A ship liquid cargo hold support material resistant to embrittlement under ultra-low temperature environment and a manufacturing method thereof

Abstract

The present application relates to the technical field of support structure material, in particular to a ship liquid cargo tank support material resistant to embrittlement under ultra-low temperature environment and a manufacturing method thereof, the material contains, by mass percentage, a high-strength modified wood matrix, nano-enhanced particles, a resin toughening agent, a light aging-resistant additive, and the balance is an auxiliary additive of a silane coupling agent and a nano-graphene dispersion liquid. The wood matrix formed by delignification and phenolic resin impregnation, combined with the "rigidity-flexibility" resin toughening agent and nano particles, makes the material have an impact toughness of greater than or equal to 10-15 J / cm2 at-162 DEG C, and the material process is green.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of support structure materials, in particular to a ship liquid cargo tank support material resistant to embrittlement in an ultra-low temperature environment and a manufacturing method thereof. BACKGROUND

[0002] In the current global shipping boom, ship transportation plays a crucial role in the energy and chemical product industries. The performance of the support material for the liquid cargo tank, as the core component of ship transportation of liquid cargo, plays a decisive role in the safety and efficiency of ship transportation. Especially in an ultra-low temperature environment, such as when transporting liquefied natural gas (LNG), the temperature can be as low as -162℃, which puts high demands on the embrittlement resistance of the support material.

[0003] Traditional ship liquid cargo tank support materials, such as ordinary carbon steel and low alloy steel, can meet the basic mechanical performance requirements at room temperature, but in an ultra-low temperature environment, their brittle transition temperature is relatively high, and they are prone to embrittlement. When the material embrittles, its toughness drops sharply, and when subjected to external force impact or vibration, it is prone to crack propagation or even rupture, which seriously threatens the safety of ship navigation and the stability of cargo transportation. For example, there have been several incidents of liquid cargo tank leakage caused by embrittlement of the support material, resulting in not only huge economic losses but also serious environmental pollution problems.

[0004] To solve the defects of traditional materials, some research attempts to use stainless steel as the support material. Stainless steel has certain low-temperature toughness, but the cost is high, and large-scale application will significantly increase the cost of shipbuilding, which greatly limits its promotion. At the same time, some materials containing specific alloy elements have also been explored for use in low-temperature environments, but these materials often have complex processing techniques and low production efficiency, making it difficult to meet the efficient and low-cost production demands of the shipbuilding industry.

[0005] In addition, existing support materials also have insufficient corrosion resistance when faced with complex marine environments. Seawater contains a large amount of corrosive media such as chloride ions and sulfate ions, which can cause corrosion on the surface of the support material over a long period of time, weakening its mechanical properties and accelerating the embrittlement process of the material. Existing corrosion prevention measures, such as coating protection, have a significant reduction in adhesion and durability in an ultra-low temperature environment, and cannot effectively protect the material.

[0006] With the adjustment of global energy structure, the demand for clean energy LNG continues to rise, and the scale and frequency of ship transportation are increasing, which further highlights the urgency of developing high-performance ship liquid cargo tank support materials resistant to embrittlement in an ultra-low temperature environment. At present, the market urgently needs a support material that can meet the excellent embrittlement resistance requirements in an ultra-low temperature environment, as well as good economic efficiency, processability, and corrosion resistance, to promote the safe and efficient development of the ship transportation industry. SUMMARY

[0007] In view of the deficiencies of the prior art, the present application provides a ship liquid cargo tank support material resistant to embrittlement in an ultralow temperature environment and a manufacturing method thereof.

