CN103433481A - Containing La, Ce and Pr flake multi-element aluminum-zinc-silicon alloy powder and its preparation method - Google Patents

Abstract

The invention relates to a scale-shaped multi-component zinc-aluminum alloy powder containing La, Ce and Pr and a preparation method thereof, wherein the scale-shaped multi-component zinc-aluminum alloy powder has a sheet thickness of 0.1-1 μm and an average sheet diameter of 5-35 μm. And the specific composition of particle size is as follows: sheet diameter less than 5 μm accounts for ≤ 20%, sheet diameter 5 ~ 33 μm accounts for ≥ 70%, sheet diameter greater than 33 μm ≤ 10%, and the average sheet diameter of the scaly multi-component zinc-aluminum alloy powder is the same as The aspect ratio of the sheet thickness is 35-200. The scaly metal powder provided by the invention and the preparation method thereof are particularly suitable for the production of dacromet coating solutions, inorganic zinc-rich paints, heavy anti-corrosion paints and other fields.

Description

Scale multi-element Al-Zn-Si alloy powder containing La, Ce and Pr and preparation method thereof

technical field

The invention relates to a scaly multi-element aluminum-zinc-silicon alloy powder and a preparation method thereof.

Background technique

Dacromet technology was first born in the late 1950s. It is a metal coating treatment technology similar to electrogalvanizing. Mike Martin, an American scientist, developed a metal zinc flake and added aluminum flake, chromic acid, Highly dispersed water-soluble paint with deionized water as a solvent, the paint sticks to the metal substrate, and is coated and baked in a fully closed circuit to form a thin coating. Dacromet coating successfully resists the erosion of chloride ions, and the anti-corrosion technology has entered a new level, which has innovated the defect of short anti-corrosion life of the traditional process. The appearance of Dacromet coating is uniform silver gray. The coating contains 80% thin zinc flakes and aluminum flakes, and the rest is chromate. It has excellent properties, such as strong corrosion resistance, etc.; it is especially suitable for high Strength bearing parts, such as high-strength bolts used in subway projects; high heat resistance; heat resistance temperature can reach 300 °C. In addition, it also has the advantages of high permeability, high adhesion, high friction reduction, high weather resistance, high chemical resistance stability and no environmental pollution. It has been widely used in many fields such as automobiles, civil engineering, electric power, chemical industry, marine engineering, household appliances, railways, highways, bridges, tunnels, military industries, etc. in industrially developed countries. At present, there are many kinds of dacromet coating liquids, but there are still generally defects that need to be further improved, such as the need to achieve chromium removal and the need to further improve its performance, especially the performance of the more commonly used scaly alloy powders still cannot fully meet the process requirements.

In addition, the existing domestic production methods of scaly metal powder mainly include mechanical methods, physical methods and chemical methods. Among them, the mechanical methods mainly include ball milling and ultrasonic pulverization, among which ball milling is more commonly used in actual production. The ball milling method can be further divided into dry milling and wet milling. The wet milling method mainly includes the process of adding a medium such as solvent oil during the grinding process of the metal powder, and then through sorting, filtering, drying, and screening. , secondary drying, packaging and other processes can be realized. The drying process of the above-mentioned wet grinding method is complicated, the cycle is long, the efficiency is low, and the metal powder is easy to oxidize. What is more serious is that a part of the medium will remain in the dried metal powder, which will affect the use range and quality of the metal powder. However, the dry grinding process requires long-term stirring and dispersion, which increases energy consumption, and the shape and performance of the ultrafine zinc powder and aluminum powder produced by the dry grinding process are far behind the powders required by the Dacromet process. Thereby limiting the process of industrialization of chromium-free zinc-aluminum coating technology.

Therefore, providing an improved scaly alloy powder and its preparation method has become an urgent technical problem in this field.

Contents of the invention

In view of the deficiencies of the prior art, the object of the present invention is to provide a high-quality scaly multi-component zinc-aluminum alloy powder that can meet the requirements of special coatings, and to provide a preparation method with high efficiency, low cost and suitable for actual production.

