Titanium carbide porous ceramic preform, brake disc and preparation method

文档序号：355514 发布日期：2021-12-07 浏览：32次中文

阅读说明：本技术 一种碳化钛多孔陶瓷预制体、制动盘及制备方法 (Titanium carbide porous ceramic preform, brake disc and preparation method ) 是由聂广远钟梓云杨国栋王剑宋呈威于 2021-07-23 设计创作，主要内容包括：本发明涉及高速列车制动盘技术领域,公开了一种碳化钛多孔陶瓷预制体、制动盘及制备方法。碳化钛多孔陶瓷预制体,采用具有贯通气孔的有机骨架模板和如下原料烧结制得；以重量份数计,所述原料包括：40份～75份的过渡金属碳化物粉体,20份～52份的过渡金属粉体,1份～7份的还原铁粉,2份～6份的羰基铁粉；其中,所述过渡金属碳化物包括碳化钛粉；所述过渡金属粉体包括钛粉。制备得到的碳化钛多孔陶瓷预制体具有低密度、高熔点、高硬度、耐磨、耐腐蚀且稳定性好等优异的物理化学性能。本发明还提供了利用碳化钛多孔陶瓷预制体制备制动盘及制动盘的制备方法。(The invention relates to the technical field of high-speed train brake discs, and discloses a titanium carbide porous ceramic preform, a brake disc and a preparation method. The titanium carbide porous ceramic preform is prepared by sintering an organic skeleton template with through air holes and the following raw materials; the raw materials comprise the following components in parts by weight: 40 to 75 parts of transition metal carbide powder, 20 to 52 parts of transition metal powder, 1 to 7 parts of reduced iron powder and 2 to 6 parts of carbonyl iron powder; wherein the transition metal carbide comprises titanium carbide powder; the transition metal powder comprises titanium powder. The prepared titanium carbide porous ceramic preform has excellent physicochemical properties such as low density, high melting point, high hardness, wear resistance, corrosion resistance, good stability and the like. The invention also provides a brake disc prepared from the titanium carbide porous ceramic preform and a preparation method of the brake disc.)

1. A titanium carbide porous ceramic preform is characterized in that the preform is prepared by sintering an organic skeleton template with through air holes and the following raw materials; the raw materials comprise the following components in parts by weight: 40 to 75 parts of transition metal carbide powder, 20 to 52 parts of transition metal powder, 1 to 7 parts of reduced iron powder and 2 to 6 parts of carbonyl iron powder;

wherein the transition metal carbide comprises titanium carbide powder; the transition metal powder comprises titanium powder.

2. The titanium carbide porous ceramic preform of claim 1, wherein the transition metal carbide powder further comprises any one or more of chromium carbide powder, vanadium carbide powder, and tantalum carbide powder.

3. The porous ceramic preform of claim 1, wherein the transition metal powder further comprises one or more of molybdenum powder, nickel powder, and copper powder.

4. The titanium carbide porous ceramic preform according to any one of claims 1 to 3, further comprising 1 to 20 parts of boron carbide powder.

5. A method for producing a titanium carbide porous ceramic preform according to any one of claims 1 to 4, comprising:

template pretreatment: selecting an organic framework template, wherein the framework template is provided with through holes, and cleaning the organic framework template, wherein the pore diameter of the through holes is 10 PPI-30 PPI;

mixing materials: mixing the raw materials according to the proportion, and grinding the mixed powder to obtain mixed powder;

preparing slurry: adding the mixed powder into a polyol aqueous solution with the concentration of 1-3 wt.%, and fully stirring to obtain slurry, wherein the solid content of the slurry is 25-35 vol%;

dip coating: dipping the pretreated organic framework template into the prepared slurry for primary coating, fully extruding the coated organic framework template to remove redundant slurry, fully drying at room temperature, carrying out next dipping coating, and repeating the step for coating for multiple times;

firing: and (3) placing the sample which is completely and fully soaked and dried in a graphite mould, and sintering in vacuum to obtain the titanium carbide porous ceramic preform.

6. The method for preparing a titanium carbide porous ceramic preform according to claim 5, wherein the grinding comprises roller ball milling; when the ball is milled by the roller, the ball material ratio is (1-3): (1-2), the ball milling speed is 140-180 rpm, and the ball milling time is 4-8 h.

7. The method for preparing a titanium carbide porous ceramic preform according to claim 5, wherein the grinding comprises planetary ball milling; during planetary ball milling, the ball-material ratio is (8-12): (1-2), the ball milling speed is 250-350 rpm, and the ball milling time is 3-7 h.

8. The method for preparing a titanium carbide porous ceramic preform according to claim 5, wherein the vacuum sintering comprises the steps of:

heating to 600-800 ℃ at the heating rate of 2-8 ℃/min, keeping the temperature at 600-800 ℃ for 1h to fully remove gas, then transferring to argon gas protective atmosphere at the heating rate of 5-15 ℃/min to sinter, finally keeping the sintering temperature at 1500-1800 ℃ for 1h, and finally cooling along with a furnace and taking out to obtain the titanium carbide porous ceramic preform with the three-dimensional communication structure.

9. A brake disc for train braking, which is characterized by being prepared from a metal matrix and a reinforcement, wherein the metal matrix is reduced iron powder, the reinforcement is the titanium carbide porous ceramic preform according to any one of claims 1 to 4, and the mass ratio of the reduced iron powder to the titanium carbide porous ceramic preform is (6-8): (2-4).

10. A method for producing a brake disc for train braking according to claim 8, comprising the steps of:

preparing a reduced iron powder green body by pressurizing reduced iron powder;

placing the reduced iron powder green body and the titanium carbide porous ceramic prefabricated body in a crucible from bottom to top in sequence;

placing the crucible in a sintering furnace, and preparing a brake disc for train braking through a melting infiltration process; wherein the melt infiltration process conditions are as follows: the infiltration temperature is 1450-1650 ℃, the temperature is kept for 0.5-1 h, and the atmosphere is vacuum.

Technical Field

The invention relates to the technical field of brake pads of high-speed trains, in particular to a titanium carbide porous ceramic prefabricated body, a brake disc and a preparation method.

