CN109049267B - A kind of multi-channel ceramic preform under the coating of Ti-Fe micropowder and its preparation method and application - Google Patents

Abstract

The invention belongs to the field of material processing, and discloses a multi-channel ceramic preform coated with Ti-Fe micro powder, and a preparation method and application thereof. According to the invention, the alloy powder is obtained near the deep eutectic point of the Fe-Ti alloy by a Mechanical Alloying (MA) method, the melting temperature of the alloy powder can reach 1085 ℃, the alloy powder and ZTA ceramic particles are subjected to heat preservation at 1250-1550 ℃ by a pressureless sintering method, molten liquid Ti is promoted to perform activation treatment on the ZTA surface, the ZTA and surface activation effects can be obviously improved, a Ti-O transition layer is formed between the ceramic and the binder, so that the crushing strength of the preform is improved, the wettability of the ceramic surface and a steel solution is improved, and the crushing strength of the preform can reach 5 MPa.

Description

A multi-channel ceramic preform covered with Ti-Fe micropowder and its preparation method and application

technical field

The invention belongs to the field of material processing, and in particular relates to a multi-channel ceramic preform under the coating of Ti-Fe micropowder and a preparation method and application thereof.

Background technique

The ceramic particles in particle-reinforced steel matrix composites play a role in improving the wear resistance of steel materials. During the service process, the steel matrix supports the ceramic particles, making them protrude from the steel matrix with the increase of the wear amount of the steel matrix, preventing the further wear of the steel material. In the process of preparing composite materials, the bonding and forming of ceramic particles and the interface bonding strength between ceramic particles and metals are the keys to improving the performance of composite materials.

In the field of material processing, zirconia toughened alumina ceramics (ZTA) have been widely introduced as fillers into high-chromium cast iron, steel, high-manganese steel and some cemented carbides due to their excellent hardness and toughness. And its better economical applicability is also conducive to the large-scale and mass production of materials; especially in terms of material wear reduction and anti-wear, ZTA particles are often used as anti-wear enhancement phases of metal materials to improve the material's resistance to wear. Impact wear performance. In addition, in the process of iron and steel smelting, micro-nano-scale ZTA ceramic powder is often used as an inoculant to refine the grains and improve the overall mechanical properties of the material. However, due to the good interfacial stability of ZTA ceramics, the difficulty of forming, and the extremely low wettability with steel melt, it has become the main bottleneck for the development of steel-based ceramic composites.

The bonding method of the interface between ceramic particles and metal determines the bonding strength of the interface formed. At present, the interface between ceramic particles and metal is mainly mechanical bonding, and metallurgical bonding is difficult. This is mainly due to the completely different chemical properties of ceramics and metals. , thermal expansion coefficient and other characteristics, resulting in poor bonding between the ceramic particles and the metal interface. In addition, ZTA ceramic preforms are mainly prepared by a combination of mechanical alloying (MA) and pressureless sintering. The MA process uses the long-term intense impact and collision between the powder particles and the grinding ball to promote sufficient atomic diffusion between the powders. Pressureless sintering mainly generates atomic diffusion between the activated powder and the ceramic surface, and also makes the ceramic particles A certain strength can be achieved through the sintering of the powder. The powder that can have a diffusion reaction with the ceramic surface promotes the ceramic surface to have a certain metallicity, which can significantly improve the wettability of the ceramic surface in the molten metal, and achieve full contact between the ceramic surface and the metal solution in the subsequent casting infiltration process. Therefore, there is an urgent need to develop a ceramic that can be metallurgically bonded to the metal-to-metal interface.

SUMMARY OF THE INVENTION

In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the primary purpose of the present invention is to provide a method for preparing a multi-channel ceramic preform covered by Ti-Fe micropowder. In this method, the Fe-Ti mixed powder is alloyed, the Ti content is controlled in the range of 25-35wt%, and the powder and the ceramic are mixed and sintered to achieve high bonding strength between the ceramic particles, and the crushing strength of the preform can be improved. Up to 5MPa, the added Ti powder combines with O in the ZTA ceramics to form an effective activation effect on the ceramic surface.

