General knowledge of coating: research and development of black wear-resistant, anticorrosive and conductive coating

Abstract: a kind of black wear-resistant and anticorrosive conductive coating was prepared by modifying epoxy resin with silicone resin, adding a certain amount of nano molybdenum disulfide, nano aluminum powder, conductive carbon black and graphite The results show that when the content of silicone resin is 12%, the content of filler is 8%, the composition of mixed solvent is m (acetone): m (ethyl acetate): m (butyl acetate): m (xylene): 2:1:1, and the content is 48%, the coating has good wear resistance and corrosion resistance, and the surface electric resistance of the coating is 2.2 × 104 Ω / cm2 Which is the price of Dajin diatom mud Recommended brief introduction: which is the price of Dajin diatom mud? How to buy genuine diatom mud? Guangdong diatom mud agent suggests placing a basin of cold water in the air conditioning room, so that the diatom mud wall can breathe effectively The feature of the breathing wall is obvious When the indoor air is dry, the diatom mud wall will release the absorbed water quickly Put it out to help regulate the indoor dry humidity It is suggested to place a basin of cold water in the air conditioning room, so that the wall of diatom mud can breathe effectively The feature of the wall that can breathe is obvious When the indoor air is relatively dry, the wall of diatom mud will absorb the water Abstract: the epoxy resin was modified by organosilicon resin, and a kind of black wear-resistant and anticorrosive conductive coating was made by adding a certain amount of nano molybdenum disulfide, nano aluminum powder, conductive carbon black and graphite The results show that when the content of silicone resin is 12%, the content of filler is 8%, the composition of mixed solvent is m (acetone): m (ethyl acetate): m (butyl acetate): m (xylene): 2:1:1, and the content is 48%, the wear resistance and corrosion resistance of the coating are good, and the surface electric resistance of the coating is 2.2 × 104 Ω / cm2, which has good conductivity and electromagnetic resistance The coating can be applied to the electromagnetic protection of the surface of army weapon equipment Key words: conductive coating; organosilicon resin; epoxy resin; wear resistance; corrosion protection 1 With the rapid development of detection technology and guidance technology in the world, a clear stealth demand is put forward for weapons and equipment, which requires the newly developed equipment to have certain stealth protection performance Because the coating has many advantages, such as easy to use, adapt to the field and the rapid implementation of weapons and equipment under the field conditions, the shape of weapons and equipment does not need to be changed, the design is not required, and it is suitable for the promotion of the use of existing equipment, etc., so the absorbing coating is widely used as a lightning protection and wave stealth measure [1-2] Radar absorbing coating is generally composed of binder and absorbent Most absorbents are powder or fiber like, such as ferrite powder, metal ultrafine powder, ceramic fiber, conductive carbon black, graphite, conductive polymer materials, nano materials, hollow beads, etc [3-6] At present, the resins used in radar absorbing coatings include polyurethane, epoxy resin and neoprene [7-8] Epoxy resin has many forms, easy curing, strong adhesion, low shrinkage after curing, excellent mechanical properties and special chemical stability, and low price It is the most widely used resin matrix material for absorbing coating, but its wear resistance and flexibility are poor, so it needs to be modified In this paper, silicone resin was used to modify epoxy resin E-51 Silicone resin has good flexibility, heat resistance and weather resistance at low temperature, and its surface energy is low However, the compatibility of the physical blending of epoxy resin and silicone resin is poor, so it is difficult to achieve the purpose of modification Therefore, the chemical blending method is adopted, that is, the condensation reaction of hydroxyl, amino and alkoxy groups in silicone resin and hydroxyl groups in epoxy resin is used to generate block high polymer [9], so the chemical modification of epoxy resin by silicone can be realized In addition, adding rigid inorganic fillers (such as nano-SiO2, MoS2, Al2O3, modified montmorillonite, etc.) to the epoxy resin modified by organosilicon can further improve the high temperature resistance and wear resistance