Background

Along with the development of high speed and heavy load of railway transportation, the load borne by a brake disc of a high-speed train is increasingly large, and as a key part for guaranteeing the transportation safety, the brake disc of the train works under the coupling action of multiple factors such as strong friction, high heat load, large braking force, alternating heat stress and the like, the actual working temperature of the brake disc is continuously increased by heat generated by friction, the working upper limit of the existing brake material is approached, and a novel brake material with better development performance becomes a problem to be solved urgently.

The iron-based composite material designed and developed on the basis of the steel material can improve the strength, hardness, wear resistance, corrosion resistance and high temperature resistance of the steel material, can keep good initial performance at the same time, and can be used for developing parts serving under working conditions of high temperature, high speed friction and the like. However, compared with other metal-based composite materials, the iron-based composite material has the problems of poor wettability with the traditional ceramic reinforcing phase, easy segregation of the reinforcing phase and the like, and also has the problems of high specific gravity, high melting point, poor interface bonding with the reinforcing phase and the like, so that the development and application of the iron-based composite material are restricted to a certain extent, and the iron-based composite material becomes an important problem to be solved urgently for developing the iron-based friction composite material.

Disclosure of Invention

The invention provides a titanium carbide porous ceramic preform, a brake disc and a preparation method thereof, aiming at solving the problems that an iron-based composite material has poor wettability with a traditional ceramic reinforcing phase, the reinforcing phase is easy to generate segregation and the like in the prior art.

According to the first aspect of the invention, the titanium carbide porous ceramic preform is prepared by sintering an organic skeleton template with through air holes and the following raw materials, wherein the raw materials comprise, by mass percent: 60-75 wt% of transition metal carbide powder, 20-40 wt% of transition metal powder, 1-10 wt% of reduced iron powder and 2-8 wt% of carbonyl iron powder; wherein the transition metal carbide comprises titanium carbide powder; the transition metal powder comprises titanium powder.

Compared with the prior art, in the technical scheme, the transition metal carbide powder comprises titanium carbide, the transition metal powder comprises titanium powder, the titanium carbide powder and the transition metal powder are fired to serve as a framework of the titanium carbide porous ceramic preform, and the organic framework template forms a porous structure of the framework of the ceramic preform. The added reduced iron powder can be used as a metal adhesive to improve the strength of the porous ceramic preform. The added carbonyl iron powder is high in activity, small in particle size and in a pellet shape, so that sintering can be further promoted, the sintering density is improved, the defects of a ceramic framework are reduced, and after the sintering, the finally prepared titanium carbide porous ceramic preform contains a main phase TiC and a small amount of Fe detected through XRD test analysis₃And C, the prepared titanium carbide porous ceramic preform can be of a face-centered cubic structure.

In a second aspect, the present invention provides a method for preparing a titanium carbide porous ceramic preform, including:

template pretreatment: selecting an organic framework template, wherein the framework template is provided with through air holes, and cleaning the organic framework template;

mixing materials: mixing the raw materials according to the proportion, and grinding the mixed powder to obtain mixed powder;

firing: and (3) placing the sample which is completely and fully soaked and dried in a graphite mould, and sintering in vacuum to obtain the titanium carbide porous ceramic preform.

Compared with the prior art, the preparation method of the titanium carbide porous ceramic preform has the same beneficial effects as those of the titanium carbide porous ceramic preform in the technical scheme, and the details are not repeated here.

In a third aspect, the invention further provides a brake disc for train braking, which comprises a metal substrate and a reinforcement, wherein the metal substrate is reduced iron powder, the reinforcement is the titanium carbide porous ceramic preform, and the mass ratio of the reduced iron powder to the titanium carbide porous ceramic preform is (6-8): (2-4).

Compared with the prior art, the beneficial effects of the brake disc for train braking provided by the invention are the same as those of the titanium carbide porous ceramic preform in the technical scheme, and the description is omitted here.

In a fourth aspect, a method for manufacturing a brake disc for train braking is provided, which is used for manufacturing the brake disc for train braking, and includes the following steps:

preparing a reduced iron powder green body by pressurizing reduced iron powder;

placing the reduced iron powder green body and the titanium carbide porous ceramic prefabricated body in a crucible from bottom to top in sequence;

Compared with the prior art, the beneficial effects of the preparation method of the brake disc for train braking provided by the invention are the same as those of the brake disc for train braking in the technical scheme, and the detailed description is omitted here.

Drawings

FIG. 1: example 4 TiC-Fe bicontinuous phase composite material prepared by impregnating TiC porous ceramic preform fired by adding reduced iron powder and carbonyl iron powder

FIG. 2: influence of pore size in organic framework template on friction coefficient of TiC-Fe bicontinuous phase composite in examples 1, 12 and 13

FIG. 3: influence of pore size in organic framework template on wear rate of TiC-Fe bicontinuous phase composite in examples 1, 12 and 13

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In the prior art, the problems of poor wettability, easy segregation of a reinforcing phase, poor interface bonding and the like exist between an iron-based composite material and a traditional ceramic reinforcing phase. In order to solve the above problems, embodiments of the present invention provide a titanium carbide porous ceramic preform having good wettability with an iron-based composite material, which can solve the problems of easy segregation of a reinforcing phase and poor interface bonding.

