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CN-121976176-A - Neodymium iron boron magnetic steel film strengthening pretreatment method based on surface energy regulation and control

CN121976176ACN 121976176 ACN121976176 ACN 121976176ACN-121976176-A

Abstract

The invention discloses a strengthening pretreatment method of a neodymium-iron-boron magnetic steel film layer based on surface energy regulation and control, which sequentially comprises degreasing and degreasing, acid washing, ultrasonic cleaning, phosphating, sealing and solidifying processes, wherein the acid washing is treated by acid washing liquid containing nitric acid and citric acid monohydrate, the phosphating process is zinc-manganese-nickel ternary phosphating to form a micro porous phosphate conversion film, the sealing process is a surface energy modified solution containing hydrogenation heavy naphthenic fraction, 1- (2-butoxy-1-methylethoxy) -2-propanol and diethylene glycol, and the method has the advantages that the formed phosphating film has high surface energy and high dispersion component and polar component ratio through the surface energy regulation and control, shows the characteristics of high surface energy and low polarity, obviously improves the wettability and chemical affinity of coatings with different polarity characteristics, realizes firm and general interface combination with various coating materials, and meets the reliable attachment requirement of diversified coating of neodymium-iron-boron magnetic steel.

Inventors

  • TAO QINFEI
  • Lu Jieqin
  • GUAN WENWEN
  • LI GUAN

Assignees

  • 宁波韵升股份有限公司
  • 宁波韵升磁体元件技术有限公司

Dates

Publication Date
20260505
Application Date
20251230

Claims (7)

  1. 1. A strengthening pretreatment method of a neodymium iron boron magnetic steel film layer based on surface energy regulation and control is characterized in that a film layer is formed on the surface of neodymium iron boron magnetic steel through degreasing and degreasing, pickling, ultrasonic cleaning, phosphating, sealing and solidifying processes, the method is characterized in that the pickling process comprises the steps of immersing the degreased neodymium iron boron magnetic steel in pickling solution for 30-90 s, sequentially rinsing the immersed neodymium iron boron magnetic steel with two deionized water, wherein the rinsing time of each deionized water is 5-10 s, and removing the pickling solution remained on the surface of the neodymium iron boron magnetic steel, the pickling solution is formed by dissolving nitric acid and citric acid monohydrate in the deionized water, the concentration of nitric acid is 3-5wt%, and the concentration of citric acid monohydrate is 40-100 g/L; the phosphating process adopts a zinc-manganese-nickel three-system phosphating process, and a layer of continuous and microcosmic porous phosphate chemical conversion film is generated on the surface of the neodymium-iron-boron magnetic steel which is cleaned by ultrasonic waves; The sealing process specifically comprises the steps of immersing phosphated neodymium iron boron magnetic steel in a surface energy modification solution at a temperature of 40-60 ℃ for 2-4 min, wherein the surface energy modification solution is formed by dissolving a surface energy modifier in deionized water, the surface energy modifier comprises hydrogenated heavy naphthenic fraction, 1- (2-butoxy-1-methylethoxy) -2-propanol and diethylene glycol, the concentration of the hydrogenated heavy naphthenic fraction is 30-50 g/L, the concentration of the 1- (2-butoxy-1-methylethoxy) -2-propanol is 3-7 g/L, and the concentration of the diethylene glycol is 0.4-0.8 g/L.
  2. 2. The surface energy regulation-based neodymium iron boron magnetic steel film strengthening pretreatment method of claim 1, wherein the phosphating process is specifically as follows: Step S1, immersing neodymium iron boron magnetic steel subjected to ultrasonic cleaning in a phosphating solution with the temperature of 30-50 ℃ and the pH of 1.5-2.5 for 8-12 min; The phosphating solution is formed by dissolving zinc nitrate, zinc dihydrogen phosphate, phosphoric acid, manganese dihydrogen phosphate, nickel sulfate, sodium dodecyl sulfate and EDTA in water, wherein the concentration of zinc nitrate is 70-100 g/L, the concentration of zinc dihydrogen phosphate is 40-60 g/L, the concentration of phosphoric acid is 35-55 g/L, the concentration of manganese dihydrogen phosphate is 50-70 g/L, the concentration of nickel sulfate is 40-60 g/L, the concentration of sodium dodecyl sulfate is 20-40 g/L, and the concentration of EDTA is 25-45 g/L; and S2, carrying out two deionized water rinsing steps, wherein the rinsing time of each deionized water rinsing step is 5-10S.
  3. 3. The strengthening pretreatment method of the neodymium iron boron magnetic steel film layer based on surface energy regulation and control according to claim 1, wherein the degreasing and deoiling process is specifically as follows: step A1, dipping and degreasing, namely dipping the NdFeB magnetic steel in degreasing and degreasing liquid at 50-70 ℃ for 5-10 min to remove grease on the surface of the NdFeB magnetic steel; and step A2, washing the neodymium iron boron magnetic steel by two times of deionized water rinsing in sequence, wherein the rinsing time of each time of the deionized water is 5-10 s, so as to remove the degreasing and degreasing liquid remained on the surface of the neodymium iron boron magnetic steel.
  4. 4. The strengthening pretreatment method of the neodymium iron boron magnetic steel film layer based on surface energy regulation and control according to claim 3 is characterized in that degreasing and degreasing liquid is formed by dissolving sodium hydroxide, sodium carbonate, trisodium phosphate and an emulsifier OP-10 in water, wherein the concentration of the sodium hydroxide is 20-40 g/L, the concentration of the sodium carbonate is 20-30 g/L, the concentration of the trisodium phosphate is 5-10 g/L, and the concentration of the emulsifier OP-10 is 1-3 ml/L.
  5. 5. The surface energy regulation-based neodymium iron boron magnetic steel film strengthening pretreatment method according to claim 1, wherein the ultrasonic cleaning process is specifically: Step B1, ultrasonic degreasing, namely ultrasonic degreasing is carried out on the acid-washed neodymium iron boron magnetic steel by adopting ultrasonic degreasing liquid, wherein the temperature of the ultrasonic degreasing liquid is 20-40 ℃, and the pH value is 9-12; Step B2, washing the NdFeB magnetic steel after ultrasonic degreasing by two deionized water rinsing steps in sequence, wherein the rinsing time of each deionized water rinsing step is 5-10 s so as to remove residual ultrasonic degreasing liquid on the surface of the NdFeB magnetic steel; And B3, ultrasonic washing, namely placing the rinsed neodymium iron boron magnetic steel into an ultrasonic washing tank, and carrying out ultrasonic washing by adopting deionized water to wash the residual ash on the surface of the neodymium iron boron magnetic steel, wherein the treatment time is 1-3 min.
  6. 6. The surface energy regulation and control-based neodymium iron boron magnetic steel film strengthening pretreatment method is characterized in that the ultrasonic degreasing liquid is formed by dissolving potassium pyrophosphate, sodium carbonate and an emulsifier OP-10 in deionized water, wherein the concentration of the potassium pyrophosphate is 40-60 g/L, the concentration of the sodium carbonate is 5-20 g/L, and the concentration of the emulsifier OP-10 is 1-3 ml/L.
  7. 7. The strengthening pretreatment method of the neodymium iron boron magnetic steel film layer based on surface energy regulation and control of claim 1, wherein the solidification process is specifically as follows: step C1, drying the closed NdFeB magnetic steel to remove surface liquid; step C2, placing the dried neodymium iron boron magnetic steel into an oven for curing, wherein the curing temperature is 110-130 ℃, and the curing time is 20-40 min; And C3, discharging from the oven and cooling to room temperature.

