阅读说明：本技术 一种激光烧结合成碳化硼/碳粉体材料的方法 (Method for synthesizing boron carbide/carbon powder material by laser sintering ) 是由 曾和平 黄延伟 胡梦云 乔蔚 于 2021-03-24 设计创作，主要内容包括：本发明属于碳化硼材料制备技术领域,具体为一种激光烧结合成碳化硼/碳粉体材料的方法。将碳化硼反应原料粉末与稀土氧化物粉末进行高能球磨均匀混合,使用压片机将混合均匀的粉末压制成片状,放置于激光工作台固定,控制激光光斑大小、功率、烧结时间等工艺参数进行激光烧结,选用少量或微量的稀土氧化物作为激光催化激活物质,使激光共振激化稀土离子实现能量转移,持续激光能量的供应,使激化离子发生再激化以及多步级联反应和能量转移,从而诱导混合原料发生高温固相反应,生成碳化硼/碳材料,本发明方法激光能量输入低,反应快速,碳化硼的含量高,具有较好耐磨特性,且该制备方法原料利用率高,节能环保,适合大面积工业化生产。(The invention belongs to the technical field of boron carbide material preparation, and particularly relates to a method for synthesizing a boron carbide/carbon powder material by laser sintering. The boron carbide reaction raw material powder and the rare earth oxide powder are subjected to high-energy ball milling and are uniformly mixed, the uniformly mixed powder is pressed into a sheet shape by using a tablet press, the sheet shape is placed on a laser workbench for fixation, the laser spot size, the power, the sintering time and other process parameters are controlled for laser sintering, a small amount or trace rare earth oxide is selected as a laser catalytic activation substance, so that the laser resonance excitation of rare earth ions realizes energy transfer, the supply of laser energy is continued, the excitation ions are subjected to re-excitation, multi-step cascade reaction and energy transfer, the method has the advantages of low laser energy input, quick reaction, high boron carbide content and better wear resistance, and the preparation method has high raw material utilization rate, is energy-saving and environment-friendly, and is suitable for large-area industrial production.)

1. A method for synthesizing boron carbide/carbon powder material by laser sintering is characterized by comprising the following steps: (1) adding rare earth oxide powder into the reaction raw material powder to enable rare earth element ions to absorb partial laser energy and realize energy transfer and raw material cascade reaction;

(2) the method comprises the following steps of uniformly mixing raw materials of the mixed rare earth oxide by high-energy ball milling, pressing the uniformly mixed powder into a sheet by using a tablet press, fixing the sheet on a laser workbench, carrying out laser sintering, exciting rare earth sensitized ions by laser resonance to realize energy transfer, continuing the supply of laser energy, and carrying out re-excitation, multi-step cascade reaction and energy transfer on the excited ions so as to induce the mixed raw materials to carry out high-temperature solid phase reaction and generate boron carbide.

2. The method for synthesizing the boron carbide/carbon powder material by laser sintering according to claim 1, wherein the method comprises the following steps: the rare earth oxide powder in the step (1) comprises oxides of 15 lanthanides and oxides of 17 elements including scandium (Sc) and yttrium (Y) which have similar chemical properties with the lanthanides, and the reaction raw materials are induced to generate high-temperature solid-phase reaction to generate boron carbide components.

3. The method for synthesizing the boron carbide/carbon powder material by laser sintering according to claim 1, wherein the method comprises the following steps: the reaction raw materials in the step (1) are boron sources and carbon source raw materials, the boron sources comprise boric acid (H3 BO 3) and boron oxide (B2O 3), the carbon sources comprise but are not limited to graphite powder, sucrose, glucose and graphene sheets, the high-energy ball milling and mixing in the step (2) are carried out, a polyurethane ball milling tank is adopted during ball milling, absolute ethyl alcohol, acetone or deionized water and the like are used as media, the ball milling rotation speed range is 300-400rpm, the ball milling time is 8-36 hours, a blast drying box is used for drying and grinding the materials into powder after ball milling, and the particle size of the ground powder is 45-150 mu m, so that high-purity boron carbide can be generated finally.