The embodiment of the invention provides a titanium carbide porous ceramic preform which comprises the following raw materials in parts by weight: 40 to 75 parts of transition metal carbide powder, 20 to 52 parts of transition metal powder, 1 to 7 parts of reduced iron powder and 2 to 6 parts of carbonyl iron powder. In specific implementation, the transition metal carbide powder may be titanium carbide powder, and the amount of the transition metal carbide powder may be selected from 40 parts, 55 parts, 60 parts, 63.7 parts, 75 parts, and the like, and is not particularly limited herein. The transition metal powder may be titanium powder, and the amount may be selected from 20 parts, 23.3 parts, 34.5 parts, 37 parts, 52 parts, and the like, and is not particularly limited herein. The amount of the reduced iron powder to be used may be selected from 1 part, 2 parts, 5.4 parts, 3.7 parts, 7 parts, etc., and is not particularly limited. The amount of the carbonyl iron powder may be specifically selected from 2 parts, 3 parts, 4.3 parts, 5.1 parts, 6 parts, and the like, and is not particularly limited herein. Because the titanium carbide porous ceramic preform is prepared by sintering at high temperature, the bonding property between the sintered powder directly influences the strength property of the sintered finished product, and the sintering density influences the skeleton shape of the sintered finished product. Therefore, the titanium carbide porous ceramic preform provided by the embodiment of the invention can be used as a metal adhesive to improve the strength of the porous ceramic preform by adding the reduced iron powder, and the porous ceramic preform can be further promoted to be sintered by adding the carbonyl iron powder due to high activity, small particle size and pellet shape, so that the sintering density is improved, the defects of a ceramic skeleton are reduced, and the strength performance of the titanium carbide porous ceramic preform is improved. In addition, experiments prove that only when 1-2 wt% of reduced iron powder and 2-3 wt% of carbonyl iron powder are added, the prepared titanium carbide porous ceramic preform has excellent physicochemical properties such as low density, high melting point, high hardness, wear resistance, corrosion resistance, good stability and the like, and has the advantages of better excellent friction coefficient stability and low wear rate.

Meanwhile, the transition metal carbide powder also comprises one or more of chromium carbide powder, vanadium carbide powder and tantalum carbide powder. It is understood that the transition metal carbide powder may include titanium carbide powder, chromium carbide powder. Alternatively, the transition metal carbide powder may include titanium carbide powder and vanadium carbide powder. Alternatively, the transition metal carbide powder may include titanium carbide powder and tantalum carbide powder. Alternatively, the transition metal carbide powder may include titanium carbide powder, chromium carbide powder, and vanadium carbide powder. Or, the transition metal carbide powder may include titanium carbide powder, chromium carbide powder, tantalum carbide powder. Alternatively, the transition metal carbide powder may include titanium carbide powder, chromium carbide powder, vanadium carbide powder, and tantalum carbide powder. Chromium carbide powder and/or vanadium carbide powder is added, and can be used as reinforcing particles to be uniformly dispersed in the porous ceramic preform, so that the strength and the wear resistance of the preform are further improved. The added tantalum carbide powder can play a role in refining grains in the firing process, so that the strength and the hardness of the preform are further improved.

In addition, in the transition metal carbide powder, the titanium carbide powder may be 70 wt% or more of the transition metal carbide powder. Tests prove that when the transition metal carbide powder comprises titanium carbide powder, chromium carbide powder, vanadium carbide powder and tantalum carbide powder, the mass ratio of the titanium carbide powder to the chromium carbide powder to the vanadium carbide powder to the tantalum carbide powder can be (35-60): (2-5): (2-5): (1-5), and at the moment, the wear resistance, the strength and the hardness of the prepared titanium carbide porous ceramic preform can reach the optimal performances.

Further, the transition metal powder may further include one or more of molybdenum powder, nickel powder, and copper powder. Wherein, the transition metal powder can be composed of titanium powder and molybdenum powder. At this time, XRD test analysis shows that the main phase of the sintered preform is titanium carbide, and a small amount of titanium and molybdenum carbide. After the molybdenum powder is added, the molybdenum powder is coated on the surface of the titanium carbide particles, so that the subsequent preparation of the brake disc for train braking is facilitated, and the wettability of the particles and the iron melt in the infiltration process is improved. Tests prove that when the mass ratio of the addition amounts of the titanium powder and the molybdenum powder is (19-37): (1-15), when the prepared titanium carbide porous ceramic preform is used for preparing a brake disc for train braking, the infiltration wettability of the preform with an iron matrix is optimal, and the tensile strength of the prepared brake disc for train braking is optimal and can reach 340 MPa.

In addition, the transition metal powder can also be composed of titanium powder, molybdenum powder and nickel powder. Or the transition metal powder consists of titanium powder, molybdenum powder and copper powder. Or the transition metal powder consists of titanium powder, molybdenum powder, nickel powder and copper powder. When at least three transition metal powders are included, the mass ratio of the titanium powder to the transition metal powders is at least over 64 wt%, and the mass ratio of the molybdenum powder to the transition metal powders is at least over 2%. For example, when the transition metal powder is composed of titanium powder, molybdenum powder, nickel powder and copper powder, the mass ratio of the addition amounts of the titanium powder, the molybdenum powder, the nickel powder and the copper powder may be (18-42): (1-7): (0.5-1.5): (0.5 to 1.5). After the nickel powder and the copper powder are added on the basis of the titanium powder and the molybdenum powder, the nickel powder and the copper powder are dispersed in the porous ceramic preform, the nickel powder can further improve the toughness of the ceramic preform, and the copper powder can improve the thermal conductivity of the ceramic preform. The materials have synergistic effect, and the cutting resistance and the thermal stability of the titanium carbide porous ceramic preform can be further improved.

The titanium carbide porous ceramic preform can comprise boron carbide powder, and the addition amount of the boron carbide powder is 1-20 parts by weight of the porous ceramic preform. At the moment, the boron carbide powder is added, and the boron carbide powder and other components act together, so that the stability of the friction coefficient of the titanium carbide porous ceramic preform can be improved, and the wear rate is reduced.

The embodiment of the invention also provides a brake disc for train braking and a preparation method thereof. The reinforcement can be the titanium carbide porous ceramic preform. The mass ratio of the reduced iron powder to the titanium carbide porous ceramic preform is (6-8): (2-4). Specifically, the mass ratio of the reduced iron powder to the titanium carbide porous ceramic preform can be selected from 6:2, 8:4 and 6: 4. 8:2, 7:3, etc., and are not particularly limited herein.

The preparation method of the brake disc for train braking comprises the following steps:

step S10, template preprocessing: selecting an organic framework template, wherein the framework template is provided with through air holes, and cleaning the organic framework template. Wherein, the organic framework template can be selected from organic materials with a three-dimensional network framework structure. For example, the pore diameter of the polyurethane sponge can be 10PPI to 30PPI, for example, 10PPI, 20PPI, 30PPI and the like can be selected. The unit ppi (pores Per inc) specifically refers to the number of pores in the polyurethane sponge Per inch, and the size of the polyurethane sponge precursor may be 30mmx30mmx10 mm. The larger the PPI number, the smaller the pore size, the denser the three-dimensional network. Further, the organic framework template can be cleaned, and the cleaning method can refer to the prior art. In an example, the embodiment discloses a method for cleaning an organic framework template, which can specifically refer to the following steps: soaking the organic template in 10 wt.% NaOH deionized water solution for 12h to remove the inter-network membrane of the organic template, taking out the organic template, and then washing the organic template clean with deionized water. Then soaking the mixture for 6 hours by taking a 2 wt.% CMC (sodium carboxymethylcellulose, surface activity value HLB is more than 12) deionized water solution as a surfactant, taking out the mixture, and then squeezing out the redundant CMC by using a glass rod for later use.

