A composite chromium oxide coating for flexible printing and preparation method thereof

Abstract

The present invention relates to the field of metallic materials, and particularly to a composite chromium oxide coating for flexible printing and a preparation method thereof. The present invention discloses a composite chromium oxide coating for flexible printing. The composition of the composite chromium oxide coating includes a chromium oxide coating provided on the surface of steel. The mass percentage content (Wt / %) of each element is: ZrO2: 10-30%, TiO2: 1-5%, Cr2O3: 65-89%. The composite chromium oxide coating for flexible printing according to the present invention uses Cr2O3 as a substrate and adds a toughening phase thereto to prepare a toughened chromium oxide composite coating, which can densify the ceramic coating, thereby improving the bonding strength between the coating and the substrate and enhancing the coating performance.

Description

Technical Field

[0001] The invention relates to the field of metal materials, and in particular to a composite chromium oxide coating for flexible printing and a preparation method thereof. Background Art

[0002] Flexographic printing has become a major printing method for packaging printing, and the anilox roll is a mechanism for quantitatively transferring ink to the flexographic plate. Its surface is composed of countless uniformly sized and evenly distributed concave holes, namely cells (also known as "inking holes"), through which the ink is transferred to the printing plate. Therefore, the anilox roll is the "heart" of the flexographic printing press. Although the anilox roll is quite durable and wear-resistant, it can also be damaged in various forms. There are many reasons for the damage of the anilox roll. For example, plasma-sprayed chromium oxide anilox rolls will also produce microcracks during grinding. It usually adopts external cylindrical grinding. The high-speed rotating silicon carbide grinding wheel is used to grind the high-speed rotating anilox roll. The silicon carbide grinding wheel will exert a certain pressure on the anilox roll. Such pressure will cause microcracks inside the coating. We hope to improve the wear resistance of the chromium oxide coating by toughening. Most anilox roll manufacturers claim that chromium oxide ceramic rolls "will not wear out". In fact, although the ceramic roller is very wear-resistant, it will be worn and deformed by the scraper for a long time, resulting in dents, a certain degree of wear and even cracks. Offline cleaning, impact and corrosion of the anilox roller can also easily damage the anilox roller. Similarly, some printing processes and printing equipment can also cause excessive wear of the anilox roller due to their design properties. In addition, the quality of the engraved cells will also have a great impact on its damage resistance.

[0003] Chromium oxide is chromium trioxide, and its chemical formula is Cr 2 O 3 , this substance is insoluble in water, but will dissolve slightly in acidic and alkaline solvents. Chromium oxide is extremely stable in high temperature or corrosive environments. It is light green to dark green fine crystals at room temperature. It will turn brown when heated, and will still turn green after cooling. Chromium oxide is one of the coating film materials that has developed rapidly in recent years and has received widespread attention. It has good high temperature resistance, corrosion resistance, wear resistance and excellent chemical stability. At the same time, this material also has many other excellent properties, such as: strong bonding ability with the base material, low brittleness, high melting point, high hardness, etc. Cr 2 O 3 Coating research focuses on hardness and wear resistance. Although under the same spraying conditions, Cr 2 O 3 The hardness and wear resistance of the coating are better than A1 2 O 3 and TiO 2However, the traditional micron-level ceramic coating is brittle, has many surface defects, and the wear surface is relatively rough. The wear mechanism is mostly abrasive wear. Therefore, how to further improve Cr 2 O 3 coating properties, which has become Cr 2 O 3 New challenges facing coating research. Summary of the invention

[0004] In view of this, the present invention is intended to provide a composite chromium oxide coating for flexible printing and a preparation method thereof, wherein Cr 2 O 3 Taking the matrix as the substrate and adding a toughening phase therein to prepare a toughened chromium oxide composite coating can densify the ceramic coating, thereby increasing the bonding strength between the coating and the matrix and improving the coating performance.

[0005] The technical solution of the embodiment of the present invention is achieved as follows:

[0006] A composite chromium oxide coating for flexible printing, which is special in that: the composition of the composite chromium oxide coating includes a chromium oxide coating arranged on the surface of a steel material, and the weight percentage content (Wt / %) of each element is: ZrO 2 :10-30%、TiO 2 :1-5%、Cr 2 O 3 : 65-89%.