Another object of the present invention is to provide a multi-channel ceramic preform under the coating of Ti-Fe micropowder prepared by the above method.

Another object of the present invention is to provide the application of the multi-channel ceramic preform covered by the above-mentioned Ti-Fe micropowder in the preparation of high-chromium cast iron-based or high-manganese steel-based steel-based composite materials.

The object of the present invention is realized through the following scheme:

A preparation method of a multi-channel ceramic preform under the coating of Ti-Fe micropowder, which mainly comprises the following steps:

(1) Mixing powder and alloying: mixing reduced iron powder and Ti powder, then adding it into a ball mill tank for alloying by ball milling to obtain a mixed powder binder;

(2) Mixing: mixing the mixed powder binder obtained in step (1) with ZTA particles, then adding water glass as a curing agent and paraffin particles as a pore-forming agent, stirring to make the powder binder evenly coated on the Surface of ZTA ceramic particles to obtain mixed material;

(3) curing: filling the mixture obtained in step (2) into the forming mold, fixing and compacting the preform by tightening the abrasive tool, continuously introducing _CO gas for curing, and then drying and demoulding. Preform after curing and molding;

(4) Vacuum pressureless sintering: put the solidified preform in step (3) into a vacuum sintering furnace for sintering to obtain a ceramic preform with certain strength and porosity.

In order to prevent the specific surface area of the mixed powder after ball milling from increasing, and it is easy to react with oxygen in the air, usually step (1) and step (2) are carried out under protective gas, and the protective gas can be argon or nitrogen. A sort of;

The purity of the reduced iron powder described in the step (1) is 99.99%, and the particle size is less than or equal to 100 mesh; the purity of the Ti powder is 99.99%, and the particle size is less than or equal to 300 mesh;

The amount of the reduced iron powder and Ti powder described in the step (1) is controlled near the composition of the Ti-Fe eutectic region, preferably, the Ti powder accounts for 25-35wt% of the total mass of the reduced iron powder and the Ti powder;

The ball mill described in the step (1) is preferably a planetary ball mill, and the ball milling process is as follows: the ball milling time is 24-30 h, the diameter of the grinding ball is 5-10 mm, the weight ratio of the grinding ball to the mixed powder is 10:1, and the ball mill rotating speed is 300 ~450r/min.

The particle size of the ZTA ceramic particles described in the step (2) is 8 to 10 meshes; the particle size of the paraffin wax particles described in the step (2) is 10 to 12 meshes;

The dosage of the mixed powder described in the step (2) is 3 to 8 wt % of the total weight of the mixed material obtained in the step (2); the amount of the water glass (Na ₂ SiO ₃ ·9H ₂ O) described in the step (2) is The dosage is 3-7% of the weight of the alloy powder described in the step (2), preferably 5%; the dosage of the paraffin particles described in the step (2) is 1% of the total weight of the mixture obtained in the step (2). ~3wt%; the ZTA particles are the remainder;

The stirring described in the step (2) is to make the raw materials evenly mixed, and the rotating speed conventionally used in the art can achieve the purpose of this step, so there is no need to limit the stirring speed, preferably a glass rod is used to stir for 5 to 15 min;

The molding die described in step (3) is preferably a 30mm×20mm×10mm hollow cube with a Φ10mm cylinder in the middle, the die is made of wood fiber material, and each segmented module is connected by fastening bolts.

The tightening described in step (3) refers to aligning the mixture put into the mold through the center line of the mold, and then tightening the bolts.

The continuous introduction of CO ₂ in the step (3) refers to placing the molding die with the mixture in a container with an open air outlet, the inflation rate is 40-60 cm ³ /s, the inflation time is 0.5-1 h, and the The diameter of the trachea is 55-59mm, and the diameter of the air outlet is larger than that of the air inlet, but less than 100mm.

The drying described in step (3) refers to keeping the temperature in a vacuum drying oven at 60-80° C. for 1-2 hours;

The sintering described in step (4) means that the vacuum degree during the sintering process is kept at 2.9×10 ^-3 Pa, and the sintering holding temperature is controlled at 1250-1550° C. for 1 hour, and then cooled to room temperature with the furnace.

