JPS61153227A - Ceramic roll for continuous heat treating furnace - Google Patents

Abstract

PURPOSE:To compose the titled roll having durability and capable of preventing oxidation thereof and decreasing the wear, by covering the surface of roll core material made of ceramic having high temp. strength, with material superior in corrosion resistance in high temp. range. CONSTITUTION:In the title roll of the invention, the material composed mainly of C, SiC, Si3N4, BN, etc., having high strength in high temp. is used to a columnar roll core material 1. The material such as oxide ceramic (Al2O3, ZrO2, TiO2, etc.), alloy (CoCrAlY, NiCrAlY, etc.) is used to a film 2 covering circumference of the material 1. The material is superior in resistances for corrosion, wear at especially >=1,000 deg.C high temp. Said material 1 is covered with the film 2 by plasma spraying method, explosion spraying, etc. Thickness of the film 2 is selected usually from 0.05-2mm range.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a furnace roll for a continuous heat treatment furnace, and particularly to a ceramic roll for a continuous heat treatment furnace used in a high temperature atmosphere of 1000° C. or higher.

[Conventional technology]

In the past, alloys such as 5CH13 and 5CH22 made of nickel, chromium, etc. were generally used as the material for the furnace rolls of continuous heat treatment furnaces for continuously heat-treating steel sheets. This roll consisting of 5CH13° and 5CH22 is normally used in a furnace at a temperature of 800'C to 900C or less.

In addition, as shown in Figure 2, 5CH22 loses its strength at high temperatures, so it
When used in a furnace atmosphere of 00°C or higher, the roll temperature is lowered to 1000°C or lower by passing water, air, etc. into the roll.

[Problem that the invention seeks to solve]

However, in such conventional examples, the rolls in the furnace lose a large amount of heat through the cooling medium, and the steel plate being heat treated is also cooled by the cooled rolls, resulting in uneven heating. However, there was a problem in that the quality of the steel sheet deteriorated.

Therefore, in order to solve this problem, studies are being conducted to make the rolls made of ceramics, thereby eliminating the need for cooling the rolls.

However, when the roll is made of ceramics, the following problems occur.

That is, ceramics can be broadly classified into oxide-based, carbide-based, and nitride-based.

First, oxide ceramics (Al2O2, ZrO2,
5iQ2, etc.) generally have low high-temperature strength (see Figure 4), and have the problem of not being able to withstand long-term use.

In contrast to such oxide-based ceramics, rolls made of carbide-based ceramics (SiC, ZrC, etc.) and nitride-based ceramics (S i ] N4, etc.) have sufficient strength even at high temperatures ( (See Figure 4), but on the other hand, it has the problem of being extremely susceptible to oxidation at high temperatures. Also,
Even in a non-oxidizing furnace, there is a problem that the rolls become oxidized and become unusable over a long period of time because about 20 ppm of oxygen is present in the furnace.

Figure 3 shows the relationship between temperature and oxide thickness in SiC, which is a carbide ceramic, and shows the relationship between temperature and oxide thickness.
It has been shown that oxidation rapidly progresses at temperatures above 00°C.

Therefore, when a roll made of carbide ceramics such as SiC, Si3N4, etc. is used, oxides on the roll surface fall off due to sliding with the steel plate and become oxidized.

Due to repeated falling off, oxidative wear progresses, making it impossible to withstand long-term use. Furthermore, there is a problem that the peeled oxide damages the copper plate.

In addition to the above-mentioned ceramics, carbon and graphite also have sufficient strength at high temperatures, but it is well known that they have poor oxidation resistance.

[Means for solving problems]

The present invention was made by focusing on the problems of the conventional method, and the surface of a roll core material made of ceramics having high temperature strength is coated with a material having excellent oxidation resistance in a high temperature range. The structure is as follows.

[Effect]

A roll core material made of ceramics with high-temperature strength supports a steel plate that continuously passes through a furnace in a high-temperature region. The material coated on the roll core material with excellent oxidation resistance prevents the roll core material from being oxidized.

〔Example〕

An embodiment to which this invention is applied will be described below.

