect of dynamic boron-oxygen bonds, so that the coating is cooperatively prevented from tearing and falling, and reliable protection of a substrate is realized. The invention provides a new way for improving the erosion resistance of the hydraulic machinery and has practicability and economy.

Inventors

PEI JUNXIAN
KANG XUEFENG
WANG WENQUAN
WEI XINYU
TANG LEI
PU WEI
YAN YAN

Assignees

四川大学

Dates

Publication Date: 20260505
Application Date: 20260312

Claims (4)

1. A method for preparing a shearing reinforced polyurethane composite coating for erosion resistance is characterized in that the core is to prepare a dynamic boron-oxygen bond (B-O), so as to realize the instantaneous structural change and further obviously improve the protective performance, the specific steps of the preparation of the composite coating are as follows: step one, preparing a polyborosiloxane polymer 1) Weighing a certain amount of hydroxyl-terminated polydimethylsiloxane (PDMS-OH), adding boric acid (H 3 BO 3 ) according to the proportion of 1 (0.3-0.5), and fully stirring in a beaker to ensure uniform mixing; 2) Polymerizing the mixture under the condition of 180 ℃ oil bath, continuously stirring to ensure uniform reaction, taking out the mixture after the polymerization reaction is completed, and naturally cooling the mixture to room temperature for standby; Step two, preparing polyurethane prepolymer 1) Placing the measured polyol monomer into a three-neck flask, setting the temperature to be 110 ℃ and keeping the vacuum state for 2 hours so as to thoroughly remove trace moisture and volatile micromolecules in the system, and then introducing nitrogen as a shielding gas; 2) When the system is naturally cooled to the vicinity of 60 ℃, adding an isocyanate component and a catalyst, raising the reaction temperature to 80 ℃, maintaining constant temperature and stirring for 2 hours, measuring the NCO content in the prepolymer by a dibutylamine toluene method in the reaction process, stopping the reaction when the NCO content reaches a theoretical value, vacuumizing the obtained prepolymer to remove bubbles, and sealing and preserving the prepolymer; 3) Weighing a certain amount of prepolymer, putting the prepolymer into a 75 ℃ incubator to be completely melted, then transferring the prepolymer into a vacuum defoaming device to be treated until no obvious bubble residue exists in visual observation, heating a curing agent to 120 ℃ to be in a molten state, mixing the curing agent with the prepolymer according to a proportion, fully and uniformly stirring the mixed solution, and then carrying out vacuum degassing and stirring operation again to obtain polyurethane prepolymer; step three, preparation of composite coating 1) Weighing a certain amount of PBDMS as an additive, mixing with the polyurethane prepolymer according to the mass ratio of (4-5), adding a vulcanizing agent, and continuously and slowly stirring under the water bath condition of 25 ℃ until the PBDMS is completely dissolved in the polyurethane prepolymer to obtain a reaction material; 2) Pumping the reaction materials to vacuum in a vacuum dryer for bubble removal treatment, spraying the reaction materials onto the surface of an alloy steel sheet which is subjected to sand blasting roughening treatment and plasma activation treatment in advance, and putting the alloy steel sheet into a 70 ℃ oven until curing is complete; And (3) obtaining the shear-enhanced polyurethane composite coating through the first to third steps.
2. The method for preparing the anti-erosion shear-enhancement polyurethane composite coating according to claim 1, wherein the content of NCO in the prepolymer is 3-11% as measured by a dibutylamine toluene method.
3. The method for preparing the anti-erosion shear-enhanced polyurethane composite coating according to claim 1, wherein the ratio of the curing agent to the prepolymer is 1 (6-10).
4. The use of a shear-enhanced polyurethane composite coating according to claim 1 in hydraulic mechanical erosion resistance.

Description

Preparation method of shearing reinforced polyurethane composite coating for erosion resistance Technical Field The invention belongs to the technical field of fluid machinery erosion-resistant protective coatings. Background The hydraulic turbine is used as core equipment of hydroelectric power generation, and safe and reliable operation is an important guarantee for electric quantity supply and electric power system stability. However, sediment erosion wear has been an important factor in threatening the safety of the unit and affecting the life of the unit from the perspective of the already-put hydropower station. The erosion wear causes the loss of the material on the surface of the overcurrent and the change of the morphology, on one hand, the running efficiency of the unit is reduced, and on the other hand, the secondary problems of the unit such as the exceeding vibration, the noise and the like are caused, and serious safety accidents such as the breakage of the blades and the like can be even caused. The adoption of coating protection is an important technical means for improving the wear resistance of the hydraulic machinery, but the existing hard coating is easy to crack due to lack of toughness when being impacted by high-speed sand-containing water flow, and the elastomer coating is easy to tear due to insufficient strength. The composite coating with the hard particles added into the elastomer can achieve both strength and toughness to a certain extent, but has the problem of incompatibility of phase interfaces. Practice shows that the interfacial adhesion of the elastomer coating and the runner material and the strength of the coating are still to be improved, and the elastomer coating is easy to tear and peel under the action of high-speed sediment impact or strong cavitation, so that the elastomer coating is limited in application in sediment abrasion protection of large-scale hydraulic machinery. The invention provides a preparation method of a shear-enhanced polyurethane composite coating, which forms an interpenetrating polymer network structure through shear hardening gel and elastomer molecules, has good compatibility, can endow the elastomer with shear hardening performance, and enables the composite coating to adjust self modulus according to external impact adaptability. Under the condition of high-speed sediment, the elastomer molecules show high toughness through chain segment movement, the gel molecules show high strength through dynamic boron-oxygen bonds, more effective impact energy dissipation is realized, and the erosion resistance of the composite coating is greatly improved. Meanwhile, the modulus of the composite coating is suddenly increased by virtue of the shearing hardening effect of a dynamic boron-oxygen bond, so that the coating is cooperatively prevented from tearing and falling off, and the reliable protection of a substrate is realized. The invention provides a new way with practicability and economy for the erosion prevention of the hydraulic machinery. Disclosure of Invention The invention provides a preparation method of a shearing reinforced polyurethane composite coating for erosion resistance, wherein the core of the dynamic boron-oxygen bond (B-O) is the preparation of the dynamic boron-oxygen bond in the composite coating, so that the surface toughness can be remarkably improved, the surface impact can be reduced, the adhesion effect can be improved, and the efficient protection of hydraulic machinery under erosion can be realized. The invention provides a preparation method of a shearing reinforced polyurethane composite coating for erosion resistance, which is characterized in that the core is to prepare a dynamic boron-oxygen bond (B-O) so as to realize instantaneous structural change and further remarkably improve the protective performance, and the preparation method of the composite coating comprises the following specific steps: step one, preparing a polyborosiloxane polymer 1) Weighing a certain amount of hydroxyl-terminated polydimethylsiloxane (PDMS-OH), adding boric acid (H 3BO3) according to the proportion of 1 (0.3-0.5), and fully stirring in a beaker to ensure uniform mixing; 2) Polymerizing the mixture under the condition of 180 ℃ oil bath, continuously stirring to ensure uniform reaction, taking out the mixture after the polymerization reaction is completed, and naturally cooling the mixture to room temperature for standby; Step two, preparing polyurethane prepolymer 1) Placing the measured polyol monomer into a three-neck flask, setting the temperature to be 110 ℃ and keeping the vacuum state for 2 hours so as to thoroughly remove trace moisture and volatile micromolecules in the system, and then introducing nitrogen as a shielding gas; 2) When the system is naturally cooled to the vicinity of 60 ℃, adding an isocyanate component and a catalyst, raising the reaction temperature to 80 ℃, maintaining constant temperature and stirring for