[0007] The weight percentage (Wt / %) of each element in the composite chromium oxide coating is: ZrO 2 :10%、TiO 2 :1%、Cr 2 O 3 :89%.

[0008] The weight percentage (Wt / %) of each element in the composite chromium oxide coating is: ZrO 2 :10%、TiO 2 :5%、Cr 2 O 3 :85%.

[0009] The weight percentage (Wt / %) of each element in the composite chromium oxide coating is: ZrO 2 :20%、TiO 2 :1%、Cr 2 O 3 :79%.

[0010] The weight percentage (Wt / %) of each element in the composite chromium oxide coating is: ZrO 2 :20%、TiO2 :5%、Cr 2 O 3 : 75%.

[0011] The weight percentage (Wt / %) of each element in the composite chromium oxide coating is: ZrO 2 : 30%, TiO 2 :1%、Cr 2 O 3 : 69%.

[0012] The weight percentage (Wt / %) of each element in the composite chromium oxide coating is: ZrO 2 : 30%, TiO 2 :3%、Cr 2 O 3 : 67%.

[0013] The weight percentage (Wt / %) of each element in the composite chromium oxide coating is: ZrO 2 :30%、TiO 2 :5%、Cr 2 O 3 : 65%.

[0014] A method for preparing a composite chromium oxide coating for flexible printing, the special feature of which is that the preparation method comprises the following steps:

[0015] 1) Add chromium oxide, titanium oxide, zirconium oxide and lubricant accounting for 1% of the total raw materials into the ball mill according to the experimental ratio, and add 50% water;

[0016] 2) Add 2% polyethylene glycol as a binder, introduce it into the slurry of the ball mill, and stir evenly;

[0017] 3) During granulation, the parameters of the centrifugal spray dryer are inlet air temperature 150-250℃, outlet temperature 120℃, inverter parameter 45Hz, and constant flow pump parameter controlled at 0-100g / min.

[0018] In the above step 3), the air inlet temperature is 250°C; the constant flow pump parameter is controlled at 80g / min.

[0019] 1. The composite chromium oxide coating of the present invention is Cr 2 O 3 The invention relates to a method for preparing a toughened chromium oxide composite coating by using a substrate and adding a toughening phase thereto. By optimizing the composition of the chromium oxide ceramic coating on the surface of the anilox roller, the toughness and wear resistance of the anilox roller are improved, so that the damage resistance is improved, thereby increasing the service life of the anilox roller.

[0020] 2. Traditional chromium oxide (Cr 2 O3 Although the coating has good wear resistance, it has the problems of high brittleness and many surface defects. In order to solve these problems, the composite chromium oxide coating described in the present application is 2 O 3 Add toughening phase in the matrix: zirconium oxide (ZrO 2 ) and titanium oxide (TiO 2 ), a toughened chromium oxide composite coating is prepared, thereby improving the density, bonding strength and overall performance of the coating.

[0021] 3. In the present invention, the mass percentage of chromium oxide is 65-89%, and chromium oxide has excellent high temperature resistance, corrosion resistance and wear resistance. The proportion of 65-89% in the coating ensures that the coating maintains Cr 2 O 3 The basic characteristics of ZrO 2 and TiO 2 The composite improves its brittleness and improves the overall performance of the coating.

[0022] Zirconia (ZrO 2 ) is a material with high toughness and good wear resistance. Adding 10-30% ZrO in the coating 2 It can significantly improve the toughness of the coating and reduce the microcracks caused by grinding or other external forces, thereby improving the wear resistance and damage resistance of the coating. Titanium oxide (TiO2) plays a role in toughening and improving the coating performance. 1-5% TiO 2 The content helps to improve the bonding strength and chemical stability of the coating. At the same time, the addition of TiO2 can also promote the densification of the coating, reduce the porosity, and improve the wear resistance and corrosion resistance of the coating. 2 With TiO 2 The toughness of Cr2O3 coating can be synergistically enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1-Figure 2 The powder morphology of 500X and 2000X after sintering the No. 1 powder of the present invention;