[0008] A ship liquid cargo tank support material resistant to embrittlement in an ultralow temperature environment, comprising the following components in percentage by mass:

[0009] High-strength modified wood matrix 60%-70%: hardwood is selected, treated by delignification and cellulose skeleton is reserved; the fiber direction is arranged by mechanical pressing and magnetic field assisted orientation, forming a layered structure with axial tensile strength ≥ 150 MPa;

[0010] Nano-enhanced particles 2%-5%: composed of silicon carbide nanowhiskers and boron nitride nanosheets in a mass ratio of (2-3):1; the two are mixed by ultrasonic dispersion and mechanical ball milling;

[0011] Resin toughening agent 10%-15%: generated by cross-linking reaction of E-51 type epoxy resin and polyurethane prepolymer with NCO content of 6%-8% in a mass ratio of (1-2):1 under the action of catalyst dibutyltin dilaurate; during the reaction, 3%-8% of nanocellulose is introduced and uniformly dispersed in the cross-linked network by in-situ composite technology, forming a "rigid-flexible" dual-phase toughening structure;

[0012] Light aging resistant and corrosion resistant additives 2%-5%: including nano cerium oxide and quaternary ammonium salt corrosion inhibitor, with a mass ratio of (1-2):1; the nano cerium oxide is premixed with the quaternary ammonium salt by ball milling method; the quaternary ammonium salt corrosion inhibitor is dodecyl trimethyl ammonium bromide, and its structural formula is: ,

[0013] The balance is auxiliary additives: including silane coupling agent KH560 and nanographene dispersion liquid in a mass ratio of (1-2):1; the mass fraction of graphene in the graphene dispersion liquid is 1%-3%, which is blended with the silane coupling agent after ultrasonic peeling.

[0014] Preferably, the preparation method of the high-strength modified wood matrix comprises the following steps:

[0015] Delignification treatment: after cutting the wood into a predetermined size, immerse it in a sodium hydroxide solution with a mass fraction of 5%-10%, and treat it at a constant temperature of 60-80°C for 4-6 hours, with a solution to wood volume ratio of 5:1; after treatment, wash it with deionized water until it is neutral, and then place it in a vacuum drying oven at 80-100°C until the moisture content is ≤3%;

[0016] Resin impregnation and curing: after drying, the wood is immersed in a phenolic resin solution with a mass fraction of 35%-45%, the vacuum degree is ≤10⁻² Pa, the pressure is increased to 0.8-1.2 MPa and maintained for 30-60 minutes to ensure that the resin penetrates into the wood pores, and then dried at 60-90 degrees Celsius to a moisture content of 6-8%; hot-pressed and cured at 135-150 degrees Celsius and a pressure of 10-20 MPa for 2-4 hours to form a high-strength matrix with a density of ≥1.25-1.36 g / cm³.

[0017] Preferably, the nano-enhanced particles need to be treated in the following order:

[0018] Plasma activation: treated with a plasma device with a power of 100-300 W in an argon atmosphere for 5-10 minutes, with a gas flow of 5-10 L / min;

[0019] Amphoteric polymer coating: immerse the activated particles in an amphoteric polymer solution synthesized from acrylic acid and vinyl imidazole at a molar ratio of 1:1, and stir for 2-4 hours at 40-60 degrees Celsius to form a coating layer with a thickness of 10-50 nm;

[0020] Silane coupling agent modification: disperse the coated particles in an ethanol solution containing 0.5%-1.5% silane coupling agent KH560, ultrasonic treatment for 30-60 minutes, and then dry at 80-100 degrees Celsius for 2-4 hours.

[0021] Preferably, the dispersion degree of nanocellulose in the resin toughening agent requires that 90% or more of the nanocellulose particles have a spacing of ≤50 nm; the nanocellulose is prepared from wood pulp by sulfuric acid hydrolysis method, with a sulfuric acid concentration of 50%-60%, a hydrolysis temperature of 45-55 degrees Celsius, and a reaction time of 2-4 hours.

[0022] Preferably, the dispersion uniformity of nanocerium oxide in the light aging and corrosion resistant additive requires that the D90 particle size be ≤80 nm; after mixing, the antibacterial rate against Staphylococcus aureus is ≥99%.

