An aluminized silicon steel sheet with good wear resistance and processability and a manufacturing method thereof

Abstract

The present invention provides an aluminized silicon steel sheet with good wear resistance and processability and a manufacturing method thereof. The aluminized silicon steel sheet includes a substrate, a coating layer, a first passivation layer, and a second passivation layer. The composition of the coating layer is: 2-6% Si, 1-3% Mg, 0.5-0.8% Mn, and the balance Al. The first passivation layer contains components: fluozirconate, metavanadate, organic phosphonic acid, hydrofluoric acid, and phosphoric acid. The second passivation layer contains components: waterborne polyurethane, acrylate, polyethylene wax, and organic additives. Compared with the prior art, through reasonable design of the components of the coating layer, the first passivation layer, and the second passivation layer on the steel sheet, and by controlling hot-dip plating process, post-plating cooling process, skin pass process, coating process, etc., the present invention obtains an aluminized silicon steel sheet with good wear resistance and processability, which has good wear resistance, processability, solvent resistance, high temperature resistance, and corrosion resistance, and meets the usage requirements for applications such as drum dryers.

Description

Technical Field

[0001] The present invention belongs to the field of alloys, and particularly relates to an aluminized silicon steel plate with good wear resistance and processability and a manufacturing method thereof. Background Art

[0002] Tumble dryers are widely used in daily life. They mainly dry wet clothes by repeatedly tumbling them at high temperatures. Therefore, the steel plates used to manufacture tumble dryers need to have high-temperature resistance and corrosion resistance. When manufacturing the parts of the tumble dryer, the deformation amount is relatively large, so the steel plate needs to have good processability; when the processed steel plate contacts wet clothes, buttons, zippers, etc. in the tumble dryer, repeated friction occurs, and it also contacts laundry solvents, so the processed steel plate is required to have good wear resistance and solvent resistance. When using an aluminized silicon steel plate without a coating, the clothes and their accessories rub against the steel plate for a long time, which cannot meet the requirement of high wear resistance, and the coating is damaged, resulting in the deterioration of high-temperature resistance and corrosion resistance.

[0003] The analysis of the prior art is as follows:

[0004] The publication number CN 101709447 A, published on May 19, 2010, discloses "Production Process of Continuously Hot-Dip Aluminized Silicon Alloy Steel Plate". This patent mainly uses cold-rolled steel plates. After chemical degreasing and electrolytic degreasing, the aluminum-silicon solution is hot-dip coated on the front and back of the cold-rolled steel plates, and then passivated and dried after air knife leveling, air cooling, skin pass rolling, and tension leveling to obtain the finished product. The products described in this invention have better heat resistance, corrosion resistance, and wear resistance than galvanized plates and aluminized zinc plates. However, the steel plates described in this invention cannot meet the requirements of high wear resistance and solvent resistance.

[0005] The publication number CN 104342650 A, published on February 11, 2015, discloses "Preparation Process of Wear-Resistant Passivation Film on the Surface of Galvanized Materials". The composition of the treatment solution used in this process is: sodium silicate 54 - 58 g / L, nickel nitrate 9 - 11 g / L, boric acid 7 - 9 g / L, magnesium sulfate 6 - 8 g / L, ferrous chloride 12 - 14 g / L, trisodium phosphate 3 - 5 g / L, nano-silicon carbide 4 - 6 g / L, 70% sulfuric acid 16 - 18 g / L, sodium dodecyl sulfonate 0.5 - 1.5 g / L, and the balance is water. The passivation film prepared by this invention has excellent wear resistance and good corrosion resistance. However, the passivation film of the steel plate described in this invention is mainly composed of inorganic components and is relatively thin, and cannot meet the requirement of high wear resistance.

[0006] The invention "Galvanized Steel Sheet with Alkaline Resistance and Solvent Resistance" with the publication number CN 100391625 C was published on January 3, 2007. By coating an organic composite protective film containing fluoroacid, phosphorus-containing compound silane, waterborne polyurethane, and vanadium compound on the surface of the galvanized steel sheet, the requirements of users for strong alkaline degreasing, solvent cleaning, and high corrosion resistance are met. However, the steel sheet described in this invention cannot meet the requirements of high wear resistance and high temperature resistance.

[0007] The prior art has not solved the problems of wear resistance, solvent resistance, high temperature resistance, and corrosion resistance of the steel sheet used in tumble dryers. Summary of the Invention

[0008] The purpose of the present invention is to solve the problem that when the existing aluminized silicon steel sheet is applied to fields such as tumble dryers, it cannot meet the comprehensive requirements of high wear resistance, processing performance, solvent resistance, high temperature resistance, and corrosion resistance. The present invention provides an aluminized silicon steel sheet with good wear resistance and processing performance and its manufacturing method. Through reasonable design of the coating and coating layer components and process control, an aluminized silicon steel sheet with good wear resistance and processing performance and its manufacturing method are provided to meet the requirements of wear resistance, processing performance, solvent resistance, high temperature resistance, and corrosion resistance when applied to fields such as dryers.

