JPS638267A - Zro2 al2o3 sio2 li2o base low expansion flame spray material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a low-expansion thermal spray material used in industrial furnaces such as coke ovens that require frequent heating and cooling.

[Prior Art] In recent years, hot repair of industrial furnaces by flame spraying has been carried out and has been effective. Conventionally, the oven life of a coke oven is 15 to 2
It used to be said that the lifespan of a furnace is 30 to 35 years, but due to optimization of operating conditions and improvements in repair technology, the aim is to have a furnace life of 30 to 35 years, and better repair technology is becoming necessary.

For this reason, flame spraying technology has been applied as one of the repair techniques for coke ovens, and is used to repair damaged areas near the door, and brick removal is used to fill fallen areas or seal gas, with remarkable effects. .

Flame spraying uses different heat sources such as flammable gas and oxygen, flammable liquid and oxygen, and metal and oxygen using thermite reaction.

Thermal spraying materials described below are used in these thermal spraying methods. For example, in Japanese Patent Application Laid-open No. 55-21539, the main components are Al2O, SiC2, and liquid phase formation accelerators include Na2O, K2O, B2O3, pb.

Thermal spray materials containing 1 to 30% of Also, Steel Research No. 305. Pages 128-138 (19
In 1981), thermal spraying materials were introduced. 8 melting point] 100-1280
A material comprising approximately 70% SiC2 at 10°C has been proposed. Furthermore, in Japanese Patent Application Laid-open No. 59-227780, S
+ 02・A2. ○, L12O-based melt-resistant powder materials are described. Furthermore, JP-A-59-161681 discloses a mixture of easily oxidizable metals such as AN and Si and a refractory powder.

[Problem that the invention attempts to solve] The thermal spray materials described above have drawbacks as described below.

In other words, the thermal spray material disclosed in JP-A No. 55-21539 basically has a high coefficient of thermal linear expansion, making it difficult to apply it to industrial furnaces that require many heating and cooling cycles. (hereinafter referred to as thermal sprayed film) is prone to cracking.
! II+ has the disadvantage of being easy to peel off. Steel Research No. 305,
The thermal spray materials on pages 128-138 have melting points of 1100-12
Since the temperature is 80℃, the maximum temperature is 1300℃ like a coke oven.
Under the same operating conditions, it is close to the melting point of the sprayed material.
Due to the lack of mechanical strength and melting of the sprayed material, durability is extremely low. Furthermore, JP-A-59-227
As a result of a more detailed study of the thermal spray material described in Publication No. 780, it was found that the thermal spray material of the publication had the following drawbacks. In other words, because the melt viscosity of the thermal spray material is high,
It lacks sufficient wettability with the adhesion surface (furnace wall surface) and easily peels off.Furthermore, although it has low expansion, its coefficient of thermal expansion is not low enough, causing it to peel off due to the formation of hexagonal cracks due to repeated temperature changes. It was found that the durability was insufficient.

Furthermore, the thermal spray material disclosed in JP-A-59-161681 that utilizes thermite reaction has a high porosity and high air permeability, so it has poor gas sealing properties. Furthermore, since the surface quality is not smooth, there is a drawback that carbon adheres to the coke, making it difficult to take in and out the coke.

An object of the present invention is to provide a thermal spray material that has extremely low expansion and low melt viscosity, and thereby has good wettability with the furnace wall surface and can form a highly durable thermal spray film with excellent peeling resistance. be.

[Means for Solving the Problems] That is, the present invention consists of 5 to 50 parts by weight of a zirconia material and 50 to 95 parts by weight of a lithium material, and the component contents are ZrO2: 5 to 50% by weight, and Al2O3. : 5
~30% by weight, S +02: 30-75% by weight, Li
2O: ZrO, .Al2O, characterized in that it contains 1 to 6% by weight and contains 5% or less of impurities.

- To provide a 5iOz LLO-based low expansion thermal spray material.

[Function] The thermal spray material of the present invention is a material that can be semi-melted or melted in a flame formed from a flammable gas and oxygen or a flammable liquid and oxygen, and can be bonded to a furnace wall surface.

The thermal spraying material of the present invention is Z r O2・A I2O h・S
It is an iC2.Li2O based thermal spray material and is made of a zirconia material and a lithium material.

As the zirconia material, CaO-stabilized, MgO-stabilized and Y2O3-stabilized fused zirconia, semi-stabilized fused zirconia, baddeleyte, zircon, etc. can be used.

As the lithium-based material, lithium minerals or lithium compounds such as subodumene, betalite, lebiodolite, eucributite l-, lithium carbonate, etc. can be used.

The usage ratio of the zirconia material and the lithium material is 5 to 50 parts by weight of the zirconia material and 50 to 95 parts by weight of the lithium material.
The component content of the obtained thermal spray material is Z ro
2: 5 to 50% by weight, A1. O,: 5-30% by weight
, 5iOz: 30 to 75% by weight, Li2O: 1 to 6% by weight, and impurities not more than 5% by weight.