Step S20, preparation of a porous ceramic preform:

step S201, mixing materials: mixing the raw materials for preparing the porous ceramic preform according to the proportion, and grinding the mixed powder to obtain mixed powder;

the grinding comprises roller ball milling and/or planetary ball milling. When roller ball milling is adopted, the ball-material ratio can be (1-3): (1-2). In specific use, for example, the ball-to-feed ratio may be 1:1, 1:2, 3:1, 3:2, etc., and is not particularly limited herein. The rotation speed of the roller ball mill is 140 to 180rpm, and for example, 140rpm, 150rpm, 160rpm, 170rpm, 180rpm, and the like may be selected when the roller ball mill is used specifically, and the rotation speed is not particularly limited herein. The ball milling time of the roller ball milling is 4-8 h, and when the ball milling is used specifically, 4h, 5h, 6h, 7h, 8h and the like can be selected, and the ball milling is not limited specifically.

In addition, the grinding can also be carried out by planetary ball milling. When the planetary ball milling is adopted, the ball-material ratio is (8-12): (1-2). For example, when the pellet is used specifically, the pellet-to-feed ratio may be 8:1, 9:1.3, 10:1.6, 11:1, 12:2, or the like, and is not particularly limited herein. The planetary ball milling rotation speed may be 250 to 350rpm, and in particular, when used, for example, the planetary ball milling rotation speed may be 250rpm, 300rpm, 325rpm, 350rpm, and the like, which is not particularly limited herein. The planetary ball milling time can be 3-7 h, and when the planetary ball milling device is used, the planetary ball milling time can be 3h, 5h, 7h and the like, and is not limited specifically here.

Step S202, slurry preparation: adding the mixed powder into 1-3 wt.% aqueous solution of polyhydric alcohol, and fully stirring to obtain slurry, wherein the solid content of the slurry is 25-35 vol%. The aqueous solution of the above-mentioned polyhydric alcohol may be selected from aqueous solutions of polymer polyhydric alcohols, for example, aqueous solutions of polyvinyl alcohol, polyethylene glycol or low molecular weight polypropylene glycol. The concentration of the aqueous polyol solution may be selected from 1 wt%, 1.6 wt%, 2.3 wt%, 3 wt%, etc., and is not particularly limited herein. The solid content of the slurry may be selected from 25 vol%, 27.6 vol%, 32.5 vol%, 35 vol%, and the like, and is not particularly limited herein.

Step S203, dip coating: and dipping the pretreated organic framework template into the prepared slurry for primary coating. And (3) fully extruding the coated organic framework template to remove redundant slurry, fully drying at room temperature, and then carrying out next dip coating. This step is repeated a plurality of times for coating. The organic framework template can be fully loaded with the mixed powder raw materials through multiple dipping and coating, and the mixed powder can be uniformly coated on the organic framework template.

Step S204, firing: and (3) placing the sample which is completely and fully soaked and dried in a graphite mould, and sintering in vacuum to obtain the titanium carbide porous ceramic preform. And during the firing, heating to 600-800 ℃ at the heating rate of 2-8 ℃/min, and keeping the temperature at 600-800 ℃ for 1h to fully remove the gas. Under the temperature condition, the metal powder is bonded to form a ceramic skeleton structure, the organic skeleton template forms a porous structure in the ceramic skeleton structure, and liquid in the metal powder slurry gradually volatilizes along with the temperature rise to finally form the titanium carbide porous ceramic skeleton.

At the moment, heating and sintering are carried out at the heating rate of 5-15 ℃/min under the argon protection atmosphere, and the final sintering temperature is 1500-1800 ℃, so that the titanium carbide porous ceramic preform is prepared. Specific temperature rise rates are not particularly limited, and may be 5 ℃, 10 ℃, 15 ℃, or the like. The method can ensure that all materials are fully reacted by setting a certain heating frequency to heat, so that the internal tissues of the titanium carbide porous ceramic prefabricated body are more uniform, and all physical properties of the prepared titanium carbide porous ceramic prefabricated body are more excellent. The preparation method also comprises the steps of keeping the temperature for 1h after the sintering temperature is 1500-1800 ℃, and finally cooling and taking out the titanium carbide porous ceramic preform with the three-dimensional communication structure along with the furnace to obtain the titanium carbide porous ceramic preform. Through the heat preservation treatment process, the titanium carbide porous ceramic preform can be further refined, so that the distribution among the internal tissues of the titanium carbide porous ceramic preform is more uniform, all elements are fully alloyed, and all physical properties of the prepared titanium carbide porous ceramic preform are more excellent.

Step 30, melt infiltration: and preparing the reduced iron powder green compact by pressurizing the reduced iron powder. Specifically, reduced iron powder may be compacted into a green reduced iron powder at 60 Mpa. And placing the reduced iron powder green body and the titanium carbide porous ceramic preform in a crucible from bottom to top in sequence for melting infiltration to obtain a composite material, and finally preparing the brake disc. Wherein the melt infiltration process conditions are as follows: the infiltration temperature is 1450-1650 ℃, the temperature is kept for 0.5-1 h, and the atmosphere is vacuum. Specifically, the impregnation temperature may be 1450 ℃, 1500 ℃, 1550 ℃, 1600 ℃, 1650 ℃ or the like, and is not particularly limited herein. In addition, the crucible can be selected from a magnesium oxide crucible, a high-purity graphite crucible, a graphite-silicon carbide crucible and the like, the crucible is baked, and the baked crucible is selected, so that water vapor in the crucible can be reduced, the influence of the water vapor on the alloying of each element is avoided, meanwhile, the crucible can be protected, and the service life of the crucible is prolonged. And (3) placing the crucible in a sintering furnace, and preparing the composite friction material through a melting infiltration process.