4. The method for synthesizing the boron carbide/carbon powder material by laser sintering according to claim 1, wherein the method comprises the following steps: the raw material of the mixed rare earth oxide in the step (2) can be granulated according to actual needs to obtain a raw material with smaller microscopic particle size and higher density, and the granulation process is as follows: organic colloid materials such as PVA (polyvinyl alcohol) and the like are used as a bonding agent solute, deionized water is used as a solvent, a magnetic stirrer is used for preparing a bonding agent with the mass fraction of 1%, and the mass ratio of the bonding agent to the deionized water is 1: 1, adding the powder into the uniformly mixed powder, grinding for 4 hours, granulating, sieving with a sieve mesh of 325 meshes, pressing the sieved powder into a sheet by using a tablet machine, performing laser irradiation to remove viscosity, and performing other methods such as heat preservation and viscosity removal in a tubular furnace to improve the purity of boron carbide.

5. The method for synthesizing the boron carbide/carbon powder material by laser sintering according to claim 4, wherein the method comprises the following steps: the binder solute includes but is not limited to PVA, methoxy silane, polyurethane, silicone.

6. The method for synthesizing the boron carbide/carbon powder material by laser sintering according to claim 1, wherein the method comprises the following steps: the state of the mixed powder sintered in the step (2) may be a flake state (using a powder tablet press) or a powder state (using a synchronous feeding method).

7. The method for synthesizing the boron carbide/carbon powder material by laser sintering according to claim 1, wherein the method comprises the following steps: the laser sintering process in the step (2) can be carried out in one or more of vacuum, air, nitrogen, oxygen or argon, the size of a laser spot can be adjusted according to the size of a sample, and the sensitized ions generate energy resonance absorption under the action of laser to further transfer energy to a reactant; the laser selected for laser sintering can be a gas laser, a solid laser, a semiconductor diode laser, a fuel laser, a fiber laser, a free electron laser or a diode pumped solid laser with laser power of 100-.

Technical Field

The invention belongs to the technical field of preparation of boron carbide-based materials, and particularly relates to a method for synthesizing a boron carbide/carbon powder material by laser sintering.

Background

Boron carbide (B)₄C) The black diamond is one of the three known hardest materials (the other two materials are diamond and cubic phase boron nitride), has the characteristics of small density, high strength, excellent high-temperature stability and chemical stability and the like, and is used for light armors and armor. In addition, boron carbide absorbs a large number of neutrons without forming any radioactive isotopes, and is therefore an ideal neutron absorber in nuclear power plants. Compared with diamond and cubic boron nitride, boron carbide is easy to manufacture and low in cost, so that the boron carbide is widely used and can replace expensive diamond in the aspects of grinding, drilling and the like. But B synthesized by the conventional preparation method₄The C powder has uneven granularity and high impurity content due to objective factors, and particularly shows that the powder has coarse particles and single appearance, so that the excellent performance of the B4C is difficult to give full play, and the application of the powder is severely limited. Research shows that compared with the traditional B4C powder, the B with high purity, low dimension and uniform particle size₄The C powder can effectively improve the sintering performance of the B4C material and improve the fracture toughness of the material. Therefore, the preparation of the B4C powder with high content, uniform size, small particle size and high aspect ratio is more meaningful.

The selection of boron carbide preparation technology is the key influencing the quality of final products, the boron carbide is mainly prepared by a carbothermic reduction synthesis method at present, although the method is the main way for industrially preparing the boron carbide at present, the electric arc temperature in the preparation process is overhigh, a large amount of powder to be reacted is lost in a gaseous state, and the utilization rate of raw materials is low; the temperature difference in the furnace zone is too large, the temperature (2200-2500 ℃) of the central part of the furnace may exceed the melting point (2350 ℃) of B4C, peritectic decomposition is carried out, free C and other high boron compounds are separated out, the temperature far away from the central zone of the furnace is low, the reaction is not completely carried out, the reactant is remained, and the purity of the prepared boron carbide is not high. In addition, the following methods exist for synthesizing boron carbide: 1. the elements are directly synthesized. According to the method, elemental boron and carbon are directly subjected to chemical reaction to generate boron carbide, although the boron carbide prepared by the method is high in purity, the heat release of the chemical reaction is small, the generated boron carbide can block further diffusion of boron and carbon, so that a higher reaction temperature and a longer preparation period are needed, and in addition, the price of the elemental boron as a raw material is high, so that the preparation cost is higher; 2. chemical vapor deposition. According to the method, boron and carbon-containing gas is usually used as a boron source and a carbon source, and chemical reaction is carried out on the surface of the substrate at high temperature to prepare boron carbide, although the method is low in pollution, the prepared boron carbide is high in purity and can meet the requirement of special morphology, equipment is expensive, early investment is high, the process is complex, the yield is low, and the requirement of mass production is difficult to meet; 3. self-propagating high-temperature synthesis. The method is also called combustion synthesis, and utilizes the self-heating and self-conduction process of high chemical reaction heat between reactants to synthesize boron carbide in a carbon tube furnace. In conclusion, the invention is necessary to provide the preparation method of boron carbide, which has the advantages of simple process, low energy consumption, small pollution and short period.