[0009] The specific technical solution of the present invention is as follows:

[0010] An aluminized silicon steel sheet with good wear resistance and processing performance, including a substrate, a coating layer, a first passivation layer, and a second passivation layer.

[0011] Both the front and back surfaces of the substrate have a coating layer, a first passivation layer, and a second passivation layer.

[0012] The substrate is a cold-rolled or hot-rolled steel sheet of DDQ or HSLA grade and is fully annealed.

[0013] The coating layer includes the following mass percentage components: 2 - 6% Si, 1 - 3% Mg, 0.5 - 0.8% Mn, and the balance Al.

[0014] The first passivation layer contains components zirconium fluozirconate, metavanadate, organic phosphonic acid, hydrofluoric acid, and phosphoric acid.

[0015] The thickness of the first passivation layer is 300 - 500 nm.

[0016] The second passivation layer contains components waterborne polyurethane, acrylate, polyethylene wax, and organic additives.

[0017] The waterborne polyurethane is jointly modified by a silane coupling agent and hydroxyl silicone oil.

[0018] The thickness of the second passivation layer is 2 - 6 μm.

[0019] A manufacturing method of an aluminized silicon steel sheet with good wear resistance and processability provided by the present invention includes the following steps:

[0020] S1: Substrate hot dip plating;

[0021] S2: Post-plating cooling;

[0022] S3: Skin pass;

[0023] S4: Coating the first passivation layer;

[0024] S5: Coating the second passivation layer.

[0025] In step S1, the substrate is a cold-rolled or hot-rolled steel sheet of DDQ or HSLA grade that has been fully annealed.

[0026] In step S1, the temperature of the hot dip plating is 630 - 680 °C.

[0027] In step S1, the plating solution for the hot dip plating includes the following components by mass percentage: 2 - 6% Si, 1 - 3% Mg, 0.5 - 0.8% Mn, and the balance Al.

[0028] In step S2, the post-plating cooling is as follows: The post-plating cooling includes three stages: The first stage is cooled at a rate of 20 - 25 °C / s to 450 - 550 °C, the second stage is cooled at a rate of 5 - 10 °C / s to 180 - 200 °C, and the third stage is cooled in a quench tank to below 50 °C.

[0029] In step S2, the solution in the quench tank is a dilute NaNO2 alkaline solution with a concentration of 1 - 2% and a pH value of 8 - 9, and the treatment time is 10 - 20 s.

[0030] In step S3, the surface roughness Ra of the aluminized silicon steel sheet after skin pass is 1.0 - 2.0 μm.

[0031] In step S4, a first passivation layer passivation solution is coated. The first passivation layer passivation solution includes the following components by mass percentage: 5 - 15% fluozirconate, 3 - 8% metavanadate, 5 - 10% organic phosphonic acid, 1 - 2% hydrofluoric acid, 1 - 3% phosphoric acid, and the balance deionized water.

[0032] The fluozirconate is preferably sodium fluozirconate;

[0033] The metavanadate is preferably sodium metavanadate;

[0034] The organic phosphonic acid is preferably aminotrimethylene phosphonic acid.

[0035] After coating the first passivation layer passivation solution, the curing temperature is 70 - 120 °C, and the thickness of the first passivation layer is 300 - 500 nm.

[0036] In step S5, a second passivation layer passivation solution is coated. The second passivation layer passivation solution comprises the following components by mass percentage: 20-30% waterborne polyurethane, 5-10% acrylate, 1-3% polyethylene wax, 1-2% organic additive, and the balance deionized water.

[0037] The acrylate is preferably one of polymethyl methacrylate or polyethyl methacrylate.

[0038] The organic additive includes a curing agent, a leveling agent, and an antifoaming agent.

[0039] The curing agent is preferably melamine.

[0040] The leveling agent is preferably diacetone alcohol.

[0041] The antifoaming agent is an organosilicon resin, preferably one of methyltrichlorosilane and dimethyldichlorosilane.

[0042] When preparing the waterborne polyurethane, polyisocyanate and polyol compound are used as the main raw materials, and a silane coupling agent and hydroxyl silicone oil are added during the synthesis of the waterborne polyurethane; the percentage of the amount of the silane coupling agent in the total mass of the waterborne polyurethane reaction system is defined as A, and A is controlled to be 10-15%, and the percentage of the amount of the hydroxyl silicone oil in the total mass of the waterborne polyurethane reaction system is defined as B, and B is controlled to be 3-8%, and 1.5 < A / B < 3.5 is controlled.

[0043] For the raw materials for synthesizing the waterborne polyurethane, polyisocyanate and polyol compound are used as the main raw materials, and a hydrophilic chain extender, a neutralizing agent, a post-chain extender, an appropriate amount of catalyst, and a solvent are used as auxiliary raw materials, and it can be carried out according to the conventional method. During the synthesis of the waterborne polyurethane, it is jointly modified with a silane coupling agent and hydroxyl silicone oil.

[0044] The silane coupling agent is selected from the silane coupling agent of model KH550.

