CN107385255A - The preparation method of solid solution based ceramic metal blade material and obtained blade material - Google Patents

Abstract

The invention discloses a kind of preparation method of solid solution based ceramic metal blade material and obtained blade material, wherein, methods described is first to (Ti, W) C powder carries out pre-grinding, then with Co powder, NbC powder and TaC powder mixed grinding, filtering and dry after, green compact are pressed into, vacuum-sintering and low pressure sintering is finally carried out, obtains blade material.In the present invention, pre-grinding, crystal grain thinning are carried out to (Ti, W) C powder, its size distribution tends to be uniform, so, is advantageous to improve the intensity of material；Using the expensive TaC powder of the part or all of fictitious hosts of NbC powder, the cost of material is significantly reduced, meanwhile, the hardness and toughness of material do not reduce not only, get a promotion on the contrary, so as to reduce the abrasion of blade.

Description

Preparation method of solid solution-based cermet blade material and resulting blade material

technical field

The invention belongs to the field of cermet blade materials, and in particular relates to a solid solution-based cermet blade material, in particular to a preparation method of a solid solution-based cermet blade material and the resulting blade material.

Background technique

The traditional WC-TiC-Co cemented carbide (YT cemented carbide) has high hardness and wear resistance due to the addition of TiC, and is used as a cutting tool in machining such as turning, milling, and drilling. Knife material. However, WC-TiC-Co cemented carbide contains two hard phases, WC and TiC, which have very different physical properties. The thermal expansion coefficient, elastic modulus, microhardness, and density of WC and TiC are respectively 3.84×10 ^-5 and 7.74×10 ^-5 ℃ ^-1 , 713 and 316GPa, 1780 and 3200MPa, 15.7 and 4.93 g/cm ³ , leading to an increase in interfacial stress in the structure, which is likely to cause the formation and propagation of microcracks during cutting, and the fracture resistance is weak. It exhibits high brittleness and is prone to chipping or breaking during intermittent cutting such as milling.

With the increasing requirements of metal cutting efficiency in the modern manufacturing industry, high-speed cutting has become an inevitable trend, and in high-speed cutting, the service temperature of the tool can reach 600-1000 °C. In such a high-temperature cutting environment, tool materials are required to have more excellent high-temperature properties, including high-temperature hardness, high-temperature oxidation resistance, and the like. Among them, TaC is an effective refractory carbide additive to improve the high temperature performance of cermets. Adding TaC to cermets can inhibit grain growth, improve high temperature strength, hardness, and oxidation resistance. However, the price of TaC is quite expensive, resulting in a significant increase in the cost of materials.

Therefore, it is necessary to seek an additive that is lower in cost but does not affect the high temperature performance of cermets to replace or partially replace TaC, thereby reducing costs.

Contents of the invention

In order to solve the above problems, the present inventors have carried out intensive research. First, pre-grind the (Ti, W)C powder, and then use part or all of the NbC powder to replace the TaC powder. In this way, not only the cost is reduced, but also the performance of the material is guaranteed. , thus completing the present invention.

One aspect of the present invention provides a method for preparing a solid solution-based cermet blade material, which is embodied in the following aspects:

(1) a preparation method of a solid solution-based cermet blade material, wherein the method comprises the following steps:

Step 1, pre-grinding (Ti,W)C powder;

Step 2, adding Co powder, NbC powder and TaC powder to the pre-ground (Ti, W)C powder in step 1, and then successively grinding, filtering and drying, and pressing into a green body;

Step 3. Carrying out vacuum sintering of the green body obtained in step 2 through molding agent extraction, solid-phase sintering and liquid-phase sintering;

Step 4, performing low-pressure sintering in a low-pressure sintering furnace to obtain the solid solution-based cermet blade material.

(2) According to the method described in (1) above, it is characterized in that, in step 1,

Pre-grinding is carried out with cemented carbide balls with a diameter of 4-8 mm, preferably WC-8% Co cemented carbide balls with a diameter of 6 mm; and/or

Using absolute ethanol as the grinding medium, preferably in an amount of 200-500mL, more preferably 300-400mL; and/or

The ball to material weight ratio is (5-15): 1, preferably (8-12): 1; and/or

The grinding speed is 50-90r/min, preferably 60-70r/min; and/or

The pre-grinding is carried out for 1 to 108 hours, preferably for 5 to 72 hours, more preferably for 36 to 72 hours, for example 48 hours.

(3) The method according to the above (1) or (2), characterized in that in step 2,

The particle size of the Co powder is 0.5-2 μm, preferably 0.8-1.5 μm, more preferably 1.0-1.2 μm; and/or

Based on 100 parts by weight of the green body, the Co powder is used in an amount of 10-20%, preferably 14-16%, more preferably 15%.

(4) The method according to any one of the above (1) to (3), characterized in that, in step 2,

The particle diameters of both the NbC powder and the TaC powder are 0.8-2 μm, preferably 1.0-1.8 μm, more preferably 1.0-1.5 μm; and/or

Based on 100 parts by weight of the green body, the total amount of NbC powder and TaC powder used is 5-12%, preferably 7-9%, more preferably 8%.

(5) The method according to any one of the above (1) to (4), characterized in that, in step 2,

Based on 100 parts by weight of the green body, the amount of NbC powder is 2-10%, and the amount of TaC powder is 0-6%. Preferably, the amount of NbC powder is 4-8%, and the amount of TaC powder is 0-4%. ; More preferably, the amount of NbC powder is 6-8%, and the amount of TaC powder is 0-2%; and/or

The ratio of NbC powder to TaC powder is (0.5-10): (0-1), preferably (1-7): (0-1), more preferably (3-5): (0-1).

