中文 / EN

 

027-59715061

WeChat number

Mobile website

About us           Solution           Business

NAV

HOUSE OF WORKERS

News                 Culture            Service

Copyright© SUNNY Technologies Incorporation Limited.         鄂ICP备12010795号           Powered by www.300.cn

CONTACT

浏览器提醒组件

SUNNY TECHNOLOGIES

INCORPORATION LIMITED

Address: #101,No.6 Gaoxin Road,East Lake Hi-Tech Development District,Wuhan,P.R.China
           #2,Guangzhou Road,Tuanchenshan Development District,Huangshi,P.R.China
E-mail:
spt@sunnychina.com.cn
Tel: 156 7177 7755/027-59715061
Fax: 027-59715060

NEWS CENTER

Effect of curing process on properties of non-oriented environmentally friendly silicon steel insulating coating

Page view
  The curing process is the key process of silicon steel coating. In this paper, an environmentally friendly silicon steel insulating coating liquid is prepared, and the non-oriented silicon steel insulating coating is treated by different curing process conditions. By observing the difference of surface morphology, the rust area of ??neutral salt spray test, The size of the insulation resistance, the advantages and disadvantages of the electrochemical parameters, to evaluate the surface state of the coating, corrosion resistance, electrochemical performance, insulation properties, etc., and then evaluate the advantages and disadvantages of the coating curing process, the actual production of silicon steel coating The application is instructive.
  With the increasing demand for electrical steel in China, the production technology of electrical steel has been gradually improved. Non-oriented silicon steel occupies a huge market share in China's silicon steel production, and silicon steel coating is an indispensable key technology in the production of silicon steel products, which will definitely affect the production and development of silicon steel products, and with the development of China's silicon steel industry, Silicon steel coatings have enormous market potential. The curing process is the key process of silicon steel coating. In this paper, an environmentally friendly silicon steel insulating coating liquid is prepared, and the non-oriented silicon steel insulating coating is treated by different curing process conditions. By observing the difference of surface morphology, the rust area of ??neutral salt spray test, The size of the insulation resistance, the advantages and disadvantages of the electrochemical parameters, to evaluate the surface state of the coating, corrosion resistance, electrochemical performance, insulation properties, etc., and then evaluate the advantages and disadvantages of the coating curing process, the actual production of silicon steel coating The application is instructive.
 
  SHAPE\*MERGEFORMAT
  1.1 Preparation of the coating
  The laboratory-prepared phosphate-based non-oriented environmentally-friendly silicon steel insulating coating liquid is coated on the treated silicon steel substrate by using an anilox roller to ensure a coating amount of 1-1.5 g/cm 2 and a temperature of 300, 350, 400, 450 ° C respectively. The time is 10, 20, 30s to carry out the coating sintering and solidification, and the non-oriented environmental protection silicon steel insulating coating under different process conditions is obtained, and the performance test and characterization are carried out.
  1.2 Test characterization
  Using Shanghai Chenhua CHI660E electrochemical workstation to test the polarization curve and AC impedance of the coating, the traditional three-electrode system is used, the working area is 1cm2, the corrosive medium is 3.5% NaCl solution, the scanning rate is 5mV/s, and the AC impedance spectrum is used. The scanning frequency ranges from 10 mHz to 100 kHz and the scanning rate is 0.05 mV/s. The corrosion resistance of the coating was tested according to GB/T10125-1997 using the DCTC1200P neutral salt spray test chamber of Angelantoni, Italy. According to GB/T2522-2007, the insulation resistance of the coating was tested using an HT-2007 coating insulation resistance measuring instrument to evaluate the insulation properties of the coating. Hitachi S-3400N scanning electron microscope was used to observe the surface morphology of the environmentally friendly silicon steel insulating coating after curing. The thermal analysis of non-oriented environmentally friendly silicon steel coating liquid was carried out by using the German Netzsch STA-449C thermal analyzer under nitrogen protection at a heating rate of 10 ℃/min. The coating was subjected to infrared analysis using a Fourier transform infrared spectrometer from PerkinElmer, USA.
 