Here, both the titanium carbide and the reduced iron powder (i.e., γ -Fe) as the metal matrix in the titanium carbide porous ceramic preform have a face-centered cubic structure, and when the molten infiltration is performed at a high temperature, the both have good wettability and do not undergo a chemical reaction. At the moment, after the reduced iron powder green body arranged below is melted, the reduced iron powder green body permeates into the titanium carbide porous ceramic preform from bottom to top through capillary force, and the pores of the titanium carbide porous ceramic preform are completely filled. The titanium carbide porous ceramic preform substantially retains its original shape after infiltration with metal. After high-temperature infiltration, a composite material of a double continuous phase of titanium carbide and iron can be formed between the titanium carbide porous ceramic preform and the reduced iron powder matrix, and finally a brake disc for train braking is formed.

FIG. 1 shows a scanning electron microscope image of a TiC-Fe bicontinuous phase composite material prepared by adding reduced iron powder and TiC porous ceramic preform for infiltration. As can be seen from figure 1, in the stretching process of the brake disc, the TiC ceramic skeleton plays a role in bearing an external load and can effectively prevent dislocation slippage in the Fe matrix, and after the skeleton is broken, the metal matrix can continue to bear and generate obvious plastic deformation, so that the occurrence of breakage is delayed. Therefore, the reinforcing phase and the matrix of the double-continuous-phase train braking brake disc prepared in the embodiment of the invention play a mutual supporting role, the performance of the TiC-Fe double-continuous-phase train braking brake disc is improved, and the advantages of high hardness, high wear resistance, high heat resistance and the like of porous ceramics, high toughness, high strength, high heat conductivity and the like of metal can be exerted. Therefore, the brake disc for train braking has excellent friction performance, heat resistance and cutting resistance, and shows stable friction coefficient, low wear rate, high heat conductivity and low thermal expansion coefficient.

The titanium carbide porous ceramic preform, the brake pad for train braking and the method for manufacturing the same according to the present invention will be further described with reference to the following examples, which are merely illustrative and not intended to be limiting.

The test methods used in the following examples are all conventional methods unless otherwise specified; the equipment, raw materials and the like used in the following examples are commercially available unless otherwise specified.

The determination methods of the technical indexes of the invention are all standard methods used in the field, and specific reference can be made to the latest national standard unless otherwise stated. In addition, other raw materials used in the present invention are those generally used in the art.

Example one

The composition of the brake disc for train braking selected in the embodiment comprises: 3000g of reduced iron powder and 1000g of titanium carbide porous ceramic preform. In the embodiment, the titanium carbide porous ceramic preform is prepared by sintering an organic framework template with 10PPI through air holes and the following raw materials: 400g of transition metal carbide powder, 520g of transition metal powder, 37g of reduced iron powder, and 43g of carbonyl iron powder. Wherein the transition metal carbide powder is titanium carbide powder, and the transition metal powder is titanium powder.

The preparation method of the brake disc for train braking in the embodiment of the invention comprises the following steps:

step S10, template preprocessing: the organic framework template is made of polyurethane sponge with through air holes, wherein the pore diameter of the polyurethane sponge is 10PPI, and the size of a polyurethane sponge precursor is 30mmx30mmx10 mm.

In the step, the polyurethane sponge is cleaned by adopting the following cleaning method: soaking the organic template in 10 wt.% NaOH deionized water solution for 12h to remove the inter-network membrane of the organic template, taking out the organic template, and then washing the organic template clean with deionized water. Then soaking the mixture for 6 hours by taking a 2 wt.% CMC (sodium carboxymethylcellulose, surface activity value HLB is more than 12) deionized water solution as a surfactant, taking out the mixture, and then squeezing out the redundant CMC by using a glass rod for later use.

Step S20, preparation of a porous ceramic preform:

step S201, mixing materials: mixing the raw materials for preparing the porous ceramic preform according to the proportion, and grinding the mixed powder to obtain mixed powder. The grinding comprises roller ball milling, when the roller ball milling is adopted, the ball-material ratio can be 1:2, the rotating speed is 180rpm, and the ball milling time of the roller ball milling is 8 hours.

Step S202, slurry preparation: adding the mixed powder into a polyvinyl alcohol aqueous solution with the concentration of 1 wt.%, and fully stirring to obtain slurry, wherein the solid content of the slurry is 25 vol%.

And at the moment, heating and sintering at the heating rate of 5 ℃/min under the argon protection atmosphere, keeping the temperature for 1h after the final sintering temperature is 1500 ℃ and reaching the sintering temperature of 1500 ℃, and finally cooling along with the furnace and taking out to obtain the titanium carbide porous ceramic preform with the three-dimensional communication structure.

Step 30, melt infiltration: and preparing the reduced iron powder green compact by pressurizing the reduced iron powder. Specifically, reduced iron powder was compacted at 60Mpa to a green reduced iron powder. And placing the reduced iron powder green body and the titanium carbide porous ceramic preform in a crucible from bottom to top in sequence for melting infiltration. Wherein the melt infiltration process conditions are as follows: the infiltration temperature is 1450 ℃, the temperature is kept for 1h, and the atmosphere is vacuum. Preparing the TiC-Fe bicontinuous phase composite material through a melt infiltration process, and finally preparing the brake disc for train braking.

Through performance tests, the tensile strength of the prepared TiC-Fe bicontinuous phase composite material reaches 270 MPa.

Example two

The composition of the brake disc for train braking selected in the embodiment comprises: 1500g of reduced iron powder and 1000g of a titanium carbide porous ceramic preform. In the embodiment, the titanium carbide porous ceramic preform is prepared by sintering an organic framework template with 20PPI through air holes and the following raw materials; : 550g of transition metal carbide powder, 345g of transition metal powder, 54 g of reduced iron powder, 51 g of carbonyl iron powder; wherein the transition metal carbide powder is titanium carbide powder, and the transition metal powder is titanium powder.

The preparation method of the brake disc for train braking in the embodiment of the invention comprises the following steps:

step S10, template preprocessing: a polyurethane sponge with through air holes is selected as a framework template, wherein the pore diameter of the polyurethane sponge is 20PPI, and the size of a polyurethane sponge precursor is 30mmx30mmx10 mm.

