JPS6116408B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to rolls for heat treatment furnaces, especially various metal plates,
For example, the present invention relates to a roll for a heat treatment furnace that can be suitably used at an ambient temperature range of 300 to 1200°C in the heat treatment of silicon steel plates, stainless steel plates, aluminum plates, other alloy plates, copper and its alloy plates, etc. Conventionally, this type of roll for heat treatment includes (1) a metal roll made of a heat-resistant alloy containing high Cr and high Ni that directly supports and conveys the material to be heat treated with water cooling or non-water cooling; (2) the above-mentioned ( In order to extend the life of the heat-resistant alloy roll mentioned in 1), Al ₂ O ₃ , ZrO ₂ ,
Welded coating of ceramics such as SiO ₂ ,
Ceramic rolls made of ceramic or ceramic fibers in the form of sleeves to support and transport materials to be heat treated; (3) carbon rolls made of graphite or graphite fibers in the form of sleeves to support materials to be heat treated and used to transport; etc. have been devised and used. However, none of these furnace rolls has been able to satisfy all of the desired characteristics.
That is, water-cooled metal rolls are effective in preventing roll pickup by lowering the roll surface temperature, but have the disadvantage that the loss of heat due to water cooling becomes extremely large. For non-water-cooled metal rolls, although the heat loss due to water cooling can be eliminated, when the furnace temperature (roll temperature) is over 800℃, roll pick-ups occur frequently, causing damage to the heat-treated material. This results in a decline in quality. As a means to stabilize the quality of the heat-treated material and extend the life of the roll by preventing roll pickup of the heat-resistant alloy roll, the surface of the heat-resistant alloy roll was welded and coated with Al ₂ O ₃ , ZrO ₂ , SiO ₂ , etc. However, it has the disadvantage that it tends to cause peeling due to the difference in thermal expansion between the material and the welding layer, and this determines the life of the roll. Also, rolls with ceramic sleeves fitted onto the rolls have been used, but the mechanical strength of the ceramic sleeves themselves is weak, so not only is it necessary to be very careful when installing them, but the ceramic sleeves themselves are Due to the drawback of being easily broken, ceramic does not exhibit its roll pick-up resistance, which is an advantage. An asbestos roll made of asbestos laminates tightened around the roll shaft has also been proposed, but the drawback is that asbestos releases crystal water at temperatures above about 400°C, and asbestos itself becomes brittle at temperatures above 700°C. Furthermore, in the case of carbon rolls, there is relatively little roll pickup from a high-temperature, slightly oxidizing atmosphere to a high-temperature reducing atmosphere. For example, Tokuko Sho 47-13165
The carbon roll impregnated with chromium oxide proposed in the publication exhibits good pick-up properties in a weakly oxidizing atmosphere. However, the operating temperature of chromium oxide-impregnated carbon rolls is approximately 900°C, and if the temperature is higher than that, oxidation consumption becomes even greater, making them unusable. In addition, by using the carbon sleeve proposed in Japanese Patent Publication No. 54-10961, which is characterized by being impregnated with an aluminum phosphate aqueous solution, for heat treatment furnaces, it can be rolled resistant at high temperatures of 1000°C or higher and in a mildly oxidizing atmosphere. Good results have been obtained regarding pick-up properties. However, carbon sleep impregnated with aluminum phosphate has the disadvantage that it corrodes the shaft that serves as a support, leading to breakage of the shaft. In addition, carbon rolls are generally softer than the materials to be heat treated, and therefore have inferior wear resistance compared to metal rolls or ceramic rolls. As a result of various studies, the inventors of the present invention have developed roll pick-up resistance by utilizing the abrasion resistance, high hardness, and high strength of ceramics and the low wettability and low reactivity with fine iron powder of carbon. In order to improve the performance, it is preferable to use a material that is dense, has high strength, and further contains carbonaceous powder, and for this purpose, a dense carbonaceous powder material is used and mixed with ceramics, a binder, etc. It was found that it was desirable to mold and fire the
The application has been filed under No. 13175. If the particle size of the carbonaceous powder used here is too coarse, carbon will exist sparsely in the ceramics.
In the absence of carbon, roll pick-up resistance decreases and pick-ups are more likely to occur. In addition, when grinding the roll surface, smoothness cannot be obtained due to the difference in hardness with the ceramic component (the hardness of carbonaceous powder is smaller than that of ceramics).
