阅读说明：本技术 一种用高温氮气保护推板窑生产高纯氮化硅粉的工艺方法 (Process method for producing high-purity silicon nitride powder by using high-temperature nitrogen protection pushed slab kiln ) 是由 林敦莺 林洁静 于 2021-01-29 设计创作，主要内容包括：本发明公开了冶金技术技术领域一种用高温氮气保护推板窑生产高纯氮化硅粉的工艺方法,将高纯硅粉研磨至200目以上,将高纯硅粉与粘结剂混合搅拌后通过成型机进行成型造粒；将成型的高纯硅粒放入坩埚中送入推板窑进行连续生产；高纯硅粒先经过预热区预热,再缓慢经过进入氮化区,压缩氮气通过从降温区往预热区逆向进入,可以进行充分渗氮,最后烧结后的产品进入冷却区；研磨成高纯氮化硅粉；本发明用高温氮气保护推板窑生产出来的产品纯度高,质量稳定。因是连续化生产,人工成本低,单位能耗少,产量大。用氮化硅坩埚盛放,氮化硅球球磨不引入其他杂质。(The invention discloses a process method for producing high-purity silicon nitride powder by using a high-temperature nitrogen protection pushed slab kiln, which belongs to the technical field of metallurgy, wherein the high-purity silicon powder is ground to be more than 200 meshes, and is mixed and stirred with a binder and then is molded and granulated by a molding machine; placing the formed high-purity silicon particles into a crucible and feeding the high-purity silicon particles into a pushed slab kiln for continuous production; high-purity silicon particles are preheated in a preheating zone and slowly enter a nitriding zone, compressed nitrogen reversely enters from a cooling zone to the preheating zone to be subjected to full nitriding, and finally a sintered product enters a cooling zone; grinding into high-purity silicon nitride powder; the product produced by the high-temperature nitrogen protection pushed slab kiln has high purity and stable quality. Because of continuous production, the labor cost is low, the unit energy consumption is less, and the yield is high. The silicon nitride crucible is used for holding, and other impurities are not introduced in the silicon nitride ball milling process.)

1. A process method for producing high-purity silicon nitride powder by using a high-temperature nitrogen protection pushed slab kiln is characterized by comprising the following steps: the method comprises the following steps:

the method comprises the following steps: preparing raw materials: grinding high-purity silicon powder to be more than 200 meshes;

step two: and (3) granulation: mixing and stirring high-purity silicon powder and a binder, and then performing molding granulation by a molding machine;

step three: placing the formed high-purity silicon particles into a crucible and feeding the high-purity silicon particles into a pushed slab kiln for continuous production; high-purity silicon particles are preheated in a preheating zone and slowly enter a nitriding zone, compressed nitrogen reversely enters from a cooling zone to the preheating zone to be subjected to full nitriding, and finally a sintered product enters a cooling zone;

step four: grinding: and grinding the qualified silicon nitride product into high-purity silicon nitride powder.

2. The process method for producing high-purity silicon nitride powder by using the high-temperature nitrogen protection pushed slab kiln as claimed in claim 1, is characterized in that: in the first step, the purity of the high-purity silicon powder is more than 99.9 percent.

3. The process method for producing high-purity silicon nitride powder by using the high-temperature nitrogen protection pushed slab kiln as claimed in claim 1, is characterized in that: in the third step, the temperature of the nitriding zone of the pushed slab kiln is 1100-1400 ℃, and the time for the high-purity silicon particles to pass through the nitriding zone is 16-24 h.

4. The process method for producing high-purity silicon nitride powder by using the high-temperature nitrogen protection pushed slab kiln as claimed in claim 1, is characterized in that: in the third step, the purity of the nitrogen is more than 99.99 percent.

5. The process method for producing high-purity silicon nitride powder by using the high-temperature nitrogen protection pushed slab kiln as claimed in claim 1, is characterized in that: in the third step, the crucible is a silicon nitride crucible.

6. The process method for producing high-purity silicon nitride powder by using the high-temperature nitrogen protection pushed slab kiln as claimed in claim 1, is characterized in that: and step four, grinding by adopting silicon nitride balls.

