Method for preparing nitrogen-enriched functional gradient metal ceramic by low pressure nitriding method

A cermet and functional gradient technology, which is applied in the direction of metal material coating process, coating, solid-state diffusion coating, etc., can solve the problem of inhibiting the industrial application of nitrogen-rich functional gradient cermet materials on the surface, low production efficiency, and large investment in equipment, etc. problems, to achieve the effect of easy industrial transformation, low production cost and high equipment cost

Active Publication Date: 2014-09-24
XIAMEN TUNGSTEN
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  • Summary
  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

[0005] However, so far, the methods reported in the literature for the preparation of surface nitrogen-rich functionally graded cermets are all high-temperature and high-pressure nitriding methods, and the nitriding time is long (≥10h), and low-pressure furnace or hot isostatic pressing furnace is used as nitriding method Equipment, equipment investment is large, there are certain potential safety hazards, and the production efficiency is low, which inhibits the industrial application of surface nitrogen-rich functionally gradient cermet materials
[0006] Patent CN1603280A proposes a high-temperature, high-pressure, short-time method to prepare surface-hardened functionally graded cermets. Although the nitriding time is shortened to 1-2 hours, the nitriding pressure is as high as 90-130 MPa, and a hot isostatic pressing furnace must be used. , which not only increases the equipment cost, but also brings high-voltage operation risks
In the patent CN1772701A, it is proposed that the preparation of gradient cermets can be realized at a lower nitriding pressure of 0.08MPa, but according to its patent specification, the nitriding time is as long as 24h, and the production efficiency is low.
In addition, there is also a patent that proposes that the preparation of gradient cermets can be realized by layered paving (CN101838766A), but the preparation process firstly requires the preparation of mixtures of various components, and secondly, the mixture needs to be processed during the pressing process. Fine layered filling makes the preparation process cumbersome and difficult to apply to mass production

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  • Method for preparing nitrogen-enriched functional gradient metal ceramic by low pressure nitriding method
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  • Method for preparing nitrogen-enriched functional gradient metal ceramic by low pressure nitriding method

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Embodiment

[0021] A method for preparing nitrogen-enriched functionally graded cermets by a low-pressure nitriding method of the present invention is to put the sintered cermets into a vacuum integrated furnace, and raise the temperature to the preset nitriding temperature at a certain heating rate under the vacuum sintering state. temperature; when the temperature of the furnace body reaches the preset nitriding temperature, nitrogen partial pressure sintering process is used for nitriding, and by controlling the partial pressure and holding time, and then cooling under nitrogen atmosphere, the surface nitrogen-enriched functional gradient cermet is obtained .

[0022] The prepared nitrogen-rich functionally graded cermet has a composition gradient from the surface to the inside, the surface is rich in N, poor in Co and / or Ni and other binder phases, the alloy has a bending strength of 2200-2500 MPa, and the thickness of the surface gradient layer is 5 ~15 μm.

[0023] A method for pre...

Embodiment 1

[0028] (1) Ingredients + wet grinding: According to the 1# formula in Table 1, select Ti(CN) powder with an average particle size of 1-1.5um, and other powders with an average particle size of about 1um as raw materials, and use alcohol as the grinding medium for ingredients. Using paraffin wax as a molding agent, the amount of paraffin wax added accounts for 4% of the total material weight, the grinding ball to material ratio is 7:1, and the grinding time is 72 hours.

[0029] (2) Spray drying: spray-dry the slurry obtained in step (1) to obtain an RTP mixture with an average particle size of about 100um.

[0030] (3) Molding + sintering: the mixture obtained in step (2) is pressed at a pressure of 150 MPa, and then sintered in a vacuum furnace at a sintering temperature of 1400-1500° C. to obtain a sintered compact alloy.

[0031] (4) Gradient treatment: put the cermet alloy obtained in step (3) into a vacuum integrated furnace, raise the temperature to 1200°C under vacuum c...

Embodiment 2

[0036] The composition of the cermet alloy used in the present embodiment is the same as that in the first embodiment, and its gradient treatment process is as follows:

[0037] Put the cermet alloy into a vacuum integrated furnace, raise the temperature to 1300°C under vacuum at a sintering temperature of 5°C / min, and then switch to partial pressure sintering, the partial pressure is 6000Pa, the sintering atmosphere is a nitrogen atmosphere, and the purity of nitrogen is 99%, and the holding time is 6 hours, the surface nitrogen-enriched functional gradient cermet alloy can be obtained, wherein the thickness of the surface gradient layer is about 15 μm.

[0038] The performance of the surface gradient cermet alloy prepared by the above process is shown in Table 3.

[0039] table 3

[0040]

[0041]The surface gradient layer and the matrix were analyzed by EDS, and the composition differences are shown in Table 4.

[0042] Table 4

[0043]

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Abstract

The invention discloses a method for preparing nitrogen-enriched functional gradient metal ceramic by a low pressure nitriding method. The metal ceramic prepared by the method is Ti(C, N)-based metal ceramic which takes Ti(C, N) and/or TiC and TiN as a main hard phase and metals in the iron group such as Co and/or Ni and the like as a bonding phase. The method disclosed by the invention comprises the steps of filling a metal ceramic sintering body in a vacuum integrated furnace; in a vacuum sintering state, heating to a predetermined nitriding temperature at a heating speed being 3-7 DEG C/min, wherein the predetermined nitriding temperature is 1200-1400 DEG C; when the furnace temperature reaches the predetermined nitriding temperature, nitriding by adopting a nitrogen partial pressure sintering process, controlling the partial pressure at 2000-6000Pa, preserving the heat for 2-6 hours, and cooling in a nitrogen atmosphere to obtain the surface nitrogen-enriched functional gradient metal ceramic. The method disclosed by the invention has the characteristics of less investment, low production cost and high efficiency, and is easy to realize industrialized conversion.

Description

technical field [0001] The invention relates to the technical field of preparation of cermets, in particular to a method for preparing nitrogen-enriched functionally graded cermets by a low-pressure nitriding method. Background technique [0002] Ti(C,N)-based cermets have high hardness, wear resistance, red hardness, excellent high temperature performance and chemical stability. As a tool base material, cermets are widely used in the finishing of steel and other materials due to their good processing properties. Compared with traditional carbide tools, their higher hardness and chemical stability enable high-speed machining and improve machining Efficiency, and the processed workpiece has a good surface finish. However, it is worth pointing out that the relatively low fracture toughness of cermets greatly limits its applications. [0003] Coating technology is undoubtedly a better means to improve the performance of cermets. However, due to the difference in thermal expa...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C29/02C22C1/05C23C8/24
Inventor 马丽丽鲁攀颜延芳李兰谢海唯肖满斗吴冲浒文晓
Owner XIAMEN TUNGSTEN
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