The scale-shaped multi-component zinc-aluminum alloy powder provided by the present invention has the following components by weight percentage: Al: 15%-69%; Si: 0.2-3%; Mg: 0.1-5%; at least two kinds of rare earth elements Total amount: 0.02-0.9%, and wherein the at least two rare earth elements mainly include La, Ce and Pr; the total amount does not exceed 1% of impurities; the balance is Zn, wherein the scale-shaped multi-element zinc-aluminum alloy powder is The sheet thickness is 0.1-1 μm, the average sheet diameter is 5-35 μm, and the specific composition of particle size is: sheet diameter less than 5 μm accounts for ≤20%, sheet diameter 5-33 μm accounts for ≥70%, sheet diameter greater than 33 μm ≤10%, In addition, the aspect ratio of the average sheet diameter to sheet thickness of the scaly multi-element zinc-aluminum alloy powder is 35-200.

Preferably, the aspect ratio of the average sheet diameter to sheet thickness of the scaly multi-element zinc-aluminum alloy powder is 50-150.

Preferably, the bulk density of the scaly multi-component zinc-aluminum alloy powder is 1.0-3.0 g·cm ^-3 .

Preferably, the water-covering area of the scaly multi-element zinc-aluminum alloy powder is 0.4-2.0 m ² ·g ^-1 .

Preferably, the content of La, Ce and Pr and the percentage of the total amount of rare earth elements are ≥ 85%.

On the other hand, the present invention also provides a manufacturing method of the scale-shaped multi-element zinc-aluminum alloy powder. According to the weight percentage of each component of the scale-like multi-element zinc-aluminum alloy powder, the materials are prepared, and each component is mixed in a melting furnace according to the ratio. The zinc-aluminum alloy is prepared in the process, and then poured into zinc-aluminum alloy rods by deep well casting, and then put the zinc-aluminum alloy rods into the vacuum atomization powder making equipment to atomize into 200-500 mesh spherical zinc-aluminum alloy powders, and then cast the zinc-aluminum alloy rods Add the spherical zinc-aluminum alloy powder into the ball mill, add grinding aids and ball milling media at the same time for ball milling, and first vacuumize and then pass in an inert gas, and pass a cooling liquid into the interlayer of the ball mill to control the temperature during the ball milling process to 20-60 °C, the ball milling time is 8-20 hours, and the rotational speed of the ball mill is kept at 30-100 rpm, so that the spherical multi-component zinc-aluminum alloy powder is ball-milled into flake alloy powder, and the scale-shaped multi-component zinc-aluminum alloy powder is prepared.

Preferably, wherein the grinding aid is one or more mixtures of zinc stearate, calcium stearate, molybdenum sulfide, polyvinyl alcohol, sodium dodecylbenzenesulfonate and glycerol.

Preferably, the grinding aid is added in a ratio of 1% to 10% of the weight of the spherical multi-element zinc-aluminum powder.

Preferably, the ball milling medium is ceramic balls or steel balls with a particle size of 1-15 mm.

Preferably, the weight ratio of the ball milling medium to the spherical multi-element zinc-aluminum powder is (6-20):1.

The average sheet diameter of the scaly multi-component zinc-aluminum alloy powder of the present invention is 5-35 μm, and the specific composition of particle size is: sheet diameter less than 5 μm accounts for ≤20%, sheet diameter 5-33 μm accounts for ≥70%, and sheet diameter is greater than 33 μm ≤10%. The specific composition of the particle size in the present invention not only ensures the requirement of the average sheet diameter, but also makes the geometric size distribution of the powder uniform, and the uniform particle size distribution is conducive to reducing defects such as pores in the coating, forming a uniform "layer-by-layer ” structure, which is beneficial to inhibit the penetration of corrosive media, thereby improving the anti-corrosion performance of the coating.

The scale-shaped multi-element zinc-aluminum alloy powder of the present invention has a sheet thickness of 0.1-1 μm, an average sheet diameter of 5-35 μm, and a ratio of average sheet diameter to sheet thickness to diameter-thickness of 35-200, which greatly improves the scale-shaped multi-element zinc-aluminum alloy powder. The diameter-thickness ratio of alloy powder has great practical significance. Because of the increase of the diameter-thickness ratio, on the one hand, it can reduce the amount of zinc-aluminum alloy powder used per unit area when coating the coating, which greatly reduces the production cost; on the other hand, the increase of the diameter-thickness ratio can make the coating on the workpiece The flaky zinc-aluminum alloy powder on the surface is denser, which reduces the voids caused by excessive thickness of the flaky alloy powder or uneven sheet diameter and thickness during coating, and improves the anti-corrosion performance of the coating after coating. Therefore, compared with the prior art, the scaly multi-element zinc-aluminum alloy powder of the present invention has achieved a major breakthrough.

