A method for producing a ternary boride cermet

Abstract

The application discloses a preparation method of ternary boride cermet, and comprises the following steps: step one, screening; step two, mixing; step three, pressing; step four, degreasing; and step five, vacuum sintering. The preparation method of the ternary boride cermet provided by the application does not contain Co, only contains a small amount of tungsten and carbon, is used for reinforcing and toughening, and is cheap in price of raw material boron powder and iron powder. The preparation method has low raw material cost and simple preparation process, is very suitable for mass industrial production, and has a cost only about one third of that of a similar performance hard alloy, has a very high performance-price ratio and a wide application prospect. Meanwhile, the rare earth elements in the rare earth oxides have a 'rare earth effect', the crystal boundary is purified, oxides are generated by the oxygen elements and impurities in the cermet and are discharged, the comprehensive mechanical properties of the cermet are improved, and the cermet can meet certain service conditions of the material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cermet, in particular to a preparation method of ternary boride cermet. BACKGROUND

[0002] At present, the commonly used cutting tool materials are tool steel, hard alloy, cutting tool ceramic and superhard cutting tool material. Among them, the hard alloy accounts for about 60% of all cutting tools, and the hard alloy is also called the "tooth" of industry. The hard alloy mainly contains tungsten and cobalt, and the tungsten element is rare in the earth's crust, so it is called a strategic metal. At present, China is providing 80% of the world's demand for tungsten with 35% of the world's tungsten reserves. The large consumption of tungsten resources is not conducive to the sustainable development of the traditional hard alloy industry. Seeking tungsten-free hard alloy or hard alloy partially replacing tungsten is a research direction in the field of tool and die materials today. The ternary boride cermet has the characteristics of low density, high hardness, good electrical conductivity, good wear resistance and corrosion resistance. At present, the boronization of ternary boride cermet has been applied to injection molding die, non-ferrous metal processing tool and kiln lining and other fields.

[0003] The cermet includes hard phase and binder phase. The hard phase is widely used as the hard phase of the cermet because the transition metal carbide, nitride and boride have high strength, hardness, wear resistance and thermal stability. The most studied is the cermet taking WC, TiC, TiN, Ti(C, N) and TiB2 compounds as the hard phase and taking Co, Ni and Fe metals or alloys as the binder phase. The TiC-based cermet, TiN-based cermet and Ti(C, N)-based cermet have lower toughness and are difficult to compare with the traditional WC-based hard alloy. As for the TiB2-based cermet, the sintering property of TiB2 is poor due to the low self-diffusion coefficient of TiB2, and the brittle third phase is easily generated by the reaction between the binder metal and TiB2 in the sintering process. Therefore, the TiB2-based cermet is difficult to be prepared into a dense material by the traditional powder metallurgy method, and the performance is poor. SUMMARY

[0004] In view of the defects of the prior art, the purpose of the present application is to provide a preparation method of ternary boride cermet to solve the problems in the background art.

[0005] The technical problem solved by the present application adopts the following technical scheme:

[0006] The present application provides a preparation method of ternary boride cermet, comprising the following steps:

[0007] Step one, screening: selecting titanium powder, carbon powder, chromium powder, nitrogen powder, nickel powder, molybdenum powder, tungsten powder, iron powder and boron powder and screening them through a superfine screen classifier;

[0008] Step two, mixing: mix the sieved raw materials in step one;

[0009] Step three, pressing: press the mixed powder into shape;

[0010] Step four, debinding;

[0011] Step five, vacuum sintering: put the debound green body in step four into a vacuum sintering furnace for sintering.

[0012] Preferably, the weight parts of each raw material in step one are titanium powder 26-38 parts, carbon powder 2.5-4.7 parts, chromium powder 2-6 parts, nitrogen powder 1-5 parts, nickel powder 24-30 parts, molybdenum powder 8-12 parts, tungsten powder 5-10 parts, iron powder 1-3 parts, and boron powder 0.5-1.5 parts.

[0013] Preferably, the purity of titanium powder, carbon powder, chromium powder, nitrogen powder, nickel powder, molybdenum powder, tungsten powder, iron powder, and boron powder in step one is greater than 99.5%.

[0014] Preferably, the titanium powder, nickel powder, molybdenum powder, tungsten powder, and boron powder with a particle size less than 10 μm in step one are sieved by a superfine sieve.

