CN102336405A - Rare-earth-containing ultrafine chromium vanadium carbide composite powder and preparation method thereof - Google Patents

Abstract

The invention provides ultrafine vanadium-chromium carbide composite powder containing rare earth, and the composite powder is composed of vanadium carbide, chromium carbide and rare earth. The preparation method of the above-mentioned rare earth-containing ultrafine vanadium-chromium carbide composite powder is characterized in that: using powdery vanadate, powdery chromate, carbonaceous reducing agent and powdery rare earth as raw materials, the raw materials are placed in a ball mill tank , cemented carbide balls are grinding balls, organic solvents are used as ball milling media, and the ball milling time is limited to uniform mixing to obtain a slurry, then the slurry is heated and dried, and the organic solvent is recovered at the same time to obtain a uniformly mixed raw material powder. In a high-temperature reaction furnace, under the protection of vacuum, argon or hydrogen atmosphere, carbonize at 1000°C to 1200°C for 50min to 90min to obtain rare earth-containing vanadium-chromium carbide composite powder with an average particle size of <200nm and uniform particle size distribution.

Description

Ultrafine vanadium-chromium carbide composite powder containing rare earth and preparation method thereof

technical field

The invention belongs to the technical field of ultrafine carbide powder preparation, in particular to ultrafine vanadium-chromium carbide composite powder containing rare earth and a preparation method thereof.

Background technique

Vanadium carbide and chromium carbide belong to transition metal carbides with high melting point, hardness and high temperature strength. Widely used in metal materials, machining, metallurgy, aerospace, microelectronics, catalysis, coating materials and other fields. In particular, vanadium (chromium) carbide, as a grain growth inhibitor of cemented carbide and cermet, plays an important role in improving the properties of the alloy. For the preparation of ultra-fine cemented carbide, one of the key points is that the raw material WC powder particle size is required to be less than 0.2 μm, and the high-pressure and low-temperature HIP sintering technology should be used during sintering. Secondly, it is to select a suitable grain growth inhibitor. And VC and Cr ₃ C ₂ are the most effective grain growth inhibitors. However, when producing ultra-fine-grained cemented carbide, since the particle size of the raw material powder is controlled within 0.2 μm, the particle size of the grain growth inhibitor must also be less than 0.15 μm to achieve the inhibitory effect. Therefore, there is an urgent need for ultrafine grain growth inhibitor powders in fields such as high-efficiency ultrafine cemented carbide.

In addition, the alloy added with VC has better grain refinement effect and higher hardness than the alloy added with Cr ₃ C ₂ , but its bending strength is lower; while adding Cr ₃ C ₂ can make up for its bending resistance. The strength is disadvantageous, and the alloy has higher fracture toughness. Studies have shown that compound addition is more conducive to the improvement of alloy properties than single addition. Rare earth is also often used as an additive, which is beneficial to eliminate the pores of the alloy, refine the grains, and purify the interface, thereby improving the performance of the material.

However, the method of adding the inhibitor determines the distribution state of the inhibitor and also affects the effect of the inhibitor. Therefore, the uniform distribution of inhibitor components is the key to controlling grain growth. Nowadays, the addition of vanadium carbide, chromium carbide or rare earth mostly adopts the method of mechanical ball milling and mixing, which cannot fully disperse the powder, resulting in segregation in the alloy, resulting in unstable performance. Therefore, it is necessary to synthesize ultrafine vanadium-chromium carbide composite powder containing rare earth.

At present, the method for preparing vanadium (chromium) powder is mainly based on carbothermal reduction method, which has the following two types: 1. Precursor method, which fully mixes vanadium (chromium) source and carbon source by solution mixing, and heats and evaporates solution or spray drying to obtain a solid-phase precursor; second, the gas phase reduction method, which provides a carbon source through the cracking of gaseous hydrocarbon molecules, and finally obtains ultrafine or nanometer vanadium carbide (chromium). However, the above two methods have defects to varying degrees. For example, in the precursor method, the reactants cannot be mixed at the molecular level, and the product purity is low; in the gas phase reduction method, the equipment requirements are high, the energy consumption is large, and the product purity is not easy to control. Moreover, the two methods are complex in process and high in cost, which also limits the industrial application of these two methods.

Therefore, in order to overcome the defects of the above-mentioned preparation method in the preparation of ultra-fine grain growth inhibitor powder by carbothermal reduction, a low-cost, simple process preparation method is provided to obtain ultra-fine vanadium-chromium carbide composite powder containing rare earth, so that Meet its application in metallurgy, high temperature coating, electronics and catalysts and other fields.