[0045] The hydroxyl silicone oil is preferably polydimethylsiloxane.

[0046] In step S5, after coating the second passivation layer passivation solution, the curing temperature is 150-180°C, and the thickness of the second passivation layer is 2-6 μm.

[0047] The good processing performance of the present invention is mainly due to: the selection of the substrate steel type, the control of the coating composition and the post-plating cooling process, and the use of dilute alkali solution treatment in the third stage of post-plating cooling, which can introduce a certain amount of hydroxyl groups on the coating surface, so as to complex with metal ions in the first passivation layer and obtain a passivation film layer with better adhesion; combining the coating with the first passivation layer; adding organic phosphonic acid in the first passivation layer, the -OH, -COOH and other organic functional groups in the organic phosphonic acid, and controlling the appropriate thickness of the first passivation layer can enhance the adhesion between the coating and the second passivation layer and improve the processing performance; combining the first passivation layer with the second passivation layer, and coordinating with the composition design of the second passivation layer, finally good processing performance can be achieved. Through the control of the coating composition and the post-plating cooling process, and the composition design of the second passivation layer, the wear resistance of the steel plate after processing is finally improved.

[0048] The present invention is mainly based on the following principles:

[0049] First of all, the substrate uses cold-rolled or hot-rolled steel plates of DDQ or HSLA grades that have been fully annealed to meet the processing performance requirements for large deformation amounts.

[0050] The substrate, the coating, the first passivation layer, and the second passivation layer are an integral whole. When using ordinary-grade CQ steel plates, stamping-grade DQ steel plates, or incompletely annealed DDQ and HSLA grades, under large deformation conditions, the elongation of the substrate is insufficient, the substrate is prone to cracking, and it drives the coating and the coating to undergo large deformations and crack, reducing the adhesion of the coating, the first passivation layer, and the second passivation layer, resulting in non-compliance of processing performance, wear resistance, solvent resistance, etc.

[0051] An aluminum coating is used to meet the requirements of high-temperature resistance. Adding Si elements can inhibit the formation of the alloy layer and improve the processing performance. When the Si content is low, it cannot achieve the effect; adding too much will cause the melting point to rise, resulting in an increase in molten pool slag and affecting the surface quality. Therefore, the preferred Si content controlled in the present invention is 2-6%. Adding Mg elements improves the corrosion resistance of the coating and forms Mg2Si phase with Si elements to improve the wear resistance of the material. When too little is added, it cannot achieve the effect; when too much is added, the coating surface is easily oxidized, affecting the surface quality of the product. Therefore, the preferred Mg content controlled in the present invention is 1-3%. Adding a small amount of Mn elements can increase the hardness of the coating and improve the overall wear resistance of the material; but when too much is added, it will damage the processing performance. Therefore, the preferred Mn content controlled in the present invention is 0.5-0.8%.

[0052] Furthermore, control the appropriate zinc pot temperature. If the zinc pot temperature is too low, a normal coating structure cannot be formed, and the processing performance and corrosion resistance become poor; if the zinc pot temperature is too high, the energy consumption is high, and more slag is generated, and the surface quality becomes poor. Therefore, the preferred zinc pot temperature controlled in the present invention is 630-680°C.

[0053] Furthermore, a post - plating segmented cooling process is adopted. In the first stage, it is rapidly cooled at a rate of 20 - 25 °C / s to 450 - 550 °C to form a large number of fine Mg2Si phases, increasing the hardness of the material and improving its wear resistance. In the second stage, it is slowly cooled at a rate of 5 - 10 °C / s to 180 - 200 °C to fully solidify the coating. In the third stage, it is cooled in a quenching tank to below 50 °C to complete the cooling process. At the same time, the solution in the quenching tank is a dilute NaNO2 alkaline solution (i.e., an aqueous solution of NaNO2) with a concentration of 1 - 2% and a pH value of 8 - 9, which can introduce a certain amount of hydroxyl groups on the coating surface, thereby complexing with metal ions in the first passivation layer to obtain a passivation film layer with better adhesion and improving the overall processing performance of the material. If the treatment time is too short, the amount of hydroxyl groups is too small; if the treatment time is too long, the etching effect of the dilute alkaline solution on the coating is enhanced, both of which are not conducive to the formation of the passivation film layer. Therefore, the preferred treatment time controlled in the present invention is 10 - 20 s.

[0054] Furthermore, the roughness of the steel plate finishing is controlled. When the roughness is too small, the adhesion between the first passivation layer and the substrate is poor; when the roughness is too large, the height difference between the peaks and valleys on the steel plate surface is too large, which easily causes uneven distribution of the passivation film and affects the corrosion resistance. Therefore, the preferred roughness Ra of the steel plate surface after finishing controlled in the present invention is 1.0 - 2.0 μm.