Furthermore, the bulk density of the scaly multi-component zinc-aluminum alloy powder in the present invention is 1.0-3.0 g·cm ^-3 , which is finally obtained by the inventors' creative efforts. Because there are many factors that can affect the bulk density of powder, such as powder particle shape, size and particle size distribution, etc. And these factors will be significantly different due to different powder preparation methods and process conditions. However, the scale-shaped multi-element zinc-aluminum alloy powder described in the present invention satisfies the premise that the particle size is small and the degree of flaking is high, and through the improvement of the production process, a smaller bulk density is further realized, thereby improving the The dispersibility of the flaky multi-component zinc-aluminum alloy powder in the paint further meets the requirements of Dacromet paint.

Further, the present invention makes the water-covered area of the scale-shaped multi-element zinc-aluminum alloy powder 0.4-2.0m ² ·g ^-1 through the improvement of the production process, indicating that the scale-like multi-element zinc-aluminum alloy powder of the present invention is flaky High degree, good coverage, good dispersion in water. The water-covering area of the scaly multi-element zinc-aluminum alloy powder in the present invention has exceeded that of domestic simple zinc powder, and can even reach the standard of foreign simple zinc powder products, and has achieved very outstanding technical effects.

On the other hand, compared with the prior art, the preparation method of the scaly metal powder provided by the present invention replaces the defect of using liquid as the grinding medium in wet grinding, and grinds by adding grinding aids and ball milling media, and after drying The metal powder will not leave any medium, which ensures the range and quality of the metal powder.

Furthermore, the added grinding aids and ball milling media also ensure that no cold welding occurs between the metal powders.

Furthermore, inert gas is introduced into the closed ball mill to avoid the entry of oxygen and prevent the metal powder from oxidizing.

Further, during the ball milling process, the temperature of the metal powder is controlled between 20°C and 60°C by adjusting the amount of cooling water in the interlayer of the ball mill, and at the same time, the speed of the ball mill is adjusted at 30-100 rpm for ball milling, so that the spherical metal can be The powder is ball milled into flake metal powder.

In addition, by controlling different ball milling speeds, the quality and application range of the metal powder can be improved, so that the prepared metal powder can be used not only for Dacromet coatings, but also for other anti-corrosion coatings such as zinc-rich paints.

Furthermore, the interlayer structure of the ball mill in the present invention allows cooling liquid such as water to pass through the interlayer of the ball mill instead of directly contacting the powder. Compared with the traditional wet milling and long-time dry milling methods, the use of water cooling to control the milling temperature not only avoids the defects of wet milling, but also overcomes the need for long-term drying, greatly improving production efficiency.

In addition, the scaly multi-component zinc-aluminum alloy powder provided by the present invention is obtained by dry ball milling, which completely avoids the influence of the medium coated on the surface of the powder during wet grinding, such as solvent oil, on the performance of subsequent coatings.

Finally, due to the passivation effect of aluminum, the zinc-aluminum alloy powder provided by the present invention greatly slows down the consumption rate of zinc. , greatly improving the anti-corrosion performance and anti-corrosion life of the coating.

In summary, the scaly metal powder provided by the present invention and its preparation method are particularly suitable for the production of dacromet coating liquid, inorganic zinc-rich paint, heavy anti-corrosion paint and other fields. Not only that, the preparation method provided by the present invention can also be applied to the production of other flake metal powders, such as: aluminum powder, copper powder, copper-zinc alloy powder, silver powder and so on.

Description of drawings

Figure 1 Interlayer structure diagram of horizontal ball mill

Detailed ways

The flaky multi-element aluminum-zinc-silicon alloy powder of the present invention is made up of elements such as Al, Si, Mg, Zn and rare earth, has listed some preferred specific examples of each composition weight percentage in the present invention in the table 1, but each of the present invention The content of the constituents is not limited to the specific values listed in Table 1, and for those skilled in the art, reasonable generalization and derivation can be made on the basis of the specific values listed in Table 1.