[0023] Preferably, the manufacturing method of the ship liquid cargo tank support material resistant to embrittlement in an ultra-low temperature environment is characterized by comprising the following steps:

[0024] S1 raw material pretreatment

[0025] Wood matrix modification: after cutting the hardwood into preset size, immerse in 5%-10% mass fraction sodium hydroxide solution, constant temperature treatment at 60-80℃ for 4-6 hours to partially remove lignin; then rinse with deionized water to neutral, placed in vacuum drying oven at 80-100℃ to dry to moisture content≤3%; after drying, immerse the wood in 35%-45% mass fraction phenolic resin solution, dry to moisture content 6-8%, press to 10-20MPa, heat to 130-150℃ for 2-4 hours to form high-strength modified matrix with density≥1.25-1.36 g / cm³;

[0026] Nano-enhanced particle treatment: under argon atmosphere, use plasma equipment with power 100-300W to treat for 5-10 minutes to remove surface impurities and introduce active groups; immerse the activated particles in the amphoteric polymer solution synthesized by acrylic acid and vinyl imidazole at a molar ratio of 1:1, stir and react at 40-60℃ for 2-4 hours to form a coating layer with a thickness of 10-50nm; after coating, disperse the particles in an ethanol solution containing 0.5%-1.5% silane coupling agent KH560, ultrasonic treatment for 30-60 minutes, then dry at 80-100℃ for 2-4 hours;

[0027] S2 resin toughening agent preparation

[0028] Mix epoxy resin and polyurethane prepolymer at a mass ratio of (1-2):1, add 0.1%-0.3% dibutyltin dilaurate as catalyst; stir at 60-80℃ and add nano-cellulose gradually, control stirring speed at 300-500r / min, react for 3-5 hours until the system viscosity is stable to form a homogeneous toughening agent;

[0029] S3 composite material forming

[0030] Fix the modified wood matrix in the mold, sequentially inject the resin toughening agent, nano-enhanced particles, and light aging and corrosion resistant agent; press to 5-10MPa under vacuum environment, simultaneously apply ultrasonic vibration with frequency 20-40kHz for 10-20 minutes to eliminate interface bubbles; then heat to 100-130℃ for 4-6 hours to form a dense composite material;

[0031] After curing, coat the material surface with auxiliary additives, coating thickness 50-100μm, dry at room temperature for 24 hours;

[0032] S4 post-treatment

[0033] Low-temperature thermal cycle treatment: freeze the material in -50℃ to -30℃ environment for 12-24 hours, then heat to 50℃ at a rate of≤5℃ / min, dry for 8-12 hours to release internal stress;

[0034] Surface functionalization: After activating the surface with plasma treatment, a nano-graphene-reinforced coating is sprayed on, with a coating thickness of 10-30μm, and cured at room temperature for 48 hours.

[0035] S5 performance verification:

[0036] The final material must pass a low-temperature impact test at -162℃, with an impact toughness ≥10-15J / cm².

[0037] Preferably, during the S3 pressurization stage, the frequency of ultrasonic vibration is 20-40kHz, the amplitude is 5-10μm, and the pressure increases by 1MPa every 5 minutes during the pressurization process.

[0038] Preferably, in the plasma treatment of S4, a mixture of argon and oxygen gas is used with a gas flow rate of 8-12 L / min.

[0039] Preferably, the preparation of the nano-graphene reinforced coating includes the following steps:

[0040] Mix graphene dispersion with waterborne polyurethane emulsion at a mass ratio of 1:3-5, add 0.5%-1% leveling agent, stir at a speed of 200-400 r / min for 30-60 minutes; use a high-pressure airless spraying device with a pressure of 0.3-0.5 MPa to uniformly spray the mixture onto the material surface at a distance of 20-30 cm, with a single wet film thickness of 15-25 μm, and spray 2-3 layers in total.

[0041] Preferably, the final material must meet the following additional performance requirements: flexural strength ≥ 120 MPa; thermal conductivity ≤ 0.15 W / (m·K).

