TWI746329B - Preparation method of carbon/boron carbide composite material - Google Patents

Abstract

A method for preparing a carbon/boron carbide composite material includes the following steps: (A) providing a carbon compound, a carbon fiber, a boron compound and a binder to perform a pretreatment mixing procedure to form a precursor; (B) Put the precursor into a spray granulator for a granulation process, the precursor is mixed to form an injection material of uniform composition; (C) the injection material is fed to an injection molding machine for a compression molding process, Forming a carbon compound/boron compound green body; and (D) subjecting the carbon compound/boron compound green body to a two-stage heat treatment process to obtain a carbon/boron carbide composite material.

Description

Preparation method of carbon/boron carbide composite material

The invention relates to a method for preparing a carbon/boron carbide composite material, in particular to a method for preparing a carbon/boron carbide composite ceramic.

Carbon/boron carbide composite materials are ceramic materials with light weight and high hardness. The hardness of boron carbide is second only to diamond and cubic boron nitride in nature, especially near constant high temperature hardness (>30GPa). In boron carbide, boron and carbon are mainly combined by covalent bonds, which have the characteristics of high melting point (2450°C), high hardness, low density (2.52g/cm ³ ), good wear resistance, and strong acid and alkali resistance. However, pure boron carbide itself has disadvantages such as low fracture toughness, excessively high sintering temperature, and poor stability to metals. With the development of carbon/composite ceramic technology, special sintering of carbon/boron carbide composite ceramics has become possible. The important application levels of carbon/boron carbide composite ceramic materials include: brake discs, bearings, lightweight machine exoskeleton, thermocouples and Ballistic ceramics, etc.

The preparation methods of traditional carbon/silicon carbide composite ceramics mainly include hot pressing sintering method, precursor conversion method, chemical vapor synthesis method and reactive melting method. The hot-pressing sintering method has complex equipment, low production efficiency and high cost; the chemical vapor method has a long production cycle, high cost, and many residual pores, which make the prepared carbon/silicon carbide composite ceramics have poor mechanical properties and oxidation resistance; Preparation of melt infiltration method Short cycle and low cost are the most potential preparation methods. However, this method will produce too much free silicon, destroy the structure of carbon fiber, make the performance of carbon/silicon carbide composite ceramics worse, destroy the structure of carbon fiber, and make carbon/ The performance of silicon carbide composite ceramics deteriorates.

Therefore, how to prepare a carbon/boron carbide composite ceramic with low cost, high strength, light weight, and high thermal shock resistance, suitable for industrial production, is a problem that needs to be solved urgently.

In view of the shortcomings of the above-mentioned conventional technology, the main purpose of the present invention is to provide a preparation method of carbon/boron carbide composite material, which has simple operation and high production efficiency, and is suitable for industrial production.

Another object of the present invention is that the carbon/boron carbide composite material prepared by the preparation method of the present invention has the advantages of low raw material cost, high strength, light weight, high toughness and good friction and wear performance.

Another object of the present invention is that the carbon/boron carbide composite material prepared by the preparation method of the present invention has a weight reduction of about 60% compared with brake disc products made of common brake materials, and can withstand high temperatures of 1000°C. Corrosion resistant and lightweight, it is considered to be the most promising new generation of high-strength, lightweight and wear-resistant composite materials.

In order to achieve the above objective, according to the present invention, a method for preparing a carbon/boron carbide composite material is provided, which includes the following steps: (A) Provide a carbon compound, a carbon fiber, a boron compound and a binder for a pretreatment mixing procedure To form a precursor; (B) put the precursor into a spray granulator A granulation process is performed, and the precursor is mixed to form an injection material of uniform composition; (C) the injection material is fed to an injection molding machine for a pressure molding process to form a carbon compound/boron compound green body; and (D) The carbon compound/boron compound green body is subjected to a two-stage heat treatment process to obtain a carbon/boron carbide composite material.

The method for preparing a carbon/boron carbide composite material provided by the present invention, wherein the weight percentage of each component of the carbon compound, the carbon fiber, the boron compound and the binder in the pretreatment mixing procedure is that the carbon compound is 1 wt. %~10wt%, the carbon fiber is 1wt%~20wt%, the boron compound is 40wt%~70wt%, and the binder is 5wt%~35wt%.

In the preparation method of carbon/boron carbide composite material proposed in the present invention, the carbon compound is selected from the group consisting of graphene, carbon black and activated carbon.

The method for preparing carbon/boron carbide composite material proposed by the present invention, wherein the boron compound is selected from the group consisting of h-boron nitride, boron oxide, diborane and trialkylborane, wherein h-nitrogen The boron oxide has a hexagonal boron nitride structure.