Technical Field

The invention relates to the technical field of metallurgy, in particular to a process method for producing high-purity silicon nitride powder by using a high-temperature nitrogen protection pushed slab kiln.

Background

Silicon nitride is an important structural ceramic material, and has the excellent characteristics of high hardness, wear resistance, oxidation resistance, cold and hot shock resistance and the like. Can be used for manufacturing bearings, mechanical components of automobiles, spaceflight and the like. High purity silicon nitride powder is an industrially important material since the properties of silicon nitride molded articles are determined to a large extent by their purity. It is feasible to develop a technology that can produce high-purity silicon nitride powder at low cost.

The existing silicon nitride production mode is that a gas mixture of high-purity silicon powder and nitrogen argon is nitrided in a circular rotary furnace, and the nitriding temperature is 1100-1400 ℃. The method has the disadvantages that continuous production cannot be carried out, each reaction furnace needs to be subjected to a long cooling stage, the yield is low, the energy consumption is high, the powder is unevenly heated in the furnace due to a heating mode, and the quality of the product is unstable.

Based on the technical scheme, the invention designs a process method for producing high-purity silicon nitride powder by using a high-temperature nitrogen protection pushed slab kiln to solve the problems.

Disclosure of Invention

The invention aims to provide a process method for producing high-purity silicon nitride powder by using a high-temperature nitrogen protection pushed slab kiln, which aims to solve the problems of long cooling time, low productivity, high energy consumption, uneven heating of powder in a furnace due to a heating mode and unstable quality of the obtained product in the background art.

In order to achieve the purpose, the invention provides the following technical scheme: a process method for producing high-purity silicon nitride powder by using a high-temperature nitrogen protection pushed slab kiln comprises the following steps:

the method comprises the following steps: preparing raw materials: grinding high-purity silicon powder to be more than 200 meshes;

step two: and (3) granulation: mixing and stirring high-purity silicon powder and a binder, and then performing molding granulation by a molding machine;

step three: placing the formed high-purity silicon particles into a crucible and feeding the high-purity silicon particles into a pushed slab kiln for continuous production; high-purity silicon particles are preheated in a preheating zone and slowly enter a nitriding zone, compressed nitrogen reversely enters from a cooling zone to the preheating zone to be subjected to full nitriding, and finally a sintered product enters a cooling zone;

step four: grinding: and grinding the qualified silicon nitride product into high-purity silicon nitride powder.

Preferably, in the step one, the purity of the high-purity silicon powder is more than 99.9%.

Preferably, in the third step, the temperature of the nitriding zone of the pushed slab kiln is 1100-1400 ℃, and the time for the high-purity silicon particles to pass through the nitriding zone is 16-24 h.

Preferably, in the third step, the purity of the nitrogen is more than 99.99%.

Preferably, in the third step, the crucible is a silicon nitride crucible.

Preferably, silicon nitride balls are used for grinding in the fourth step.

Compared with the prior art, the invention has the beneficial effects that: the product produced by the high-temperature nitrogen protection pushed slab kiln has high purity and stable quality. Because of continuous production, the labor cost is low, the unit energy consumption is less, and the yield is high. The silicon nitride crucible is used for holding, and other impurities are not introduced in the silicon nitride ball milling process.

By utilizing the characteristic of the high-temperature nitrogen protection pushed slab kiln, the furnace is uniformly heated in a closed kiln with sufficient nitrogen protection, and the nitriding is performed at the temperature of 1100-1400 ℃. And continuous production is carried out through computer program setting. The high-purity silicon nitride powder particles have sufficient nitriding time in the kiln, and the powder particles have small air holes, so that the heating and nitrogen filling are more sufficient. Therefore, the purity of the produced silicon nitride product is high. And because the continuous production is adopted, the productivity is greatly improved, and the unit energy consumption is reduced.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