A multi-channel ceramic preform under the coating of Ti-Fe micropowder prepared by the above method.

The application of the multi-channel ceramic preform under the coating of the above-mentioned Ti-Fe micropowder in the preparation of high-chromium cast iron-based or high-manganese steel-based steel-based composite materials.

The mechanism of the present invention is:

Ti and O have good bonding characteristics, but pure Ti has a melting point of 1670 ° C, which is much higher than the melting temperature of steel materials, which is not conducive to bonding with oxygen in ZTA, and has a reduced surface activation effect on ZTA. ) method to obtain the alloy powder near the deep eutectic point of Fe-Ti alloy, the melting temperature of the alloy powder can reach 1085 ℃, and the alloy powder and ZTA ceramic particles are kept at 1250-1550 ℃ by the pressureless sintering method, Promote the activation of the ZTA surface by molten Ti, which can significantly improve the ZTA surface activation. A Ti-O transition layer is formed between the ceramic and the binder, which increases the crushing strength of the preform and improves the wetting of the ceramic surface and the iron and steel solution. The crushing strength of the preform can reach 5MPa.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

(1) Fe-Ti micropowder, as a binder of ceramic particles, can form a diffusion reaction with the atoms on the ceramic surface, which can greatly improve the reaction characteristics of the ceramic surface, and the strength and formability of the preform are improved.

(2) During the shaping and curing process of the preform, the reaction between the curing agent and _CO2 can shape the preform, which can speed up the shaping of the preform with complex structure. The preparation of metal matrix composites can significantly improve the shaping efficiency of preforms and the forming ability of complex shapes.

(3) The addition of paraffin particles can improve the void formation ability of the preform, increase the honeycomb porous characteristics of the preform, and improve the infiltration ability of ZTA ceramics.

Description of drawings

Fig. 1 is a photograph of the multi-channel ceramic preform under the coating of Ti-Fe micropowder prepared in Example 1;

2 is a backscattered image of the ceramic particles and the binder in the preform after sintering in Example 1 and an EDS line scan image of the transition layer.

3 is a test chart of the wetting angle between the ZTA ceramic surface and high-chromium cast iron after sintering in Example 1.

Detailed ways

The present invention will be described in further detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

The reagents used in the examples can be routinely purchased from the market unless otherwise specified. The ball mill used in the examples is a YXQM planetary ball mill.

The porosity of the preform is measured by the Archimedes drainage method. The specific calculation steps are as follows: The voids of the ceramic preform are open pores, and the volume percentage of the pores occupied by the whole material is measured by the Archimedes method, and the pores are represented by P. Rate. In the test, the porosity of the preform was determined by the boiling method. First, weigh the required dry weight of the sample, denoted as m ₀ ; put the weighed sample into a clean beaker, and pour distilled water into the beaker until the sample is submerged. Next, place the beaker on an electric furnace and heat it to boiling, and keep it in a boiling state for 1-2 hours, so that the distilled water can completely penetrate into the voids of the preform. Then stop heating and let it come down to room temperature. Then quickly take out the sample and put it into the balance tray prepared in advance for weighing, and weigh the suspension weight m ₁ of the saturated sample in water; take out the saturated sample, wipe off the water on the surface of the saturated sample, and quickly weigh the saturated sample. For the mass m ₂ of the sample, the porosity P is calculated by the formula.

P=(m ₂ -m ₀ )/(m ₂ -m ₁ )

The crush strength of the preform was measured by the following steps: The prepared hollow cylindrical ZTA ceramic preform was placed between two flat plates of the testing machine, so that the axis of the sample was parallel to the flat plate. Continuous loading without vibration, loading speed between 0.5MPa/s-3MPa/s, loading time 10s, crush strength according to the formula:

K=F(De)/Le ²

Where: K—radial crushing strength, in megapascals (MPa);

F - crushing load, the unit is Newton (N);

L—the length of the sample, in millimeters (mm);

D—the outer diameter of the sample, in millimeters (mm);

e—the wall thickness of the sample, in millimeters (mm).