[0024] Figure 3-Figure 4 The powder morphology of 500X and 2000X after sintering the No. 2 powder of the present invention;

[0025] Figure 5-Figure 6 The powder morphology of 500X and 2000X after sintering No. 3 powder of the present invention;

[0026] Figure 7-Figure 8 The powder morphology of 500X and 2000X after sintering No. 4 powder of the present invention;

[0027] Figure 9-10The powder morphology of 500X and 2000X after sintering No. 5 powder of the present invention;

[0028] Figure 11-Figure 12 The powder morphology of 500X and 2000X after sintering No. 6 powder of the present invention;

[0029] Figure 13-14 The powder morphology of 500X and 2000X after sintering No. 7 powder of the present invention;

[0030] Figure 15-16 The powder morphology of 500X and 2000X after sintering No. 8 powder of the present invention;

[0031] Figure 17-Figure 18 The powder morphology of 500X and 2000X after sintering No. 9 powder of the present invention;

[0032] Fig.19 is the microhardness of the 9 comparative coatings described in the present invention;

[0033] Fig. 20A , Fig. 20B , Fig. 20C The pure Cr of comparative example 3 is 2 O 3 Microscopic morphology of the coating at 1000X, 2000X, and 5000X;

[0034] Fig.21A , Fig.21B , Fig. 21C These are the microscopic morphology images of coating No. 1 at 1000X, 2000X, and 5000X;

[0035] Fig.22A , Fig. 22B , Fig. 22C These are the microscopic morphology images of coating No. 2 at 1000X, 2000X, and 5000X;

[0036] Fig.23A , Fig. 23B , Fig.23C These are the microscopic morphology images of coating No. 3 at 1000X, 2000X, and 5000X respectively;

[0037] Fig.24A , Fig. 24B , Fig.24C These are the microscopic morphology images of coating No. 4 at 1000X, 2000X, and 5000X;

[0038] Fig.25A , Fig.25B , Fig.25C These are the microscopic morphology images of coating No. 5 at 1000X, 2000X, and 5000X respectively;

[0039] Fig.26A , Fig.26B , Fig.26C These are the microscopic morphology images of coating No. 6 at 1000X, 2000X, and 5000X;

[0040] Fig.27A , Fig.27B , Fig.27C These are the microscopic morphology images of coating No. 7 at 1000X, 2000X, and 5000X;

[0041] Fig.28A , Fig.28B , Fig.28C These are the microscopic morphology images of coating No. 8 at 1000X, 2000X, and 5000X;

[0042] Fig.29A , Fig.29B , Fig.29C These are the microscopic morphology images of coating No. 9 at 1000X, 2000X, and 5000X;

[0043] Fig.30 This is the microscopic morphology of coating No. 2 at 5000X;

[0044] Fig.31 for Fig.30 Energy spectrum of point 1 in the middle;

[0045] Fig.32 for Fig.30 Energy spectrum of point 2 in the middle;

[0046] Fig.33 for Fig.30 Energy spectrum of point 3 in the middle;

[0047] Fig.34 The porosity bar graphs of the 10 coatings;

[0048] Fig.35 is the XRD pattern of coating No. 1;

[0049] Fig.36 is the XRD pattern of coating No. 5;

[0050] Fig.37 is the XRD pattern of coating No. 9;

[0051] Fig.38 It is a dot-line graph of cup crack depth of 10 coatings;

[0052] Fig.39 The dot-line graphs of the drop weight failure heights of 10 types of coatings are shown. DETAILED DESCRIPTION

[0053] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0054] The present invention provides a composite chromium oxide coating for flexible printing. Different from the prior art, the composite chromium oxide coating for flexible printing provided by the present invention comprises a chromium oxide coating arranged on the surface of a steel material, and the weight percentage (Wt / %) of each element is: ZrO 2 :10-30%、TiO 2 :1-5%、Cr 2 O 3 : 65-89%.

[0055] The weight percentage (Wt / %) of each element in the above chromium oxide coating is: ZrO 2 :10%、TiO 2 :1%、Cr 2 O 3 :89%.

[0056] The weight percentage (Wt / %) of each element in the above chromium oxide coating is: ZrO 2 :10%、TiO 2 :5%、Cr 2 O 3 :85%.

