CN101798236B - Ceramic inner cylinder for preheater of dry method cement rotary kiln - Google Patents

Abstract

The invention relates to a ceramic inner cylinder of a preheater of a dry method cement rotary kiln, which belongs to the technical field of silicate. The ceramic inner cylinder is prepared from the following components in percentage by weight: 75-80 percent of alpha-Si3N4, 5-8 percent of Al2O3, 3-5 percent of SiO2, 2-3 percent of ZrO2, 1-3 percent of Y2O3 and 5-10 percent of returning blank, wherein the alpha-phase content in the alpha-Si3N4 is more than 90 percent, the fineness of the alpha-Si3N4 is controlled to be below 3mu m for 20 percent, 3-20mu m for 40 percent and 20-40mu m for 40 percent, the fineness of the Al2O3 is below 3mu m, the fineness of the ZrO2 is below 1mu m and the fineness of the Y2O3 is below 2mu m. A coating layer is arranged on the surface of the inner cylinder and is a boron nitride coating layer. The invention has long service life.

Description

Ceramic inner cylinder for dry process cement rotary kiln preheater

technical field

The invention relates to a ceramic inner cylinder for a dry-process cement rotary kiln preheater, belonging to the technical field of silicates.

Background technique

The preheater in front of the cement rotary kiln is equipped with an inner cylinder (or hanging piece). Due to the harsh working environment (high temperature\oxidation\corrosion\wear), the inner cylinder is usually assembled by heat-resistant steel hanging plates. The upper layer can be provided with a fixed frame, and the bottom layer can be provided with a connecting plate for reinforcement. The hanging board is an arc panel, with a hanging hole on the top of the hanging board, and a corresponding hook on the lower end of the hanging board. The lower hanging board hanging hole is hung on the upper hanging board hook, and connected in sequence. , the service life is still short, and the five-stage inner cylinder is only 6-12 months.

Contents of the invention

The purpose of the present invention is to provide a ceramic inner cylinder for dry-process cement rotary kiln preheater, which has a long service life.

The ceramic inner cylinder for dry-process cement rotary kiln preheater according to the present invention, the weight percentage of its ingredients is composed of:

α-Si ₃ N ₄ powder 75-80%, AL ₂ O ₃ 5-8%, SiO ₂ 3-5%, ZrO ₂ 2-3%, Y ₂ O ₃ 1-3% and back blank 5-10% .

Boron nitride fibers increase the toughness of the material.

Among them, the α-phase content in α-Si ₃ N ₄ is >90%.

The fineness of ingredients is controlled as α-Si ₃ N ₄ powder below 3μm 20%, 3--20μm 40%, 20--40μm 40%, AL ₂ O ₃ below 3μm, ZrO ₂ below 1μm and Y ₂ O ₃ below 2μm, SiO ₂ It is a commercially available powder.

There is a coating layer on the surface of the inner cylinder, and the coating layer is a boron nitride coating layer, which can be coated with 1μm boron nitride micro-powder paste and then fired. The surface is anti-corrosion, anti-oxidation, and improves the anti-oxidation ability of the material.

Using molding techniques such as injection molding, extrusion or isostatic pressing, the internal structure of the green body is uniform and the product performance is stable. It is best to add molding additives during molding to improve molding performance.

The preparation process is as follows: batching, homogenization, pulping/sliming/dry pressing powder, forming, surface coating, drying, semi-finished product processing, non-destructive testing, nitrogen protection induction heating/vacuum reaction sintering, post-processing and surface treatment, non-destructive testing Wait for inspection.

The ceramic inner cylinder of the cement kiln preheater of the present invention has a long service life of more than 2 years.

Detailed ways

Below in conjunction with embodiment the present invention will be further described.

Example 1

The ceramic inner cylinder for dry-process cement rotary kiln preheater according to the present invention, the weight percentage of its ingredients is composed of:

α-Si ₃ N ₄ powder 80%, AL ₂ O ₃ 5%, SiO _2: 5%, ZrO ₂ 3%, Y ₂ O ₃ 1%, boron nitride fiber 1%, back blank 5%.

Among them: α-phase content in α-Si ₃ N ₄ is 93%.

The fineness of ingredients is controlled as follows: α-Si ₃ N ₄ powder below 3μm 20%, 3--20μm 40%, 20--40μm 40%, AL ₂ O ₃ below 3μm, ZrO ₂ below 1μm and Y ₂ O ₃ below 2μm, SiO ₂ is commercially available fine powder.

Mix the ingredients evenly by ball milling with water as the medium, then add 1.0% polyvinyl alcohol and mix for 2 hours to obtain the slurry, dry and granulate, take the granulated material below 40 mesh and above 140 mesh, and shape it under isostatic pressure at 120Mpa The body was obtained, and the surface coating was coated with 1 μm boron nitride micropowder paste. After drying, it was fired at 1700° C. under the protection of nitrogen atmosphere, and kept for 6 hours.

Example 2

The dry-process cement rotary kiln preheater ceramic inner cylinder according to the present invention, its batching weight percentage is composed of:

α-Si ₃ N ₄ powder 75%, AL ₂ O ₃ 8%, SiO _2: 5%, ZrO ₂ 3%, Y ₂ O ₃ 1%, boron nitride fiber 1%, back blank 7%.

Among them: the α-phase content in α-Si ₃ N ₄ is 91%.