The preparation method of carbon/boron carbide composite material proposed by the present invention, wherein the binder is selected from the group consisting of asphalt, polyvinylpyrrolidone, polypropylene, polyvinyl alcohol and silane coupling agent

The preparation method of carbon/boron carbide composite material proposed by the present invention, wherein the pretreatment mixing procedure is to mix the carbon compound, The mixing time of the carbon fiber, the boron compound and the binder is between 1 and 4 hours.

In the preparation method of carbon/boron carbide composite material proposed by the present invention, in step B, the inlet temperature of the spray granulator is above 200 degrees, and the outlet temperature is above 100 degrees.

In the preparation method of the carbon/boron carbide composite material proposed by the present invention, the pressure of the injection molding machine in step C is ≧130kgf, and the temperature is between 150°C and 250°C.

The method for preparing carbon/boron carbide composite material proposed by the present invention, wherein the two-stage heat treatment process of step D is a first stage vacuum heat treatment and a second stage atmosphere heat treatment, wherein the temperature of the first stage vacuum heat treatment The temperature is greater than 1000°C and the calcination time is at least 1 hour, wherein the temperature of the second-stage atmosphere heat treatment is greater than 1900°C, and the calcination time is at least 2 hours.

In the method for preparing carbon/boron carbide composite materials provided by the present invention, the first-stage vacuum heat treatment system uses a high-frequency calciner or a vacuum calciner.

In the method for preparing carbon/boron carbide composite materials proposed in the present invention, the gas system introduced in the second-stage atmosphere heat treatment is a passivation gas, and the passivation gas is selected from the group consisting of argon, helium, and hydrogen. Group.

The above summary and the following detailed description and drawings are for the purpose of further explaining the methods and means adopted by this creation to achieve the intended purpose And efficacy. The other purposes and advantages of this creation will be elaborated in the subsequent descriptions and diagrams.

S101-S104: steps

The first figure is a flow chart of the preparation method of the carbon/boron carbide composite material of the present invention; the second figure is the finished product diagram made according to the preparation method of the carbon/boron carbide composite material of the present invention.

The following is a specific example to illustrate the implementation of this creation. Those who are familiar with this technique can easily understand the advantages and effects of this creation from the content disclosed in this manual.

Please refer to the first figure, which is the preparation method of the carbon/boron carbide composite material of the present invention. The steps may include: (A)) providing a carbon compound, a carbon fiber, a boron compound and a binder for a pretreatment Mixing procedure to form a precursor S101; (B) Put the precursor into a spray granulator for a granulation process, and mix the precursor to form an injection material S102 of uniform composition; (C) Feed the injection material Perform a press molding process to an injection molding machine to form a carbon compound/boron compound green body S103; (D) The carbon compound/boron compound green body is subjected to a two-stage heat treatment process to obtain a carbon/boron carbide composite material S104.

The embodiment of the preparation method proposed in the present invention provides a method for preparing a carbon/boron carbide composite material. The steps may include: Step (A): adding carbon compounds with a weight percentage of 1 wt% to 10 wt% and carbon fibers with a weight percentage of 1 wt% to 20 wt% , 40wt%~70wt% boron compound and 5wt%~35wt% binder are ball milled and mixed for 1 to 4 hours to form a carbon compound/boron compound precursor. In this embodiment, the boron compound can be h-boron nitride , Boron oxide, diborane or trialkylborane, the binder can be pitch, polyvinylpyrrolidone, polypropylene, polyvinyl alcohol or silane coupling agent or at least one, preferably pitch, carbon fiber is polymer fiber or pitch The base material is carbonized and graphitized to form a carbon fiber with a carbon content of more than 80%. It has the advantages of high specific strength, large specific modulus, high temperature mechanical properties and good thermal properties. The carbon powder can be graphene, carbon Black or activated carbon or a combination thereof; (B) Put the body into the spray granulator before step (A) to mix it to form a uniform injection material. The inlet temperature of the spray granulator is set to 220 degrees or more, and the outlet temperature is set 100 degrees or more; (C) the injection material of step (B) is fed to the ceramic injection molding machine for pressure molding to the required model size to form a carbon compound/boron compound green body, and the injection molding machine parameters are set to pressure ≧ 130kgf, set to a temperature between 150°C and 250°C; step (D) vacuum sintering the carbon compound/boron compound green body at a temperature above 1000°C and a calcination time of at least 1 hour, and then calcining at a temperature greater than 1900°C Time At least 2 hours of atmospheric calcination to convert the carbon compound/boron compound to form a boron carbide crystalline phase to obtain a carbon/boron carbide composite ceramic, which promotes a better bonding force.

Please refer to Figure 2. The second figure is the finished product made according to the method for preparing the carbon/boron carbide composite material of the present invention.