(6) The method according to any one of the above (1) to (5), characterized in that, in the grinding of step 2, SD rubber molding agent is added, preferably, its dosage is 2-10%, more preferably , and its dosage is 3-7%, such as 5% and 6%.

(7) The method according to any one of the above (1) to (6), characterized in that, in step 3,

The forming agent is removed as follows: heat preservation at 300-800°C and 5-20Pa for 0.2-3h to remove the forming agent; preferably, heat preservation at 400-700°C and 10-15Pa for 0.5-2h to remove the forming agent; Preferably, heat preservation at 500-600°C and 10-15Pa for 1-2 hours to remove the molding agent; and/or

Carry out solid-phase stage sintering at 1000-1500°C and 3-15Pa for 0.5-2h; preferably, hold at 1200-1300°C and 5-10Pa for 1-1.5h for solid-phase sintering; and/or

Liquid-phase sintering at 1200-1600°C and 0.5-8Pa for 0.5-4h; preferably, liquid-phase sintering at 1300-1500°C and 1-5Pa for 1-3h; more preferably, at 1350- 1450 ℃, 1 ~ 5Pa under heat preservation for 1h to carry out liquid phase sintering.

(8) The method according to any one of the above (1) to (7), characterized in that, in step 4, low-pressure sintering is carried out at a protective gas pressure of 5-10 MPa and 1000-1800 ° C for 30-120 min , preferably, low-pressure sintering is carried out under an argon pressure of 5-10 MPa and a temperature of 1200-1600°C for 30-100 minutes, more preferably, argon pressure of 5-10 MPa and a temperature of 1300-1500°C for 40-80 minutes. sintering.

Another aspect of the present invention provides a solid solution-based cermet blade material, which is embodied in the following aspects:

(9) A solid solution-based cermet blade material, which is preferably prepared by the method described in (1) to (8) above, characterized in that the material is made of a composition comprising Co powder , WC powder and NbC powder, and optionally TaC powder.

(10) The material according to (9) above, wherein in the material

The total content of NbC powder and TaC powder is 5-12%, preferably 7-9%, more preferably 8%; and/or

The consumption of NbC powder is 2～10%, the consumption of TaC powder is 0～6%; Preferably, the consumption of NbC powder is 4～8%, the consumption of TaC powder is 0～4%; More preferably, the consumption of NbC powder The dosage is 6-8%, and the dosage of TaC powder is 0-2%; and/or

The ratio of NbC powder to TaC powder is (0.5-10):(0-1), preferably (1-7):(0-1), more preferably (3-5):(0-1).

Description of drawings

Fig. 1 shows the microstructure figure of the material that embodiment 1 and embodiment 3～5 obtain;

Fig. 2 shows the SEM image of the (Ti, W) C solid solution powder obtained by pre-ball milling for different times in Experimental Example 1;

Fig. 3 shows the XRD pattern of (Ti, W) C solid solution powder obtained by pre-ball milling for different times in Experimental Example 2.

detailed description

The following describes the present invention in detail, and the features and advantages of the present invention will become more clear and definite along with these descriptions.

One aspect of the present invention discloses a method for preparing a solid solution-based cermet blade material, wherein the method includes the following steps:

Step 1. Pre-grinding (Ti,W)C powder.

Among them, the general (Ti,W)C powder will have residual C, resulting in larger grain size and wider particle size distribution. Therefore, in the present invention, the (Ti, W) C powder is pre-ground, so that the (Ti, W) C powder particles are broken, the grains are refined, and the particle size distribution tends to be uniform, which is conducive to improving the strength of the material .

According to a preferred embodiment of the present invention, in step 1, in the (Ti,W)C powder, the weight ratio of TiC:WC is 30:70.

Wherein, the (Ti,W)C powder is (Ti,W)C powder with a weight ratio of TiC:WC in (Ti _0.42 ,W _0.58 )C of 30:70, which is close to saturation. According to the TiC-WC pseudo-binary phase diagram, at the cemented carbide sintering temperature, the maximum solubility of WC in TiC is 72-75%, and commercially available (W, Ti) C solid solutions have different degrees of saturation (WC solid solubility ), there are unsaturated solid solutions of TiC:WC=50:50 and 40:60, there are nearly saturated solid solutions of 30:70, and supersaturated solid solutions of 17:83, etc. Using unsaturated solid solution as raw material to prepare cemented carbide, it is easy to form a ring structure of solid solution phase (inner layer WC content is low, while outer layer WC content is higher); using supersaturated solid solution as raw material to prepare cemented carbide is easy In the sintering process, long strips of coarse WC are precipitated, resulting in a decrease in the performance of the alloy. Based on the above reasons, this study uses a nearly saturated solid solution of TiC:WC=30:70.

In the present invention, the method of replacing WC and TiC mixed hard phase with (Ti, W)C as the main hard phase can reduce the residual stress caused by the difference in physical properties of WC and TiC, and then improve the fracture of the alloy. Toughness and impact toughness, so it can reduce the formation and propagation of cracks in the tool material during interrupted cutting, and reduce chipping or breaking of the tool.

In the prior art, it involves the direct reaction of metal oxides and carbon black, and the preparation of composite solid solution carbides through carbonization and reduction reactions. However, after the raw materials are proportioned, dry grinding, boat pressing, It is carbonized at 2300°C, then crushed and sieved. Under this condition, first, in order to improve the purity of the powder and reduce the content of impurities, it is necessary to keep it at high temperature for a long time to achieve complete carbonization and the formation of a single-phase solid solution. Therefore, the preparation The particle size of the compound solid solution powder produced is relatively coarse; due to the large grain size of the powder, if the raw materials of other components with finer particles and smaller grain sizes are mixed at the same time to prepare cermets, it is likely to cause abnormal grains of the local hard phase Second, if the carbonization is not complete, it is not easy to obtain a single-phase complex solid solution, and the residual carbon black will lead to a high carbon content in the later preparation of cermets, while the carbon content is too high If the temperature is high, the liquid phase sintering temperature will be lowered, which will easily promote the growth of grains, resulting in low hardness.