The fineness of ingredients is controlled as α-Si ₃ N ₄ 20% below 3μm, 40% at 3--20μm, 40% at 20--40μm, AL ₂ O ₃ below 3μm, ZrO ₂ below 1μm and Y ₂ O ₃ below 2μm, and SiO ₂ is Commercially available fine powder.

Additional molding additives: 2130 resin: 15%; glycerin: 1%; paraffin wax 3%; methyl cellulose 2%;

Knead evenly for 100 minutes (requires 90-120 minutes).

Extrusion:

Vacuum mud refining, vacuum degree 0.2 MPa (required to be greater than 0.1 MPa), refining three times, moisturizing and stale homogenization for 25 hours, extrusion molding.

dry top coat

The product is first sent to 40°C and dried for 48 hours at a humidity of 70% (requires 60-80%); when it reaches 60°C, it is coated with a surface coating, and the resin is cured at 200°C for 48 hours.

Firing:

After the product has passed the non-destructive flaw detection test, it is installed in the furnace, and the room temperature reaches 1700 ℃ after 8 hours, fired under the protection of nitrogen atmosphere, kept for 4 hours, cooled to 50 ℃ for 6 hours, and released from the furnace. After surface treatment such as sand blasting, the product is packaged after passing the non-destructive testing and other inspections.

Example 3

The dry-process cement rotary kiln preheater ceramic inner cylinder according to the present invention, its batching weight percentage is composed of:

α-Si ₃ N ₄ powder 76%, AL ₂ O ₃ 8%, SiO _2: 3%, ZrO ₂ 2.5%, Y ₂ O ₃ 2% and back blank 8.5%.

Among them: α-phase content in α-Si ₃ N ₄ is 93%.

The fineness of ingredients is controlled as α-Si ₃ N ₄ powder below 3μm 20%, 3--20μm 40%, 20--40μm 40%, AL ₂ O ₃ below 3μm, ZrO ₂ below 1μm and Y ₂ O ₃ below 2μm, SiO ₂ It is a commercially available powder.

For extrusion molding, the product is first sent to 40°C and dried for 48 hours at a humidity of 75%; at 60°C, the surface coating is coated with 1 μm boron nitride micro-powder paste, and the resin is cured at 205°C for 48 hours.

Firing:

After the product has passed the non-destructive flaw detection test, it is installed in the furnace, and the room temperature reaches 1680°C after 8.5 hours, fired under the protection of nitrogen atmosphere, kept for 4 hours, cooled to 50°C for 6 hours, and released from the furnace. After surface treatment such as sand blasting, the product is packaged after passing the non-destructive testing and other inspections.

Example 4

The dry-process cement rotary kiln preheater ceramic inner cylinder according to the present invention, its batching weight percentage is composed of:

α-Si ₃ N ₄ powder 77%, AL ₂ O ₃ 6%, SiO _2: 4%, ZrO ₂ 3%, Y ₂ O ₃ 2.5% and back blank 7.5%.

Among them: α-phase content in α-Si ₃ N ₄ is 91.5%.

The fineness of ingredients is controlled as α-Si ₃ N ₄ powder below 3μm 20%, 3--20μm 40%, 20--40μm 40%, AL ₂ O ₃ below 3μm, ZrO ₂ below 1μm and Y ₂ O ₃ below 2μm, SiO ₂ It is a commercially available powder.

For extrusion molding, the product is first sent to 40°C and dried at 78% humidity for 48 hours; when it reaches 60°C, the surface coating is coated with 1 μm boron nitride micropowder paste, and the resin is cured at 200°C for 48 hours.

Firing:

After the product has passed the non-destructive flaw detection test, it is installed in the furnace, and the room temperature reaches 1700 ℃ after 8 hours, fired under the protection of nitrogen atmosphere, kept for 4 hours, cooled to 50 ℃ for 6 hours, and released from the furnace. After surface treatment such as sand blasting, the product is packaged after passing the non-destructive testing and other inspections.

The product performance indicators are as follows:

Density: >3.0g/cm ³

Bending strength at room temperature: >850MPa

    1000°C Bending Strength: > 800MPa

Hardness: Hv＞1950kg/mm ³

              Fracture toughness: >5.5MPa.m ^1/2 .

High hardness, good fracture toughness, good high temperature performance.

Claims (3)

1. ceramic inner cylinder for preheater of dry method cement rotary kiln is characterized in that its ingredients by weight percentage composition is:

α-Si ₃N ₄Powder 75-80%, AL ₂O ₃5-8%, SiO ₂3-5%, ZrO ₂2-3%, Y ₂O ₃1-3% and time blank 5-10%; α-Si ₃N ₄In α phase content＞90%;

The batching fineness is controlled to be α-Si ₃N ₄Powder 3 μ m are following 20%, 3--20 μ m40%, 20--40 μ m40%, AL ₂O ₃3 μ m are following, ZrO ₂Following and the Y of 1 μ m ₂O ₃Below the 2 μ m;

SiO ₂Be commercially available micro mist;

Preparation flow is as follows: batching, homogenizing, slurrying or refining mud or dry-pressing powder, moulding, surface coating, drying, work in-process processing, non-destructive test(ing)(NDT), nitrogen protection induction heating or vacuum reaction sintering, post-treatment and surface treatment, nondestructiving inspecting test.

2. ceramic inner cylinder for preheater of dry method cement rotary kiln according to claim 1 is characterized in that there is coatings on the inner core surface.

3. ceramic inner cylinder for preheater of dry method cement rotary kiln according to claim 2 is characterized in that coatings is the coating boron nitride film layer.