Example 1:

(1) Take the purity of 99.99%, the particle size of 100-200 mesh, the reduced Fe powder and the Ti powder with a purity of 99.99% and a particle size of 300 mesh, and mix the powder according to the total weight of the Ti powder and the iron powder. Go to the ball milling tank for ball milling and alloying. The ball milling process is as follows: the ratio of ball to material is 10:1, the rotation speed is 300r/min, and the ball milling time is 24h, so that Fe and Ti powders can be uniformly mixed to obtain powder binder.

The particle size of the mixed powder after ball milling becomes smaller, the surface energy increases sharply, and the powder easily reacts with oxygen in the air, so it is necessary to take out the powder in a glove box with inert gas;

(2) In a mold composed of a 30mm×20mm×10mm hollow cube with a Φ10mm cylinder in the middle, select 30g of ZTA ceramic particles with a particle size of 8-10 mesh (ZrO ₂ accounts for 20wt.%, Al ₂ O ₃ accounts for 80wt.%) , 2.4g of Ti-Fe mixed micropowder, 0.12g of water glass, and 0.65g of 10-12 mesh paraffin wax particles as a pore-forming agent. Stir with a glass rod for 10 min to make the binder evenly coat the surface of the ZTA particles, and the whole process is carried out in a _N2 protective atmosphere.

(3) Put the preform into the glove box, open the air outlet, and fill with CO ₂ gas, the gas introduction time is 0.5h, and the inflation rate is 50 cm ³ /s. After the preform is cured and formed, the mold is placed in 60 In a constant temperature furnace at ℃, the temperature is kept for 30 minutes for drying, and the preform is demolded and taken out.

(4) The preform was prepared by pressureless sintering. The vacuum degree of the sintering process was kept at 2.9×10 ^-3 Pa, the sintering holding temperature was 1300 ℃, the holding time was 1 h, and the surface-activated multi-channel ZTA ceramics were prepared by cooling to room temperature with the furnace. prefab.

FIG. 1 is a photograph of the ZTA ceramic preform obtained in the example.

Figure 2 is the backscattered image of the ceramic particles and the binder in the preform after sintering in Example 1 and the EDS line scan of the transition layer. It can be seen from Figure 2 that the oxygen and powder binder in the ZTA ceramic Ti is the main component to form the transition layer. Ti reacts with O in ZTA ceramics to form oxides, and there are oxygen loss areas on the surface of the ceramics, and these areas form effective activation; 2um ~ 8um of Ti is formed between the ceramics and the binder. -O transition layer, the bonding strength between ceramic particles is high, no obvious cracking phenomenon is found, the porosity of the preform is 60%, and the crushing strength is 5MPa.

Figure 3 shows the measurement results of the wetting angle between the ZTA surface and metallic high-chromium cast iron after sintering in Example 1. It can be seen that the wetting angle is less than 15.1°, and the ceramic surface shows a good wetting effect, indicating that the sintered ZTA ceramic The surface can be well wetted by wear-resistant steel liquid, which can form effective bonding or element diffusion at the composite interface, which is beneficial to the formation of metallurgical interface.

Example 2

(1) Put the ball mill tank into the glove box, pass in the inert gas, and take the reduced Fe powder with a purity of 99.99% and a particle size of 100-200 meshes and a Ti powder with a purity of 99.99% and a particle size of 300 meshes. The total weight ratio of powder is 25wt.% for powder mixing; the ball mill tank is tightly sealed and alloyed in a YXQM planetary ball mill, wherein the grinding ball diameter is 10mm, the ball-to-material ratio is 10:1, the rotation speed is 300r/min, and the ball milling time 24h, the Fe and Ti powders were fully reacted to obtain powder binders.

Since the particle size of the mixed powder after ball milling becomes smaller, the surface energy increases sharply, and the powder easily reacts with oxygen in the air. Therefore, the ball mill jar is still placed in a glove box filled with inert gas to open the jar to collect the powder, and the The extracted alloy powder is stored in a closed container;

(2) In a mold composed of a 30mm×20mm×10mm hollow cube with a Φ10mm cylinder in the middle, select 30g of ZTA ceramic particles with a particle size of 8-10 mesh (ZrO ₂ accounts for 20wt.%, Al ₂ O ₃ accounts for 80wt.%) , 2.4g of Ti-Fe mixed micropowder, 0.12g of water glass, and 0.65g of 10-12 mesh paraffin wax particles as a pore-forming agent. Stir with a glass rod for 10 min, the binder is evenly coated on the surface of the ZTA particles, and the whole process is carried out in a _N2 protective atmosphere.