[0015] Preferably, the mixing in step two adopts a dry mixing method or a wet mixing method. When the wet mixing method is adopted, it needs to be dried before being pressed into shape.

[0016] Preferably, a promoter is added before pressing in step three, and the promoter is polyvinyl alcohol aqueous solution, and the addition ratio is 4 wt% of the mixed material.

[0017] Preferably, the pressing process in step three is carried out by a pressure of 140-180 MPa.

[0018] Preferably, the debinding process in step four is carried out in a vacuum furnace with a vacuum degree≧10 Pa, and the temperature is raised to 300-600℃ at a rate of 2-5℃ / min.

[0019] Preferably, the vacuum degree in the vacuum furnace in step five is≧1.0×10-2 Pa, and the vacuum sintering is divided into three stages.

[0020] First stage: the green body is heated to 780-980℃ at a rate of 3-7℃ / min, and the temperature is kept for 60-120 min;

[0021] Second stage: then the temperature is raised to 1100-1350℃ at a rate of 2-4℃ / min, and the temperature is kept for 40-60 min;

[0022] Third stage: the furnace temperature is rapidly reduced to below 980℃ at a cooling rate of 10-18℃ / min.

[0023] Compared with the prior art, the present application has the following advantages:

[0024] The preparation method of the ternary boride cermet provided by the present application does not contain Co and only contains a small amount of tungsten and carbon, the raw material boron powder and iron powder used for enhancing and toughening are cheap, the raw material cost is low, the preparation process is simple, and the present application is very suitable for mass industrial production. The manufacturing cost of the present application is only about one third of that of a hard alloy with similar performance, and the present application has a very high performance-price ratio and a wide application prospect. Meanwhile, the rare earth elements in the rare earth oxides are used to purify the grain boundaries, and the oxygen elements and impurities in the cermet generate oxides and are discharged, so that the comprehensive mechanical properties of the cermet are improved, and the cermet can meet certain service conditions of the material. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0026] Embodiment 1.

[0027] The present application provides a preparation method of a ternary boride cermet, which comprises the following steps:

[0028] Step one, screening: titanium powder, carbon powder, chromium powder, nitrogen powder, nickel powder, molybdenum powder, tungsten powder, iron powder and boron powder are screened by a superfine screen classifier;

[0029] Step two, mixing: the raw materials screened in step one are mixed;

[0030] Step three, pressing: the mixed powder is pressed into a shape;

[0031] Step four, debinding;

[0032] Step five, vacuum sintering: the debound green body in step four is placed in a vacuum sintering furnace for sintering.

[0033] In step one of the present embodiment, the weight parts of each raw material are as follows: titanium powder 26 parts, carbon powder 2.5 parts, chromium powder 2 parts, nitrogen powder 1 part, nickel powder 24 parts, molybdenum powder 8 parts, tungsten powder 5 parts, iron powder 1 part and boron powder 0.5 part.

[0034] In step one of the present embodiment, the purity of the titanium powder, the carbon powder, the chromium powder, the nitrogen powder, the nickel powder, the molybdenum powder, the tungsten powder, the iron powder and the boron powder is greater than 99.5%.

[0035] The titanium powder, nickel powder, molybdenum powder, tungsten powder and boron powder with a particle size less than 10 μm are screened by the ultra-fine sieve classifier in step one of the embodiment.

[0036] In step two of the embodiment, the mixing is performed in a dry mixing mode or a wet mixing mode. When the wet mixing mode is used, the mixture needs to be dried before being pressed.

[0037] In step three of the embodiment, a promoter is added before pressing. The promoter is a polyvinyl alcohol aqueous solution, and the addition ratio is 4 wt% of the mixture.

[0038] In step three of the embodiment, the pressing process is performed at a pressure of 140 MPa.

[0039] In step four of the embodiment, the debinding process is performed in a vacuum furnace with a vacuum degree of ≧10 Pa, and the temperature is raised to 300 ℃ at a rate of 2 ℃ / min.

[0040] In step five of the embodiment, the vacuum sintering in the vacuum furnace is divided into three stages.

[0041] In the first stage, the green compact is heated to 780 ℃ at a rate of 3 ℃ / min, and is kept for 60 min.

[0042] In the second stage, the temperature is then raised to 1100 ℃ at a rate of 2 ℃ / min, and is kept for 40 min.

[0043] In the third stage, the furnace temperature is rapidly reduced to below 980 ℃ at a cooling rate of 10 ℃ / min.

[0044] Embodiment 2.

