阅读说明：本技术 一种基于多孔碳模板制备多孔wc陶瓷的方法 (Method for preparing porous WC ceramic based on porous carbon template ) 是由 张阔 于方丽 张海鸿 唐健江 于 2020-05-28 设计创作，主要内容包括：本发明涉及多孔陶瓷领域,公开了一种基于多孔碳模板制备多孔WC陶瓷的方法,该方法由多孔碳模板的预加工、多孔碳模板完全转化为多孔WC陶瓷以及多孔WC陶瓷的烧结三个步骤完成。本发明方法工艺简单,成本低廉,且易于制备形状复杂的构件,大大拓展了该法制备的多孔WC陶瓷的使用范围。(The invention relates to the field of porous ceramics, and discloses a method for preparing porous WC ceramics based on a porous carbon template. The method has simple process and low cost, is easy to prepare components with complex shapes, and greatly expands the application range of the porous WC ceramics prepared by the method.)

1. A method for preparing porous WC ceramics based on a porous carbon template is characterized by comprising the following steps:

s100, processing the porous carbon template into a required size;

s200, weighing the mass of the processed porous carbon template, and calculating the mole number of the porous carbon template;

s300, weighing tungsten oxide powder;

s400, taking mixed powder of sodium chloride and potassium chloride;

s500, grinding and uniformly mixing the tungsten oxide powder and the mixed powder to obtain reaction powder;

s600, embedding the processed porous carbon template into reaction powder, and then putting the reaction powder and the reaction powder into a crucible together;

s700, placing the crucible in a vacuum atmosphere furnace, and then carrying out molten salt reaction; cooling the reaction product to room temperature along with the furnace after the reaction is finished, boiling off salt by using hot water, and drying to obtain a sample;

s800, placing the sample in a sintering furnace for sintering, wherein the sintering temperature is 2000-2200 ℃, the heat preservation time is 1-3 h, and cooling the sample to room temperature along with the furnace after sintering is completed to obtain the porous WC ceramic.

2. The method of claim 1, wherein in step S100, the porous carbon template is porous graphite, carbonized wood, or foam.

3. The method according to claim 1, wherein in step S100, the porosity of the porous carbon template is 60% to 90%.

4. The method according to claim 1, wherein in step S300, the molar ratio of tungsten oxide to porous carbon template is (6-10): 1.

5. the method of claim 1, wherein in step S700, the molten salt reaction is performed under vacuum or flowing argon shield conditions.

6. The method of claim 1, wherein in step S700, the reaction temperature of the molten salt reaction is 1300 ℃ to 1500 ℃ and the reaction time is 10 to 15 hours.

7. The method of claim 1, wherein in step S800, the sintering is performed under vacuum or a protective atmosphere.

8. The method of claim 1, wherein in step S400, the ratio of sodium chloride: the molar ratio of potassium chloride is 1: 1.

9. The method according to claim 1, wherein in the step S500, the mass ratio of the tungsten oxide powder to the mixed powder is 1 (10-20).

Technical Field

The invention belongs to the technical field of porous ceramic materials, and particularly relates to a method for preparing porous WC ceramics based on a porous carbon template.

Background

The porous WC ceramic not only has the excellent performances of WC ceramic, such as high hardness, frictional wear resistance, high temperature resistance, corrosion resistance and the like, but also has the characteristics of large specific surface area, low density, good permeability, controllable pore structure and pore shape and the like of a porous material, so that the porous WC ceramic has wide application in industrial environments such as high temperature, corrosive media, frictional wear and the like. In addition, WC generally has good wettability with liquid metals, and therefore porous WC ceramics are also often used for preparing cermets, or as preforms for preparing metal matrix composites by liquid metal infiltration, such as green bodies for preparing ZrC/W composites by reaction infiltration, and the like.

At present, the method for preparing porous WC ceramics mainly comprises S100 gel casting process, such as the literature "gel casting preparation of tungsten carbide porous ceramics" (silicate paper, 2016, 12: 1681-; although the blank prepared by the process has higher density, strength and small shrinkage after molding, suspension slurry with higher solid phase volume fraction and low viscosity is difficult to prepare, and the gel process is more complex; s200, a reaction sintering method, namely pressing tungsten oxide particles into a green body, and then carrying out carbonization reduction by using methane to generate porous WC. For example, the document "preparation of porous carbide ceramics by reaction sintering" (proceedings of engineering science 2015 (37): 751-756). Although the process temperature is low, the strength is low because the bonding is poor and the microstructure is not uniform.

The carbon template method is a commonly used process for preparing porous ceramics, and the process comprises mixing a carbon template (such as carbon particles, porous carbon and the like) and ceramic particles or ceramic slurry to form a composite material, then removing the template and sintering to obtain the porous ceramics. Since the removal of the carbon template is generally performed under an oxidizing atmosphere, the process is only suitable for oxide ceramics or silicon carbide ceramics having strong oxidation resistance, such as "a method for preparing porous silicon carbide ceramics based on a template" in the patent application No. 201510577885.6, "a method for preparing alumina porous ceramics using a bio-template" in the patent application No. 201910989253.9, and the like. WC is large in density (15.8 g/cm)³) The slurry is not easy to prepare and is not oxidation-resistant, so that at present, few published documents about porous WC ceramics prepared based on porous carbon templates are reported at home and abroad.