The invention utilizes the laser sintering technology to control the reaction process by adjusting the proportion of reaction raw materials, catalytic active elements, the input energy of laser, the sintering time and the spot size. The powder to be reacted is irradiated by laser, rare earth ions are activated, high energy is generated to catalyze reactants, high-temperature solid phase reaction is induced, continuous supply of laser energy excites more rare earth ions to sensitize and generate multi-step cascade reaction, and the boron carbide/carbon powder material is prepared at low energy consumption.

The characteristics of the boron carbide/carbon powder prepared by the method, such as thickness, crystallinity, lattice type and lattice size, can be directly controlled by adjusting laser power, sintering time and spot size. The technology has the characteristics of simple process flow, simple device, low environmental requirement, short synthesis period, high raw material utilization rate and the like. Is expected to be applied to the industrial production of preparing boron carbide-based materials on a large scale.

Disclosure of Invention

The invention aims to provide a method for synthesizing a boron carbide/carbon powder material by laser sintering, which has the characteristics of simple process, low energy consumption, less pollution, short period and the like.

The invention provides a method for synthesizing a boron carbide/carbon powder material by laser sintering, which is characterized by comprising the following steps: (1) adding rare earth oxide powder into the reaction raw material powder to enable rare earth element ions to absorb partial laser energy and realize energy transfer and raw material cascade reaction;

(2) the method comprises the following steps of uniformly mixing raw materials of the mixed rare earth oxide by high-energy ball milling, pressing the uniformly mixed powder into a sheet by using a tablet press, fixing the sheet on a laser workbench, carrying out laser sintering, exciting rare earth sensitized ions by laser resonance to realize energy transfer, continuing the supply of laser energy, and carrying out re-excitation, multi-step cascade reaction and energy transfer on the excited ions so as to induce the mixed raw materials to carry out high-temperature solid phase reaction and generate boron carbide.

Preferably, the rare earth oxide powder in step (1) comprises oxides of 15 lanthanides and oxides of 17 elements including scandium (Sc) and yttrium (Y) which have similar chemical properties with the lanthanides, and the reaction raw materials are induced to undergo a high-temperature solid-phase reaction to generate a boron carbide component.

Preferably, the reaction raw materials in the step (1) are boron sources and carbon source raw materials, the boron sources include boric acid (H3 BO 3) and boron oxide (B2O 3), the carbon sources include but are not limited to graphite powder, sucrose, glucose and graphene sheets, the high-energy ball milling and mixing in the step (2) are carried out, a polyurethane ball milling tank is adopted during ball milling, absolute ethyl alcohol, acetone or deionized water and the like are used as media, the ball milling rotation speed range is 300-400rpm, the ball milling time is 8-36 hours, a blast drying box is used for drying and grinding the mixture into powder after ball milling, and the particle size of the ground powder is 45-150 mu m, so that high-purity boron carbide can be generated finally.

Preferably, the raw material of the mixed rare earth oxide in the step (2) can be granulated according to actual needs to obtain a raw material with smaller microscopic particle size and higher density, and the granulation process is as follows: organic colloid materials such as PVA (polyvinyl alcohol) and the like are used as a bonding agent solute, deionized water is used as a solvent, a magnetic stirrer is used for preparing a bonding agent with the mass fraction of 1%, and the mass ratio of the bonding agent to the deionized water is 1: 1, adding the powder into the uniformly mixed powder, grinding for 4 hours, granulating, sieving with a sieve mesh of 325 meshes, pressing the sieved powder into a sheet by using a tablet machine, performing laser irradiation to remove viscosity, and performing other methods such as heat preservation and viscosity removal in a tubular furnace to improve the purity of boron carbide.

Preferably, the binder solute includes, but is not limited to, PVA, methoxysilane, polyurethane, silicone.