[0045] The embodiment provides a preparation method of a ternary boride cermet.

[0046] In step one, the titanium powder, carbon powder, chromium powder, nitrogen powder, nickel powder, molybdenum powder, tungsten powder, iron powder and boron powder are screened by an ultra-fine sieve classifier.

[0047] In step two, the screened raw materials in step one are mixed.

[0048] In step three, the mixed powder is pressed into a green compact.

[0049] In step four, the green compact is debound.

[0050] In step five, the debound green compact in step four is placed into a vacuum sintering furnace for sintering.

[0051] The weight parts of each raw material in step one of the embodiment are titanium powder 38 parts, carbon powder 4.7 parts, chromium powder 6 parts, nitrogen powder 5 parts, nickel powder 30 parts, molybdenum powder 12 parts, tungsten powder 10 parts, iron powder 3 parts, and boron powder 1.5 parts.

[0052] The purity of the titanium powder, the carbon powder, the chromium powder, the nitrogen powder, the nickel powder, the molybdenum powder, the tungsten powder, the iron powder, and the boron powder in step one of the embodiment is greater than 99.5%.

[0053] In step one of the embodiment, the titanium powder, the nickel powder, the molybdenum powder, the tungsten powder, and the boron powder with a particle size less than 10 μm are screened by a superfine sieve classifier.

[0054] In step two of the embodiment, the mixing is performed in a dry mixing manner or a wet mixing manner. When the wet mixing manner is used, the mixture needs to be dried before being pressed into a shape.

[0055] In step three of the embodiment, a promoter is added before pressing. The promoter is an aqueous polyvinyl alcohol solution, and the addition ratio is 4 wt% of the mixture.

[0056] In step three of the embodiment, the pressing process is performed by pressing at a pressure of 180 MPa.

[0057] In step four of the embodiment, the process of debinding is performed in a vacuum furnace with a vacuum degree of ≧10 Pa, and the temperature is raised to 600 ℃ at a rate of 5 ℃ / min.

[0058] In step five of the embodiment, the vacuum sintering in the vacuum furnace is divided into three stages, and the vacuum degree is ≧1.0×10-2 Pa.

[0059] The first stage is to raise the temperature of the pressed compact to 980 ℃ at a rate of 7 ℃ / min and keep the temperature for 120 min.

[0060] The second stage is to raise the temperature to 1350 ℃ at a rate of 4 ℃ / min and keep the temperature for 60 min.

[0061] The third stage is to rapidly reduce the temperature of the furnace to below 980 ℃ at a cooling rate of 18 ℃ / min.

[0062] Embodiment 3.

[0063] The embodiment provides a preparation method of a ternary boride cermet.

[0064] Step one, screening: selecting titanium powder, carbon powder, chromium powder, nitrogen powder, nickel powder, molybdenum powder, tungsten powder, iron powder, and boron powder and screening them by a superfine sieve classifier.

[0065] Step two, mixing: mixing the screened raw materials in step one.

[0066] Step three, pressing: pressing the mixed powder into a shape.

[0067] Step four, defatting;

[0068] Step five, vacuum sintering: the defatted green body in step four is put into a vacuum sintering furnace for sintering.

[0069] The weight parts of each raw material in step one of the embodiment are titanium powder 32 parts, carbon powder 3.6 parts, chromium powder 4 parts, nitrogen powder 3 parts, nickel powder 27 parts, molybdenum powder 10 parts, tungsten powder 7.5 parts, iron powder 2 parts, and boron powder 1 part.

[0070] The purity of the titanium powder, carbon powder, chromium powder, nitrogen powder, nickel powder, molybdenum powder, tungsten powder, iron powder, and boron powder in step one of the embodiment is greater than 99.5%.

[0071] The titanium powder, nickel powder, molybdenum powder, tungsten powder, and boron powder with a particle size less than 10 μm are screened by a superfine sieve classifier in step one of the embodiment.

[0072] The mixing in step two of the embodiment is performed by dry mixing or wet mixing. When wet mixing is used, the mixture needs to be dried before being pressed.

[0073] The accelerator is added before pressing in step three of the embodiment. The accelerator is an aqueous polyvinyl alcohol solution, and the addition ratio is 4 wt% of the mixture.

[0074] The pressing process in step three of the embodiment is performed by pressing at a pressure of 160 MPa.