Step S20, preparation of a porous ceramic preform:

step S201, mixing materials: mixing the raw materials for preparing the porous ceramic preform according to the proportion, and grinding the mixed powder to obtain mixed powder. The grinding comprises roller ball milling, when the roller ball milling is adopted, the ball-material ratio can be 3:1, the rotating speed is 140rpm, and the ball milling time of the roller ball milling is 4 h.

Step S202, slurry preparation: adding the mixed powder into a polyvinyl alcohol aqueous solution with the concentration of 1.6 wt.%, and fully stirring to obtain slurry, wherein the solid content of the slurry is 27.6 vol%.

And at the moment, heating and sintering at the heating rate of 10 ℃/min under the argon protection atmosphere, keeping the sintering temperature at 1600 ℃ for 1h after reaching the sintering temperature of 1600 ℃, and finally cooling along with the furnace and taking out to obtain the titanium carbide porous ceramic preform with the three-dimensional communication structure.

Step 30, melt infiltration: and preparing the reduced iron powder green compact by pressurizing the reduced iron powder. Specifically, reduced iron powder was compacted at 60Mpa to a green reduced iron powder. And placing the reduced iron powder green body and the titanium carbide porous ceramic preform in a crucible from bottom to top in sequence for melting infiltration. Wherein the melt infiltration process conditions are as follows: the infiltration temperature is 1500 ℃, the temperature is kept for 1h, and the atmosphere is vacuum. Preparing the TiC-Fe bicontinuous phase composite material through a melt infiltration process, and finally preparing the brake disc for train braking.

Through performance tests, the tensile strength of the prepared TiC-Fe bicontinuous phase composite material reaches 260 MPa.

EXAMPLE III

The composition of the brake disc for train braking selected in the embodiment comprises: 2000g of reduced iron powder and 1000g of titanium carbide porous ceramic preform. In the embodiment, the titanium carbide porous ceramic preform is prepared by sintering an organic framework template with 30PPI through air holes and the following raw materials: 637g of transition metal carbide powder, 233g of transition metal powder, 70g of reduced iron powder, and 60g of carbonyl iron powder. Wherein the transition metal carbide powder is titanium carbide powder, and the transition metal powder is titanium powder.

The preparation method of the brake disc for train braking in the embodiment of the invention comprises the following steps:

step S10, template preprocessing: a polyurethane sponge with through air holes is selected as a framework template, wherein the aperture of the polyurethane sponge is 30PPI, and the size of a polyurethane sponge precursor is 30mmx30mmx10 mm.

Step S20, preparation of a porous ceramic preform:

step S201, mixing materials: mixing the raw materials for preparing the porous ceramic preform according to the proportion, and grinding the mixed powder to obtain mixed powder. The grinding comprises roller ball milling, when the roller ball milling is adopted, the ball-material ratio can be 3:2, the rotating speed is 160rpm, and the ball milling time of the roller ball milling is 6 h.

Step S202, slurry preparation: adding the mixed powder into a polyvinyl alcohol aqueous solution with the concentration of 2.3 wt.%, and fully stirring to obtain slurry, wherein the solid content of the slurry is 32.5 vol%.

And at the moment, heating and sintering at the heating rate of 15 ℃/min under the argon protection atmosphere, keeping the sintering temperature at 1700 ℃ finally, keeping the temperature for 1h after the sintering temperature reaches 1700 ℃, and finally cooling along with the furnace and taking out to obtain the titanium carbide porous ceramic preform with the three-dimensional communication structure.

Step 30, melt infiltration: and preparing the reduced iron powder green compact by pressurizing the reduced iron powder. Specifically, reduced iron powder was compacted at 60Mpa to a green reduced iron powder. And placing the reduced iron powder green body and the titanium carbide porous ceramic preform in a crucible from bottom to top in sequence for melting infiltration. Wherein the melt infiltration process conditions are as follows: the infiltration temperature is 1550 ℃, the temperature is kept for 1h, and the atmosphere is vacuum. Preparing the TiC-Fe bicontinuous phase composite material through a melt infiltration process, and finally preparing the brake disc for train braking.

Through performance tests, the tensile strength of the prepared TiC-Fe bicontinuous phase composite material reaches 280 MPa.

Example four

The composition of the brake disc for train braking selected in the embodiment comprises: 7000g of reduced iron powder and 3000g of a titanium carbide porous ceramic preform. In the embodiment, the titanium carbide porous ceramic preform is prepared by sintering an organic framework template with 30PPI through air holes and the following raw materials: 1800g of transition metal carbide powder, 1110g of transition metal powder, 30g of reduced iron powder and 60g of carbonyl iron powder. Wherein the transition metal carbide powder is titanium carbide powder, and the transition metal powder is titanium powder.

The preparation method of the brake disc for train braking in the embodiment of the invention comprises the following steps:

Step S20, preparation of a porous ceramic preform:

step S201, mixing materials: mixing the raw materials for preparing the porous ceramic preform according to the proportion, and grinding the mixed powder to obtain mixed powder. The grinding adopts planetary ball milling, when roller ball milling is adopted, the ball-material ratio is 8:2, the rotating speed is 350rpm, and the ball milling time of the roller ball milling is 7 hours.

Step S202, slurry preparation: adding the mixed powder into a polyvinyl alcohol aqueous solution with the concentration of 3 wt.%, and fully stirring to obtain slurry, wherein the solid content of the slurry is 35 vol%.

And at the moment, under the argon protective atmosphere, heating and sintering at the heating rate of 10 ℃/min, keeping the sintering temperature at 1750 ℃ for 1h after the sintering temperature reaches 1750 ℃, and finally cooling along with the furnace and taking out to obtain the titanium carbide porous ceramic preform with the three-dimensional communication structure.

Step 30, melt infiltration: and preparing the reduced iron powder green compact by pressurizing the reduced iron powder. Specifically, reduced iron powder was compacted at 60Mpa to a green reduced iron powder. And placing the reduced iron powder green body and the titanium carbide porous ceramic preform in a crucible from bottom to top in sequence for melting infiltration. Wherein the melt infiltration process conditions are as follows: the infiltration temperature is 1600 ℃, the temperature is kept for 0.5h, and the atmosphere is vacuum. Preparing the TiC-Fe bicontinuous phase composite material through a melt infiltration process, and finally preparing the brake disc for train braking.