According to a preferred embodiment of the present invention, in step 1, pre-grinding is carried out using cemented carbide balls with a diameter of 4-8 mm.

In a further preferred embodiment, in step 1, WC-8%Co cemented carbide balls with a diameter of 6mm are used for pre-grinding.

Among them, the main purpose of grinding during the preparation of cermet mixtures is to transfer energy to powder particles through grinding. The grinding efficiency is directly related to the size of the grinding ball. The smaller the diameter of the grinding ball, the smaller the gap between the balls. The frequency of contact and grinding of powder is relatively high, so spheres with smaller diameters have higher grinding efficiency than spheres with larger diameters. Generally, 6mm balls are used for ball milling of fine-grained or sub-fine-grained mixtures, so that the grinding efficiency is high, and it is not easy to unload if grinding balls lower than 4mm are used. In addition, WC-8% Co cemented carbide balls are selected because the cemented carbide with higher Co content has lower hardness and poor wear resistance. During ball milling, the loss of the grinding ball is large, and the worn part is equivalent to Impurities affect the composition of powder raw materials; cemented carbide with lower Co content has higher hardness, but also greater brittleness. During ball milling, when the ball falls from the top of the ball mill tank and impacts the powder raw material, brittle damage may occur, thus It also increases the loss of grinding balls and affects the composition of powder raw materials.

According to a preferred embodiment of the present invention, in step 1, absolute ethanol is used as the grinding medium.

In a further preferred embodiment, in step 1, the amount of absolute ethanol used is 200-500 mL.

In a further preferred embodiment, in step 1, the amount of absolute ethanol is 300-400 mL.

Among them, absolute ethanol is used as the grinding medium for wet ball milling. The amount of absolute ethanol should not be too small, too little will lead to insufficient grinding, and it should not be too much, too much will lead to difficulty in later liquid phase recovery.

According to a preferred embodiment of the present invention, in step 1, during pre-grinding, the ball-to-material weight ratio is (5-15):1, and the grinding speed is 50-90 r/min.

In a further preferred embodiment, in step 1, during the pre-grinding, the ball-to-material weight ratio is (8-12):1, and the grinding speed is 60-70 r/min.

According to a preferred embodiment of the present invention, in step 1, the pre-grinding is carried out for 1-108 hours.

In a further preferred embodiment, the pre-grinding is carried out for 5-72 hours.

In a further preferred embodiment, the pre-grinding is carried out for 36-72 hours, for example, 48 hours.

Among them, if the pre-grinding time is less than 1h, the degree of crushing of (Ti,W)C powder particles is not enough; if the pre-grinding time is longer than 108h, the particle size change of the powder is not as obvious as at the beginning, because the particle size of the powder is already lower than that of the grinding ball The gap between the milling effect is reduced.

Step 2. Add Co powder, NbC powder and TaC powder to the (Ti,W)C powder pre-ground in step 1, then grind, filter and dry in sequence, and then press into a green body.

According to a preferred embodiment of the present invention, in step 2, the particle size of the Co powder is 0.5-2 μm.

In a further preferred embodiment, in step 2, the particle size of the Co powder is 0.8-1.5 µm.

In a further preferred embodiment, in step 2, the particle size of the Co powder is 1.0-1.2 μm.

Among them, in the present invention, Co powder is used as the binder phase.

According to a preferred embodiment of the present invention, in step 2, based on 100 parts by weight of the green body, the Co powder is used in an amount of 10-20%.

In a further preferred embodiment, in step 2, based on 100 parts by weight of the green body, the Co powder is used in an amount of 14-16%.

In a further preferred embodiment, in step 2, based on 100 parts by weight of the green body, the Co powder is used in an amount of 15%.

Wherein, in the present invention, it can be realized to utilize high content of Co to carry out the preparation of blade material, wherein, the higher the Co content, the material toughness improves, but the hardness decreases, therefore, in the prior art, the Co content is all less, Generally not more than 10%, because too much will affect the hardness. However, in the invention, the use of NbC powder and/or TaC powder can refine the crystal grains and improve the hardness of the material. Therefore, in the present invention, the addition of high-content Co is realized, which not only improves the toughness of the material but also does not affect the hardness of the material. On the other hand, the wettability of the NbC powder used in the present invention to the binder phase Co is better than that of TaC powder. Therefore, in summary, in the material of the present invention, Co can be added in a high content.

According to a preferred embodiment of the present invention, in step 2, the particle diameters of the NbC powder and the TaC powder are both 0.8-2 μm.

In a further preferred embodiment, both the particle diameters of the NbC powder and the TaC powder are 1.0-1.8 µm.

In a further preferred embodiment, in step 2, the particle diameters of the NbC powder and the TaC powder are both 1.0-1.5 μm.

Among them, adding TaC powder to cermets can inhibit grain growth, improve high-temperature strength, hardness, and oxidation resistance. At the same time, NbC powder also has the effect of refining grains. Therefore, the particle size of the two It can't be too big, but it shouldn't be too small, too small and easy to reunite.

According to a preferred embodiment of the present invention, in step 2, based on 100 parts by weight of the green body, the total amount of NbC powder and TaC powder used is 5-12%.

In a further preferred embodiment, in step 2, based on 100 parts by weight of the green body, the total amount of NbC powder and TaC powder used is 7-9%.

In a further preferred embodiment, in step 2, based on 100 parts by weight of the green body, the total amount of NbC powder and TaC powder used is 8%.

