CN102492394A - Preparation method of hexagonal tabular nano-crystal corundum abrasive - Google Patents

Abstract

The invention discloses a hexagonal plate-like nanocrystalline corundum abrasive. The raw material components and their weight percent content are: 99.15-99.85% Al ₂ (SO ₄ ) ₃ 18H ₂ O or Al(NO ₃ ) ₃ 9H ₂ O , 0.15-0.85% additive; the raw material components and weight percentage content of the additive are: 0-50% nano-SiO ₂ , 0-45% Fe(NO ₃ ) ₃ , 0-30% Y(NO ₃ ) ₃ , 5-100% Ca(NO ₃ ) ₂ , 0-70% Mg(NO ₃ ) ₂ and 0-25% Cr(NO ₃ ) ₃ . The invention adopts a liquid phase method to synthesize an aluminum-containing precursor, and is calcined at a high temperature to make a hexagonal plate-shaped nanocrystalline corundum abrasive. The hardness of the corundum abrasive is equivalent to that of the existing ceramic corundum abrasive, and the toughness is better than that of the existing ceramic corundum. Abrasives increased by 9 to 25%.

Description

Preparation method of hexagonal plate-like nanocrystalline corundum abrasive

technical field

The invention relates to a grinding tool, in particular to a preparation method of a hexagonal plate-like nanocrystalline corundum abrasive.

Background technique

Grinding is an important way of precision machining. With the advancement of science and technology, new materials and difficult-to-machine materials continue to emerge, which pose new challenges to grinding precision, processing efficiency and processing capacity. Traditional abrasives are often difficult to meet the needs of modern processing. Therefore, there is an urgent need for new abrasives that can meet different grinding needs.

Nanocrystalline corundum abrasive particles are composed of countless small nanocrystals, which are different from corundum abrasives prepared by traditional melting methods. The difference in structure will inevitably lead to differences in performance and application. Compared with the large single crystal corundum abrasive prepared by the traditional melting method, the nanocrystalline corundum abrasive has the advantages of good toughness, good self-sharpening, sharp abrasive grains, and good durability of the grinding wheel. At the same time, the nanocrystalline corundum abrasive can be controlled by controlling the nanocrystal size, Shape and other microstructures to adjust its different properties and adapt to different grinding application needs.

Corundum abrasives for different purposes have different toughness requirements, and hexagonal plate-shaped nano-alumina can significantly improve its fracture toughness. Therefore, preparing a hexagonal plate-shaped corundum abrasive is an effective way to improve its toughness.

Contents of the invention

The purpose of the present invention is to improve the toughness of the existing abrasives, and provide a hexagonal plate-shaped nanocrystalline corundum abrasive capable of significantly improving its fracture toughness and a preparation method thereof.

The present invention is realized through the following technical solutions.

A hexagonal plate-shaped nanocrystalline corundum abrasive, the raw material components and their weight percentages are: 99.15-99.85% Al ₂ (SO ₄ ) ₃ 18H ₂ O or Al(NO ₃ ) ₃ 9H ₂ O, 0.15-0.85% %additive;

The raw material components of the additive and their weight percentage contents are: 0-50% nanometer SiO ₂ , 0-45% Fe(NO ₃ ) ₃ , 0-30% Y(NO ₃ ) ₃ , 5-100% Ca( NO ₃ ) ₂ , 0-70% Mg(NO ₃ ) ₂ and 0-25% Cr(NO ₃ ) ₃ .

The preparation method of the hexagonal plate-like nanocrystalline corundum abrasive has the following steps:

(1) Dissolve Al ₂ (SO ₄ ) ₃ 18H ₂ O or Al(NO ₃ ) ₃ 9H ₂ O in water, filter to remove impurities after complete dissolution, and prepare 0.1-0.6 mol/L Al ³⁺ solution;

(2) Add ammonia water to the solution of step (1) and stir to make it completely sol or precipitate, and then obtain Al(OH) _3gel through suction filtration and washing process;

(3) According to the content of the raw material components and their weight percentages: 99.15-99.85% Al ₂ (SO ₄ ) ₃ ·18H ₂ O or Al(NO ₃ ) ₃ ·9H ₂ O, the ratio of 0.15-0.85% additives, the A corresponding amount of additives is added to the colloid in step (2), and the additives are evenly distributed;

(4) step (3) contains additive Al(OH) _Colloid drying, regranulation and screening and classification;

(5) Calcining the sieved and classified abrasive in step (4) at 1150° C. to 1400° C., and then further sieving and grading to obtain a hexagonal plate-like nanocrystalline corundum abrasive.