[0057] The weight percentage (Wt / %) of each element in the above chromium oxide coating is: ZrO 2 :20%、TiO 2 :1%、Cr 2 O 3 :79%.

[0058] The weight percentage (Wt / %) of each element in the above chromium oxide coating is: ZrO 2 :20%、TiO 2 :5%、Cr 2 O 3 : 75%.

[0059] The weight percentage (Wt / %) of each element in the above chromium oxide coating is: ZrO 2 :30%、TiO 2 :1%、Cr 2 O 3 : 69%.

[0060] The weight percentage (Wt / %) of each element in the above chromium oxide coating is: ZrO 2 :30%、TiO 2 :3%、Cr 2 O3 : 67%.

[0061] The weight percentage (Wt / %) of each element in the above chromium oxide coating is: ZrO 2 :30%、TiO 2 :5%、Cr 2 O 3 : 65%.

[0062] A method for preparing a composite chromium oxide coating for flexible printing of the present invention comprises the following steps:

[0063] 1) Preparation of slurry

[0064] The chromium oxide composite powder of the present invention is mainly used for plasma spraying. The solvent used in the test is pure water that has been purified through two steps. Polyethylene glycol with water-soluble polymer properties is selected as a binder. However, if only a binder is added, the resulting composite ceramic powder is less spherical and the shape of the resulting powder particles is irregular. Therefore, a lubricant needs to be added because the presence of the lubricant can avoid the problem of slurry sticking to the wall and clogging during the granulation process.

[0065] Polyethylene glycol is used as a binder, and a volatile lubricant is added thereto. Both are volatile additives, which can ensure that the obtained sample has good fluidity, uniform and dense particles, and does not affect the spraying performance of the powder. At the same time, the addition of the lubricant improves the defects caused by the use of polyethylene glycol alone, avoids the occurrence of nozzle clogging and wall sticking when the slurry enters the granulator, improves the feeding efficiency and increases the sample yield.

[0066] First, according to the experimental ratio, chromium oxide, titanium oxide, zirconium oxide and a lubricant accounting for 1% of the total raw materials are placed in a ball mill, and then 50% of the total raw materials weight of water are added. Ball milling is carried out for 2 hours. After that, the prepared glue is introduced into the ball-milled slurry and stirred evenly to obtain the mixed slurry required for spray granulation.

[0067] 2) Spray granulation

[0068] The process parameters of the granulator in the spray granulation process are very important for the particle size and sphericity of the produced powder. Therefore, it is necessary to control the three parameters in the spray granulation, mainly including the nozzle speed, inlet and outlet temperature and constant flow pump parameters.

[0069] Nozzle speed: The speed directly affects the particle size of the produced powder, that is, the larger the speed, the smaller the powder particle size. In addition, too low a nozzle speed will cause nozzle blockage, while too high a speed will easily damage the nozzle rotor. At the same time, the produced powder particle size is too small, which affects the fluidity of the powder. After preliminary adjustment tests, it was finally concluded that the inverter parameters of the present invention need to be controlled at about 45Hz.

[0070] Inlet and outlet temperature: Increasing the inlet and outlet temperatures can increase the powder output and completely volatilize the additives, but as the inlet temperature increases, the bulk density of the powder will decrease. Generally, the inlet temperature is adjusted between 150-250℃, and the exhaust outlet temperature must be stable to ensure that the moisture content of the powder is consistent. The inlet air temperature is 250℃, and the outlet temperature is controlled at 120℃ to obtain the required sample.

[0071] Constant flow pump parameters: This system is mainly responsible for providing feeding pressure to the nozzle, that is, the flow rate of the slurry is controlled by the constant flow pump. The range of the constant flow pump is 0-100g / min. Too low flow rate will affect the test efficiency, but too high flow rate will easily lead to nozzle blockage and incomplete sample drying, so the constant flow pump parameters should be controlled at around 80g / min.

