JPH03287716A - Supporting member for material to be heated in heating furnace - Google Patents

Abstract

PURPOSE:To make long service life of a supporting member for material to be heated by using metal and ceramics composite materials, in which increase mixing ratio of the ceramics to the metal step by step toward water cooling pipe direction from contacting part of simple metal body, of the supporting member. CONSTITUTION:On the cooling pipe 6, the metal and ceramics composite material 4 having heat resistant strength is arranged through a metal vessel 5, and at the upper layer, further the metal and ceramics composite material 2, 3 are arranged and further the most upper part is covered with the simple metal body 1 to make the contacting part with the material to be heated. In the above supporting member for the material to be heated in a heating furnace, the above composite materials 2, 3, 4 increase the mixing ratio of ceramics to the metal step by step toward the water cooling pipe at least in two or more steps. By this method, the supporting member having the long service life with excellent joinability between the basis material 4 and the composite materials 2, 3 at upper part and high resistance to crack and detachment, is obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a hot rolling process in which the component ratio of ceramics and metal is changed stepwise in at least two steps or more from the contact portion of a heated object to a base material. The present invention relates to a support member for an object to be heated in a heating furnace for heat treatment of steel materials.

[Prior Art] In general, a heating furnace support member for holding a heated object such as a slab in a heating furnace has a diameter of 110 mm for stable operation of the furnace.
High-temperature compression resistance, oxidation resistance, high-temperature scale reactivity resistance, mechanical shock resistance, thermal shock resistance, and abrasion resistance at temperatures exceeding 0°C are required.

Conventionally, heat-resistant alloys have been mainly used as support members for heated objects in heating furnaces, or internal water cooling has been used to maintain high-temperature compressive strength in high-temperature environments of 1100°C or higher and to prevent creep deformation. was being administered. However, because
This type of cooling lowers the temperature of the contact surface between the object to be heated and the support member for the object to be heated in the heating furnace, forming low-temperature spots called skid marks, making it difficult to uniformly heat the object to be heated. Ta.

In recent years, in order to solve this problem, it has been proposed to focus on the heat resistance, heat insulation, etc. of ceramic materials or ceramic-metal composite materials, and to utilize them as supporting members for objects to be heated in heating furnaces. However, ceramics generally have the problem of poor mechanical or thermal shock properties and are easily cracked, and also have high strength at high temperatures (SiC, Si3N).
Grade 4 ceramics have the problem of reacting with the scale of the slab at high temperatures, vitrifying it, causing cracks, and wear and tear. In addition, ceramics/metal composites are
It has higher toughness than ceramics alone, and has higher high-temperature strength than metals, making it useful, but when used for a long period of time, the ceramic and Ix may fall off due to reactions between the ceramic and scale, and metal parts wear out due to wear, resulting in short-term use. It becomes the lifespan.

In order to solve the above-mentioned problem, a heat-resistant material such as a single ceramic or a composite material of ceramic and metal as shown in Fig. 2 is used, and the surface of the heat-resistant material is coated with metal to prevent direct contact with the heated object. An example of a support member with a structure that avoids contact can be seen. (Unexamined Japanese Patent Publication No. 62-17118) [Problems to be Solved by the Invention] However, in this heated object support member for a heating furnace, metal is coated on the surface of a heat-resistant material such as a single ceramic or a composite material of ceramic and metal. Due to the structure, the adhesion between ceramic and metal deteriorates due to the difference in thermal expansion, and in addition, cracking or peeling occurs due to heating, cooling, and reciprocal compressive loads from the heated object. There was a problem with the lifespan.

The present invention addresses the above-mentioned problems of the conventional heated object support members for heating furnaces, namely the shortcomings of skid buttons made of heat-resistant alloys such as low high-temperature compressive strength and the occurrence of skid marks, and We are trying to solve problems such as cracks and damage caused by shock loads applied by worn-out heated objects due to reactions with oxidized scale that occur in heated object support members for heating furnaces made of composite materials, and peeling and cracking of surface coating materials. It is something to do.

[Means for Solving the Problems] In the present invention, the contact portion with the heated object is made of a single metal, and the mixing ratio of ceramics to the metal is increased stepwise by at least two steps in the direction of the metal and the water cooling vibe. The gist of the present invention is a support member for a heated body in a heating furnace, which is characterized by being made of a metal/ceramic composite material.