A process method for producing high-purity silicon nitride powder by using a high-temperature nitrogen protection pushed slab kiln comprises the following steps:

the method comprises the following steps: preparing raw materials: high-purity silicon powder is ground to be more than 200 meshes, the specific surface area of the material is increased, the reaction is accelerated, and the material is easier to blow into a stirring bin by a blower for stirring;

step two: and (3) granulation: mixing and stirring high-purity silicon powder and a binder, and then forming and granulating by a forming machine, wherein the high-purity silicon in a powder structure is easily blown up by nitrogen, the surface of the high-purity silicon powder is fully reacted, the bottom layer is not fully reacted with the nitrogen, particles are prepared, and tiny air holes are formed in the particles, so that the nitrogen can be conveniently flushed in; the distance between the particles is beneficial to nitriding the particles at the bottom layer by nitrogen;

step three: placing the formed high-purity silicon particles into a crucible and feeding the high-purity silicon particles into a pushed slab kiln for continuous production; high-purity silicon particles are preheated in a preheating zone and slowly enter a nitriding zone, compressed nitrogen reversely enters from a cooling zone to the preheating zone to be subjected to full nitriding, and finally a sintered product enters a cooling zone;

step four: grinding: and grinding the qualified silicon nitride product into high-purity silicon nitride powder.

Further, in the step one, the purity of the high-purity silicon powder is more than 99.9%.

Further, in the third step, the temperature of the nitriding zone of the pushed slab kiln is 1100-.

Furthermore, in the third step, the purity of the nitrogen is more than 99.99%.

Further, in the third step, the crucible is a silicon nitride crucible.

Further, in the fourth step, silicon nitride balls are adopted for grinding.

One embodiment of the invention:

example 1:

(1) preparing raw materials: grinding 10 kg of 99.99% high-purity silicon powder into 200-mesh powder, adding a binder, and stirring to form a stirring material; the binder can adopt any one or a mixture of any several of polyethylene glycol, polyvinyl butyral and methyl acrylate.

(2) And (3) molding and granulating: and (4) molding and granulating the stirred material.

(3) Heating: the formed silicon particles are placed in a silicon nitride crucible, automatic production is carried out through a high-temperature nitrogen protection pushed slab kiln, the silicon particles in the silicon nitride crucible sequentially pass through a preheating zone, a nitriding zone, a cooling zone and a cooling zone of the pushed slab kiln, the temperature of the nitriding zone is 1300 ℃, the time for the high-purity silicon particles to pass through the nitriding zone is 20 hours, and compressed nitrogen with the purity of 99.99% reversely enters from the cooling zone to the preheating zone.

(4) And sampling and analyzing the cooled silicon nitride product.

(5) Grinding: grinding was performed using a ball mill made of silicon nitride balls.

(6) Packaging: and packaging the product and warehousing.

The target composition of the high purity silicon nitride in the above examples is shown in Table 1, unit: % of the total weight of the composition.

Si	N	O
			60.68	38.1	0.65

TABLE 1

Example 2:

(1) preparing raw materials: grinding 10 kg of 99.9% high-purity silicon powder into 200-mesh powder, adding a binder, and stirring to form a stirring material; the binder can adopt any one or a mixture of any several of polyethylene glycol, polyvinyl butyral and methyl acrylate.

(2) And (3) molding and granulating: and (4) molding and granulating the stirred material.

(3) Heating: the formed silicon particles are placed in a silicon nitride crucible, automatic production is carried out through a high-temperature nitrogen protection pushed slab kiln, the silicon particles in the silicon nitride crucible sequentially pass through a preheating zone, a nitriding zone, a cooling zone and a cooling zone of the pushed slab kiln, the temperature of the nitriding zone is 1300 ℃, the time for the high-purity silicon particles to pass through the nitriding zone is 20 hours, and compressed nitrogen with the purity of 99.99% reversely enters from the cooling zone to the preheating zone.

(4) And sampling and analyzing the cooled silicon nitride product.

(5) Grinding: grinding was performed using a ball mill made of silicon nitride balls.

(6) Packaging: and packaging the product and warehousing.

The target composition of the high purity silicon nitride in the above examples is shown in Table 2, unit: % of the total weight of the composition.

Si	N	O
			60.53	38.05	0.69

TABLE 2

The electrical equipment is connected with an external power supply through an external control switch.

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.