[0072] 3) Sintering of powder

[0073] The chromium oxide composite powder after granulation is basically spherical and has obvious granularity, but the surface porosity of the powder particles is high and the surface density is very poor. Further sintering is required to make the surface dense, thereby improving its density and strength. The chromium oxide composite powder used for spraying in this experiment is made by spray granulation and sintering in a molybdenum wire furnace under high temperature conditions. The final sintering temperature is 1330 degrees Celsius.

[0074] 4) Powder crushing and screening

[0075] After sintering, the powder will shrink to a certain extent and agglomerate into blocks, so the blocks need to be broken into powders and sieved according to the required particle size to obtain the powder used for plasma spraying. The part below the -325 mesh sieve is the powder for the spraying working layer.

[0076] After continuous exploration and research by the inventors, the plasma spraying powders with different composition ratios prepared by the above method are shown in Table 1 below:

[0077]

[0078] Example 1

[0079] A composite chromium oxide coating for flexible printing, comprising a chromium oxide coating disposed on a steel surface, wherein the weight percent content (wt / %) of each element is: ZrO 2 :10%、TiO 2 :1%、Cr 2 O 3 :89%.

[0080] Example 2

[0081] A composite chromium oxide coating for flexible printing, comprising a chromium oxide coating disposed on a steel surface, wherein the weight percent content (wt / %) of each element is: ZrO 2 :10%、TiO 2 :3%、Cr 2 O 3 :87%.

[0082] Example 3

[0083] A composite chromium oxide coating for flexible printing, comprising a chromium oxide coating disposed on a steel surface, wherein the weight percent content (wt / %) of each element is: ZrO 2 :10%、TiO 2 :5%、Cr 2 O 3 :85%.

[0084] Example 4

[0085] A composite chromium oxide coating for flexible printing, comprising a chromium oxide coating disposed on a steel surface, wherein the weight percent content (wt / %) of each element is: ZrO 2 :20%、TiO 2 :1%、Cr 2 O 3 :79%.

[0086] Example 5

[0087] A composite chromium oxide coating for flexible printing, comprising a chromium oxide coating disposed on a steel surface, wherein the weight percent content (wt / %) of each element is: ZrO 2 :20%、TiO 2 :3%、Cr 2 O 3 : 77%.

[0088] Example 6

[0089] A composite chromium oxide coating for flexible printing, comprising a chromium oxide coating disposed on a steel surface, wherein the weight percent content (wt / %) of each element is: ZrO 2 :20%、TiO 2 :5%、Cr 2 O 3 : 75%.

[0090] Example 7

[0091] A composite chromium oxide coating for flexible printing, comprising a chromium oxide coating disposed on a steel surface, wherein the weight percent content (wt / %) of each element is: ZrO 2:30%、TiO 2 :1%、Cr 2 O 3 : 69%.

[0092] Example 8

[0093] A composite chromium oxide coating for flexible printing, comprising a chromium oxide coating disposed on a steel surface, wherein the weight percent content (wt / %) of each element is: ZrO 2 :30%、TiO 2 :3%、Cr 2 O 3 : 67%.

[0094] Example 9

[0095] A composite chromium oxide coating for flexible printing, comprising a chromium oxide coating disposed on a steel surface, wherein the weight percent content (wt / %) of each element is: ZrO 2 :30%、TiO 2 :5%、Cr 2 O 3 : 65%.

[0096] Comparative Example 1

[0097] A composite chromium oxide coating for flexible printing, comprising a chromium oxide coating disposed on a steel surface, wherein the weight percent content (wt / %) of each element is: ZrO 2 :30%、TiO 2 :0%、Cr 2 O 3 : 70%.

[0098] Comparative Example 2

[0099] A composite chromium oxide coating for flexible printing, comprising a chromium oxide coating disposed on a steel surface, wherein the weight percent content (wt / %) of each element is: ZrO 2 :0%、TiO 2 :5%、Cr 2 O 3 : 95%.

[0100] Comparative Example 3

[0101] A composite chromium oxide coating for flexible printing, comprising a chromium oxide coating disposed on a steel surface, wherein the weight percent content (wt / %) of each element is: ZrO 2 :0%、TiO 2 :0%、Cr 2 O 3 : 100%.