[Function] The present invention utilizes an already invented metal/ceramic composite material (Patent Application No. 63-0807
35), it has excellent heat resistance and creep resistance, and by providing a metal layer on the surface layer, there is no contact reaction with the heated material, and there is no contact between the metal layer and the base material. In between, cracking and peeling due to thermal expansion are prevented by changing the ceramic components in stages within a range where the difference in component ratio does not exceed 25% by volume or more.

[Example] The present invention will be described below based on an example shown in the accompanying drawings.

FIG. 1 is a cross-sectional front view showing an embodiment of the heated object support member for a heating furnace of the present invention, and shows a state where it is attached on a water-cooled pipe. In the figure, metal/ceramic composite material (
The base material 4 is a metal/ceramic composite material having heat-resistant strength, and the top thereof is covered with a metal 11. Between the metal 1 and the metal/ceramic composite material (base material) 4, the component ratio of metal and ceramic is changed stepwise.

However, the thickness of the metal 1 was set to 5 mm from the viewpoints of high-temperature compressive strength, creep strength, and peeling resistance.

It may be within the range of 2.0 mm to 5.0 mm and 0+ nm. In addition, the portion where the component ratio was changed was made of two layers, and the thickness was set to t'L of 2.5 mm. The thickness of each layer is 1.5+nm to 5mm, and two or more layers may be used.The total component change group is 5,0+y+[I+~20
, Omm is preferable from the viewpoint of high temperature compressive strength, creep strength and peeling resistance. However, it is desirable to set the ceramic volume ratio between each layer so that the difference is 25% by volume or less. If it is more than that, there is a risk of cracking due to the difference in thermal expansion. The main components used here are shown in Tables 1 and 2.

Note that the heated object support member for a heating furnace of the present invention is manufactured in the following order.

(2) Metal powder with a particle size of 250 μm or less and ceramic powder with a particle size of 100 μm or less are mixed and placed in a metal container 5.

At the same time, the container is filled with a mixture in which the ceramic component ratio is decreased, and the container is filled with the component ratio being changed sequentially until the top is filled with metal 1 alone.

■Cover the container, degas it to a near vacuum, and then seal it.

■ Hot isostatic pressing treatment (HIP treatment) is performed at 1150° C. or higher, 80 MPa or higher, and holding time is 1 hour or longer to form the product.

■Process the molded product to the specified dimensions.

A mounting test was conducted for about 6 months on the heating furnace heated object support member [component change section 2 layer (sample A)] having the above-mentioned shape. For comparison, Table 3 also shows the results for [0 layer of compositional change, that is, only a single surface metal (sample B), and a sample in which all metals were used up to the base material (sample C). The operating conditions for this experiment were a furnace temperature of 1330° C. and a surface pressure applied to the support member of 15 kg/mm 2 .

As shown in Table 3, the material A of the present invention exhibited good results, with no cracking or peeling, and the amount of compressive deformation was much smaller than that of the conventional equivalent material B.

In this example, TiN was used for the ceramic portion of the base material, but Al2O3 or AIN alone or two or more of them may be used (TiN may be further mixed).

[Effects of the Invention] As explained above, the heated object support member for a heating furnace has the following effects.

The metal and ceramic composition is bonded to the top of the base material, which is a heat-resistant metal/ceramic composite material 4, by changing the composition in stages, so it has excellent bonding properties with the base material, is resistant to cracking and peeling, and has a long life. It is.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the structure and mounting state of the heated object support member for a heating furnace of the present invention. FIG. 2 is a conceptual diagram showing the structure of a conventional support member. FIG. 3 is a diagram showing the state of wear and tear on the material of the present invention after 6 months of use. 4th UA is a diagram of the wear and tear situation of the conventional equivalent material ■ after 6 months of use. 1...Metal alone, 2.3.4...Metal/ceramic composite material, 5...Metal container, 6...Skit.

Claims (1)

[Claims] 1. The contact part with the heated object is made of a single metal, and the metal-ceramic composite material is made of a metal-ceramic composite material in which the mixing ratio of ceramic to metal is increased by at least two steps or more in the direction of the metal and the water-cooled pipe. A support member for a heated object in a heating furnace.