[0055] Furthermore, a first passivation layer is coated on the steel plate. As the main salt for forming the first passivation layer, if the content of fluozirconate is too little, it cannot play a passivation role; when the content is relatively high, it is not easy to form a film synergistically with other components. Therefore, the preferred content of fluozirconate controlled in the present invention is 5 - 15%. Furthermore, a small amount of vanadate is added to the passivation solution to obtain a composite film with "self - healing" performance. When the content is relatively low, the film - forming rate is too slow, the passivation film is thin and the corrosion resistance is not ideal; when the content is relatively high, too many vanadium ions combine with OH - groups, resulting in too fast deposition rate of vanadium hydroxide, causing the passivation film to be loose, easy to fall off, and the corrosion resistance to decrease. Therefore, the preferred content of vanadate controlled in the present invention is 3 - 8%. Furthermore, an appropriate amount of organic phosphonic acid is added. It can not only seal the pores between inorganic passivation films, but also may complex with zirconium ions in the solution to control the formation rate of the passivation film to make it more uniform and dense, increasing the corrosion resistance. And the - OH, - COOH and other organic functional groups in the organic phosphonic acid can enhance the adhesion between the coating and the second passivation layer, improving the processing performance and corrosion resistance. If too little is added, it cannot play an effect; if too much is added, it is not easy to form a film synergistically with other components. Therefore, the preferred content of organic phosphonic acid controlled in the present invention is 5 - 10%. Furthermore, an appropriate amount of hydrofluoric acid is added. The presence of F - in hydrofluoric acid reacts with zirconium ions in the solution to form ZrF6 2-The complex keeps the passivation stable. When too little is added, it fails to function; when too much is added, the film-forming speed of the passivation film is too fast and it becomes loose, deteriorating the corrosion resistance. Therefore, in this solution, the addition amount of hydrofluoric acid is preferably controlled at 1-2%. Further, phosphoric acid is added as a pH regulator. When the amount of phosphoric acid used is small, some reactions in the preparation of the passivation solution are incomplete, and the time for forming the passivation film is long. The corrosion resistance of the passivation film prepared in a short time is poor. When the addition amount of phosphoric acid is large, the corrosiveness of the solution is strong, corroding the coating in a short time and affecting the corrosion resistance of the passivated plate. Therefore, in this solution, the addition amount of phosphoric acid is preferably controlled at 1-3%.

[0056] Further, control the curing temperature of the first passivation layer. When the curing temperature is too low, the passivation film cannot be completely cured and is prone to cracking after processing and forming; when the curing temperature is too high, the passivation film is prone to powdering and cracking. Therefore, in the present invention, the curing temperature of the first passivation layer is preferably controlled at 70-120 °C.

[0057] Further, control the thickness of the first passivation layer. When the thickness of the first passivation layer is too small, the bonding force between the second passivation layer and the coating is poor, and the processing performance of the material is poor; when the thickness of the first passivation layer is too large, it is easy to cause uneven coating, affecting the uniformity of the bonding force between the second passivation layer and the coating, and cracks are prone to appear during processing. Therefore, in the present invention, the thickness of the first passivation layer is preferably controlled at 300-500 nm.

[0058] Further, a second passivation layer is coated on the first passivation layer. When too little waterborne polyurethane is added, the corrosion resistance, solvent resistance, wear resistance, etc. are poor. When too much is added, it is difficult to cure. Therefore, in the present invention, the content of waterborne polyurethane is controlled to be 20-30%. However, single waterborne polyurethane has disadvantages such as low mechanical strength, poor water resistance, and slow film-forming curing rate. Therefore, in the present invention, it is modified. The addition of silane coupling agent can improve the strength of the film layer and increase the wear resistance. When too little is added, the improvement of wear resistance is limited. When too much is added, the hardness is too high and the processing performance deteriorates. Therefore, in the present invention, the proportion of silane coupling agent A is preferably controlled to be 10-15%; at the same time, adding an appropriate amount of hydroxy silicone oil can improve the toughness of the film layer. When too little is added, the contribution to toughness is small. When too much is added, the viscosity is too high and it is not easy to crosslink and form a film with other components. Therefore, in the present invention, the proportion of hydroxy silicone oil B is preferably controlled to be 3-8%; moreover, the inventors of the present invention found that when 1.5 < A / B < 3.5, the performance of the second passivation layer reaches a balance of toughness, and the wear resistance, processability, and solvent resistance are all good. Further, adding an appropriate amount of acrylate can reduce the viscosity of the coating, improve the crosslinkability of the resin, and form a suitable coating film thickness. When added in excess, the coating stability becomes poor. Therefore, in the present invention, the content of acrylate is preferably controlled to be 5-10%. Further, adding 1-3% of polyethylene wax as a lubricant to disperse the coating components to make the coating uniform. Further, adding a total of 1-2% of curing agent, leveling agent, and defoaming agent can play the roles of curing, leveling, and defoaming.

[0059] Further, control the curing temperature of the second passivation layer. When the curing temperature is too low, the film layer is not completely cured and the corrosion resistance is poor. When the curing temperature is too high, the porosity of the coating becomes larger, and at the same time, the internal stress increases during curing, and the coating is prone to cracking. In the present invention, the curing temperature of the second passivation layer is preferably controlled to be 150-180 °C.