[0042] Compared with existing technologies, the beneficial effects of this invention are:

[0043] 1. The high-strength wood matrix formed by delignification treatment and phenolic resin impregnation has a fiber orientation structure that significantly improves low-temperature toughness. The "rigid-flexible" dual-phase structure in the resin toughening agent works synergistically with the nano-reinforcing particles to make the material's impact toughness at -162℃ ≥10-15J / cm², which is more than 3 times higher than that of traditional metal materials, effectively inhibiting the initiation and propagation of low-temperature cracks.

[0044] 2. Light aging resistant and corrosion resistant additives endow the material with excellent limiting oxygen index and antibacterial rate, and achieve aging resistance through uniform dispersion of nano-cerium oxide; surface auxiliary additives form a dense protective layer, significantly improving the durability of the material in marine environments.

[0045] 3. Modified wood matrix replaces traditional metal materials, reducing density and achieving lightweight ship support structure, thus reducing fuel consumption and carbon emissions; the raw materials are engineered bamboo, renewable nanocellulose and low-cost resin system, the overall production cost is lower than the stainless steel solution, and the economic benefits are outstanding.

[0046] 4. Plasma activation, amphoteric polymer coating, and vacuum ultrasonic vibration molding processes ensure improved interfacial bonding strength; low-temperature thermal cycling treatment replaces high-energy-consuming annealing processes; bio-based raw materials and pollution-free processes align with the development trend of green shipbuilding materials. Attached Figure Description

[0047] Figure 1 This is a flowchart of a method for preparing a ship cargo tank support material resistant to embrittlement under ultra-low temperature conditions, as proposed in this invention.

[0048] Figure 2 This is a line graph comparing the cryogenic impact toughness and flexural strength of the examples and comparative examples;

[0049] Figure 3 This is a bar chart comparing the intensity retention rate and antibacterial rate after UV aging of the examples and comparative examples;

[0050] Figure 4 This is a radar comparison chart created by standardizing the dimensions of the relevant performance indicators of the embodiments and comparative examples. Detailed Implementation

[0051] Example 1

[0052] Formulation composition: High-strength modified wood matrix: 65%; Nano-reinforcing particles: 3.5% (SiC nanocrystals:BN nanosheets = 2.5:1); Resin toughening agent: 13% (E-51 epoxy resin:PU prepolymer = 1.5:1, 5% nanocellulose); Light aging resistant and preservative additives: 3.5% (nano-cerium oxide and quaternary ammonium salt preservatives, mass ratio 1.5:1); Auxiliary additives: Balance (KH560:graphene dispersion = 1.5:1)

[0053] Preparation method

[0054] Wood matrix modification: Birch, beech, and other woods were cut into 50 cm × 20 cm × 5 cm blocks and impregnated in 8 wt% NaOH solution (liquid-to-wood volume ratio 5:1) for 5 hours at 75°C. After rinsing with deionized water, they were vacuum dried (90°C, 4 hours) until the moisture content was ≤2.8%. The blocks were then impregnated with 36 wt% phenolic resin solution, pressurized under vacuum (≤10⁻²Pa) to 1.2 MPa for 45 minutes, and cured at 140°C for 3 hours, resulting in a density of 1.25 g / cm³.

[0055] Nanoparticle reinforcement: SiC / BN mixed particles were activated by Ar plasma (200 W, 8 L / min, 8 min). They were then coated with an amphoteric polymer (acrylic acid: vinylimidazole = 1:1, stirred at 50°C for 3 h), resulting in a coating thickness of 30 nm. The particles were dispersed in a 1 wt% KH560 ethanol solution, sonicated for 40 min, and dried at 90°C for 3 h.

[0056] Synthesis of resin toughening agent: E-51 epoxy resin and PU prepolymer (NCO 7%) were mixed at a ratio of 1.5:1, and 0.2 wt% catalyst was added. 5 wt% nanocellulose (prepared by sulfuric acid hydrolysis) was added at 70°C, and the mixture was stirred at 400 rpm for 4 hours.

[0057] Composite material molding: Vacuum pressure of 8 MPa, synchronous 30 kHz ultrasonic vibration (amplitude 8 μm) for 15 minutes.

[0058] Step curing: 100°C / 1 h → 120°C / 2 h → 130°C / 2 h.