(3) Put the preform into the glove box, open the air outlet, and fill with CO ₂ gas, the gas introduction time is 0.5h, and the inflation rate is 50 cm ³ /s. After the preform is cured and formed, the mold is placed in the In a constant temperature furnace at 60°C, hold the temperature for 30 minutes for drying, and then demould the preform.

(4) The preform was prepared by pressureless sintering, the vacuum degree of the sintering process was kept at 2.9×10 ^-3 Pa, the sintering temperature was 1250°C, the holding time was 1h, and the surface-activated multi-channel ZTA ceramics were prepared by cooling to room temperature with the furnace. prefab.

The obtained ZTA ceramic preform can be judged from the backscattered image of the ceramic particles and the binder in the sintered preform and the EDS line scan image of the transition layer, and a Ti-O transition of about 1um to 3um is formed between the ceramic particles and the binder. layer, the porosity of the preform is 62%, and the crushing strength is 1MPa.

In Example 2, the wetting angle between the ZTA surface and the metallic high-chromium cast iron after sintering is also less than 15.1°, which shows that the ZTA ceramic surface after sintering in this example can be well wetted by the wear-resistant steel liquid, and can form an effective composite interface. Bonding or diffusion of elements favors the formation of metallurgical interfaces.

Example 3:

(1) Take the purity of 99.99%, the particle size of 100-200 mesh, the reduced Fe powder and the Ti powder with a purity of 99.99% and a particle size of 300 mesh, and mix the powder according to the total weight of the Ti powder and the iron powder by 35wt.%, and then add Go to the ball milling tank for ball milling alloying. The ball milling process is as follows: the ratio of ball to material is 10:1, the rotation speed is 300r/min, and the ball milling time is 24h, so that Fe and Ti powders can be uniformly mixed to obtain powder binder.

The particle size of the mixed powder after ball milling becomes smaller, the surface energy increases sharply, and the powder easily reacts with oxygen in the air, so it is necessary to take out the powder in a glove box with inert gas;

(2) In a mold composed of a 30mm×20mm×10mm hollow cube with a Φ10mm cylinder in the middle, select 30g of ZTA ceramic particles with a particle size of 8-10 mesh (ZrO ₂ accounts for 20wt.%, Al ₂ O ₃ accounts for 80wt.%) , 2.4g of Ti-Fe mixed micropowder, 0.12g of water glass, and 0.65g of 10-12 mesh paraffin wax particles as a pore-forming agent. Stir with a glass rod for 10 min, the binder is evenly coated on the surface of the ZTA particles, and the whole process is carried out in a _N2 protective atmosphere.

(3) Put the preform into the glove box, open the air outlet, and fill with CO ₂ gas, the gas introduction time is 0.5h, and the inflation rate is 50 cm ³ /s. After the preform is cured and formed, the mold is placed in the In a constant temperature furnace at 60°C, hold the temperature for 30 minutes for drying, and then demould the preform.

(4) The preform was prepared by pressureless sintering, the vacuum degree of the sintering process was kept at 2.9×10 ^-3 Pa, the sintering holding temperature was 1300 ℃, the holding time was 1 h, and the surface-activated multi-channel ZTA was prepared by cooling to room temperature with the furnace Ceramic preforms.

The obtained ZTA ceramic preform can be determined from the backscattering image of the ceramic particles and the binder in the sintered preform and the EDS line scan of the transition layer. A 2um-5um Ti-O transition layer is formed between the ceramic and the binder. The bonding strength between ceramic particles is high, and no obvious cracking phenomenon is found. The porosity of the preform is 61%, and the crushing strength is 5MPa.