[0102] The preparation method of the composite chromium oxide coating in Examples 1-9 and Comparative Examples 1-3 comprises the following steps:

[0103] 1) According to the experimental ratio, the corresponding chromium oxide, titanium oxide and zirconium oxide are prepared, the total raw materials and lubricant accounting for 1% of the total raw materials are added into a ball mill, ball milled for 2 hours, and water accounting for 50% of the total raw materials is added;

[0104] 2) Add 2% of the total raw material weight of polyethylene glycol as a binder, introduce it into the slurry of the ball mill, and stir evenly;

[0105] 3) The parameters of the centrifugal spray dryer during granulation are as follows: inlet air temperature 250°C, outlet temperature 120°C, inverter parameter 45Hz, and constant flow pump parameter controlled at 80g / min.

[0106] 4) Finally, the powder was plasma sprayed to prepare a coated sample. The process parameters of supersonic plasma spraying were voltage 120V, current 440A, main gas flow rate 100L / min, powder feeding amount 20g / min, carrier gas flow rate 10L / min, and spray gun distance 95mm.

[0107] Powder and coating performance analysis

[0108] 1) Powder morphology and particle size analysis

[0109] The nine kinds of powders prepared by the centrifugal spray drying method in Examples 1-9 were observed under a scanning electron microscope after sintering. Figure 1-18 As shown, by observing the microscopic morphology of the 9 composite powders of Examples 1-9, it can be seen that the sphericity of the powders is good and the particle size is moderate, which can be used for later plasma spraying to prepare coatings. The powder used for plasma spraying can only prepare high-performance coatings within a certain particle size distribution range, because too large powder particles will cause the powder delivery tube to be easily blocked, and too small particles will cause serious burning of the powder. At the same time, fine powders are also easily adsorbed on the wall of the powder delivery tube, resulting in reduced aperture, difficulty in powder delivery, and even gun blocking. The quality of the coating obtained by plasma spraying depends largely on the particle size of the spraying powder. When the spraying parameters and other factors are determined, the more uniform the particle size of the spraying powder, the more fully the powder melts during the high-temperature heating and melting process of the spraying, and the higher the density of the prepared coating. The particle size of the powder prepared in this experiment is required to be around 15~45 μm, and the density and other aspects of the coating obtained within this size range are optimal. In this paper, LS-609 laser particle size analyzer was used to analyze the laser particle size of 9 kinds of powders, and the obtained powder particle size test results were made into a particle size distribution diagram, as shown in Figure 1-18As shown in the powder particle size distribution diagram, it can be seen that more than 80% of the 9 kinds of powders in Examples 1-9 have a particle size between 15 and 45 μm, and the particle size distribution is uniform, which can be used for subsequent plasma spraying.

[0110] 2) Analysis of powder fluidity and bulk ratio

[0111] To test the fluidity and bulk ratio of the powders prepared in Examples 1-9 and Comparative Examples 1-3, 50 g of powder was placed in the equipment funnel. It was found that the powders in each group could not flow down the funnel wall naturally, so it was considered that they had no fluidity. Then, auxiliary means were used to make the powder flow into the 25 cm volume below. 3 Fill the cylindrical container and weigh it. Then calculate the bulk density = mass of powder in the cylindrical container / 25, in g / cm 3 .

[0112] The measured bulk ratios of powders No. 1 to No. 9 are 1.272 g / cm 3 , 1.372 g / cm 3 , 1.464 g / cm 3 , 1.368g / cm 3 , 1.468 g / cm 3 , 1.640 g / cm 3 , 1.476 g / cm 3 , 1.572 g / cm 3 , 1.556 g / cm 3 The powders prepared in Comparative Examples 1-3 have a bulk density of 1.468 g / cm 3 , 1.452g / cm 3 , 1.267g / cm 3 .

[0113] 3) Performance analysis of coating

[0114] In order to explore the effects of composite powders with different component contents on the various properties of the coating, the chromium oxide composite coatings prepared in Examples 1-9 and Comparative Examples 1-3 were subjected to microhardness tests, surface morphology and porosity analysis, XRD analysis, cupping tests and drop hammer tests.