Through performance tests, the tensile strength of the prepared TiC-Fe bicontinuous phase composite material reaches 290 MPa.

EXAMPLE five

Fig. 1 illustrates a scanning electron microscope image of a brake disc for train braking prepared by the method for preparing a brake disc for train braking provided by the embodiment of the invention. The composition of the brake disc for train braking selected in the embodiment comprises: 4000g of reduced iron powder and 1000g of titanium carbide porous ceramic preform. In the embodiment, the titanium carbide porous ceramic preform is prepared by sintering an organic framework template with 30PPI through air holes and the following raw materials: 750g of transition metal carbide powder, 200g of transition metal powder, 20g of reduced iron powder, and 30g of carbonyl iron powder. Wherein the transition metal carbide powder is titanium carbide powder, and the transition metal powder is titanium powder.

The preparation method of the brake disc for train braking in the embodiment of the invention comprises the following steps:

Step S20, preparation of a porous ceramic preform:

step S201, mixing materials: mixing the raw materials for preparing the porous ceramic preform according to the proportion, and grinding the mixed powder to obtain mixed powder. The grinding adopts planetary ball milling, when roller ball milling is adopted, the ball-material ratio is 12:1, the rotating speed is 250rpm, and the ball milling time of the roller ball milling is 3 h.

Step S202, slurry preparation: adding the mixed powder into a polyvinyl alcohol aqueous solution with the concentration of 2.4 wt.%, and fully stirring to obtain slurry, wherein the solid content of the slurry is 28.1 vol%.

And at the moment, heating and sintering at the heating rate of 15 ℃/min under the argon protective atmosphere, keeping the sintering temperature at 1800 ℃ to the sintering temperature of 1800 ℃ for 1h, and finally cooling along with a furnace and taking out to obtain the titanium carbide porous ceramic preform with the three-dimensional communication structure.

Step 30, melt infiltration: and preparing the reduced iron powder green compact by pressurizing the reduced iron powder. Specifically, reduced iron powder was compacted at 60Mpa to a green reduced iron powder. And placing the reduced iron powder green body and the titanium carbide porous ceramic preform in a crucible from bottom to top in sequence for melting infiltration. Wherein the melt infiltration process conditions are as follows: the infiltration temperature is 1650 ℃, the temperature is kept for 0.5h, and the atmosphere is vacuum. Preparing the TiC-Fe bicontinuous phase composite material through a melt infiltration process, and finally preparing the brake disc for train braking.

Through performance tests, the tensile strength of the prepared TiC-Fe bicontinuous phase composite material reaches 280 MPa.

EXAMPLE six

Compared with the embodiment 4, in the embodiment of the invention, only the composition of the transition metal powder in the titanium carbide porous ceramic preform is different, and the transition metal powder in the embodiment of the invention comprises titanium powder and molybdenum powder, wherein the mass ratio of the titanium powder to the molybdenum powder is 37:1, and the others are unchanged.

Through performance tests, the tensile strength of the prepared TiC-Fe bicontinuous phase composite material reaches 320 MPa.

EXAMPLE seven

Compared with the embodiment 4, in the embodiment of the present invention, only the compositions of the transition metal carbide powder and the transition metal powder in the titanium carbide porous ceramic preform are different, and the transition metal carbide in the embodiment of the present invention includes titanium carbide powder and chromium carbide powder, wherein the amount of the titanium carbide powder accounts for 70 wt% of the amount of the transition metal carbide. The transition metal powder consists of titanium powder and molybdenum powder, wherein the mass ratio of the addition amount of the titanium powder to the addition amount of the molybdenum powder is 19:15, and the others are unchanged.

Through performance tests, the tensile strength of the prepared TiC-Fe bicontinuous phase composite material reaches 340 MPa.

Example eight

Compared with the embodiment 4, in the embodiment of the present invention, only the compositions of the transition metal carbide powder and the transition metal powder in the titanium carbide porous ceramic preform are different, and in the embodiment of the present invention, the transition metal carbide is composed of titanium carbide powder, chromium carbide powder, vanadium carbide powder, and tantalum carbide powder, wherein the mass ratio of the addition amounts of the titanium carbide powder, the chromium carbide powder, the vanadium carbide powder, and the tantalum carbide powder may be 60: 2: 2: 1. the transition metal powder consists of titanium powder, molybdenum powder, nickel powder and copper powder, wherein the mass ratio of the addition amounts of the titanium powder, the molybdenum powder, the nickel powder and the copper powder can be 18: 7: 1.5: 1.5, others are unchanged.

Through performance tests, the tensile strength of the prepared TiC-Fe bicontinuous phase composite material reaches 370 MPa.

Example nine

Compared with the embodiment 4, in the embodiment of the present invention, only the compositions of the transition metal carbide powder and the transition metal powder in the titanium carbide porous ceramic preform are different, and in the embodiment of the present invention, the transition metal carbide is composed of titanium carbide powder, chromium carbide powder, vanadium carbide powder, and tantalum carbide powder, wherein the mass ratio of the addition amounts of the titanium carbide powder, the chromium carbide powder, the vanadium carbide powder, and the tantalum carbide powder may be 35: 5: 5: 5. the transition metal powder consists of titanium powder, molybdenum powder, nickel powder and copper powder, wherein the mass ratio of the addition amounts of the titanium powder, the molybdenum powder, the nickel powder and the copper powder can be 42: 1: 0.5: 0.5, others are unchanged.

Through performance tests, the tensile strength of the prepared TiC-Fe bicontinuous phase composite material reaches 350 MPa.

Example ten

Compared with the embodiment 4, the embodiment of the invention also comprises 100g of boron carbide, and the other compositions are not changed.

Through performance tests, the tensile strength of the prepared TiC-Fe bicontinuous phase composite material reaches 305 MPa.

EXAMPLE eleven

Compared with the embodiment 4, the embodiment of the invention also comprises 2000g of boron carbide, and the other compositions are not changed.