When the ZrO content exceeds 50% by weight, the apparent viscosity during thermal spraying increases, which deteriorates the wettability with the furnace wall.
This is undesirable because it lowers the adhesive strength, increases the coefficient of thermal expansion, and deteriorates the thermal shock resistance, so it is desirable that the ZrO2 content is 50% by weight or less.
If the O2 content is less than 5% by weight, it will easily flow down during melting, making appropriate repair difficult.
Since the temperature is 300″C or less, mechanical strength is lost under the operating conditions of a coke oven, which is not preferable.

If the AZ, O, content is less than 5% by weight, it is undesirable because a low coefficient of thermal expansion cannot be obtained due to the balance with the chemical components of the pond, and if it exceeds 30% by weight, it is also undesirable for the same reason. .

In addition, a range of 30 to 75% by weight of 5102 content is suitable for obtaining a low expansion coefficient, and within this range, workability is good and wettability with the furnace wall is good. preferred.

If the L i 2O content is less than 1% by weight, low expansion properties cannot be obtained, and if it exceeds 6% by weight, the cutting temperature will be low, which is not preferable.

The thermal spray material of the present invention is made by mixing a zirconia material and a lithium material, and the particle size of both materials is 1.
If the particle size exceeds nI, which is preferably nI 11 or less, the meltability in a flame will be insufficient and rebound loss will increase significantly, which is undesirable. Furthermore, since it is necessary to transport the material over a long distance from the material tank to the nozzle, it is desirable that the material particle size is 20% or less of particles with a particle size of 10 μm or less.

In this way, it is possible to obtain a thermal spray material that has good ejectability, low melt viscosity, and can form a thermal spray film with extremely low expansion.

As the thermal spraying method, a method of melting the thermal spraying material of the present invention by introducing it into a flame formed by a flammable liquid and oxygen or a flammable gas and oxygen can be applied. flame temperature is 1
It is preferable to use a thermal spraying method that produces a temperature of 500°C or higher.
If the flame temperature is less than 1500°C, the material will not be melted and the adhesion rate will be extremely poor. The conditions that can be used in the thermal spraying method are described below, taking the case of using propane gas and oxygen gas as an example: Propane gas/oxygen gas volume ratio 1/6 to 1/4 Preferably 115 Powder supply amount 10 to 40 kg/ Time spraying distance M: 150 to 200 mII + Application thickness: 5 to 30 mm [Example] The present invention will be described below with reference to Examples and Comparative Examples.

1 m Inventive products I~■ having the blending ratios listed in Table 1 below
Comparative products I and ■ were obtained.

Inventive product I was produced by flame spraying using oxygen-propane.
~V and comparative products I and (2) were thermally sprayed onto silica bricks, and their properties were measured. The obtained results are also listed in Table 1.

The thermal spraying conditions used in this example are as follows: Propane gas 10t4m'/hour Oxygen gas
5ON shoulder 3/hour spraying distance
2OOn+m Construction thickness: 5 to 30I Banner operation: Manual - Next, each thermal spraying material was sprayed onto silica bricks preheated to 1100°C to conduct a panel spalling test. The heating and cooling conditions were a 10 minute cycle of water cooling at 1100° C. and 15 minutes of spraying, repeated 20 times. As can be seen from Table 1, all of the thermal spray materials of the present invention had high adhesive strength and bending strength, exhibited extremely excellent heat spalling resistance, and were found to be able to form dense thermal sprayed films.

m The products of the present invention (■) and (■) shown in Table 1 were sprayed onto the damaged area near the furnace mouth and the area where bricks had fallen off at the back of the furnace, respectively, of an Otto-type coke oven manufactured by Company A.

The thermal spraying conditions used in this example are as follows: Propane gas 1ONm/hour Oxygen gas
478m)/hour Powder supply amount 2
8ky/hour Thermal spraying distance 2O0I Application thickness 5-30III+1 Banner operation Manual The invention product ■ is particularly excellent in heat spalling resistance, but it is somewhat lacking in heat resistance, so it is used near the kiln mouth, and the invention product ■Although the heat resistance and spalling properties are slightly inferior, it has excellent heat resistance, so it was used on the back side. As a result, almost 100% remained after two years of operation, demonstrating excellent durability.

[Effects of the Invention] The thermal spray material of the present invention exhibits low melt viscosity, so it has extremely good wettability to the furnace wall, extremely high adhesive strength, excellent mechanical strength, and can easily form a dense structure. Because it is a thermally sprayed film that exhibits low expansion properties, it has extremely high resistance to heating and cooling cycles.

Furthermore, the toughness characteristic of zirconia can be imparted, making it difficult to crack.

Due to the above characteristics, the thermal spray material of the present invention can be applied to areas where there is a lot of mechanical wear and significant temperature changes, and because it has a dense structure, it also shows excellent gas sealing properties.

As described above, the product of the present invention is a thermal spray material that can form a dense thermal spray film with low expansion, high resistance to thermal shock, and excellent mechanical strength.

Claims (1)

[Claims] Zirconia material 5 to 50 parts by weight and lithium material 5
It consists of 0 to 95 parts by weight, and the component content is ZrO_2:5 to
50% by weight, Al_2O_3: 5-30% by weight, SiO
ZrO_ characterized by _2: 30 to 75% by weight, Li_2O: 1 to 6% by weight, and impurities of 5% by weight or less
2・Al_2O_3・SiO_2・Li_2O-based low expansion thermal spray material.