Among them, TaC is an effective refractory carbide additive that improves the high-temperature performance of cermets, but the price of TaC is quite expensive, resulting in a significant increase in the cost of materials. Therefore, in the present invention, NbC powder with low price is used to replace Part or all of TaC powder.

Specifically: (1) At present, the market price of NbC powder is only 1/4 to 1/5 of that of TaC powder. Therefore, replacing part or all of TaC powder with NbC powder can significantly reduce the cost; The wettability of the medium binder phase Co is better than that of TaC powder, and the increase in wettability can reduce the pores in the material and improve the strength of the material; (3) The room temperature hardness of NbC powder and TaC powder are 2400HV and 1800HV, respectively, and NbC The hardness of NbC powder is higher than that of TaC powder, and the hardness of NbC powder decreases slowly with the increase of temperature, and has a high temperature hardness significantly higher than that of TaC powder, which is very beneficial for high-speed cutting; (4) NbC powder and TaC powder The bonding temperatures with steel are 1250°C and 1200°C, respectively, so when cutting steel with cermet tools, NbC powder has better resistance to bond wear than TaC powder.

According to a preferred embodiment of the present invention, in step 2, based on 100 parts by weight of the green body, the amount of NbC powder is 2-10%, and the amount of TaC powder is 0-6%.

In a further preferred embodiment, in step 2, based on 100 parts by weight of the green body, the amount of NbC powder used is 4-8%, and the amount of TaC powder used is 0-4%.

In a further preferred embodiment, in step 2, based on 100 parts by weight of the green body, the amount of NbC powder used is 6-8%, and the amount of TaC powder used is 0-2%.

Among them, in the present invention, some or all of the TaC powder is replaced by cheap NbC powder, which not only reduces the cost, but also, the inventor has found through a large number of experiments that the performance of the material will not decline, but will increase. Especially when NbC powder replaced TaC powder more, specifically, when the amount of NbC powder was more than (or completely replaced) TaC powder, the hardness and fracture toughness of the material were all improved, which was unexpected by the inventor, but the experiment The results do give such a conclusion. Therefore, in the present invention, using NbC powder to partially replace or completely replace TaC powder not only greatly reduces the cost, but also significantly improves the mechanical properties of the material.

According to a preferred embodiment of the present invention, in step 2, the amount ratio of NbC powder to TaC powder is (0.5-10): (0-1).

In a further preferred embodiment, in step 2, the amount ratio of NbC powder to TaC powder is (1-7):(0-1).

In a further preferred embodiment, in step 2, the amount ratio of NbC powder to TaC powder is (3-5):(0-1).

Among them, in the invention, when the amount of NbC powder is more than that of TaC powder, not only the cost can be greatly reduced, but also the hardness and toughness of the material can be effectively improved.

In the present invention, the reason why only NbC powder is used to replace TaC powder without adopting materials such as ZrC powder is that in vacuum, the wetting angle of Co in cermet to ZrC powder is 35°, and the wettability is not good, resulting in The pores in the material increase and the density decreases, so that the bending strength and hardness of the material decrease.

According to a preferred embodiment of the present invention, in step 2, a cemented carbide ball with a diameter of 4 to 8 mm is used for grinding.

In a further preferred embodiment, in step 2, WC-8%Co cemented carbide balls with a diameter of 6mm are used for grinding.

According to a preferred embodiment of the present invention, in step 2, absolute ethanol is used as the grinding medium.

In a further preferred embodiment, the amount of absolute ethanol is 200-500 mL.

In a further preferred embodiment, the consumption of dehydrated alcohol is 300～400mL.

Among them, absolute ethanol is used as the grinding medium for wet ball milling. The amount of absolute ethanol should not be too small, too little will cause the raw materials not to be completely covered by absolute ethanol, so that the raw materials are easily oxidized during the grinding process, and it should not be too much. Too much will lead to a decrease in grinding efficiency.

According to a preferred embodiment of the present invention, in step 2, the ball to material weight ratio is (5-15):1, the grinding speed is 50-90 r/min, and the grinding time is 24-60 hours.

In a further preferred embodiment, the ball to material weight ratio is (8-12):1, the grinding speed is 60-70 r/min, and the grinding time is 24-40 hours, for example, 36 hours.

According to a preferred embodiment of the present invention, during the grinding in step 2, SD rubber forming agent is added.

In a further preferred embodiment, the SD rubber molding agent is used in an amount of 2-10%.

In a further preferred embodiment, the SD rubber molding agent is used in an amount of 3-7%, such as 5% and 6%.

Wherein, since the material is mainly composed of refractory metal tungsten carbide and cobalt as a binder phase, its powder cannot be formed under pressure during the pressing process. Therefore, a forming agent needs to be added during pressing. The performance of the molding agent is a key factor that directly affects the performance of the blank and sintered products. In the present invention, adopt SD forming agent, wherein, SD forming agent is a kind of transparent egg white color or light yellow solution, nontoxic, no irritating smell, its dispersibility is good, can disperse evenly in the mixed material when grinding Among them, its viscosity is good, and the doped product can show good formability.

According to a preferred embodiment of the present invention, in step 2, pass through a 300-500 mesh sieve.

In a further preferred embodiment, in step 2, pass through a 400 mesh sieve.

According to a preferred embodiment of the present invention, in step 2, the drying is vacuum drying.

In a further preferred embodiment, in step 2, the drying is carried out at 1-6Pa and 80-120°C.

In a further preferred embodiment, in step 2, the drying is carried out at 2-5 Pa and 90-100°C.

According to a preferred embodiment of the present invention, in step 2, the green compact is pressed at 300-600 MPa.

In a further preferred embodiment, in step 2, the green compact is pressed at 400-500 MPa.

Step 3. Vacuum sintering the green body obtained in step 2 by successively removing the molding agent, sintering at the solid phase stage and sintering at the liquid phase stage.