Disclosure of Invention

The invention aims to provide a method for preparing porous WC ceramics based on a porous carbon template, which solves the problem of complex process in the existing method for preparing porous WC ceramics.

The technical scheme adopted by the invention is as follows:

a method for preparing porous WC ceramics based on a porous carbon template comprises the following steps:

s100, processing the porous carbon template into a required size;

s200, weighing the mass of the processed porous carbon template, and calculating the mole number of the porous carbon template;

s300, weighing tungsten oxide powder;

s400, taking mixed powder of sodium chloride and potassium chloride;

s500, grinding and uniformly mixing the tungsten oxide powder and the mixed powder to obtain reaction powder;

s600, embedding the processed porous carbon template into reaction powder, and then putting the reaction powder and the reaction powder into a crucible together;

s700, placing the crucible in a vacuum atmosphere furnace, and then carrying out molten salt reaction; cooling the reaction product to room temperature along with the furnace after the reaction is finished, boiling off salt by using hot water, and drying to obtain a sample;

s800, placing the sample in a sintering furnace for sintering, wherein the sintering temperature is 2000-2200 ℃, the heat preservation time is 1-3 h, and cooling the sample to room temperature along with the furnace after sintering is completed to obtain the porous WC ceramic.

As a further improvement of the present invention, in step S100, the porous carbon template is porous graphite, carbonized wood or foam.

As a further improvement of the present invention, in step S100, the porosity of the porous carbon template is 60% to 90%.

In a further improvement of the present invention, in step S300, the molar ratio of tungsten oxide to the porous carbon template is (6-10): 1.

as a further improvement of the present invention, in step S700, the molten salt reaction is performed under vacuum or flowing argon protection.

As a further improvement of the method, in the step S700, the reaction temperature of the molten salt reaction is 1300-1500 ℃, and the reaction time is 10-15 h.

As a further improvement of the present invention, in step S800, the sintering is performed under vacuum or in a protective atmosphere.

As a further improvement of the present invention, in step S400, the ratio of sodium chloride: the molar ratio of potassium chloride is 1: 1.

As a further improvement of the invention, in the step S500, the mass ratio of the tungsten oxide powder to the mixed powder is 1 (10-20).

Compared with the prior art, the invention has the following advantages:

the method is completed by three steps of preprocessing the porous carbon template, completely converting the porous carbon template into porous WC ceramics and sintering the porous WC ceramics. The porous carbon template is completely converted into the porous tungsten carbide through the molten salt reaction process, and compared with other processes for preparing the porous ceramic by using a carbon template method, the oxidation of the tungsten carbide does not occur because the step of removing residual carbon by oxidation is not needed. The mechanical properties such as bending strength and the like of the porous ceramic can be greatly improved by sintering the completely converted porous WC. The method has simple process and low cost, and is particularly suitable for preparing components with various complex shapes because the porous carbon template is easy to process, thereby greatly expanding the application range of the porous WC ceramics prepared by the method.

Drawings

FIG. 1 is a photomicrograph of the porous graphite of example 2 of the present invention;

wherein: (a) the figure is a low-magnification morphology photo; (b) the figure is a high-power morphology photo;

FIG. 2 is a micrograph of a porous WC ceramic according to example 2 of the present invention;

wherein: (a) the figure is a low-magnification morphology photo; (b) the figure is a high magnification morphology photo.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, shall fall within the scope of protection of the present invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The invention relates to a method for preparing porous WC ceramics based on a porous carbon template, which comprises the following steps:

s100, processing a porous carbon template into a size required by design;

the porous carbon template is porous graphite, carbonized wood, foam and the like. The porosity is 60-90%.

S200, weighing the mass of the processed porous carbon template, and calculating the mole number of the porous carbon template;

s300, according to the mole ratio of tungsten oxide to the processed porous carbon template, the tungsten oxide to the processed porous carbon template is (6-10): 1, weighing tungsten oxide powder;

s400, preparing sodium chloride: weighing mixed powder of sodium chloride and potassium chloride according to the molar ratio of 1: 1;

s500, pouring tungsten oxide powder and mixed powder into a mortar according to the mass ratio of 1: 10-1: 20, grinding and uniformly mixing to obtain reaction powder;

s600, embedding the processed porous carbon template into reaction powder, and then putting the reaction powder and the reaction powder into a graphite crucible together;

s700, placing the graphite crucible in a vacuum atmosphere furnace, and carrying out molten salt reaction under the protection of vacuum or flowing argon. Cooling the reaction product to room temperature along with the furnace after the reaction is finished, boiling off salt by using hot water, and drying to obtain a sample; the reaction temperature of the molten salt reaction is 1300-1500 ℃, and the reaction time is 10-15 h.

S800, placing the obtained sample in a sintering furnace, wherein the sintering temperature is 2000-2200 ℃, and the heat preservation time is 1-3 h. Sintering under the condition of vacuum or protective atmosphere, and cooling with the furnace to obtain the porous WC ceramics.

The invention is described in further detail below with reference to the figures and the embodiments.