[0115] 4) Coating microhardness test

[0116] Microhardness test shows that the hardness of Q235 steel is generally between 200-300HV0.3, and the hardness of the base layer is between 300-450HV0.3. The closer to the working layer, the greater the hardness. Figure 19-2As shown in Table 9, the average microhardness of coating No. 9 of Example 9 is about 712.9 HV0.3 at the maximum, the average microhardness of coating No. 4 is about 544.0 HV0.3 at the minimum, and the hardness of coating No. 7, 8, and 9 is obviously larger. The specific average microhardness is shown in Table 2 below:

[0117]

[0118] 5) Surface micromorphology of coating

[0119] The cross-sections of the coatings of Examples 1 to 9 and the coating of Comparative Example 3 were ground and polished, and their surface morphologies were observed and analyzed under a scanning electron microscope. Photos were taken at 1000 times, 2000 times, and 5000 times, respectively. The cross-sectional morphologies are as follows: Fig. 20A , Fig. 20B , Fig. 20C , Fig.21A , Fig.21B , Fig. 21C , Fig.22A , Fig. 22B , Fig. 22C , Fig.23A , Fig. 23B , Fig.23C , Fig.24A , Fig. 24B , Fig.24C , Fig.25A , Fig.25B , Fig.25C , Fig.26A , Fig.26B , Fig.26C , Fig.27A , Fig.27B , Fig.27C , Fig.28A , Fig.28B , Fig.28C , Fig.29A , Fig.29B , Fig.29C , as shown. Observing the scanning electron microscope image, (Comparative Example 3) pure Cr 2 O 3 And the coatings of No. 1, No. 2, No. 4 and No. 5 have more holes.

[0120] 6) Surface energy spectrum analysis of coating

[0121] EDS spectrum analysis of the light-colored phase region and the dark-colored phase region revealed (e.g. Figure 30-Figure 33 As shown in Table 3, the lighter phase is the Zr-rich region, the darker phase is the Cr-rich region, and the distribution of Ti is relatively uniform. Combined with the SEM image of the coating cross section, it can be observed that the coating is composed of a hard phase Cr. 2 O 3 With toughening phase ZrO 2 Alternating composition and interspersed with binder phase TiO2 This makes the coating have higher hardness and higher toughness.

[0122]

[0123] 7) Porosity analysis of coating

[0124] Image analysis software Image Pro-plus was used to identify the coating microscopic morphology of 10 coatings at 2000X and analyze the porosity of the coatings. Three pictures of different areas of the coatings were selected to analyze and calculate the porosity and take the average value. 2 O 3 Coating, 9 kinds of Cr in Examples 1-9 2 O 3 The porosity of the composite coating is Fig.34 . After comparing the data, it can be seen that compared with other coatings, the porosity of coatings 7, 8, and 9 is significantly lower, indicating that the increase of zirconium oxide content can reduce the porosity of the coating. And the porosity of coating 3 is significantly lower than that of coatings 1 and 2, and that of coating 6 is significantly lower than that of coatings 4 and 5, indicating that a certain amount of TiO 2 Can increase Cr 2 O 3 Powder spraying deposition efficiency promotes the densification of ceramic coating, thereby increasing the bonding strength between coating and substrate and improving coating performance.

[0125] The porosities of Comparative Example 1, Comparative Example 2, and Comparative Example 3 are 6.58%, 2.25%, and 6.24%, respectively.

[0126] The No. 1, No. 5 and No. 9 coatings were tested by XRD. Figure 35-37 As shown, the compound distribution of the three coatings was observed and it was found that the same substances were generated.

[0127] 8) Cupping test of comparative coating

[0128] The pure Cr in comparative example 3 is 2 O 3 Coating, 9 kinds of Cr in Examples 1-9 2 O 3 The composite coating and the coating of comparative example 1-2 were subjected to a cupping test, and the distance the punch moved when the first crack appeared on the coating surface was recorded, and a dot-line graph was drawn as shown in FIG. Fig.38 As shown, it was found that the pure Cr in Comparative Example 3 (No. 0) 2 O 3 The crack depth of the coating is extremely small, that is, the toughness is very poor, and the Cr 2 O 3The crack depths of coatings 1, 2, 3, 4, 5, 6, 7, 8, and 9 show a step-like increase, indicating that within a certain range, as ZrO 2 The increase of Cr 2 O 3 The toughness of the coating is improved to a certain extent.