Among them, sintering can remove the pores in the workpiece, make it completely (or basically) dense, and make the porous powder compact into a product with a certain structure and performance.

According to a preferred embodiment of the present invention, the exfoliation of the molding agent is carried out as follows: heat preservation at 300-800° C. and 5-20 Pa for 0.2-3 hours to exfoliate the molding agent.

In a further preferred embodiment, in step 3, the molding agent is removed as follows: heat preservation at 400-700° C. and 10-15 Pa for 0.5-2 hours to remove the molding agent.

In a further preferred embodiment, in step 3, the exfoliation of the molding agent is carried out as follows: heat preservation at 500-600° C. and 10-15 Pa for 1-2 hours to exfoliate the molding agent.

Among them, as the temperature rises in the initial stage of sintering, the SD-forming agent gradually decomposes and vaporizes, and the sintered body is excluded. At the same time, the contact stress between powder particles is gradually eliminated, the binder Co powder begins to recover and recrystallize, and the surface diffusion begins. Occurred, the briquetting strength increased.

According to a preferred embodiment of the present invention, in step 3, solid-phase stage sintering is carried out at 1000-1500° C. and 3-15 Pa for 0.5-2 hours.

In a further preferred embodiment, in step 3, solid-phase stage sintering is carried out at 1200-1300° C. and 5-10 Pa for 1-1.5 hours.

Among them, at this stage, the solid-phase reaction and diffusion intensify, the plastic flow is enhanced, and the sintered body shrinks significantly.

According to a preferred embodiment of the present invention, in step 3, liquid-phase stage sintering is carried out at 1200-1600° C. and 0.5-8 Pa at a temperature of 0.5-4 hours.

In a further preferred embodiment, in step 3, liquid-phase sintering is carried out at 1300-1500° C. and 1-5 Pa for 1-3 hours.

In a further preferred embodiment, in step 3, liquid-phase sintering is carried out at 1350-1450°C and 1-5 Pa for 1 hour.

Among them, at this stage, the liquid phase appears in the sintered body, and the shrinkage is completed quickly, followed by crystallization transformation, forming the basic organization and structure of the alloy.

Step 4, performing low-pressure sintering in a low-pressure sintering furnace to obtain the solid solution-based cermet blade material.

According to a preferred embodiment of the present invention, in step 4, low-pressure sintering is carried out under a protective gas pressure of 5-10 MPa and a temperature of 1000-1800° C. for 30-120 minutes.

In a further preferred embodiment, in step 4, low-pressure sintering is carried out under an argon pressure of 5-10 MPa and a temperature of 1200-1600°C for 30-100 min.

In a further preferred embodiment, in step 4, low-pressure sintering is carried out under an argon pressure of 5-10 MPa and a temperature of 1300-1500°C for 40-80 minutes.

According to another aspect of the present invention, a solid solution-based cermet blade material is provided, which is preferably prepared by the above-mentioned method, wherein the material is made of a composition, and the composition includes Co powder, WC powder and NbC powder , and optionally TaC powder.

According to a preferred embodiment of the present invention, in the material, the total content of NbC powder and TaC powder is 5-12%.

In a further preferred embodiment, in the material, based on 100 parts by weight of the green body, the total content of NbC powder and TaC powder is 7-9%.

In a further preferred embodiment, in the material, based on 100 parts by weight of the green body, the total content of NbC powder and TaC powder is 8%.

Among them, TaC is an effective refractory carbide additive that improves the high-temperature performance of cermets, but the price of TaC is quite expensive, resulting in a significant increase in the cost of materials. Therefore, in the present invention, NbC powder with low price is used to replace Part or all of TaC powder.

According to a preferred embodiment of the present invention, in the material, the amount of NbC powder is 2-10%, and the amount of TaC powder is 0-6%.

In a further preferred embodiment, in the material, the amount of NbC powder is 4-8%, and the amount of TaC powder is 0-4%.

In a further preferred embodiment, in the material, the amount of NbC powder is 6-8%, and the amount of TaC powder is 0-2%.

Among them, in the present invention, some or all of the TaC powder is replaced by cheap NbC powder, which not only reduces the cost, but also, the inventor has found through a large number of experiments that the performance of the material will not decline, but will increase. Especially when NbC powder replaced TaC powder more, specifically, when the amount of NbC powder was more than (or completely replaced) TaC powder, the hardness and fracture toughness of the material were all improved, which was unexpected by the inventor, but the experiment The results do give such a conclusion. Therefore, in the present invention, using NbC powder to partially replace or completely replace TaC powder not only greatly reduces the cost, but also significantly improves the physical properties of the material.

According to a preferred embodiment of the present invention, in the material, the amount ratio of NbC powder to TaC powder is (0.5-10): (0-1).

In a further preferred embodiment, in the material, the amount ratio of NbC powder to TaC powder is (1-7):(0-1).

In a further preferred embodiment, in the material, the amount ratio of NbC powder to TaC powder is (3-5):(0-1).

Among them, in the invention, when the amount of NbC powder is more than that of TaC powder, not only the cost can be greatly reduced, but also the hardness and toughness of the material can be effectively improved.

Wherein, the content of other components in the obtained material is also consistent with the content of each component in the above method.

The beneficial effects that the present invention has:

(1) The present invention carries out pre-grinding to (Ti, W) C powder, refines crystal grain, and its particle size distribution tends to be even, like this, helps to improve the intensity of material;

(2) The present invention adopts NbC powder to partially or completely replace expensive TaC powder, which can significantly reduce the cost of materials on the one hand;

(3) The present invention uses NbC powder to partially or completely replace expensive TaC powder. On the other hand, it is also found that the hardness and toughness of the material are not reduced, but improved, thereby reducing the wear of the blade;

(4) The present invention realizes the addition of high-content Co and improves the toughness of the material.

