JPH02175679A - Heat-resistant supporting member - Google Patents

Abstract

PURPOSE:To obtain the title member excellent in heat-resistant mechanical strength, durability, etc., by filling a heat-resistant metal in the pores of a porous ceramics having three-dimensional network type pores and by providing the resultant cermet material on the contact surface of an object to be heated. CONSTITUTION:A heat resistant metal 4 (e.g. Ni-Cr alloy) is first filled in the pores of a porous ceramics 3 (e.g. alumina) having three-dimensional network-type (e.g. honeycomb or foam-shaped) pores. The resultant cermet material is then provided on at least the contact surface of an object to be heated on a heat-resistant supporting member 1. Thereby the objective heat- resistant supporting material durable to long-term use, suitable as skid buttons or hearth rolls to support objects to be heated such as steel pieces in a furnace can be produced. Inclusion of the ceramics will also reduce thermal conductivity and suppress skid mark development.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat-resistant support member such as a skit button or a hearth roll that supports an object to be heated such as a steel billet in a heating furnace or the like.

[Prior Art] Conventionally, when a steel billet or the like is heated in a heating furnace, a metal support member such as a skid button, skit rail or hearth roll has been used to support the steel billet.

However, in high-temperature heating furnaces, the metal support members are easily damaged by heat loads, so a method has been adopted in which a portion of the support members are air-cooled or water-cooled. As a result, low-temperature spots called skit marks occur on the steel billet, which is the object to be heated, and the steel billet becomes unevenly deformed during hot working.
This caused deterioration in product quality and dimensional accuracy.

In order to alleviate and remove these low-temperature spots, it is necessary to heat the entire heating furnace more than necessary or to locally heat the vicinity of the supporting members of the heating furnace. There were two problems, such as shortening the lifespan of structures.

The present inventors replaced this metal support member with silicon nitride (Si3NJ) and silicon carbide (SjC), which have excellent heat insulation properties.
As a result of conducting an actual furnace test on a support member made of ceramics, it was confirmed that the use of a support member made of ceramics is effective in reducing the aforementioned skit marks. However, it has been found that support members made of brittle materials such as ceramics tend to crack due to the shearing force and vibrations that act when objects to be heated are transported, and cannot withstand long-term use.

Focusing on these points, metal-ceramic composite materials that have the good properties of both metals and ceramics have recently attracted attention, and by optimizing the properties and blending amount of ceramic powder, toughness, compressive strength, and heat insulation properties can be improved. A new heat-resistant composite material for heat-resistant support members has been proposed. (
For example, JP-A-51-149454, JP-A-60-
200948) [Problems to be Solved by the Invention] However, these ceramic-dispersed cermet type heat-resistant support members are susceptible to high temperature, heavy weight, and high loading of objects to be heated such as steel pieces supported by the members. If the usage environment is harsh due to frequent use, the heat-resistant metal layer that covers the cermet-type sintered core is likely to crack, resulting in a decrease in the support strength of the heat-resistant support member, which supports the heated object. It was observed that the supporting surface was sinking. This is presumed to be because the heat-resistant metal layer covering the sintered core exceeded its reinforcement limit and buckled due to temporary overload acting on the sintered core. In addition, when the object to be heated hits one side, the two parts located in the high temperature area may be laterally deformed. It is presumed that this occurs because there is no lateral resistance due to the heat-resistant metal parts constituting the matrix, shear force, etc.

Furthermore, for the upper surface of the heat-resistant support part, the heat-resistant metal part has the role of securing toughness by connecting the extremely wear-resistant ceramics, but the heat-resistant metal part is selected because it has inferior wear resistance than ceramics. Due to the gradual wear and loosening of the matrix on the upper surface, the dispersed ceramic chips would fall off, resulting in increased wear and tear, making it difficult for the cermet to fully exhibit its characteristics.

These problems are presumed to be due to the fact that the ceramic particles are dispersed within the metal layer and have a three-dimensional network structure, or that the matrix is made of metal. Therefore, the present inventors have developed a heat-resistant support member that fully exhibits the characteristics of both ceramics and metals by having both ceramics and metals have a three-dimensional network structure, and by intertwining them with each other, they have completed the present invention.

[Means for Solving the Problems] Therefore, in order to solve the above-mentioned problems, the heat-resistant support member of the present invention has a structure in which the heat-resistant support member of the present invention has pores in a porous ceramic having three-dimensional mesh-like pores having substantially the same shape as a honeycomb or a foam. The skid button is characterized in that all or part of the skid button is filled with a cermet material filled with a heat-resistant metal.

The heat-resistant metal or alloy used for the heat-resistant support member of the present invention must be a material with compressive strength that can withstand heat loads, and must have characteristics that make it easy to pressure mold (sinter) and easily wet porous ceramics. It is something that you have. Desirably, a Ni-based or Ni-Cr-based heat-resistant alloy, such as a Fe-Ni-Cr-Co-based alloy.

Fe-Ni-Cr system, Cr-Ni system, Ni-Cr-M
Alloys such as o-Co are used. In addition, for porous ceramics with three-dimensional network pores, if the working temperature is 1100°C or higher, the melting temperature or decomposition temperature is 15°C.
Materials with a temperature of 00°C or higher, such as Al2O2, Zr (hr,
Oxide ceramics such as AQ2Cb-Cr203 are preferred.

In order to fill the three-dimensional mesh-like pores of these porous ceramics with heat-resistant metal, there are two methods: placing porous ceramics in a mold and casting molten metal, and filling porous ceramics with metal powder and using the old method. There is a method of forming a three-dimensional continuum structure in a heat-resistant metal by sintering the powder by performing P treatment.