The ammoniacal liquor of described step (2) is precipitation agent.

The internal microscopic grain size of the hexagonal plate-shaped nano-corundum abrasive prepared in the step (5) is 40nm-2μm.

The invention has the beneficial effects of providing a hexagonal plate-shaped nanocrystalline corundum abrasive capable of significantly improving the fracture toughness of the abrasive and a preparation method thereof. The hardness of the corundum abrasive is equivalent to that of the existing ceramic corundum abrasive, and the toughness is lower than The existing ceramic corundum abrasives are improved by 9-25%.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments.

The grinding application effect of alumina is obviously affected by the size and shape of its internal grains. The fine-grained structure of the abrasive can improve the grinding accuracy, and the microscopic plate-like structure of the abrasive can improve the toughness of the abrasive. In view of the above reasons, the present invention adopts a liquid phase method to synthesize an aluminum-containing precursor, and then calcines at a high temperature to prepare a hexagonal plate-like nanocrystalline corundum abrasive.

The present invention uses commercially available analytical pure as raw material.

Example 1

99.85% Al(NO ₃ ) ₃ .9H ₂ O and 0.15% additives are used as raw materials, and the raw material components and weight percentage content of the 0.15% additive are 30% nano-SiO ₂ , 5% Y(NO ₃ ) ₃ , 10% Fe(NO ₃ ) ₃ , 26% Ca(NO ₃ ) ₂ , 14% Mg(NO ₃ ) ₂ and 15% Cr(NO ₃ ) ₃ .

First, dissolve Al(NO ₃ ) ₃ 9H ₂ O in water, filter to remove impurities, and prepare a 0.1mol/L aqueous solution containing Al ³⁺ ;

In above-mentioned solution, add precipitating agent ammoniacal liquor dropwise and stir to make the aqueous solution containing this Al ³⁺ fully gel, then through suction filtration, washing obtain Al(OH) ₃ gel;

Add 0.15% additives to Al(OH) ₃ colloids and mix well; dry the Al(OH) ₃ colloids containing additives to obtain Al(OH) ₃ solids, regranulate and sieve and classify;

The pre-screened and classified Al(OH) ₃ is calcined at 1400°C, and then further screened and classified to obtain plate-shaped nanocrystalline corundum abrasives with different particle sizes.

The microscopic grain size inside the corundum abrasive is 1.23μm, and the toughness is 3.18±0.12MPa·m ^1/2 .

Example 2

99.5% Al ₂ (SO ₄ ) ₃ ·18H ₂ O and 0.5% additives are used as raw materials, and the raw material components and weight percentage content of the 0.5% additive are 10% nano-SiO ₂ , 30% Fe(NO ₃ ) _3. 18% Y(NO ₃ ) ₃ , 15% Ca(NO ₃ ) ₂ and 27% Mg(NO ₃ ) ₂ .

First, dissolve Al(NO ₃ ) ₃ 9H ₂ O in water, filter to remove impurities, and prepare a 0.2mol/L aqueous solution containing Al ³⁺ ;

In above-mentioned solution, add precipitating agent ammoniacal liquor dropwise and stir to make the aqueous solution containing this Al ³⁺ fully gel, then through suction filtration, washing obtain Al(OH) ₃ gel;

Add 0.5% additive to the Al(OH) ₃ colloid and mix well. Al(OH) solid obtained by drying the Al(OH) _colloid containing the additive, _{regranulating} and sieving and classifying;

The pre-screened and classified Al(OH) ₃ is calcined at 1150°C, and then further screened and classified to obtain plate-shaped nanocrystalline corundum abrasives with different particle sizes.

The microscopic grain size inside the corundum abrasive is 60nm, and the toughness is 3.41±0.06MPa·m ^1/2 .

Example 3

Using 99.3% Al(NO ₃ ) ₃ ·9H ₂ O and 0.7% additives as raw materials, the raw material components and weight percentage content of the 0.7% additives are 9% Fe(NO ₃ ) ₃ , 21% Ca(NO ₃ ) ₂ , 45% Mg(NO ₃ ) ₂ and 25% Cr(NO ₃ ) ₃ .

First, dissolve Al(NO ₃ ) ₃ 9H ₂ O in water, filter to remove impurities, and prepare a 0.4mol/L aqueous solution containing Al ³⁺ ;

In above-mentioned solution, add precipitating agent ammoniacal liquor dropwise and stir to make the aqueous solution containing this Al ³⁺ fully gel, then through suction filtration, washing obtain Al(OH) ₃ gel;

Add 0.7% additive to the Al(OH) ₃ colloid and mix well.