Contents of the invention

The object of the present invention is to provide a new rare earth-containing ultrafine vanadium-chromium carbide composite powder and its preparation method. The rare earth-containing ultrafine vanadium-chromium carbide composite powder is composed of vanadium carbide, chromium carbide and rare earth.

The preparation method of the ultrafine vanadium-chromium carbide composite powder containing rare earth of the present invention, the embodiment of this method is as follows:

Using powdered vanadate, powdered chromate, carbonaceous reducing agent and powdered rare earth as raw materials, the above raw materials are placed in a ball mill jar, cemented carbide balls are used as grinding balls, and organic solvent is used as a ball milling medium. The ball milling time is Mix uniformly to obtain a slurry, then heat and dry the slurry, and recover the organic solvent at the same time to obtain a uniformly mixed raw material powder. The powder is placed in a high-temperature reaction furnace under the protection conditions of vacuum, argon or hydrogen atmosphere. Carbonization under the conditions of 1000°C-1200°C and 50min-90min to obtain rare earth-containing vanadium-chromium carbide composite powder with an average particle size of <200nm and uniform particle size distribution.

Further, the powdered vanadate may be any one of the following or a mixture thereof: ammonium metavanadate (NH ₃ VO ₄ ), ammonium polyvanadate ((NH ₃ ) ₂ V ₆ O ₁₆ ) , vanadium oxalate (C ₁₀ O ₂₀ V ₂ );

Further, the powdery chromate may be any one of the following or a mixture thereof: ammonium dichromate ((NH ₃ ) ₂ Cr ₂ O ₇ ), ammonium chromate ((NH ₃ ) ₂ CrO ₄ ), chromium citrate (C ₆ H ₅ O ₇ Cr·4H ₂ O), chromium oxalate (Cr ₂ (C ₂ O ₄ ) ₃ );

Further, the carbonaceous reducing agent can be selected from any one of the following: nano-carbon black, nano-activated carbon, glucose or sucrose;

Further, the powdery rare earth raw material is an oxide or salt of at least one rare earth element among Ce, La, Nd, Y, Sm, Sc, and Pr;

Further, the weighing weight of the four raw materials is calculated according to the ratio of V ₈ C ₇ : Cr ₃ C ₂ : Re being 1-2.5: 3-2.5: 0.05-0.25, and the carbonaceous reducing agent is 16%~30%;

Further, the organic solvent is absolute ethanol or hexane;

Further, the slurry is heated and dried at a heating temperature of 80-100°C;

Further, the high-temperature reaction furnace is a carbon tube furnace, a tube furnace, a microwave sintering furnace, a rotary furnace, a shaft furnace, a shaking furnace, a pusher kiln or a tunnel kiln;

The present invention has following beneficial effect:

(1) The present invention provides ultra-fine vanadium-chromium carbide composite powder containing rare earth by a new in-situ synthesis process, which adds a new type to metal carbide materials.

(2) The rare earth-containing vanadium-chromium carbide composite powder provided by the present invention has uniform distribution of the rare earth phase and other components, which can effectively solve the problem of rare earth phase segregation in the alloy.

(3) The reaction time is short, saving energy. The invention can prepare superfine powder under the conditions of 1000-1200 DEG C and 50-90 minutes, which greatly saves energy.

(4) The process is simple. The method of the invention can be completed by one-time carbonization, the process is simple, the operation is convenient, and the equipment used is conventional equipment, which is suitable for industrial production.

(5) The product has high purity, is easy to control, and has uniform and fine particle size. Using carbonaceous reducing agent, the amount of carbon is controllable, the particle size of the composite powder produced by the reaction is less than 200nm, the particle size distribution range is narrow, and the impurity content is small.

Detailed ways

The rare earth-containing vanadium-chromium carbide composite powder and the preparation method thereof of the present invention will be further described through examples.

Example 1:

According to the mass ratio of V ₈ C ₇ : Cr ₃ C ₂ : Re of 1:3:0.05, weigh 9.52 g of powdered ammonium metavanadate and 31.51 g of powdered ammonium dichromate equal to the moles of V, Cr, and Re. With powdery yttrium oxide 0.29g, nano-carbon black 8.18g (carbon content is 16.62%), above-mentioned raw material is added in the ball mill jar that 200ml alcohol is housed and mixes. Use YG6 alloy balls with a diameter of 8 mm, the ball-to-material ratio is 5:1, and the ball milling time is 24 hours. Then, heat and dry the mixed slurry in a drier, and recover alcohol at the same time to obtain a uniformly mixed raw material powder. The powder In a high-temperature reaction furnace, under vacuum conditions, carbonize at 1000°C to 1200°C for 50min to 90min to obtain rare earth-containing vanadium-chromium carbide composite powder with an average particle size of <200nm and uniform particle size distribution.