of the coating The results show that the adhesion strength and impact wear resistance of the modified coating are greatly improved In addition, adding a certain amount of conductive carbon black and graphite can greatly reduce the surface resistance of the coating film, thus having a certain conductivity and electromagnetic resistance 2 Experiment 2.1 main raw materials and instruments Epoxy resin E-51, silicone resin and curing agent T31, Jiangxi Yichun excellent chemical company; carbon black (2000 mesh), graphite powder (3000 mesh), antioxidant 1010, Tianjin Chemical Reagent Company; nano molybdenum disulfide, nano aluminum powder, Wuhan Jiangbei chemical reagent company; acetone, ethyl acetate, butyl acetate and xylene, Tianjin Tianda chemical reagent factory Electronic balance (fa2004n), Shanghai Precision Scientific Instrument Co., Ltd.; precision electric mixer, Jiangsu Jintan ronghua Instrument Manufacturing Co., Ltd.; acl-385 surface impedance meter, Shaanxi Spectrum Technology Co., Ltd.; salt spray test box (1804), ms-255 wet sand rubber wheel wear test machine, Tianjin Tianyu experimental company 2.2 for coating manufacturing, firstly, the epoxy resin is dissolved in the mixed solvent, and then the silicone resin and coating additives are added after it is completely dissolved at room temperature, and the reaction is conducted for 2h at the temperature of 40-60 ° C, then the filler and antioxidant are added, and the mixture is stirred at high speed and even, then the component a of the black wear-resistant coating can be made When using, mix component A and component B of curing agent in a certain proportion 2.3 performance test 2.3.1 wear resistance test The abrasion resistance of coating film shall refer to GB / t1768-2006 determination of abrasion resistance of paints and varnishes rotating rubber wheel method The abrasion test of wet sand rubber wheel is adopted The principle is to use the rotating rubber wheel to drive the mineral sand, sand, sand and other abrasives mixed with water to produce abrasion on various metal or non-metal materials, and determine the relative abrasion of materials according to the weight loss The coating thickness is (25 ± 5) μ m, the material is 45 steel matrix, the rotating speed is 600 R / min, the load is 40 n Before the experiment, pre grind for 200 revolutions, accurately weigh and then start the formal experiment After 1000 revolutions of wear, weigh accurately and calculate the relative wear rate 2.3.2 accelerated corrosion test of salt spray box this test is used to verify the anti-corrosion performance of silicone resin with different content on the coating film The experiments were carried out with A3 steel, 20 steel, 45 steel, of which gun steel is the commonly used pcrnimov alloy steel in weapon equipment The specification of the test piece is 25mm × 50mm × 3mm, which shall be treated according to the method specified in GB / t9271-2008 standard test panel for paints and varnishes, and then the mixed silicone resin coating with different content shall be sprayed on the surface of the test piece respectively, and the film thickness shall be 0.03mm after being completely dried, which shall be placed in the salt spray box In order to compare with the coating, the blank test pieces were placed in the salt spray box, and the experiment was carried out at the same time The salt spray test conditions are set in accordance with GB / t10125-1997 salt spray test for corrosion test in artificial atmosphere, and the test is conducted in accordance with GB / t1771-1991 determination of neutral salt spray resistance of paints and varnishes 2.3.3 the surface resistance shall be measured in accordance with GB / t1410-2006 test method for volume resistivity and surface resistivity of solid insulating materials 3 Results and discussion 3.1 results in order to increase the surface wear resistance of the coating, nano molybdenum disulfide was added to the coating, which has excellent wear resistance The effect of the amount of nano molybdenum disulfide on the wear resistance of the coating is shown in Table 1 Table 1 the effect of the amount of nano molybdenum disulfide on the wear resistance of the coating It can be seen from table 1 that with the increase of the proportion of nano molybdenum disulfide, the relative wear rate of the coating decreases significantly, but when the content of nano molybdenum disulfide in the coating is greater than 1.0%, the relative wear rate of the coating does not change much Considering the cost, 12% nano molybdenum disulfide was added into the