Al(OH) solid obtained by drying the Al(OH) _colloid containing the additive, _{regranulating} and sieving and classifying;

The pre-screened and classified Al(OH) ₃ is calcined at 1310°C, and then further screened and classified to obtain plate-shaped nanocrystalline corundum abrasives with different particle sizes.

The microscopic grain size inside the corundum abrasive is 560nm, and the toughness is 3.27±0.10MPa·m ^1/2 .

Example 4

99.15% Al(NO ₃ ) ₃ ·9H ₂ O and 0.85% additive are used as raw materials, and the 0.85% additive is 100% Ca(NO ₃ ) ₂ .

First, dissolve Al ₂ (SO ₄ ) ₃ ·18H ₂ O in water, filter to remove impurities, and prepare a 0.6mol/L aqueous solution containing Al ³⁺ ;

In above-mentioned solution, add precipitating agent ammoniacal liquor dropwise and stir to make the aqueous solution containing this Al ³⁺ fully gel, then through suction filtration, washing obtain Al(OH) ₃ gel;

Add 0.85% additive to the Al(OH) ₃ colloid and mix well;

Al(OH) solid obtained by drying the Al(OH) _colloid containing the additive, _{regranulating} and sieving and classifying;

Calcinate the pre-screened and classified Al(OH) ₃ at 1220°C, and then further screen and classify to obtain plate-shaped nanocrystalline corundum abrasives with different particle sizes;

The microscopic grain size inside the corundum abrasive is 120nm, and the toughness is 3.36±0.08MPa·m ^1/2 .

The microscopic grain size of the corundum abrasive in the prior art is generally 0.2-5 μm, and the toughness is 2.75-2.91 MPa·m ^1/2 , while the microscopic grain size of the corundum abrasive of the present invention is 40 nm-2 μm, and the toughness is 3.18-2 μm. 3.45MPa·m ^1/2 , which reduces the microscopic grain size inside the corundum abrasive and increases the toughness of the corundum abrasive by 9-25%.

The present invention is not limited to the above-described embodiments, and changes in many details are possible without departing from the scope and spirit of the present invention.

Claims (4)

1. tabular nanocrystalline corundum abrasive of side, feed composition and weight percent content thereof are: 99.15～99.85%Al ₂(SO ₄) ₃18H ₂O or Al (NO ₃) ₃9H ₂O, 0.15～0.85% additive;

The feed composition of said additive and weight percent content thereof are: 0～50% nanometer SiO ₂, 0～45%Fe (NO ₃) ₃, 0～30%Y (NO ₃) ₃, 5～100%Ca (NO ₃) ₂, 0～70%Mg (NO ₃) ₂With 0～25%Cr (NO ₃) ₃

2. the preparation method of the tabular nanocrystalline corundum abrasive of six sides of claim 1 has following steps:

(1) with Al ₂(SO ₄) ₃18H ₂O or Al (NO ₃) ₃9H ₂O is water-soluble, treats to dissolve fully after-filtration and removes impurity, is made into the Al of 0.1～0.6mol/L ³⁺Solution;

(2) adding ammoniacal liquor and stirring make its complete colloidal sol or depositionization in the solution of step (1), obtain Al (OH) through suction filtration, washing process again ₃Gel;

(3) by feed composition and weight percent content thereof be: 99.15～99.85%Al ₂(SO ₄) ₃18H ₂O or Al (NO ₃) ₃9H ₂O, the ratio of 0.15～0.85% additive joins the respective amount additive in the colloid in the step (2), and makes distribution of additives even;

(4) step (3) is contained the Al (OH) of additive ₃Colloid is dry, again granulation and sieving and classification;

(5) with step (4) sieved with the fractionated abrasive material 1150 ℃～1400 ℃ calcinings, further sieve again and classification, make the tabular nanocrystalline corundum abrasive of six sides.

3. according to the preparation method of the tabular nanocrystalline corundum abrasive of six sides of claim 2, it is characterized in that the ammoniacal liquor of said step (2) is precipitation agent.

4. according to the preparation method of the tabular nanocrystalline corundum abrasive of six sides of claim 2, it is characterized in that the micro-grain-size in inside of the tabular Nano Alumina Abrasive of six sides that said step (5) makes is 40nm～2 μ m.