[0060] Further, control the thickness of the second passivation layer. When the coating thickness is too small, the wear resistance and solvent resistance are poor. When the coating thickness is too large, it is not easy to cure and the leveling property is poor, which is likely to cause coating unevenness. Therefore, in the present invention, the thickness of the second passivation layer is preferably controlled to be 2-6 μm.

[0061] Compared with the prior art, through reasonable design of the coating, the first passivation layer, and the second passivation layer components on the steel plate, and by controlling hot-dip plating process, post-plating cooling process, skin pass process, coating process, etc., the present invention obtains an aluminized silicon steel plate with good wear resistance and processing performance, which has good wear resistance, processing performance, solvent resistance, high temperature resistance, and corrosion resistance, meeting the use requirements for applications such as drum dryers. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 It is a schematic cross-sectional view of the aluminized silicon steel plate of the present invention. Detailed implementation mode

[0063] A method for manufacturing an aluminized silicon steel sheet with good wear resistance and processability according to the present invention is specifically described through examples.

[0064] Examples 1 - 6

[0065] A method for manufacturing an aluminized silicon steel sheet with good wear resistance and processability includes the following steps:

[0066] S1: Matrix hot dip plating: The matrix is a cold-rolled or hot-rolled steel sheet of DDQ or HSLA grade that has been fully annealed; the temperature of hot dip plating is 630 - 680 °C; the plating solution for hot dip plating includes the following components by mass percentage: 2 - 6% Si, 1 - 3% Mg, 0.5 - 0.8% Mn, and the balance Al. The plating solution components and contents, as well as the hot dip plating temperature for each specific example, are shown in Table 1. The balance not shown in the plating layer components of Table 1 is Al.

[0067] S2: Post-plating cooling: Post-plating cooling includes three stages: The first stage cools at a rate of 20 - 25 °C / s to 450 - 550 °C, the second stage cools at a rate of 5 - 10 °C / s to 180 - 200 °C, and the third stage cools in a quenching tank to below 50 °C; the solution in the quenching tank is a dilute NaNO2 alkaline solution with a concentration of 1 - 2% and a pH value of 8 - 9, and the treatment time is 10 - 20 s. The post-plating cooling process and parameters for each specific example are shown in Table 1.

[0068] S3: Skin pass: The surface roughness Ra of the aluminized silicon steel sheet after skin pass is 1.0 - 2.0 μm. The surface roughness after skin pass for each specific example is shown in Table 1.

[0069] S4: Coating the first passivation layer: Coating a passivation solution for the first passivation layer, the passivation solution for the first passivation layer includes the following components by mass percentage: 5 - 15% fluozirconate, 3 - 8% metavanadate, 5 - 10% organic phosphonic acid, 1 - 2% hydrofluoric acid, 1 - 3% phosphoric acid, and the balance deionized water. After coating the passivation solution for the first passivation layer, the curing temperature is 70 - 120 °C, and the thickness of the first passivation layer is 300 - 500 nm. The process parameters for coating the first passivation layer and the composition of the first passivation layer for each specific example are shown in Table 2.

[0070] S5: Coating the second passivation layer: Coating the passivation liquid for the second passivation layer, where the passivation liquid for the second passivation layer comprises the following components by mass percentage: 20 - 30% aqueous polyurethane, 5 - 10% acrylate, 1 - 3% polyethylene wax, 1 - 2% organic additive, and the balance deionized water; the acrylate is preferably polymethyl methacrylate. The 1.2% organic additive not shown in Table 2; specifically, 0.5% melamine curing agent, 0.2% diacetone alcohol leveling agent, and 0.5% dimethyldichlorosilane defoaming agent.

[0071] After coating the passivation liquid for the second passivation layer, the curing temperature is 150 - 180°C, and the thickness of the second passivation layer is 2 - 6 μm. The process parameters for coating the second passivation layer and the compositions of the first and second passivation layers in specific examples are shown in Table 2.

[0072] Comparative Example 1 - Comparative Example 18

[0073] A manufacturing method of an aluminized silicon steel sheet is carried out according to the method described in the above examples, with the difference being the parameters of each step. Specifically, the process parameters of the manufacturing methods of the aluminized silicon steel sheets in Comparative Example 1 - Comparative Example 18 are shown in Table 1 and Table 2.

[0074] The substrate used in each example and comparative example is a fully annealed DDQ - grade steel sheet.

[0075] In Table 1, the dilute alkali solution used in the third stage of each example and comparative example refers to a dilute alkali solution with a concentration of 1.5% and a pH value of 8.

[0076] The aqueous polyurethane described in the present invention is jointly modified by a silane coupling agent and hydroxyl silicone oil. The specific preparation method is as follows:

[0077] S1. In a four - necked flask equipped with a condenser, mechanical stirrer, and thermometer, under nitrogen protection, add 45 - 60% isophorone diisocyanate (polyisocyanate), 10 - 20% polypropylene glycol (polyol compound), and 0.05 - 0.5% dibutyltin dilaurate (catalyst) by mass fraction. Slowly heat the system to 50°C, keep the temperature for 20 min, then slowly heat the system to 70°C and keep the temperature for 100 min.