In the embodiment of the present invention, the pressure of the injection molding machine can also be between 130-250kgf.

In the embodiment of the present invention, the inlet temperature of the spray granulator can be between 200-300°C, and the outlet temperature can be between 100-160°C.

In the embodiment of the present invention, the vacuum heat treatment temperature of the carbon compound/boron compound green body can be between 1000° C. and 1200° C., and the calcination time can be between 1-5 hours.

In the embodiment of the present invention, the temperature of the atmosphere calcination can be between 1900-2100°C, and the calcination time is between 2 and 14 hours

In the embodiment of the present invention, the heat treatment equipment for vacuum sintering can be a high frequency calciner or a vacuum calciner.

In the embodiment of the present invention, the equipment for the atmosphere calcination may be an atmosphere calcination furnace, the gas introduced into it is a passivation gas, and the passivation gas may be one or a combination of argon, helium, or hydrogen.

The preparation method of the carbon/boron carbide composite material of the present invention has the following advantages: (1) The present invention is a precursor conversion method that does not directly use boron carbide as a raw material. During the granulation process, the precursor is heated and then rapidly cooled, and a uniform solid composition is ejected material. The advantage of granulation is that it can improve the flow and uniformity of the traditional injection, and then through the atmosphere and vacuum heat treatment, the precursor (carbon boron compound) is converted into boron carbide, and the uniformity of the cracking reaction is improved, and the cost of raw materials is reduced. (2) The carbon/boron carbide composite material of the present invention has simple operation, low raw material cost, indirect use of boron carbide as a precursor, and can increase the density and is suitable for industrial production. The carbon/boron carbide composite material obtained by the preparation method of the present invention has the advantages of high strength, light weight, high toughness, good friction and wear performance and the like.

The above-mentioned embodiments are merely illustrative to illustrate the characteristics and effects of this creation, and are not intended to limit the scope of the essential technical content of this creation. Anyone familiar with this technique can modify and change the above-mentioned embodiments without violating the spirit and scope of creation. Therefore, the scope of protection of the rights of this creation should be listed in the scope of patent application described later.

S101-S104: steps

Claims (6)

A method for preparing a carbon/boron carbide composite material includes the following steps: (A) providing a carbon compound, a carbon fiber, a boron compound and a binder to perform a pretreatment mixing procedure to form a precursor, wherein the The weight percentages of the carbon compound, the carbon fiber, the boron compound, and the binder in the pretreatment mixing procedure are: the carbon compound is 1wt%~10wt%, the carbon fiber is 1wt%~20wt%, and the boron compound is 40wt%~70wt% and the binder is 5wt%~35wt%, the carbon compound is selected from the group consisting of graphene, carbon black and activated carbon, and the boron compound is selected from the group consisting of h-boron nitride and boron oxide , Diborane and trialkyl borane, wherein h-boron nitride is a hexagonal boron nitride structure, and the binder is selected from pitch, polyvinylpyrrolidone, polypropylene, polyvinyl alcohol And silane coupling agent; (B) put the precursor into a spray granulator for a granulation process, the precursor is mixed to form an injection material of uniform composition; (C) the injection material is fed to An injection molding machine performs a compression molding process to form a carbon compound/boron compound green body; and (D) the carbon compound/boron compound green body is subjected to a two-stage heat treatment process to obtain a carbon/boron carbide composite material , Wherein the two-stage heat treatment process is a first stage vacuum heat treatment and a second stage atmosphere heat treatment, wherein the temperature of the first stage vacuum heat treatment is greater than 1000°C, and the calcination time is at least 1 hour, wherein the first stage vacuum heat treatment The temperature system of two-stage atmosphere heat treatment If it is greater than 1900°C, the calcination time is at least 2 hours. The method for preparing a carbon/boron carbide composite material according to claim 1, wherein the pretreatment mixing procedure is to mix the carbon compound, the carbon fiber, the boron compound and the binder by ball milling, and the ball milling mixing time is Between 1~4 hours. The method for preparing a carbon/boron carbide composite material according to claim 1, wherein in step B, the inlet temperature of the spray granulator is 220°C or higher, and the outlet temperature is 100°C or higher. The method for preparing a carbon/boron carbide composite material according to claim 1, wherein the pressure of the injection molding machine in step C is greater than 130kgf, and the temperature is between 150°C and 250°C. The method for preparing a carbon/boron carbide composite material according to claim 1, wherein the first-stage vacuum heat treatment system uses a high-frequency calcination furnace or a vacuum calcination furnace. The method for preparing a carbon/boron carbide composite material according to claim 1, wherein the gas system introduced in the second-stage atmosphere heat treatment is a passivation gas, wherein the passivation gas is selected from argon, helium, and hydrogen Formed group.

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