Through performance tests, the tensile strength of the prepared TiC-Fe bicontinuous phase composite material reaches 310 MPa.

Example twelve

Compared with the embodiment 1, the aperture size of the organic framework template in the embodiment of the invention is 20PPI, and other compositions and preparation conditions are unchanged.

Through performance tests, the tensile strength of the prepared TiC-Fe bicontinuous phase composite material reaches 280 MPa.

EXAMPLE thirteen

Compared with the embodiment 1, the aperture size of the organic framework template in the embodiment of the invention is 30PPI, and other compositions and preparation conditions are unchanged.

Through performance tests, the tensile strength of the prepared TiC-Fe bicontinuous phase composite material reaches 310 MPa.

Comparative example 1 compared with example 6, the reduced iron powder contained in the titanium carbide porous ceramic preform was replaced with iron powder in equal amounts, and the others were not changed.

Through performance tests, the tensile strength of the prepared TiC-Fe bicontinuous phase composite material reaches 210 MPa.

Comparative example 2 compared with example 6, the carbonyl iron powder contained in the titanium carbide porous ceramic preform was replaced with iron powder in equal amounts, and the rest was unchanged.

Through performance tests, the tensile strength of the prepared TiC-Fe bicontinuous phase composite material reaches 225 MPa.

Comparative example 3 compared with example 6, the reduced iron powder and carbonyl iron powder contained in the titanium carbide porous ceramic preform were replaced with iron powder in equal amounts, and the others were not changed.

Through performance tests, the tensile strength of the prepared TiC-Fe bicontinuous phase composite material reaches 140 MPa.

Comparative example 4 compared with example 6, the reduced iron powder of the metal matrix in the brake disc for train braking was replaced with iron powder in equal amount, and the rest was unchanged.

Through performance tests, the tensile strength of the prepared TiC-Fe bicontinuous phase composite material reaches 250 MPa.

Further, the friction coefficient and wear rate of the composite materials prepared in example 1, example 12 and example 13 were measured. The test results are shown in fig. 2 and 3. As can be seen from fig. 2 and 3, when the pore size of the porous pore in the selected organic framework template is reduced from 10PPI to 30PPI, the larger the PPI value is, the smaller the pore size of the organic framework template is, the more dense the three-dimensional network structure is, and the higher the volume content of TiC in the prepared porous ceramic preform is. Furthermore, the volume content of ceramic phase TiC in the TiC-Fe bicontinuous phase composite material is improved, the property difference among different materials in the composite material is increased, and the friction coefficient is further reduced. As can be seen from fig. 2, when the pore diameter of the organic framework template is 30PPI, the pressure change on the surface of the composite material is more stable. In addition, when the pore size of the organic framework template is reduced from 10PPI to 30PPI, the volume content of TiC in the titanium carbide porous ceramic preform is increased, so that the volume content of ceramic phase TiC in the TiC-Fe bicontinuous phase composite material is increased, the property difference among different materials in the composite material is increased, the wear rate of the composite material is reduced, and as can be seen from FIG. 3, when the pore size of the organic framework template is 30PPI, the pressure change on the surface of the composite material is more stable. It should be understood that the pressure variation can be understood as the braking force variation of the brake pad applying pressure to the surface of the brake disc during braking, such as light braking and heavy braking. That is, the organic framework template has a pore size of 30PPI, and the friction coefficient and the friction rate of the composite material are basically stable under different braking forces. In addition, the embodiment of the invention further verifies that the larger the aperture size value of the organic framework template in the porous ceramic is, the more stable the wear resistance of the composite material is. When the aperture size of the organic framework template in the porous ceramic is larger than 30PPI, the ratio of titanium carbide to the metal matrix in the composite material is further increased, and the wear resistance of the composite material is reduced.

Further, the present invention provides a test example, wherein the brake discs prepared in examples 1 to 13 and comparative examples 1 to 4 are subjected to a friction and wear test on a friction and wear testing machine, and the test conditions are as follows: the diameter of the brake disc prepared by the embodiment of the invention is 750mm, the friction radius is 305mm, the disc load is 8.5t, the wheel diameter is 920mm, the bilateral braking pressure is 36kN, and the initial temperature is 50-60 ℃. The results are shown in table 1 (3 runs per speed, averaged):

TABLE 1 brake disc Friction wear test results

From the test results, the brake disc of the invention still has good friction stability at high speed: (1) the titanium carbide porous ceramic preform prepared by adopting the transition metal carbide powder, the transition metal powder, the reduced iron powder and the carbonyl iron powder is soaked with the reduced iron powder to prepare the brake disc, under different friction rates, the maximum value of the fluctuation range of the friction coefficient is only 0.14, and the wear rate is also lower and is only 0.05-0.07 cm³and/MJ. (2) When molybdenum powder is added into the transition metal powder, the tensile strength of the prepared composite material is greatly improved, the fluctuation range of the friction coefficient of the prepared brake disc is smaller under different friction rates, the maximum value of the fluctuation range of the friction coefficient is only 0.005, and the wear rate is further reduced to 0.03-0.04 cm³and/MJ. (3) When any one or more of chromium carbide powder, vanadium carbide powder and tantalum carbide powder is further added into the transition metal carbide powder, the fluctuation range of the friction coefficient of the brake disc at different friction rates is further smaller, and the wear rate is further reduced. (4) In the comparative example, after carbonyl iron powder and/or reduced iron powder in the titanium carbide porous ceramic is replaced by common iron powder, the fluctuation value of the friction coefficient of the brake disc is increased and the wear rate is also greatly improved. (5) In the comparative example, after the reduced iron powder as the metal matrix was replaced with the ordinary iron powder, the friction coefficient fluctuation value and the wear rate of the brake disc manufactured by impregnating the ordinary iron powder with the titanium carbide porous ceramic preform were also increased and the wear rate was also increased substantiallyAnd (4) improving.

All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without inventive step, are within the scope of the present invention.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention and do not limit the spirit and scope of the present invention. Various modifications and improvements of the technical solutions of the present invention may be made by those skilled in the art without departing from the design concept of the present invention, and the technical contents of the present invention are all described in the claims.

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Titanium carbide porous ceramic preform, brake disc and preparation method

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