Description

Neodymium iron boron magnetic steel film strengthening pretreatment method based on surface energy regulation and control Technical Field The invention relates to a neodymium iron boron magnetic steel pretreatment method, in particular to a neodymium iron boron magnetic steel film strengthening pretreatment method based on surface energy regulation and control. Background Neodymium iron boron magnetic steel is widely applied to the fields of wind power, automobiles, consumer electronics and the like due to the extremely high magnetic energy product. However, the neodymium-rich phase in the chemical components of the ceramic has high chemical activity, is extremely easy to generate electrochemical corrosion in a humid environment, and severely limits the service life and the application range of the ceramic. In order to improve the corrosion resistance of the NdFeB magnetic steel, a pretreatment process is generally adopted in industry, and a film layer is formed on the surface of the NdFeB magnetic steel. The film layer not only can provide a certain physical isolation function, but also can improve the surface chemical stability, and forms a certain mechanical interlocking and chemical combination with the subsequently coated organic coating (such as epoxy resin, electrophoretic paint and the like), thereby enhancing the overall protective performance. Currently, the main pretreatment method for neodymium iron boron magnetic steel is phosphating treatment, namely, a layer of phosphate crystal film (phosphating film) is generated on the surface of the neodymium iron boron magnetic steel through chemical conversion. However, the conventional phosphating process has the following inherent drawbacks: (1) The surface energy structure is unfavorable for combining with a nonpolar or weak polar coating, and the phosphating film has higher surface energy, but the surface energy composition is mainly composed of a polar component gamma p, and a dispersion component gamma d is relatively low, so that the surface of the phosphating film presents high polarity characteristics. This characteristic makes it less wettable for high performance polymer coatings (e.g., certain fluorocarbon coatings, specialty encapsulation glues, etc.) that are non-polar or weakly polar, with insufficient chemical affinity between the two. The interface bonding mainly depends on the physical anchoring effect provided by the microporous pores of the phosphate film, and the chemical bonding effect is weaker. (2) The adhesive force of the coating is easy to degrade in a complex environment, namely, the coating-phosphating film interface which is anchored by only the micropores of the phosphating film and is combined with limited polarity is easy to fail in a long-term thermal stress, mechanical stress or damp-heat environment, so that the coating is peeled off, a corrosive medium is invaded, and finally, the corrosion of the NdFeB magnetic steel is initiated. Although passivation or oil-coating sealing treatments are currently often performed after phosphating to seal the surface pores of the phosphating film and to promote short-term corrosion resistance, these methods do not substantially improve the surface energy structure of the phosphating film, and in particular do not enhance the interfacial chemical bonding between the same and non-polar or weakly polar coatings. Therefore, the film layer formed by the traditional phosphating process has the defects of limited suitability and insufficient long-term bonding reliability when coping with diversified coating systems. Disclosure of Invention The invention aims to provide a surface energy regulation-based strengthening pretreatment method for a neodymium iron boron magnetic steel film. The method can form a phosphating film with high surface energy and higher ratio gamma d/γp of dispersion component to polar component on the surface of the neodymium iron boron magnetic steel, and has the characteristics of high surface energy and low polarity, and the surface energy structure of the phosphating film can obviously improve the wettability and chemical affinity of the phosphating film to different polar characteristic coatings, so that firm and universally applicable interface combination with various coating materials (including nonpolar, weak polar and polar coatings) is realized, and the reliable attachment requirement of the neodymium iron boron magnetic steel on diversified coating systems in different application scenes is met. The technical scheme includes that the strengthening pretreatment method for the NdFeB magnetic steel film layer based on surface energy regulation comprises the steps of sequentially carrying out degreasing and degreasing, pickling, ultrasonic cleaning, phosphating, sealing and solidifying processes on the NdFeB magnetic steel to form a film layer on the surface of the NdFeB magnetic steel, wherein the pickling process comprises the steps of immersing the degrease