[0078] S2. Add 3 - 5% dimethylolpropionic acid (hydrophilic chain extender), heat the system to 90°C, and keep the temperature for 100 min.

[0079] S3. After the above reaction is completed, cool down. During the cooling process, add 0.5 - 2% acetone to reduce the viscosity of the system. When the temperature drops to 40°C, add triethylamine according to the molar ratio of triethylamine (neutralizing agent) to dimethylolpropionic acid (hydrophilic chain extender) of 1:1, and carry out the neutralization and salt - formation reaction for 20 min to obtain an aqueous polyurethane prepolymer.

[0080] S4. Slowly and evenly drip distilled water into the prepolymer, and perform high-speed shear emulsification at 25°C. During the emulsification process, add 1-2% of diethylenetriamine (post-extension agent) to crosslink the emulsion.

[0081] S5. When the water-dripping emulsification process is approaching the end, drip silane coupling agent and hydroxy silicone oil into the system. After the modifier is added, continue to drip water until complete emulsification, and continue stirring for 30 min to ensure that the reaction between isocyanate groups and amino groups is complete and uniform. The percentage of the amount of silane coupling agent in the total mass of the aqueous polyurethane reaction system is defined as A, and A is controlled to be 10-15%. The percentage of the amount of hydroxy silicone oil in the total mass of the aqueous polyurethane reaction system is defined as B, and B is controlled to be 3-8%. And control 1.5 < A / B < 3.5;

[0082] S6. Remove acetone by reduced pressure distillation to obtain the modified aqueous polyurethane product.

[0083] Table 1 Specific parameters of the coatings, cooling, and roughness of each example and comparative example

[0084]

[0085]

[0086]

[0087] Table 2 Specific parameters of the first passivation layer and the second passivation layer of each example and comparative example

[0088]

[0089]

[0090]

[0091] The horizontal data in Table 1 and Table 2 above represent the parameters that do not meet the requirements of the present invention.

[0092] The wear resistance, processability, and solvent resistance of the original plate and the processed steel plate were tested for the examples and comparative examples respectively. The test methods are as described below.

[0093] The original plate refers to the steel plate without deformation, and the processed steel plate refers to the steel plate after the processability test (8 mm cup drawing test was carried out using a cup drawing testing machine).

[0094] (1) Test method for wear resistance of the original plate: Use a Taber linear abrasion tester to conduct wear resistance tests. Rotate at a speed of 60 r / min with a 500 g weight for 50,000 times, and observe the surface state of the steel plate. The level where there is no abnormality on the surface is defined as 0, the level where the coating is worn and the plating layer is not worn is defined as 1, and the level where the plating layer is worn and the steel substrate is exposed is defined as 2. Level 0 is qualified, and levels 1 and 2 are both unqualified.

[0095] (2) Test method for processing performance of the original plate: Conduct an 8 mm cupping test using a cupping testing machine, and observe the cracking ratio of the surface coating of the steel plate. The level with no cracking is defined as 0, the level where 0 < cracking ratio ≤ 5% is defined as 1, the level where 5 < cracking ratio ≤ 10% is defined as 2, and the level where the cracking ratio > 10% is defined as 3. Level 0 is qualified, and levels 1, 2, and 3 are all unqualified.

[0096] (3) Test method for solvent resistance of the original plate: First measure the original chromaticity of the steel plate, then place it in a 2% laundry detergent solvent at 50 °C for 168 hours and measure the chromaticity of the steel plate again. Calculate the color difference △E before and after placement. △E ≤ 3 is qualified, defined as √; △E > 3 is unqualified, defined as ×.

[0097] (4) Test method for wear resistance of the processed steel plate: Use a Taber linear abrasion tester to conduct wear resistance tests on the specimens after the 8 mm cupping test. Rotate at a speed of 60 r / min with a 500 g weight for 30,000 times, and observe the surface state of the steel plate. The level where there is no abnormality on the surface is defined as 0, the level where the coating is worn and the plating layer is not worn is defined as 1, and the level where the plating layer is worn and the steel substrate is exposed is defined as 2. Level 0 is qualified, and levels 1 and 2 are both unqualified.

[0098] (5) Test method for solvent resistance of the processed steel plate: Place the cupped sample in a 2% laundry detergent solvent at 50 °C for 168 hours, and then observe the color change of the processed part. No color change is qualified, defined as √; color change is defined as ×.

[0099] The test results of each example and comparative example are shown in Table 3. It can be seen from the table that:

[0100] The performance test results of Examples 1 - 6 are good. Both the original plate and the processed steel plate can meet the requirements of wear resistance, processing performance, and solvent resistance.

[0101] Comparative Example 1 is an aluminized silicon steel plate without a passivation layer. It has good processing performance but poor wear resistance. After wear resistance testing, the steel substrate is exposed, and its solvent resistance is unqualified.