[Example] An example of the present invention will be described based on the drawings. Figures 1 to 1]
FIG. 0 is a sectional view showing an embodiment in which the present invention is applied to a cylindrical skit button.

In the embodiment shown in FIG. 1, the entire skit button l is composed of a porous ceramic 3 having three-dimensional mesh-like pores and a heat-resistant metal 4 filled in the three-dimensional mesh-like pores. It is made of cylindrical cermet material.

An object to be heated, such as a steel piece, is supported on the top surface 2a, and the bottom surface 2b is connected to a water cooling pipe to be cooled.

The embodiment shown in FIG. 2 has the same basic structure as the embodiment shown in FIG. The remaining lower part is a cylindrical fired crystal made of heat-resistant metal 5, a cast product, etc.

The embodiment shown in FIGS. 3 and 4 is an example in which a heat-resistant metal layer 6 is coated around the cermet material shown in FIGS. 1 and 2. In addition, the embodiment shown in FIGS. 5 and 6 is similar to FIG.
This is an example in which a heat-resistant metal layer 6.7 is coated around the cermet material shown in FIG. 2 and on the contact surface of the heated material.

In the embodiment shown in FIGS. 7 and 8, the mixing ratio of ceramics and heat-resistant metal in the cermet material is changed, that is, porous ceramics 3' and 4' with small pores are placed on the top.
It is made of a cermet material in which porous ceramics 3 and 4 having larger pores in the lower part than in the upper part are filled and bonded with continuous heat-resistant metal. Also, Figures 9 and 10
The embodiment shown in the figure is an example in which the periphery of the cermet material shown in FIGS. 7 and 8 and the contact surface of the heated material are coated with a heat-resistant metal layer.

In these examples, the three-dimensional continuum of ceramics and metal are intertwined with each other, so the above problems can be solved, and by containing an appropriate amount of ceramics, the heat insulation of the part that comes into contact with the heated object can be improved. or improved.

Note that the present heat-resistant support member and the water-cooled pipe can be joined by welding directly to the upper surface of the water-cooled pipe, or by welding the present heat-resistant support member to a pedestal and then welding the upper surface of the water-cooled pipe and the pedestal.

Specific examples of the present invention will be described below.

[Specific Example] Alloy powder with a particle size of 60 mesh or less produced by the molten metal spray method is filled into commercially available porous ceramics having three-dimensional network pores, this mixture is used as a core, and metal is placed around the core. The powder-filled can is placed in a cylindrical mild steel can with an inner diameter of 70m+n, and these are used as an upper structure.A metal powder corresponding to the lower structure is filled from above this upper structure, and a lid is placed on each of the mild steel cans. . Then, each piece of mild steel is welded in a N2 atmosphere, the inside is evacuated and sealed, and then hot isostatically pressed (HTP) at 1200°C and under a pressure of 1 ton/cm2 for 1 hour.
) treatment was applied. Heat-resistant alloys 4, 5.6 and 7 used
The composition of and the material of porous ceramics are shown in Table 1. The can material at both ends and sides of each of the obtained cylindrical mild steels was cut off to take out a sintered body, and a heat load test was conducted on this sintered body.

Test conditions Load conditions: Pressure 50 kg/c in the axial direction of the sample (sintered body)
Repeat the cycle of applying a direct load at m2 for 5 seconds and then holding it without load for 7 seconds (apply impact load once every 100 cycles) Heating temperature: 1.3508C Atmosphere Two atmosphere test time: 4 hours (approximately 1200 cycles) After the test, we observed the deformation and degree of damage of the samples, calculated the deformation rate, and evaluated the heat resistance of each sample. The results are shown in Table 1.

As is clear from Table 1, the present invention (sample Nos. 2 to 6)
The skid button, which has porous ceramics inside, maintains a healthy state as a heat-resistant support member and maintains (deformation rate ≦
2%) It can be seen that it is superior to the conventional product (sample No. 1).

(Effects of the Invention) As described above, by applying a cermet material in which the pores of porous ceramics having three-dimensional mesh pores are filled with heat-resistant metal to the skid button, the heat resistance strength can be improved and the pores can be used for a long period of time. It was found to withstand use. Also,
It has been found that by incorporating ceramics, the thermal conductivity can be lowered, contributing to the reduction of skit marks.

[Brief explanation of the drawing]

1 to 10 are sectional views showing embodiments in which the present invention is applied to a skid button. 1... Skit button, 2... Porous ceramics having three-dimensional network-like pores, 4... Heat-resistant metal filled in three-dimensional network-like pores, 5, 6.7... Heat-resistant metal.

Claims (1)

[Scope of Claims] 1. A heat-resistant support member having, on the contact surface of a heated material, a cermet material in which the pores of a porous ceramic having three-dimensional mesh-like pores are filled with a heat-resistant metal. 2. A porous ceramic having a three-dimensional network of small pores has a cermet in which the small pores are filled with a heat-resistant metal on the contact surface of the material to be heated, and the three-dimensional network of the above-mentioned porous ceramic is located below the cermet. A heat-resistant support member comprising a cermet having pores larger than air pores and filled with a heat-resistant metal. 3. The heat-resistant support member according to claim 1 or 2, wherein the cermet material is coated with a heat-resistant metal layer. 4. The heat-resistant support member according to claim 1 or 2, wherein the periphery of the cermet material and the contact surface of the heated material are coated with a heat-resistant metal layer.