[0059] The surface is coated with an 80μm layer of auxiliary additives and dried at room temperature for 24 hours.

[0060] Post-treatment: Low-temperature cycling: freezing at -40°C for 18 hours, heating to 50°C at 3°C / min and drying for 10 hours. Argon-oxygen plasma treatment (10 L / min), spraying two layers of graphene coating (20 μm / layer).

[0061] Example 2

[0062] Formulation composition: High-strength modified wood matrix: 70%; Nano-reinforcing particles: 5% (SiC:BN=3:1); Resin toughening agent: 10% (Epoxy resin:PU=2:1, 8% nanocellulose); Light aging resistant and preservative additives: 5% (Cerium oxide:quaternary ammonium salt=2:1); Auxiliary additives: Balance (KH560:graphene=2:1)

[0063] Preparation method

[0064] Matrix modification: The wood matrix was cut into laminated boards and immersed in a 10 wt% NaOH solution (80°C, 6 hours). Fiber orientation was assisted by a magnetic field (0.5 T). The boards were then impregnated with a 26 wt% phenolic resin solution; vacuum pressure was applied to 20 MPa, and the boards were cured at 150°C for 4 hours, resulting in a density of 1.36 g / cm³.

[0065] Nanoparticle treatment: Ar plasma activation (300 W, 10 L / min, 10 min). Amphoteric polymer coating (stirring at 60°C for 4 h), coating thickness 50 nm. Surface contact angle ≤15° after silane coupling agent modification.

[0066] Toughening agent synthesis: Nanocellulose was hydrolyzed with 60 wt% sulfuric acid (55°C, 3 hours) to obtain particles with a size of 20-50 nm. It was then dispersed in situ in an epoxy-PU crosslinked network (stirred at 500 rpm for 5 hours).

[0067] High pressure molding: Vacuum pressure of 10 MPa, synchronous 40 kHz ultrasonic vibration (amplitude 10 μm) for 20 minutes.

[0068] Rapid curing: 100°C / 0.5 h → 130°C / 3 h → 150°C / 1 h.

[0069] Spray a 3-layer graphene-polyurethane coating (total thickness 30μm).

[0070] Example 3

[0071] Formulation composition: High-strength modified wood matrix: 60%; Nano-reinforcing particles: 4% (SiC:BN=2:1); Resin toughening agent: 12% (Epoxy resin:PU=1:1, 3% nanocellulose); Light aging resistant and preservative additives: 2% (Cerium oxide:quaternary ammonium salt=1:1); Auxiliary additives: Balance (KH560:graphene=1:1)

[0072] Preparation method

[0073] Simplified wood treatment: Maple blocks were impregnated with 5 wt% NaOH solution (60°C, 4 hours) and dried at 80°C for 3 hours. Phenolic resin was impregnated under a pressure of 1 MPa and cured at 120°C for 2 hours, resulting in a density of 1.3 g / cm³.

[0074] Nanoparticle treatment: Plasma activation (100 W, 5 min) followed by coating. Dispersed in 0.5 wt% KH560 ethanol solution, sonicated for 30 min, and dried at 80°C for 2 h.

[0075] Resin toughening agent: 3 wt% nanocellulose content, stirred at 300 rpm for 3 hours, viscosity 2500 mPa·s.

[0076] Low-pressure molding: molding pressure 5 MPa, curing at 100°C for 4 hours.

[0077] Single-layer graphene coating (15μm), without plasma pretreatment.

[0078] Comparative Example

[0079] Traditional 304 stainless steel support material

[0080] Preparation method

[0081] Smelting and rolling: Electric arc furnace smelting (1600°C), Cr 18-20 wt%, Ni 8-10.5 wt%.

[0082] Hot-rolled to 20 mm thick sheet (1200°C).

[0083] Solution treatment: Hold at 1050°C for 1 hour, then quench in water.

[0084] Surface treatment: Sandblasting roughness Ra 3.2μm.