Example 2:

According to the mass ratio of V ₈ C ₇ : Cr ₃ C ₂ : Re of 1:1:0.1, weigh 19.04 g of powdery ammonium metavanadate, 25.35 g of powdery ammonium chromate and Powdery cerium chloride 1.76g, nano activated carbon 12.01g (the carbon content is 20.64%), above-mentioned raw material is added in the ball mill tank that 200ml alcohol is housed and mixes. Use YG6 alloy balls with a diameter of 8 mm, the ball-to-material ratio is 5:1, and the ball milling time is 24 hours. Then, heat and dry the mixed slurry in a drier, and recover alcohol at the same time to obtain a uniformly mixed raw material powder. The powder In a high-temperature reaction furnace, under vacuum conditions, carbonize at 1000°C to 1200°C for 50min to 90min to obtain rare earth-containing vanadium-chromium carbide composite powder with an average particle size of <200nm and uniform particle size distribution.

Example 3:

According to the mass ratio of V ₈ C ₇ : Cr ₃ C ₂ : Re of 3:5:0.2, weigh 39.70 g of powdered vanadium oxalate, 31.51 g of powdered ammonium dichromate and powdered Lanthanum oxide 0.7g, sucrose 30.52g (the amount of carbon is 30.0%), above-mentioned raw material is added in the ball mill tank that 400ml alcohol is housed and mixes. Use YG6 alloy balls with a diameter of 8 mm, the ball-to-material ratio is 5:1, and the ball milling time is 24 hours. Then, heat and dry the mixed slurry in a drier, and recover alcohol at the same time to obtain a uniformly mixed raw material powder. The powder In a high-temperature reaction furnace, under vacuum conditions, carbonize at 1000°C to 1200°C for 50min to 90min to obtain rare earth-containing vanadium-chromium carbide composite powder with an average particle size of <200nm and uniform particle size distribution.

Example 4:

According to the mass ratio of V ₈ C ₇ : Cr ₃ C ₂ : Re 5: 6: 0.25, weigh 19.04 g of powdery ammonium metavanadate, 62.64 g of powdery chromium citrate and Powdery samarium oxide 0.60g, nanometer carbon black 9.20g (carbon content is 25.96%), above-mentioned raw material is added in the ball mill tank that 300ml alcohol is housed and mixes. Use YG6 alloy balls with a diameter of 8 mm, the ball-to-material ratio is 5:1, and the ball milling time is 24 hours. Then, heat and dry the mixed slurry in a drier, and recover alcohol at the same time to obtain a uniformly mixed raw material powder. The powder In a high-temperature reaction furnace, under vacuum conditions, carbonize at 1000°C to 1200°C for 50min to 90min to obtain rare earth-containing vanadium-chromium carbide composite powder with an average particle size of <200nm and uniform particle size distribution.

Example 5:

According to the mass ratio of V ₈ C ₇ : Cr ₃ C ₂ : Re of 1:1:0.1, weigh 9.52 g of powdery ammonium metavanadate and 8.11 g of powdery ammonium polyvanadate equal to the moles of V, Cr, and Re. g, powdery ammonium dichromate 21.0g, powdery yttrium oxide 0.59g and powdery cerium oxide 0.61g, glucose 25.75g (carbon content is 30.0%), the above-mentioned raw materials are added in the ball mill tank that 300ml alcohol is housed and carry out mix. Use YG6 alloy balls with a diameter of 8 mm, the ball-to-material ratio is 5:1, and the ball milling time is 24 hours. Then, heat and dry the mixed slurry in a drier, and recover alcohol at the same time to obtain a uniformly mixed raw material powder. The powder In a high-temperature reaction furnace, under vacuum conditions, carbonize at 1000°C to 1200°C for 50min to 90min to obtain rare earth-containing vanadium-chromium carbide composite powder with an average particle size of <200nm and uniform particle size distribution.

Embodiment 6:

According to the mass ratio of V ₈ C ₇ : Cr ₃ C ₂ : Re of 1:3:0.05, weigh 9.52 g of powdered ammonium metavanadate, 15.33 g of powdered chromium oxalate, 21.0 g of ammonium dichromate, 0.29 g of powdery neodymium oxide, and 8.86 g of nano-carbon black (a carbon content of 16.20%) are added into a ball mill jar equipped with 200 ml of alcohol for mixing. Use YG6 alloy balls with a diameter of 8 mm, the ball-to-material ratio is 5:1, and the ball milling time is 24 hours. Then, heat and dry the mixed slurry in a drier, and recover alcohol at the same time to obtain a uniformly mixed raw material powder. The powder In a high-temperature reaction furnace, under vacuum conditions, carbonize at 1000°C to 1200°C for 50min to 90min to obtain rare earth-containing vanadium-chromium carbide composite powder with an average particle size of <200nm and uniform particle size distribution.