Preferably, the mixed powder sintered in the step (2) may be in the form of a tablet (using a powder tableting machine) or a powder (using a synchronous feeding method).

Preferably, the laser sintering process in the step (2) can be performed in one or more of vacuum, air, nitrogen, oxygen or argon, the size of a laser spot can be adjusted according to the size of a sample, and the sensitized ions generate energy resonance absorption under the action of laser to further transfer energy to a reactant; the laser selected for laser sintering can be a gas laser, a solid laser, a semiconductor diode laser, a fuel laser, a fiber laser, a free electron laser or a diode pumped solid laser with laser power of 100-.

The invention has the beneficial effects that:

respectively calculating and weighing three raw materials with corresponding mass according to 0%, 1%, 3% and 5% of ingested mass fraction of Yb oxide Yb2O3 serving as a raw material, performing high-energy ball milling and mixing on the raw materials, boron oxide and carbon powder (according to a molar ratio B: C = 4: 7), wherein the ball milling rotation speed is 300rpm, ethanol is used as a ball milling medium, the raw materials are fully and uniformly mixed to obtain raw material mixture powder, drying, grinding and sieving the mixture powder obtained by ball milling in a 100 ℃ oven, wherein the mesh number of the sieve is 325 meshes, the particle size of the powder is preferably 45-150 mu m, then pressing the sieved powder into sheets by using a tablet press, placing the sheets on a laser worktable clamp for sintering, and enabling the raw material mixture to perform laser-activated self-propagating high-temperature solid-phase reaction, wherein the laser wavelength is 980nm, the laser sintering power is 2700W, the spot diameter is 7 x 7mm, and the sintering time is, and generating boron carbide. The obtained boron carbide has the characteristics of high purity, fine crystal grains, compact material, good wear resistance and the like, is suitable for being used in military supplies such as light armors, armor shields and the like, and the related laser sintering activation self-propagating growth technology has the characteristics of simple process, low cost, rapidness, high efficiency, small environmental pollution, low energy consumption and the like, and is suitable for large-scale industrial application.

Drawings

FIG. 1 Low Power Long-time laser sintering morphology and XRD Pattern

FIG. 2 shows laser sintering morphology and XRD pattern of different Yb2O3 contents

FIG. 3 shows different laser power sintering morphology and XRD pattern

FIG. 4 shows a boron carbide/carbon mixed powder sintered on a stainless steel substrate at a laser power of 1700W.

Detailed Description

The invention is further described below by means of specific examples:

example 1, with a B: C ratio of 4:7, and an oxide Yb2O3 of a rare earth element Yb, in terms of intake mass fractions of 0%, 1%, 3%, and 5%, B2O3, graphite powder, and Yb2O3 were weighed and respectively weighed, and were sufficiently and uniformly mixed to obtain a raw material mixture powder, the mixture powder obtained by ball milling was dried and ground in an oven at 100 ℃, and the ground raw material was granulated and ground to obtain a product having a smaller microscopic particle size and a high density, and the granulation process was as follows: organic colloid materials such as PVA and the like are used as a binder solute, deionized water is used as a solvent, a binder with the mass fraction of 1% is prepared, the binder is added into the uniformly mixed powder in two to three times, grinding is carried out for 4 hours, sieving is carried out, the mesh number of a sieve is 325 meshes, the particle size of the powder is preferably 45-150 mu m, then the sieved powder is pressed into a sheet shape by a tablet press, the sheet shape is placed into a muffle furnace for viscosity removal (the temperature rising rate is 1 ℃/min, the temperature is raised to 500 ℃, the temperature is kept for 2 hours), the sample after viscosity removal is placed on a laser workbench clamp for sintering, the laser wavelength is 980nm, the laser sintering power is 2600W, the spot diameter is 7 x 7mm, the raw material mixture is subjected to laser-activated self-propagating high-temperature solid phase reaction, and the laser action time.