It should be noted that, on the basis of providing a high-quality flaky multi-component zinc-aluminum alloy powder that can meet the requirements of special coatings, the flaky aluminum-zinc-silicon The performance of the alloy powder is far beyond the scale-shaped alloy powder in the prior art, indicating that the internal microstructure of the scale-shaped aluminum-zinc-silicon alloy powder of the present invention has also undergone very large changes, although these microscopic changes cannot be achieved by the scale-shaped aluminum alloy powder. The structure and/or composition etc. of zinc-silicon alloy powder are further limited and described, but through the further description of the performance parameters in Table 1, those skilled in the art can clearly know the effect it plays on the scale-shaped aluminum-zinc-silicon alloy powder of the present invention. Limitation.

However, performance parameters such as bulk density and covered water area involved in Table 1 are not essential technical features to solve the present invention, but are only better technical solutions that the present invention further obtains relative to the prior art. For the present invention, the core content lies in the setting of the composition of the scale-like multi-element zinc-aluminum alloy powder, especially the setting of the specific composition of the powder sheet thickness, sheet diameter, particle size and aspect ratio to achieve the suitable for the production of Daq The purpose of the invention of Luo et al. On this basis, the further improvement of the production process all makes the technical effect more prominent and superior. Therefore, in the following Table 1 in the description, record the two performance parameters of bulk density and water cover area at the same time, and it is only for more detailed and convenient introduction of the technical solution of the present invention, rather than as a solution to the technical problem of the present invention. The necessary technical characteristics are described.

Similar to this, Table 1 further provides the composition and specific content of the rare earth elements used in the present invention and is also described as a preferred embodiment. Those skilled in the art should be able to determine that it is not only the use of the rare earth elements given in Table 1. Only rare earth elements and their content can solve their technical problems, and those skilled in the art can certainly determine that as long as the total amount of rare earth elements is within the range of 0.02-0.9%, two kinds of rare earth elements and their contents are given in Table 1. Basically, adding other rare earth elements in an appropriate amount can also solve its technical problems. Therefore, the two rare earth elements in Table 1 are also not described as essential conditions.

Table 1 each composition (percentage by weight) and performance parameter thereof

In conjunction with accompanying drawing 1, the implementation method of preparing scale-shaped multi-element zinc-aluminum alloy powder according to the present invention is described in detail. First, the materials are prepared according to the requirements, and the zinc-aluminum alloy is prepared in a melting furnace according to the ratio of each component, and then poured by deep well casting into zinc-aluminum alloy rods. Then, put the zinc-aluminum alloy rod into the vacuum atomization powder making equipment and atomize it into a spherical powder of 200 to 500 meshes, then add the spherical zinc-aluminum alloy powder into the ball mill, and add grinding aids at the same time, and the ball milling medium is used for ball milling. After vacuuming, inert gas is introduced into the interlayer 1 of the ball mill to control the milling temperature at 20-60°C, the milling time is 8-20 hours, and the rotational speed of the ball mill is kept at 30-100 rpm. The alloy powder is ball milled into flake alloy powder to prepare scale-like multi-element zinc-aluminum alloy powder.

The ball mill adopted in the present invention is a ball mill interlayer 1 added on the basis of the prior art horizontal ball mill, so that a cooling liquid can be passed into the interlayer 1 to control the ball milling temperature, thereby realizing the separation of the cooling liquid and the powder without contact. The purpose of the invention to overcome the defects of wet grinding.

Preferably, the ball milling aids include zinc stearate, calcium stearate, molybdenum sulfide, polyvinyl alcohol, sodium dodecylbenzenesulfonate, glycerol and the like. The amount of stearate and molybdenum sulfide is 1-10% of the metal powder weight.

Preferably, the diameter of the ball milling medium is 1-15 mm, preferably ceramic balls or steel balls, etc., and the ratio of it to the raw material aluminum-zinc-silicon alloy powder is 6:1 to 20:1.

Preferably, the running speed of the ball mill is not lower than 30r/min, and the preferred selection range is 30-100r/min.