In Example 3, the wetting angle between the ZTA surface and the metallic high-chromium cast iron after sintering is also less than 15.1°, which indicates that the ZTA ceramic surface after sintering in this example can be well wetted by the wear-resistant steel liquid, and can form an effective composite interface. Bonding or diffusion of elements favors the formation of metallurgical interfaces.

The above-mentioned embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, The simplification should be equivalent replacement manners, which are all included in the protection scope of the present invention.

Claims (8)

1. A preparation method of a multi-channel ceramic preform coated by Ti-Fe micro powder is characterized by mainly comprising the following steps:

(1) mixing powder and alloying: mixing reduced iron powder and Ti powder, and adding the mixture into a ball milling tank for ball milling to alloy, thereby obtaining a mixed powder binder;

(2) mixing materials: mixing the mixed powder binder obtained in the step (1) with ZTA particles, adding water glass as a curing agent and paraffin particles as a pore-forming agent, and stirring to uniformly coat the powder binder on the surfaces of the ZTA ceramic particles to obtain a mixed material;

(3) and (3) curing: filling the mixed material obtained in the step (2) into a forming die, shaping and compacting the prefabricated body by a fastening grinding tool, and continuously introducing CO₂Curing the gas, drying and demoulding to obtain a cured and molded prefabricated body;

(4) vacuum pressureless sintering: placing the prefabricated body after being cured and molded in the step (3) into a vacuum sintering furnace for sintering to obtain a ceramic prefabricated body with certain strength and porosity;

the amount of the reduced iron powder and the Ti powder in the step (1) is 25-35 wt% of the total mass of the reduced iron powder and the Ti powder;

the ball milling process in the step (1) comprises the following steps: the ball milling time is 24-30 h, the diameter of the grinding ball is 5-10 mm, the weight ratio of the grinding ball to the mixed powder is 10:1, and the rotating speed of the ball mill is 300-450 r/min.

2. The method for preparing a multi-channel ceramic preform coated with Ti-Fe micropowder according to claim 1, wherein:

and (3) performing the step (1) and the step (2) under protective gas, wherein the protective gas is one of nitrogen or argon.

3. The method for preparing a multi-channel ceramic preform coated with Ti-Fe micropowder according to claim 1, wherein:

the purity of the reduced iron powder in the step (1) is 99.99%, and the granularity is less than or equal to 100 meshes; the purity of Ti powder is 99.99%, and the granularity is less than or equal to 300 meshes.

4. The method for preparing a multi-channel ceramic preform coated with Ti-Fe micropowder according to claim 1, wherein:

the using amount of the mixed powder in the step (2) is 3-8 wt% of the total weight of the mixed material obtained in the step (2); the amount of the water glass in the step (2) is 3-7% of the weight of the alloy powder in the step (2); the dosage of the paraffin particles in the step (2) is 1-3 wt% of the total weight of the mixed material obtained in the step (2); the balance of ZTA particles.

5. The method for preparing a multi-channel ceramic preform coated with Ti-Fe micropowder according to claim 1, wherein:

the fastening in the step (3) is to center and joint the mixed material placed in the mold through the center line of the mold, and then fasten bolts;

continuously introducing CO in the step (3)₂The gas means that a mould containing the mixed material is placed in a container with an open air outlet, and the aeration rate is 40-60 cm³The inflation time is 0.5-1 h, the pipe diameter of the air inlet pipe is 55-59 mm, and the pipe diameter of the air outlet hole is larger than that of the air inlet hole but smaller than 100 mm;

and (3) drying refers to keeping the temperature in a vacuum drying oven at 60-80 ℃ for 1-2 h.

6. The method for preparing a multi-channel ceramic preform coated with Ti-Fe micropowder according to claim 1, wherein:

the sintering in the step (4) is firingThe vacuum degree in the process of forming is kept at 2.9 × 10^-3Pa, controlling the sintering heat preservation temperature at 1250-1550 ℃, preserving the heat for 1h, and cooling to room temperature along with the furnace.

7. A Ti-Fe micropowder-coated multi-channel ceramic preform prepared according to the method of any one of claims 1 to 6.

8. The use of the Ti-Fe micropowder-coated multi-channel ceramic preform of claim 7 in the preparation of steel-based composites.

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