Example

The present invention is further described below by specific examples. However, these embodiments are merely exemplary and do not constitute any limitation to the protection scope of the present invention.

Example 1

Weigh the raw materials by weight percentage to prepare solid solution-based cermets, in which Co with a particle size of 1.17 μm accounts for 15%, NbC with a particle size of 1.45 μm accounts for 6%, TaC with a particle size of 1.36 μm accounts for 2%, and the rest is Co with a particle size of 2.6 μm. (Ti,W)C, (Ti,W)C is (Ti _0.42 ,W _0.58 )C, wherein the weight ratio of TiC and WC is 30:70.

(1) Add (Ti,W)C powder to the drum ball mill for pre-grinding treatment. The grinding ball is Φ6mm WC-8wt% Co cemented carbide ball, the weight ratio of ball to material is 8:1, and the grinding medium is anhydrous Ethanol, the addition amount is 300mL, the grinding speed is 60r/min, and the grinding time is 36h.

(2) After pre-grinding the solid solution raw materials, add Co powder, NbC powder, and TaC powder and mix and grind for 36 hours. After the mixture is ground, the cermet slurry is filtered through 400 mesh, and the vacuum drying temperature is 100°C, and the vacuum degree is 5Pa. The addition amount of SD rubber forming agent is 6wt%. The mixture was pressed into a green body under 400MPa.

(3) The green body is kept at 600°C in a vacuum furnace for 2 hours, and the molding agent is removed under a vacuum degree of 15Pa. The sintering temperature is 1250°C, the temperature is 1.5h, and the vacuum degree is 10Pa to complete the solid phase sintering. The sintering temperature is 1420°C, the holding time is 1h, and the liquid phase sintering is completed under a vacuum degree of 5Pa.

(4) Put the sintered cermet in a low-pressure sintering furnace. The low-pressure sintering is carried out at 1450°C, the holding time is 75min, and the argon pressure is 5MPa.

The prepared solid solution-based cermet has a density of 99.15%, a Vickers hardness of 1800MPa, and a fracture toughness of 11.2MPa·m ^1/2 . Its microstructure is shown in Figure 1a.

Example 2

The raw materials were weighed by weight to prepare solid solution-based cermets, wherein Co with a particle size of 1 μm accounted for 15%, NbC with a particle size of 1.22 μm accounted for 7%, TaC with a particle size of 1.08 μm accounted for 1%, and the rest were 4.5 μm ( Ti,W)C, (Ti,W)C is (Ti _0.42 ,W _0.58 )C, wherein the weight ratio of TiC and WC is 30:70.

(1) Add (Ti,W)C powder to the drum ball mill for pre-grinding treatment. The grinding ball is Φ6mm WC-8wt% Co cemented carbide ball, the weight ratio of ball to material is 12:1, and the grinding medium is anhydrous Ethanol, the addition amount is 400mL, the grinding speed is 70r/min, and the grinding time is 48h.

(2) After pre-grinding the solid solution raw materials, add Co powder, NbC powder, and TaC powder and mix and grind for 36 hours. After the mixture is ground, the cermet slurry is filtered through 400 mesh, and the vacuum drying temperature is 90°C, and the vacuum degree is 2Pa. The addition amount of SD rubber molding agent is 5wt%. The mixture was pressed into a green body at 500MPa.

(3) The molding agent is removed from the green body in a vacuum furnace at 550°C for 1.2h and a vacuum of 10Pa. The sintering temperature is 1220°C, the holding time is 1h, and the vacuum degree is 5Pa to complete the solid phase sintering. The sintering temperature is 1400°C, the holding time is 1h, and the vacuum degree is 1Pa to complete the liquid phase sintering.

(4) Put the initially sintered cermet in a low-pressure sintering furnace, the low-pressure sintering is carried out at 1480°C, the holding time is 45min, and the argon pressure is 8MPa.

The density of the prepared solid solution-based cermet is 99.05%, the Vickers hardness is 1805MPa, and the fracture toughness is 10.9MPa·m ^1/2 .

Example 3

Repeat the process of Example 1, the difference is that NbC powder accounts for 8%, and no TaC powder is added.

The prepared solid solution-based cermet has a Vickers hardness of 1820MPa and a fracture toughness of 10.8MPa·m ^1/2 , and its microstructure is shown in Figure 1b.

Example 4

Repeat the process of Example 1, the difference is that the NbC powder accounts for 4%, and the TaC powder accounts for 4%.

The Vickers hardness of the prepared solid solution-based cermet is 1750MPa, and the fracture toughness is 10.5MPa·m ^1/2 , and its microstructure is shown in c in Fig. 1 .

Example 5

Repeat the process of Example 1, the difference is that NbC powder accounts for 2%, and TaC powder accounts for 6%.

The prepared solid solution-based cermet has a Vickers hardness of 1725MPa and a fracture toughness of 10.4MPa·m ^1/2 , and its microstructure is shown in Figure 1d.

comparative example

Comparative example 1

The preparation process of Example 1 was repeated, with the difference that: TaC powder accounted for 8%, and no NbC powder was added.

The Vickers hardness of the prepared solid solution-based cermet is 1760MPa.

Among them, compared with Comparative Example 1, NbC powder is used to partially or completely replace TaC powder in Examples 1 to 5, and the hardness of the obtained material does not decrease too much. Therefore, it shows that in the case of using NbC powder to reduce costs, and It did not lead to a substantial decrease in the hardness of the material. Moreover, in Examples 1 to 3, when the amount of NbC powder used is large, the hardness of the obtained material is higher than that of the comparative example, which further illustrates that when the amount of NbC powder is large, not only the cost is significantly reduced, but also , the hardness of the material has been improved.