[0102] The Si content in the coating of Comparative Example 2 is low, the alloy layer between the coating and the steel substrate is too thick, cracks are likely to occur in the coating during processing, and the treatment time of the dilute alkali solution in the quenching tank is too short, resulting in a small number of hydroxyl groups formed. The bonding force between the coating and the first passivation layer is weak. Under the coating of the present invention, the unprocessed original plate has good wear resistance and solvent resistance. However, when processed and deformed, the cracks in the coating gradually expand towards the first passivation layer and the second passivation layer. When testing the wear resistance of the processed steel plate, the steel substrate leaks out. The laundry detergent solvent penetrates into the steel plate through the cracks in the coating, and the solvent resistance of the processed steel plate is unqualified.

[0103] The Mg content in the coating of Comparative Example 3 is low, and it is impossible to form a large number of Mg2Si phases. Moreover, the surface roughness Ra after skin pass is low, and the bonding force between the first passivation layer and the coating is poor. Under the coating of the present invention, the unprocessed original plate has good wear resistance and solvent resistance. However, when processed and deformed, cracks are likely to appear at the interface between the two and expand towards the second passivation layer. The wear resistance and solvent resistance of the processed steel plate are poor.

[0104] The Mn content in the coating of Comparative Example 4 is low, and the cooling rate of the coating is low, so the Mg2Si phase is relatively coarse. The cooling rate of the coating of Comparative Example 6 is large, and the Mg2Si phase is less, and the hardness of the coating is low. Under the coating of the present invention, the unprocessed original plate has good wear resistance and solvent resistance. However, when processed and deformed, compared with the examples, under the same deformation amount, the tensile deformation amount of the passivation layer driven by the coating becomes larger. Microcracks appear in the coating of the processed steel plate. When conducting the solvent resistance test, the laundry detergent solvent enters the steel plate, and the solvent resistance is unqualified. At the same time, when conducting the wear resistance test, the coating wears and the steel substrate leaks out.

[0105] The Mn content in the coating of Comparative Example 5 is high, and the coating is hard. Under the coating of the present invention, the unprocessed original plate has good wear resistance and solvent resistance. However, when processed and deformed, the coating is prone to cracking and expands towards the first passivation layer and the second passivation layer. And without treatment with dilute alkali solution, the bonding force between the coating and the first passivation layer is poor, which increases the tendency of the coating to crack during processing. When testing the wear resistance of the processed steel plate, the coating wears and the steel substrate leaks out. When conducting the solvent resistance test, the laundry detergent solvent enters the steel plate, and the solvent resistance is unqualified.

[0106] Comparative Example 7 is a commercially available organic chromium-free passivator. The coating has good flexibility and can meet the requirements of processing performance, but the wear resistance and solvent resistance are unqualified.

[0107] Comparative Example 8 is a commercially available inorganic chromium-free passivator. The coating has poor flexibility, poor processing performance, and unqualified wear resistance and solvent resistance.

[0108] Comparative Example 9 is a commercially available inorganic-organic composite passivator. The coating has good flexibility and can meet the requirements of processing performance, but the wear resistance and solvent resistance are unqualified.

[0109] For Comparative Example 10, under the coating of the second passivation layer of the present invention, the unprocessed original plate has good wear resistance and solvent resistance. However, during processing and deformation, due to the low content of organic phosphonic acid in the first passivation layer and the small number of organic functional groups such as -OH and -COOH, the bonding force between the coating and the second passivation layer is weak, and microcracks are easily generated during processing. When the wear resistance of the processed steel plate is tested, the coating wears, while the coating of the present invention does not show wear due to the coating composition and process control of the present invention. Moreover, the effect of closing the pores between the passivation films of the first passivation layer is limited. When the solvent resistance of the processed steel plate is tested, the solution easily enters the interior of the coating, and the solvent resistance performance is unqualified.

[0110] For Comparative Example 11, under the coating of the second passivation layer of the present invention, the unprocessed original plate has good wear resistance and solvent resistance. However, during processing and deformation, since too many vanadium ions in the first passivation layer combine with OH- functional groups, reducing the proportion of the number that can combine with the second passivation layer, the bonding force between the coating and the second passivation layer is weak, and the processing performance is unqualified. And the curing temperature is low, and the first passivation layer is prone to cracking after processing and forming and spreads to the second passivation layer, and the wear resistance and solvent resistance of the processed steel plate are unqualified.

[0111] For Comparative Example 12, under the coating of the second passivation layer of the present invention, the unprocessed original plate has good wear resistance and solvent resistance. However, during processing and deformation, due to the low content of fluozirconate in the first passivation layer and the thin first passivation layer, the bonding force between the second passivation layer and the coating is weak, the processing performance is unqualified, and cracks are easily generated. The wear resistance and solvent resistance of the processed steel plate are unqualified.

[0112] For Comparative Example 13, the content of waterborne polyurethane in the second passivation layer is low, and the solvent resistance of the original plate is unqualified. During the wear resistance test, the coating wears and the coating leaks, and the wear resistance is unqualified. The wear resistance and solvent resistance of the processed steel plate are also unqualified.