[0075] The defatting process in step four of the embodiment is performed in a vacuum furnace with a vacuum degree of ≧10 Pa, and the temperature is raised to 450℃ at a rate of 4℃ / min.

[0076] The vacuum sintering in step five of the embodiment is performed in a vacuum furnace with a vacuum degree of ≧1.0×10-2 Pa, and is divided into three stages.

[0077] The first stage: the green body is heated to 880℃ at a rate of 5℃ / min, and is kept at this temperature for 90 min;

[0078] The second stage: then the temperature is raised to 1225℃ at a rate of 3℃ / min, and is kept at this temperature for 50 min;

[0079] The third stage: the furnace temperature is rapidly reduced to below 980℃ at a cooling rate of 14℃ / min.

[0080] The innovation of the present application is that:

[0081] The preparation method of the ternary boride cermet provided by the application does not contain Co, only contains a small amount of tungsten and carbon, is used for enhancing and toughening raw material boron powder and iron powder, is cheap in price, is low in raw material cost, is simple in preparation process flow, is very suitable for mass industrial production, has only about one third of the manufacturing cost of a similar performance hard alloy, has very high performance price ratio and wide application prospect, utilizes the "rare earth effect" of rare earth elements in rare earth oxides to purify the grain boundary, generates oxides with oxygen elements and impurities in the cermet to be discharged, improves the comprehensive mechanical properties of the cermet, and can meet certain service conditions of the material.

[0082] It will be obvious to a person skilled in the art that, as the application is not limited to the details of the exemplary embodiments described above, the application can be implemented in other concrete forms without departing from the spirit or essential characteristics of the application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, and the scope of the application is defined by the appended claims rather than the above description, and it is intended to embrace all changes and modifications that fall within the meaning and scope of the equivalent elements of the claims.

[0083] Furthermore, it should be understood that, although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the present specification is described in this way only for the sake of clarity, and a person skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be combined appropriately to form other embodiments that can be understood by a person skilled in the art.

Claims

1. A method for producing a ternary boride cermet, characterized by, It comprises the following steps: Step one, screening: selecting titanium powder, carbon powder, chromium powder, nitrogen powder, nickel powder, molybdenum powder, tungsten powder, iron powder, boron powder, and screening them through a superfine screen classifier; Step two, mixing: mixing the screened raw materials in step one; Step three, pressing: pressing the mixed powder into a shape; Step four, debinding; Step five, vacuum sintering: placing the debound green body in step four into a vacuum sintering furnace for sintering; The weight parts of each raw material in step one are as follows: titanium powder 26-38 parts, carbon powder 2.5-4.7 parts, chromium powder 2-6 parts, nitrogen powder 1-5 parts, nickel powder 24-30 parts, molybdenum powder 8-12 parts, tungsten powder 5-10 parts, iron powder 1-3 parts, and boron powder 0.5-1.5 parts; The purity of the titanium powder, carbon powder, chromium powder, nitrogen powder, nickel powder, molybdenum powder, tungsten powder, iron powder, and boron powder in step one is greater than 99.5%; The titanium powder, nickel powder, molybdenum powder, tungsten powder, and boron powder with a particle size less than 10 μm are screened through a superfine screen classifier in step one; A promoter is added before pressing in step three, and the promoter is an aqueous polyvinyl alcohol solution, and the addition ratio is 4 wt% of the mixed material; The vacuum degree in the vacuum furnace in step five is ≧1.0×10-2 Pa, and the vacuum sintering is divided into three stages; First stage: heating the pressed body to 780-980 ℃ at a rate of 3-7 ℃ / min, and keeping the temperature for 60-120 min; Second stage: then heating to 1100-1350 ℃ at a rate of 2-4 ℃ / min, and keeping the temperature for 40-60 min; Third stage: rapidly cooling the furnace temperature to below 980 ℃ at a cooling rate of 10-18 ℃ / min.

2. The method for preparing a ternary boride cermet according to claim 1, characterized in that, The mixing in step two adopts a dry mixing method or a wet mixing method, and when the wet mixing method is adopted, it needs to be dried before pressing into a shape.

3. The method for preparing a ternary boride cermet according to claim 1, characterized in that, The pressing process in step three is performed at a pressure of 140-180 MPa.

4. The method for preparing a ternary boride cermet according to claim 1, characterized in that, The debinding process in step four is performed in a vacuum furnace with a vacuum degree ≧10 Pa, and the temperature is raised to 300-600 ℃ at a rate of 2-5 ℃ / min.