Comparative example 2

Repeat the preparation process of Example 1, the difference is: no NbC powder and TaC powder are added.

The Vickers hardness of the prepared solid solution-based cermet is 1450MPa.

When NbC powder and TaC powder are not added, the hardness of the material is significantly reduced, indicating that the presence of NbC powder and TaC powder can refine the crystal grains and improve the hardness of the material.

Comparative example 3

The preparation process of Example 1 was repeated, with the difference that the amounts of NbC powder were 1%, 2%, 3% and 4% respectively, and no TaC powder was added.

The Vickers hardnesses of the prepared solid solution-based cermets are 1530MPa, 1560MPa, 1611MPa, and 1652MPa, respectively.

Comparing it with Examples 2-3, the hardness obtained in the 4 groups of experiments in Comparative Example 3 is all lower, indicating that in the material, the amount of NbC powder used as a refined grain should not be too small.

Comparative example 4

The preparation process of Example 1 was repeated, with the difference that the amounts of TaC powder were 1%, 2%, 3% and 4%, respectively, and no NbC powder was added.

The Vickers hardnesses of the prepared solid solution-based cermets are 1510MPa, 1580MPa, 1596MPa, and 1590MPa, respectively.

Comparing it with Examples 2-3, the hardness obtained by the 4 groups of experiments in Comparative Example 4 is all lower, indicating that in the material, the amount of TaC powder used as a refined grain should not be too small.

At the same time, in combination with Comparative Examples 3-4, it can be seen that the amount of TaC powder and/or NbC powder used as grain refinement is very important, and the amount should not be too small, too small will lead to a decrease in hardness.

Comparative example 5

The preparation process of Example 1 was repeated, except that (Ti,W)C was not pre-milled.

The Vickers hardness of the prepared solid solution-based cermet is 1615MPa.

Comparing Comparative Example 5 with Example 1, when the (Ti, W) C solid solution pre-milling is not performed, the hardness of the material is significantly reduced, indicating that the grains of (Ti, W) C solid solution powder can be refined by pre-ball milling size, thereby significantly increasing the hardness of the sintered material.

Experimental example

Experimental example 1

The (Ti, W) C solid solution powder used in Example 1 was pre-milled for 0h, 36h, 72h and 108h respectively, and then subjected to SEM testing. The results are shown in Figure 2, where a is pre-ball milling 0h, and b is pre-ball milling 36h, c is pre-milling 72h, d is pre-milling 108h.

in:

It can be seen from Figure 2(a) that the original (Ti,W)C solid solution powder particles have no obvious edges and corners, appearing approximately square or round, and the powder particle size distribution is relatively wide, among which the larger particles are close to 3-5 μm, while the smaller Particles are about 0.5μm;

It can be seen from Figure 2(b) that after 36 hours of ball milling, the (Ti,W)C solid solution powder particles began to be broken, and the particle size distribution tended to be uniform. The large particles in the original powder were broken, and the average particle size of the powder was about 1~ 2μm;

It can be seen from Figure 2(c) that as the ball milling time is extended to 72h, the (Ti,W)C solid solution powder is further refined, and an ultrafine (0.5 μm) solid solution powder is obtained;

It can be seen from Figure 2(d) that when the ball milling time continues to extend to 108h, the particle size change of the powder is not as obvious as at the beginning. This is because the particle size of the powder is already lower than the gap between the balls, and the effect of ball milling is reduced. , therefore, ball milling after pre-milling to a certain extent will reduce the efficiency of ball milling.

Experimental example 2

The (Ti,W)C solid solution powder used in Example 1 was pre-milled for 0 h, 36 h, 72 h and 108 h, respectively, and then XRD test was performed, and the results are shown in FIG. 3 .

It can be seen from Figure 3 that the diffraction peaks near the angles of 35.91°, 41.71°, 60.45°, 72.37° and 76.14° are respectively related to (111), (200), (220), (311) and (222) etc. corresponding to the diffractive surface.

According to JCPDF65-0242, (Ti,W)C powder, as a solid solution of WC in TiC, has the same face-centered cubic crystal structure as TiC, and belongs to the Fm-3m space group. After ball milling for different times, (Ti,W ) C solid solution powder still maintains its cubic structure.

It can also be seen from Figure 3 that as the grinding time increases, the diffraction peaks broaden, especially at the (220), (311) and (222) diffraction planes. Among them, the reason for the broadening of the diffraction peak may be the broadening (crystalline size) caused by the grain size. The smaller the grain size, the larger the reciprocal sphere and the broadening of the diffraction peak. Therefore, calculations were performed using Jade 5.0 to obtain grain sizes of 99nm, 34.6nm, 31.5nm and 29.3nm (with milling time), respectively.

It shows that pre-grinding can significantly reduce the grain size and refine the grains, and, with the normal grinding time, the grains gradually decrease, but in the later stage of grinding, the degree of grain refinement decreases, so the general grinding does not exceed 72h.

Experimental example 3

SEM tests were carried out on the materials obtained in Example 1 and Examples 3-5, and the obtained microstructures are shown in a to d in FIG. 1 , respectively.

Experimental example 4

Utilize embodiment 1 and embodiment 3～5 and the blade material that comparative example 1 obtains to make the blade that model is WNMG080408-ZM, then the 9SiCr alloy tool steel round bar (Φ=45mm) through quenching and tempering treatment is cut, Among them, cutting conditions: cutting speed Vc=63.62m/min, feed speed f=0.12mm/r, cutting depth ap=0.2mm, cutting time t=5min; cutting method: dry cutting, that is, no cutting fluid is used. The results are shown in Table 1.

Table 1 cutting experiment results

As can be seen from Table 1, compared with Example 1, Comparative Example 1 does not use NbC, and its flank wear is the most serious, indicating that the addition of NbC can reduce the degree of wear of the knife face. Among them, when the addition amount of NbC is 6wt%, and the addition amount of TaC is 2wt% (Example 1), the cutting wear resistance is the best.