[0085] Epoxy zinc-rich primer (50μm) + polyurethane topcoat (50μm)

[0086] Key performance indicators for the examples and comparative examples are shown in the table below:

[0087] Table 1

[0088] ,

[0089] Conclusion: This example demonstrates significantly superior performance compared to the comparative example in terms of ultra-low temperature impact toughness, thermal conductivity, antibacterial rate, and UV aging resistance. Among these, Example 2 exhibits the best overall performance with balanced performance across most indicators.

[0090] The production efficiency analysis of the examples and comparative examples is shown in the table below:

[0091] Table 2

[0092] ,

[0093] Conclusion: The material of this invention reduces weight by 89% and production energy consumption by more than 80% compared to traditional stainless steel. Example 1 achieves the best balance between performance and cost, Example 2 is suitable for high-end marine applications, while traditional materials result in a three-fold increase in total life-cycle cost due to frequent maintenance.

[0094] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A ship cargo tank support material resistant to embrittlement under ultra-low temperature conditions, characterized in that, By weight percentage, it includes the following components: High-strength modified wood matrix 60%-70%: selected hardwood, treated with delignification and retaining the cellulose skeleton; Its fibers are oriented by mechanical pressing and magnetic field assistance to form a layered structure with an axial tensile strength ≥150MPa; 2%-5% of nano-reinforcing particles: composed of silicon carbide nanocrystals and boron nitride nanosheets in a mass ratio of (2-3):1; the two are mixed by ultrasonic dispersion and mechanical ball milling; 10%-15% Resin toughening agent: It is generated by cross-linking reaction of E-51 type epoxy resin and polyurethane prepolymer with NCO content of 6%-8% at a mass ratio of (1-2):1 under the action of catalyst dibutyltin dilaurate; 3%-8% nanocellulose is introduced during the reaction process and uniformly dispersed in the cross-linking network through in-situ composite technology to form a "rigid-flexible" biphase toughening structure. Light aging resistant and corrosion-preserving additives 2%-5%: including nano-cerium oxide and quaternary ammonium salt preservatives, with a mass ratio of (1-2):1; the nano-cerium oxide is premixed with the quaternary ammonium salt by ball milling; the quaternary ammonium salt preservative is dodecyltrimethylammonium bromide, with the following structural formula: , The remainder is auxiliary additives: including silane coupling agent KH560 and nano-graphene dispersion in a mass ratio of (1-2):1; the graphene dispersion contains 1%-3% graphene by mass, and is blended with silane coupling agent after ultrasonic exfoliation. The nano-reinforced particles need to undergo the following processing in sequence: Plasma activation: Under an argon atmosphere, use a plasma device with a power of 100-300W to process for 5-10 minutes, with a gas flow rate of 5-10L / min; Amphoteric polymer coating: The activated particles are immersed in an amphoteric polymer solution synthesized from acrylic acid and vinyl imidazole in a molar ratio of 1:1, and stirred at 40-60℃ for 2-4 hours to form a coating layer with a thickness of 10-50nm. Silane coupling agent modification: The coated particles are dispersed in an ethanol solution containing 0.5wt%-1.5wt% silane coupling agent KH560, ultrasonically treated for 30-60 minutes, and then dried at 80-100℃ for 2-4 hours.

2. The ship cargo tank support material resistant to embrittlement under ultra-low temperature conditions according to claim 1, characterized in that, The dispersion of nanocellulose in the resin toughening agent requires that more than 90% of the nanocellulose particles have a spacing of ≤50nm; the nanocellulose is prepared from wood pulp by sulfuric acid hydrolysis, with a sulfuric acid concentration of 50wt%-60wt%, a hydrolysis temperature of 45-55℃, and a reaction time of 2-4 hours.

3. The ship cargo tank support material resistant to embrittlement under ultra-low temperature conditions according to claim 2, characterized in that, The dispersion uniformity of nano-cerium oxide in the light-resistant and anti-corrosion additives requires a D90 particle size ≤ 80 nm; the antibacterial rate against Staphylococcus aureus after mixing is ≥ 99%.

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