Example 1:

Take 10Kg of 300-mesh aluminum-zinc-silicon alloy powder raw material, 0.4Kg of zinc stearate, and 200Kg of steel balls into the ball mill. After vacuuming, nitrogen is introduced, and cooling water is connected to ensure that the temperature during the ball milling process is between 30-40°C. . After ball milling at a speed of 50r/min for 10 hours, the material is discharged, and the ball milled powder is put into a polishing machine for polishing. The polished powder is classified to obtain flake Al-Zn-Si alloy powder.

Example 2:

Get 10Kg of 200-mesh aluminum-zinc-silicon alloy powder raw material, 0.1Kg of polyvinyl alcohol, 0.2Kg of calcium stearate, and 120Kg of steel balls and put them into the ball mill. Between 30-40°C, ball mill at a speed of 100r/min for 14 hours to discharge the material, put the ball-milled powder into a polishing machine for polishing, and classify the polished powder to obtain flake-shaped aluminum-zinc-silicon alloy powder.

Claims (10)

1. the polynary Zn-Al alloy powder of flakey, its components based on weight percentage is: A1:15%-69%; Si:0.2-3%; Mg:0.1-5%; The total amount of at least two kinds of rare earth elements: 0.02-0.9%, and wherein said at least two kinds of rare earth elements mainly comprise La, Ce and Pr; Total amount is no more than 1% impurity; Surplus is Zn, the sheet of the polynary Zn-Al alloy powder of wherein said flakey is thick is 0.1～1 μ m, average sheet footpath is 5～35 μ m, and specifically consisting of of granularity wherein: the sheet footpath is less than 5 μ m and accounts for≤and 20%, sheet footpath 5～33 μ m account for >=and 70%, the sheet footpath is greater than 33 μ m≤10%, and the average sheet footpath of the polynary Zn-Al alloy powder of described flakey and the thick radius-thickness ratio of sheet are 35～200.

2. the polynary Zn-Al alloy powder of flakey as claimed in claim 1, the radius-thickness ratio that the average sheet footpath of the polynary Zn-Al alloy powder of wherein said flakey and sheet are thick is 50～150.

3. the polynary Zn-Al alloy powder of flakey as claimed in claim 1, the apparent density of the polynary Zn-Al alloy powder of wherein said flakey is 1.0～3.0gcm ^-3.

4. the polynary Zn-Al alloy powder of flakey as claimed in claim 1, the lid water area of the polynary Zn-Al alloy powder of wherein said flakey is 0.4～2.0m ²g ^-1.

5. the polynary Zn-Al alloy powder of flakey as claimed in claim 1, La wherein, the content of Ce and Pr accounts for the percentage of rare earth element total amount >=85%.

6. a method for preparing the polynary Zn-Al alloy powder of the described flakey of claim 1, percentage by weight according to polynary each component of Zn-Al alloy powder of the described flakey of claim 1 is got the raw materials ready, each component is made in smelting furnace to allumen by proportioning, pour into the allumen rod by the deep-well forging type again, then, the allumen rod is put into to the vacuum atomizing powder manufacturing apparatus and be atomized into the spherical allumen powder of 200～500 purpose, again described spherical allumen powder is joined in ball mill, add grinding aid and ball-milling medium to carry out ball milling simultaneously, and pass into again inert gas after first vacuumizing, pass into cooling liquid in the ball mill interlayer and take that to control temperature in mechanical milling process be 20-60 ℃, Ball-milling Time is 8～20 hours, keeping drum's speed of rotation is 30～100 rev/mins, thereby the described spherical polynary allumen sphere of powder is worn into to the sheet alloy powder, prepare the polynary Zn-Al alloy powder of described flakey.

7. method as claimed in claim 6, wherein grinding aid is one or more mixing in zinc stearate, calcium stearate, molybdenum sulfide, polyvinyl alcohol, neopelex, glyceryl alcohol.

8. method as claimed in claim 6, wherein grinding aid adds according to 1%～10% ratio of described spherical polynary zinc-aluminium powder weight.

9. method as claimed in claim 6, wherein ball-milling medium is Ceramic Balls or steel ball, its particle diameter is the 1-15 millimeter.

10. method as claimed in claim 6, wherein ball-milling medium and described spherical polynary zinc-aluminium powder are by weight being (6～20): 1.