filler, that is to say, the content of nano molybdenum disulfide in the coating was 1.0% 3.2 effect of silicone resin content on the anticorrosion performance of the coating the main film-forming material of the coating is epoxy resin, which has excellent adhesion, high filling capacity, chemical resistance, high anticorrosion performance and water resistance after the coating is formed However, due to the poor flexibility and weather resistance of the epoxy coating surface, the brittleness is large, and the accelerated corrosion resistance is poor, so the surface performance of the coating is improved by adding the silicone resin with better flexibility See Table 2 for the effect of the amount of silicone resin on the corrosion resistance of the coating It can be seen that with the increase of silicone resin content, the anti-corrosion performance of the coating has been greatly improved, but when the silicone resin content is greater than 12%, the improvement of the anti-corrosion performance is not obvious, so the silicone resin content of the coating is 12% Table 2 Effect of silicone resin content on salt spray corrosion test results of coating 3.3 effect of filler content on conductivity of coating carbon black, graphite and nano aluminum powder are all good electrical conductors with good conductivity and electromagnetic shielding performance Taking carbon black, graphite and nano aluminum powder as fillers, the effect of the amount of carbon black, graphite and nano aluminum powder on the surface resistivity of the coating is shown in Figure 1 Fig 1 the change of surface resistivity of coating with the amount of filler It can be seen from Fig 1 that when the amount of carbon black, graphite and nano aluminum powder mixed filler increases from 4% to 6%, the surface resistance of coating decreases sharply; when the amount of filler exceeds 8%, the surface resistivity of coating decreases slowly, and at the same time, too much filler will reduce the adhesion of coating Therefore, considering the physical and electrical properties of the coating, the best adding proportion of filler is 8% At this time, the surface resistivity of the coating is 2.2 × 104 Ω / cm2, and the coating has certain protective performance for electromagnetic wave 3.4 determination of mixed solvent the solvent used in the coating is to dissolve the base material into a solution with appropriate viscosity, which is convenient for spraying or brushing, and to obtain a uniform coating After spraying or brushing, the solvent must be volatilized from the coating Therefore, the choice of solvent is very important It is found that the solvents that can completely dissolve epoxy resin and silicone resin are ethyl acetate, butyl acetate, amyl acetate, acetone, butanone, methyl isobutyl ketone, toluene, xylene, etc Considering the speed of film formation and solubility parameters, a large number of experiments have been carried out to determine the solvent and ratio of the coating: m (acetone): m (ethyl acetate): m (butyl acetate): m (xylene): 2:1:1:1 Under this condition, the surface of the coating is relatively flat At room temperature, the surface drying time is 2 h, and the actual drying time is about 24 h 3.5 coating performance test results the coating formula determined according to the above test is (expressed by mass fraction): the coating formula, wherein the filler is composed of 40% carbon black (2000 mesh), 10% graphite powder (3000 mesh), 12% nano molybdenum disulfide and 38% nano aluminum powder (all mass fractions), and the mixed solvent is composed of acetone, ethyl acetate, butyl acetate and xylene according to the mass ratio of 2:1:1:1 The coating developed by this formula has certain wear-resistant, corrosion-resistant and conductive functions, and can be used as anti electromagnetic materials See Table 3 for main performance test results of coating film Table 3 main performance test results of coating film 4 Conclusion a kind of wear-resistant, corrosion-resistant and conductive coating was developed with epoxy resin as the main film-forming material The coating can be cured at room temperature, surface dried in 2H and dry in 24h After modified by silicone resin, the coating has good salt spray resistance; after adding a certain amount of nano molybdenum disulfide, the wear resistance of the coating has been greatly improved; by adding conductive fillers (including carbon black, graphite powder and aluminum powder), the surface electrical resistance of the coating has reached 2.2 × 104 Ω / cm2, with certain electrical conductivity