Embodiment 7:

According to the mass ratio of V ₈ C ₇ : Cr ₃ C ₂ : Re of 3:5:0.2, weigh 17.13 g of powdered ammonium metavanadate and 31.51 g of powdered ammonium dichromate equal to the moles of V, Cr, and Re. With powdery lanthanum chloride 1.6g, carbon black 9.69g (carbon content is 16.17%), above-mentioned raw material is added in the ball mill jar that 200ml alcohol is housed and mixes. Use YG6 alloy balls with a diameter of 8 mm, the ball-to-material ratio is 5:1, and the ball milling time is 24 hours. Then, heat and dry the mixed slurry in a drier, and recover alcohol at the same time to obtain a uniformly mixed raw material powder. The powder In a high-temperature reaction furnace, under vacuum conditions, carbonize at 1000°C to 1200°C for 50min to 90min to obtain rare earth-containing vanadium-chromium carbide composite powder with an average particle size of <200nm and uniform particle size distribution.

Claims (10)

1. the ultra-fine vanadium carbide chromium composite powder that contains rare earth is characterized in that said composite powder forms by vanadium carbide, chromium carbide and rare earth are compound.

2. contain the preparation method of the ultra-fine vanadium carbide chromium composite powder of rare earth, it is characterized in that: with powdery vannadate, powdery chromic salt, carbonaceous reducing agent and powdery rare earth is raw material, and above-mentioned raw materials is placed ball grinder; Sintered carbide ball is an abrading-ball, and organic solvent is as ball-milling medium, and the ball milling time exceeds to mix; Make slip; With the slip heat drying, reclaim organic solvent simultaneously then, the raw material powder that obtains mixing; With this powder in high temperature reaction stove; Under vacuum, argon gas or the hydrogen atmosphere protective condition, carbonization obtains median size＜200nm, the vanadium carbide chromium composite powder that contains rare earth of even particle size distribution under 1000 ℃～1200 ℃, 50min～90min condition.

3. the method that contains the ultra-fine vanadium carbide chromium composite powder of rare earth according to the described preparation of claim 2 is characterized in that said powdery vannadate can select any one or its mixture in following for use: ammonium meta-vanadate (NH ₃VO ₄), poly ammonium vanadate ((NH ₃) ₂V ₆O ₁₆), vanadium oxalate (C ₁₀O ₂₀V ₂).

4. the method that contains the ultra-fine vanadium carbide chromium composite powder of rare earth according to the described preparation of claim 2 is characterized in that said powdery chromic salt can select any one or its mixture in following for use: ammonium dichromate ((NH ₃) ₂Cr ₂O ₇), ammonium chromate ((NH ₃) ₂CrO ₄), chromium citrate (C ₆H ₅O ₇Cr4H ₂O), chromium+oxalic acid (Cr ₂(C ₂O ₄) ₃).

5. the method that contains the ultra-fine vanadium carbide chromium composite powder of rare earth according to the described preparation of claim 2 is characterized in that said carbonaceous reducing agent can select any one in following for use: nanometer carbon black, nano active charcoal, glucose or sucrose;

6. contain the method for the ultra-fine vanadium carbide chromium composite powder of rare earth according to the described preparation of claim 2, it is characterized in that oxide compound or salt that said powdery rare earth raw material is at least a REE among Ce, La, Nd, Y, Sm, Sc, the Pr.

7. the method that contains the ultra-fine vanadium carbide chromium composite powder of rare earth according to the described preparation of claim 2 is characterized in that the weigh of said four kinds of raw materials, according to V ₈C ₇: Cr ₃C ₂: Re is 1～2.5: 3～2.5: 0.05～0.25 ratio is calculated, and carbonaceous reducing agent is 16%～30% of a gross weight.

8. contain the method for the ultra-fine vanadium carbide chromium composite powder of rare earth according to the described preparation of claim 2, it is characterized in that said organic solvent is absolute ethyl alcohol or hexane.

9. contain the method for the ultra-fine vanadium carbide chromium composite powder of rare earth according to the described preparation of claim 2, it is characterized in that said slip heat drying, Heating temperature is 80～100 ℃.

10. contain the method for the ultra-fine vanadium carbide chromium composite powder of rare earth according to the described preparation of claim 2, it is characterized in that said high temperature reaction stove is carbon tube furnace, tube furnace, microwave agglomerating furnace, rotary kiln, shaft furnace, grate, pushed bat kiln or tunnel;