FIG. 1 shows a sectional view of a roll A according to the invention. In the figure, 1 is C, SiC, which has high strength at high temperatures.
, 5ixN+, BN, ZrB, Zr5i and other carbon-based, carbide-based, nitride-based, boride-based, silicide-based materials as main components, and cylindrical roll core materials made of compounds such as sialon. It is.

In the figure, 2 is a film that covers the circumferential surface of the roll core material 1.

This film 2 is made of oxide ceramics (A1203.Z
rO2, TiO2, Cr2O3゜MgO, ZrSiO4
,AA203- SiC2゜Al1203- TiO2
, ZrO2-Al120i.

Cr2O3-Al1203 etc.), alloys (CoCrAj!
Y,N1CrAji! Y, N1CrA#Y, NiCr,
NIAl), CoMoCrSi, CoCrW, etc.), composite materials (CoCrWNi-Cr2O3, CoCrTaA
nY-Al1z 03, etc.). These materials have excellent oxidation resistance and wear resistance at high temperatures, especially above 1000°C, and are stable in high-temperature atmospheres containing oxygen.
, materials consisting of one or more types of oxides such as MgO, and materials that produce stable oxides at high temperatures such as AA, Cr, and N.
j.

There are alloy materials containing one or more types of metal elements such as Ta, and composite materials of these oxides and alloys.

Methods for coating the roll core material 1 with the film 2 include plasma spraying, water plasma spraying, explosive spraying, chemical vapor deposition, etc., and the method may be selected as appropriate depending on the material properties of the film material. be.

Further, the thickness of this coating 2 is in the range of 0.03 to 20 mm, and although it varies depending on conditions such as the thickness, width, and weight of the rope plate, it is usually selected in the range of 0.05 to 211 mm. .

Furthermore, after coating the roll core material 1 with the coating 2, hot isostatic pressing may be performed to increase the strength of the coating 2.

Table 2 shows that the furnace atmosphere temperature is 1200℃ and the oxygen concentration is 20pp.
This figure compares the wear resistance of rolls tested in a continuous heat treatment furnace with a steel sheet passing speed of 200 m/min. Note that the thickness of the film 2 is 0.5 tnm.

Table 1 Conventional A7!203t:l-ru (No. 1 in the table)
The carbon type (positive 2) was removed after two months of use.
).

While the nitride-based (11kL3) and carbide-based (No. 4) rolls were oxidized and worn in a short period of time, the rolls No. 5 to No. 10 having the coating 2 according to the present invention suffered from oxidation wear. It can be seen that the wear resistance is 3 to 12 times higher than that of the uncoated roll of grade 4.

Note that the coating material is CoCrA6Y (Na5).

CoMoCr5i (隘6) alloy with excellent oxidation resistance, C
oCrTaAl1Y-Aff203 (Nap).

Composite material of CoCrWNi-Cr203 (Nl18) oxide and alloy with excellent oxidation resistance, ZrS i0
4 (11k19) and ZrO2 (10) in the order of their oxidation resistance. In addition, if the core material of the coated roll of this invention is a carbide-based nitride-based material, there is no big difference.
Excellent effects were obtained in all cases.

〔Effect of the invention〕

As is clear from the above explanation, in this invention,
The roll core material is made of a ceramic material that is strong at high temperatures, providing durability, and the roll core material is coated with a material with excellent oxidation resistance to prevent oxidation of the roll. It has the effect of preventing and reducing wear. Therefore, since the roll can withstand long-term use, there is an effect of reducing the running cost of the device.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a roll according to the present invention, and Fig. 2 is a 5C
A graph showing the relationship between temperature and strength of H22, Figure 3 is Si
Figure 4 is a graph showing the relationship between the furnace temperature of C and the thickness of the oxide.
2 is a graph showing the bending strength of O2, Al2203) at 1000°C and 1200°C. A... Roll, 1... Roll core material, 2
・・・・・・Film.

Claims (1)

[Claims] A roll for a continuous heat treatment furnace, characterized in that the surface of a roll core material made of ceramics having high temperature strength is coated with a material having excellent oxidation resistance in a high temperature range.