The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions should not be construed as limiting the present invention. Those skilled in the art understand that without departing from the spirit and scope of the present invention, various equivalent replacements, modifications or improvements can be made to the technical solutions and implementations of the present invention, all of which fall within the scope of the present invention. The protection scope of the present invention shall be determined by the appended claims.

Claims (10)

1. a kind of preparation method of solid solution based ceramic metal blade material, it is characterised in that the described method comprises the following steps：

Step 1, pre-grinding is carried out to (Ti, W) C powder；

Step 2, Co powder, NbC powder and TaC powder be added in (Ti, W) C powder of step 1 pre-grinding, be then ground successively, After filtering and drying, green compact are pressed into；

Step 3, the green compact that step 2 obtains are passed sequentially through with forming agent abjection, solid phase stage sintering and liquid phase stage sintering progress Vacuum-sintering；

Step 4, low pressure sintering is carried out in low-pressure sintering furnace, obtain the solid solution based ceramic metal blade material.

2. according to the method for claim 1, it is characterised in that in step 1,

Pre-grinding is carried out using a diameter of 4~8mm sintered carbide ball, it is preferred to use a diameter of 6mm WC-8%Co hard closes Gold goal carries out pre-grinding；And/or

Absolute ethyl alcohol is used as abrasive media, preferably its dosage is 200~500mL, more preferably 300~400mL；And/or

Ball material weight ratio is (5~15)：1, be preferably (8~12)：1；And/or

Grinding rate is 50~90r/min, preferably 60~70r/min；And/or

The pre-grinding carries out 1~108h, preferably carries out 5~72h, more preferably carries out 36~72h, such as 48h.

3. method according to claim 1 or 2, it is characterised in that in step 2,

The particle diameter of Co powder is 0.5~2 μm, preferably 0.8~1.5 μm, more preferably 1.0~1.2 μm；And/or

Based on the green compact of 100 parts by weight, the dosage of Co powder is 10~20%, preferably 14~16%, more preferably 15%.

4. the method according to one of claims 1 to 3, it is characterised in that in step 2,

The particle diameter of NbC powder and TaC powder is 0.8~2 μm, preferably 1.0~1.8 μm, more preferably 1.0~1.5 μm；And/or

Based on the green compact of 100 parts by weight, total dosage of NbC powder and TaC powder is 5~12%, preferably 7~9%, more preferably 8%.

5. the method according to one of Claims 1-4, it is characterised in that in step 2,

Based on the green compact of 100 parts by weight, the dosage of NbC powder is that the dosage of 2~10%, TaC powder is 0~6%；Preferably, NbC powder Dosage be that the dosage of 4~8%, TaC powder is 0~4%；It is highly preferred that the dosage of NbC powder is for the dosage of 6~8%, TaC powder 0~2%；And/or

The amount ratio of NbC powder and TaC powder is (0.5~10)：(0~1), it is preferably (1~7)：(0~1), more preferably (3~ 5)：(0~1).

6. the method according to one of claim 1 to 5, it is characterised in that in the grinding of step 2, add SD rubber into Type agent, it is preferable that its dosage is 2~10%, it is highly preferred that its dosage is 3~7%, such as 5% and 6%.

7. the method according to one of claim 1 to 6, it is characterised in that in step 3,

The forming agent abjection is carried out as follows：0.2~3h is incubated under 300~800 DEG C, 5~20Pa, deviates from forming agent；It is preferred that Ground, 0.5~2h is incubated under 400~700 DEG C, 10~15Pa, deviates from forming agent；It is highly preferred that in 500~600 DEG C, 10~ 1~2h is incubated under 15Pa, deviates from forming agent；And/or

0.5~2h is incubated under 1000~1500 DEG C, 3~15Pa and carries out solid phase stage sintering；Preferably, in 1200~1300 DEG C, be incubated 1~1.5h under 5~10Pa and carry out solid phase stage sintering；And/or

0.5~4h is incubated under 1200~1600 DEG C, 0.5~8Pa and carries out liquid phase stage sintering；Preferably, in 1300~1500 DEG C, be incubated 1~3h under 1~5Pa and carry out liquid phase stage sintering；Enter it is highly preferred that being incubated 1h under 1350~1450 DEG C, 1~5Pa Row liquid phase stage sinters.

8. the method according to one of claim 1 to 7, it is characterised in that in step 4, in protective gas pressure 5~ 10MPa, be incubated under 30~120min at 1000~1800 DEG C and carry out low pressure sintering, it is preferable that in 5~10MPa of argon pressure, At 1200~1600 DEG C be incubated 30~100min under carry out low pressure sintering, it is highly preferred that in 5~10MPa of argon pressure, 1300~ It is incubated at 1500 DEG C under 40~80min and carries out low pressure sintering.

9. a kind of solid solution based ceramic metal blade material, it is preferably prepared using claim 1 to 8 methods described, its feature It is, the material is made up of a kind of composition, and the composition includes Co powder, WC powder and NbC powder, and optional TaC powder.

10. material according to claim 9, it is characterised in that in the material

The total content of NbC powder and TaC powder is 5~12%, preferably 7~9%, more preferably 8%；And/or

The dosage of NbC powder is that the dosage of 2~10%, TaC powder is 0~6%；Preferably, the dosage of NbC powder is 4~8%, TaC powder Dosage be 0~4%；It is highly preferred that the dosage that the dosage of NbC powder is 6~8%, TaC powder is 0~2%；And/or

The amount ratio of NbC powder and TaC powder is (0.5~10)：(0~1), it is preferably (1~7)：(0~1), more preferably (3~ 5)：(0~1).