[0129] The cupping crack depths of Comparative Examples 1, 2 and 3 are 1.00 mm, 0.89 mm and 0.54 mm respectively.

[0130] 9) Drop weight test of comparative coating

[0131] The pure Cr in comparative example 3 is 2 O 3 Coating, 9 kinds of Cr in Examples 1-9 2 O 3 The composite coating and the coating of comparative example 1-2 were subjected to a drop hammer test, and the height of the hammer falling when the first crack appeared on the coating surface was recorded, and a dot-line graph was drawn as shown in FIG. Fig.39 As shown, the analysis results show that the pure Cr 2 O 3 The coating can withstand the lowest hammer drop height, that is, the toughness is the worst, and the damage height of coatings 1 to 9 in Examples 1-9 almost shows a linear upward trend, indicating that a certain amount of ZrO 2 With TiO 2 Can enhance Cr 2 O 3 Toughness of coating.

[0132] The cupping crack depths of Comparative Examples 1, 2 and 3 are 7.56 cm, 6.23 cm and 4.33 cm respectively.

[0133] In summary,

[0134] 1. By comparing the microhardness of the 9 coatings in Examples 1-9, the microhardness of coating No. 9 is the highest, about 712.9HV0.3. Overall, the hardness of coating No. 7, 8, and 9 is obviously too high.

[0135] 2. Compared with other coatings, the porosity of coatings 7, 8, and 9 is significantly lower, indicating that the increase of zirconium oxide content can reduce the porosity of coatings. And the porosity of coating 3 is significantly lower than that of coatings 1 and 2, and that of coating 6 is significantly lower than that of coatings 4 and 5, indicating that a certain amount of TiO 2 Can improve C r2 O 3 Powder spraying deposition efficiency promotes the densification of ceramic coating, thereby increasing the bonding strength between coating and substrate and improving coating performance.

[0136] 3. The cupping test results show that pure Cr 2 O 3 The crack depth of the coating is extremely small, that is, the toughness is very poor, and the Cr 2 O 3 The crack depths of coatings 1, 2, 3, 4, 5, 6, 7, 8, and 9 show a step-like increase, indicating that within a certain range, as ZrO 2 The increase of Cr 2 O 3 The toughness of the coating is improved to a certain extent.

[0137] 4. Analysis of the drop weight test results showed that pure Cr 2 O 3 The coating can withstand the lowest hammer drop height, that is, the toughness is the worst, while the other coatings 1 to 9 have an almost linear upward trend in their damage heights, indicating that a certain amount of ZrO 2 With TiO 2 Can enhance Cr 2 O 3 Toughness of coating.

[0138] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A composite chromium oxide coating for flexible printing, characterized in that: The composition of the composite chromium oxide coating includes a chromium oxide coating disposed on the surface of the steel material, and the weight percentage content (Wt / %) of each element is: ZrO2: 30%, TiO2: 5%, Cr2O3: 65%; The particle size of the granulated powder forming the chromium oxide coating is 15 to 45 μm.

2. A method for preparing a composite chromium oxide coating for flexible printing, characterized in that: The preparation method comprises the following steps: 1) Add chromium oxide, titanium oxide, zirconium oxide and lubricant accounting for 1% of the total raw materials into a ball mill according to the experimental ratio, and add 50% of water; The composition of the composite chromium oxide coating includes a chromium oxide coating disposed on the surface of the steel material, and the weight percentage content (Wt / %) of each element is: ZrO2: 30%, TiO2: 5%, Cr2O3: 65%; 2) Add 2% polyethylene glycol as a binder, introduce it into the slurry of the ball mill, and stir it evenly; 3) The parameters of the centrifugal spray dryer during granulation are inlet air temperature 150-250°C, outlet temperature 120°C, inverter parameter 45Hz, and constant flow pump parameter controlled at 0-100g / min; the particle size of the granulated powder is 15-45μm.

3. The preparation method according to claim 2, characterized in that: In step 3), the air inlet temperature is 250° C. and the constant flow pump parameter is controlled at 80 g / min.

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