  SHAPE\*MERGEFORMAT
  2.1 corrosion resistance
  The neutral salt spray test was used to evaluate the corrosion resistance of the coating. The percentage of rust area after the 5h neutral salt spray test is shown in Figure 1.
  It can be seen from Fig. 1 that in the neutral salt spray test, the corrosion resistance of the coating generally increases gradually with the increase of the curing temperature (300-450 ° C) under the same curing time. Among them, when the curing temperature is 300 ℃, the corrosion percentage of the coating under the three curing times is significantly higher than that under other process conditions, and the corrosion resistance of the coating is relatively poor, indicating that the coating is not completely cured at this temperature. When the curing temperature is 350 ℃, the corrosion percentage decreases with the increase of curing time, indicating that the corrosion resistance of the coating is continuously improved with the increase of curing time (10-30s). When the curing temperature is 400 ℃, the corrosion percentage of the coating under three curing times is significantly lower than that under other process conditions, and the corrosion resistance is high. The corrosion resistance is especially excellent when the curing time is 20s and 30s. At 450 ℃, the corrosion percentage of 10s and 20s is lower, but when the curing time reaches 30s, the corrosion percentage of the coating is obviously increased, indicating that the corrosion resistance of the coating is poor.
  2.2 insulation performance
  The insulation performance of environmentally friendly silicon steel insulation coating is characterized by the measured insulation resistance value. The insulation resistance of the coating under different process conditions is shown in Fig. 2.
  It can be seen from Figure 2 that the effects of different curing processes on the insulation properties of the coatings are not the same. When the curing temperature is 300 ° C, the insulation resistance of the coating increases slightly as the curing time increases. At 300 ° C, the maximum insulation resistance is only 175 Ωmm2. When the curing temperature reaches 350 ° C, the insulation resistance of the coating increases significantly with the increase of curing time. When curing for 30 s, the insulation resistance can reach 300 Ωmm 2 or more. When the curing temperature is 400 ℃, the curing time is 20s and 30s, and the insulation resistance is obviously improved when it is cured for 10s, but the difference between the two is not large. However, when the curing temperature is 450 ° C, it can be found that the insulation resistance value increases with the curing time, the variation trend is parabolic, and the resistance value at each curing time is lower than 400 ° C.
  2.3 Surface topography
  In order to explore the microscopic morphology of the coating surface under different process conditions, combined with the test results of neutral salt spray test and insulation performance, the silicon steel coating is selected at 300 ° C + 10 s, 350 ° C + 30 s, 400 ° C + 20 s, 450 ° C + Four representative process conditions of 30s, the surface topography is shown in Figure 3. SHAPE\*MERGEFORMAT
  It can be clearly seen from Fig. 3 that the surface morphology of the coating is different under the four process conditions: when the curing process is 300 ° C + 10 s, the coating color is light and translucent, and the surface of the silicon steel substrate can be seen to be uneven. The coating is basically uncured; when the curing process is 350 ° C + 20 s, the color of the coating is significantly deepened, but the morphology of the substrate can be found faintly, and the degree of curing increases; when the curing process is 400 ° C + 20 s, the coating The surface is uniform and dense, and the coverage is good, and the degree of curing of the coating is good. When the curing process is 450 ° C + 30 s, the coating has obvious defects, the surface is scorched, the silicon steel substrate is exposed, and the block and powder morphology are aggregated. , indicating that the temperature is too high at this time, so that the coating is over-cured. The microscopic morphology of the coating under different processes can well explain the relationship between corrosion resistance and insulation properties of the coating.
  2.4 electrochemical performance test
  2.4.1 Tafel polarization curve
  Combined with the experimental results of the neutral salt spray test and the insulation performance test, the Tafel polarization curves of the substrate and the four process conditions were selected, as shown in Fig. 4, and the electrochemical parameters are listed in Table 1.
  It can be obtained from Fig. 4 and Table 1: under the four kinds of process conditions, the corrosion currents are basically the same, and belong to the same order of magnitude. The corrosion potential is not much different, but the curing temperature is 400 ℃, the curing time is 20s, and the polarization resistance value is 30s. 2 times under other conditions, the electrochemical parameters of the coating under this process condition are relatively excellent. At this time, the coating can effectively block the corrosion of chloride ions on the sample, and the transfer rate of electrons between the anode and the cathode is reduced. Small, reducing the corrosion rate. The protection ratio of the coating to the substrate under different process conditions is shown in Table 1. Under the four process conditions, the protection ratio of the coating is more than 98%, which can basically meet the protection of the coating on the substrate, which is consistent with the experimental results of the neutral salt spray test and the insulation resistance value. The corrosion protection rate of the coating at 400 ℃+20s is as high as 99.53%, which indicates that the coating has the best protection effect on the substrate under this process condition.
  2.4.2 AC impedance spectrum
  The AC impedance spectrum of the new environmentally friendly silicon steel insulating coating under different curing conditions.
  It can be concluded from Fig. 5 that the impedance arcs under the four process conditions are quite different. When the curing temperature is 400 ° C and the curing time is 20 s, the impedance radius of the coating is the largest, and the impedance is significantly larger than that of the other three process conditions. The radius of the arc.
  Table 2 lists the circuit value of the equivalent circuit, Rs is the solution resistance, RPO is the resistance inside the coating hole, Rt is the polarization resistance of the coating corrosion reaction, Cc is the coating capacitance, and Cdl is the electric double layer capacitance. The larger the Rt value, C. The smaller the value, the better the protection of the coating. When the curing process is 400 ℃+20s, the Rt value is as high as 70,561 Ωcm2, and the Cc value is one order of magnitude smaller than other conditions, indicating that the coating has the best protection effect. Combined with the electrochemical parameters in the Tafel polarization curve, the electrochemical properties of the coating are excellent when the curing conditions are 400 ℃ + 20 s, which improves the corrosion resistance of the coating.
 
  SHAPE\*MERGEFORMAT
  Different curing processes have different effects on the properties of the coating. When the curing process is 400 ° C + 2 Os, the coating properties are optimal. The non-oriented environmentally friendly silicon steel insulating coating covers the silicon steel substrate well, and the coating surface is dense and uniform, and the coating protection rate is as high as 99.53%. In the 5h neutral salt spray test, the percentage of rust area was only 6%, the electrochemical parameters were significantly better than other conditions, and the insulation resistance value reached 300 Ω·mm2.