[0113] For Comparative Example 14, the waterborne polyurethane in the second passivation layer is not modified, and the wear resistance, solvent resistance, and processing performance of the original plate are unqualified. Microcracks occur in the second passivation layer of the processed steel plate, and the wear resistance and solvent resistance are further deteriorated.

[0114] For Comparative Example 15, the ratio of modifier A / modifier B in the second coating is too small, and the wear resistance of the original plate is unqualified, while the processing performance and solvent resistance are good, and the wear resistance of the processed steel plate is also unqualified.

[0115] For Comparative Example 16, the ratio of modifier A / modifier B in the second passivation layer is too large, and the second passivation layer is too thick. The wear resistance and solvent resistance of the original plate are good, but the processing performance is poor, and microcracks are easily generated. The solvent resistance and wear resistance of the processed steel plate are further deteriorated.

[0116] The curing temperature of the second passivation layer in Comparative Example 17 is relatively high, the porosity of the coating becomes larger, the wear resistance of the original plate is poor, and at the same time, the internal stress increases during curing, the coating is prone to cracking, and the wear resistance after processing deformation deteriorates further. At the same time, during the solvent resistance performance test, the solvent easily enters the interior of the coating, and the solvent resistance performance is unqualified.

[0117] The thickness of the second passivation layer in Comparative Example 18 is relatively small, and the wear resistance and solvent resistance of both the original plate and the processed steel plate are unqualified.

[0118] Table 3 Test Results

[0119]

[0120]

[0121] The above description only gives a specific exemplary description of the present invention. It should be noted that the specific implementation of the present invention is not limited by the above methods. As long as various non-substantive improvements are made by adopting the technical concept and technical solution of the present invention, or the technical concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. An aluminized silicon steel sheet with good wear resistance and processability, characterized in that, The aluminized silicon steel sheet with good wear resistance and processability includes a substrate, a coating layer, a first passivation layer and a second passivation layer; The coating layer includes the following components by mass percentage: 2~6% Si, 1~3% Mg, 0.5~0.8% Mn, and the balance Al; The passivation solution of the first passivation layer includes the following components by mass percentage: 5~15% fluozirconate, 3~8% metavanadate, 5~10% organic phosphonic acid, 1~2% hydrofluoric acid, 1-3% phosphoric acid, and the balance deionized water; The passivation solution of the second passivation layer includes the following components by mass percentage: 20~30% waterborne polyurethane, 5~10% acrylate, 1~3% polyethylene wax, 1~2% organic additive, and the balance deionized water; When preparing the waterborne polyurethane, polyisocyanate and polyol compound are used as the main raw materials, and a silane coupling agent and hydroxyl silicone oil are added during the synthesis of the waterborne polyurethane; the dosage of the silane coupling agent accounts for the percentage of the total mass of the waterborne polyurethane reaction system, defined as A, and A is controlled to be 10~15%, the dosage of the hydroxyl silicone oil accounts for the percentage of the total mass of the waterborne polyurethane reaction system, defined as B, and B is controlled to be 3~8%, and 1.5<A / B<3.5 is controlled.

2. The aluminized silicon steel sheet with good wear resistance and processability according to claim 1, characterized in that, The thickness of the first passivation layer is 300~500 nm.

3. The aluminized silicon steel sheet with good wear resistance and processability according to claim 1 or 2, characterized in that, The thickness of the second passivation layer is 2~6 μm.

4. A manufacturing method of the aluminized silicon steel sheet with good wear resistance and processability according to any one of claims 1 - 3, characterized in that, The manufacturing method includes the following steps: S1: Hot dip coating of the substrate; S2: Post-plating cooling; S3: Skin pass; S4: Coating the first passivation layer; S5: Coating the second passivation layer.

5. The manufacturing method according to claim 4, characterized in that, In step S2, the post-plating cooling is as follows: The post-plating cooling after hot dip coating includes three stages: the first stage is cooled to 450~550 °C at a rate of 20~25 °C / s, the second stage is cooled to 180~200 °C at a rate of 5~10 °C / s, and the third stage is cooled to below 50 °C through a quench tank; the solution in the quench tank is a dilute NaNO2 alkaline solution with a concentration of 1~2% and a pH value of 8~9, and the treatment time is 10~20 s.

6. The manufacturing method according to claim 4, characterized in that, After coating the passivation solution of the first passivation layer, the curing temperature is 70~120 °C.

7. The manufacturing method according to claim 4, characterized in that, In step S5, when coating the passivation solution of the second passivation layer, the passivation solution of the second passivation layer includes the following components by mass percentage: 20~30% waterborne polyurethane, 5~10% acrylate, 1~3% polyethylene wax, 1~2% organic additive, and the balance deionized water; the organic additive includes a curing agent, a leveling agent, and an antifoaming agent.

8. The manufacturing method according to claim 4 or 7, characterized in that, After coating the passivation solution of the second passivation layer, the curing temperature is 150~180 °C.

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