Creates a step. Due to the occurrence of this level difference, pick-up is likely to occur from the level difference part, and the durability of the roll is reduced. Based on the results of these various studies, we decided to reduce the particle size of the carbonaceous powder used (74 μm or less).
Although we attempted to solve the problem by doing so, it turned out that the results were not satisfactory. As a result of further studies, the inventors of the present invention found that excellent characteristics can be exhibited by using a carbon material containing ceramic materials such as Al ₂ O ₃ and SiO ₂ as ash as a carbon source. In this carbon material, the ceramic material is dispersed in the carbon in extremely small units, and the carbon and ceramics are evenly composited, so that the hardness of the carbonaceous powder is improved. In addition, with respect to oxidative wear of carbonaceous powder, ceramics contained as ash forms a protective film on the surface of graphite particles, which reduces the rate of oxidative wear and makes it possible to obtain rolls with high roll pick-up resistance. can. That is, the object of the present invention is to provide a roll for a heat treatment furnace that eliminates the above-mentioned problems encountered in furnace rolls that support and convey materials to be heat treated in a high-temperature atmosphere furnace, and that has excellent roll pick-up resistance and wear resistance. In order to achieve this objective, the present invention uses a carbon material containing ceramic materials such as Al ₂ O ₃ and SiO ₂ as ash instead of the carbonaceous material of the earlier application (Japanese Patent Application No. 13175/1982). The present invention proposes a heat treatment roll that is characterized in that it can be used. As the carbon source used in the present invention, a fine powder carbon material (preferably 74 μm or less) such as earthy graphite or scale graphite containing a ceramic material such as Al ₂ O ₃ or SiO ₂ as ash is used. In this fine powder carbon material, it is more preferable that the ash content is 10 wt% or more, and the content of Al ₂ O ₃ and SiO ₂ in the ash is 50 wt% or more. Using such a carbon material, the roll is blended with a carbon content of 5 to 40% or more. A binder is added to the above carbon material, ceramic powder of one or more of oxides, nitrides, and carbides, and then thoroughly mixed to form a sleeve. Molding methods include isostatic pressing, extrusion molding, press molding, vibration molding, and the like. The compact thus formed is fired in a non-oxidizing atmosphere. In the present invention, carbon components are added as a powder raw material in the required amount to ceramics with excellent wear resistance in order to suppress the reaction with fine iron powder and improve roll pick-up resistance and wear resistance. It is possible to obtain an excellent carbon-containing ceramic sleeve, and at the same time, by using a carbon source containing ceramic materials such as Al ₂ O ₃ and SiO ₂ as ash, it is possible to improve the oxidation resistance and further improve the hardness of the carbon material. Shows excellent roll pick-up resistance. However, when the carbon component contained in the fired sleeve is less than 5%, the lubricity and the effect of suppressing reaction with fine iron powder are reduced, and the thermal shock resistance is reduced. On the other hand, if the carbon content exceeds 40%, mechanical strength decreases, leading to a decrease in wear resistance and oxidation resistance. 40% is required, preferably in the range of 10-40%. Examples will be described in detail below. Example Ceramic powder such as Al ₂ O ₃ , MgO, Si ₃ N ₄ , SiC, etc., containing earthy graphite containing 15% ash with a particle size of 74 μm or less (the content of Al ₂ O ₃ and SiO ₂ in the ash is 68%) ) and blended with phenolic resin, kneaded, molded, and fired in a non-oxidizing atmosphere. After firing, the sleeve was ground with diamond to a surface smoothness of 100 μm or less, and was used as a roll for a heat treatment furnace. The fired sleeve obtained as described above was heated in an actual steel sheet heat treatment furnace (temperature 800 to 1050℃, N ₂ −H ₂ −
The following table shows the results of using the product for 1800 hours in a H ₂ O atmosphere. For comparison, a carbon-free Al ₂ O ₃ roll, a carbon-impregnated Al ₂ O ₃ roll, and a low carbon-containing MgO roll were used under the same conditions, and the results are also listed in the table below.

[Table] As shown in the above examples, it can be seen that the roll of the present invention exhibited excellent roll pick-up resistance and greatly contributed to extending the life of the roll.

Claims (1)

[Claims] 1. In the furnace roll that supports and conveys the material to be heat treated in a heat treatment furnace with a high temperature atmosphere, the roll shaft has a
Contains 5 to 40% carbon material containing ceramic materials such as Al ₂ O ₃ and SiO ₂ as ash as a carbon component,
1. A roll for a heat treatment furnace, comprising a fired body made of ceramics such as oxide, nitride, or carbide.