In example 2, H3BO3, graphite powder, and Yb2O3, which are weighed and weighed respectively according to the intake mass fraction of 0%, are used as raw materials in a B: C ratio of 4:7, and the corresponding mass of Yb oxide Yb2O3 is subjected to high-energy ball milling and mixing, wherein the ball milling rotation speed is 300rpm, the ball milling time is 12 hours, ethanol is used as a ball milling medium, the raw materials are sufficiently and uniformly mixed to obtain raw material mixture powder, the mixture powder obtained by ball milling is dried and ground in an oven at 100 ℃, the ground raw materials are granulated and ground to obtain a product with smaller microscopic particle size and high density, and the granulation process is as follows: organic colloid materials such as PVA and the like are used as a binder solute, deionized water is used as a solvent, a binder with the mass fraction of 1% is prepared, the binder is added into the uniformly mixed powder in two to three times, grinding is carried out for 4 hours, sieving is carried out, the mesh number of a sieve is 325 meshes, the particle size of the powder is preferably 45-150 mu m, then the sieved powder is pressed into a sheet shape by a tablet press, the sheet shape is placed into a muffle furnace for discharging and sticking (the heating rate is 1 ℃/min, the temperature is increased to 500 ℃, the temperature is kept for 2 hours), the sample after discharging and sticking is placed on a laser workbench clamp for sintering, the laser wavelength is 980nm, the laser sintering power is 500W, the spot diameter is 7 x 7mm, and the sintering time is 60 s. FIG. 1 is a low power long time laser sintering profile and XRD pattern.

Example 3, B2O3, sucrose and Yb2O3 of corresponding mass are respectively weighed according to the mass fraction of 1%, 3% and 5% of the oxide of the rare earth element Yb with the B: C ratio of 4:1, the three raw materials are fully and uniformly mixed by high-energy ball milling, ethanol is used as a ball milling medium, the ball milling rotation speed is 300rpm, the time is 12 hours, raw material mixture powder is obtained by fully and uniformly mixing, the mixture powder obtained by ball milling is dried, ground and sieved in an oven at 100 ℃, the mesh number is 100-. FIG. 2 shows laser sintering morphology and XRD pattern of different Yb2O3 contents.

Example 4, B2O3, glucose and Yb2O3 of corresponding mass are respectively calculated and weighed according to 3% of ingested mass fraction with a B: C ratio of 4:1, and are used as raw materials to be subjected to high-energy ball milling mixing, the ball milling rotation speed is 300rpm, the ball milling time is 12h, ethanol is used as a ball milling medium, the raw material mixture powder is obtained by sufficiently and uniformly mixing, the mixture powder obtained by ball milling is dried and ground in a 100 ℃ oven, and is sieved, the mesh number of the sieve is 100 minus 325 meshes, the particle size of the powder is preferably 45 to 150 μm, then the sieved powder is pressed into a sheet by a tablet press, the sheet is placed on a laser worktable clamp to be subjected to laser sintering, the laser wavelength is 980nm, the laser power W is 1800W, and the spot diameter is 7 × 7mm, so that the raw material mixture is subjected to laser-activated self-propagating high-temperature solid phase reaction, and the laser action time is 3 s. FIG. 3 shows different sintering morphologies and XRD patterns of laser power.

Example 5, with a B: C ratio of 4:7, and an oxide Yb2O3 of a rare earth element Yb, in terms of intake mass fractions of 0%, 1%, 3%, and 5%, B2O3, graphite powder, and Yb2O3 were weighed and respectively weighed in corresponding mass amounts, and were sufficiently and uniformly mixed to obtain a raw material mixture powder, the mixture powder obtained by ball milling was dried and ground in an oven at 100 ℃, and the ground raw material was granulated and ground to obtain a product having a smaller microscopic particle size and a high density, and the granulation process was as follows: organic colloid materials such as PVA and the like are used as a binder solute, deionized water is used as a solvent, a binder with the mass fraction of 1% is prepared, the binder is added into the uniformly mixed powder in two to three times, grinding is carried out for 4 hours, sieving is carried out, the mesh number of a sieve is 325 meshes, the particle size of the powder is preferably 45-150 mu m, then the sieved powder is pressed into a sheet shape by a tablet press, the sheet shape is placed into a muffle furnace for discharging and sticking (the heating rate is 1 ℃/min, the temperature is increased to 500 ℃, the temperature is kept for 2 hours), the sample after discharging and sticking is placed on a laser worktable clamp for sintering, the laser wavelength is 980nm, the laser sintering power is 1700W, the spot diameter is 7 x 7mm, the raw material mixture is subjected to laser-activated self-propagating high-temperature solid phase reaction, and the laser action. FIG. 4 is an SEM image of a boron carbide/carbon mixed powder sintered on a stainless steel substrate at a laser power of 1700W.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.