TWI355422B - - Google Patents

Description

1355422 Π) Description of the Invention [Technical Field of the Invention] The present invention relates to a carbon material suitable for use as a he.arth roll for a heat treatment furnace for steel materials, which is used as a carbon material. The method of using the furnace roll and the furnace roll. [Prior Art] φ In a heat treatment furnace for heat-treating steel materials, a furnace roll for transporting (also including moving in and out) the steel materials (especially steel strips) is placed in the furnace. The furnace roll is continuously used for a long time in a high-temperature nitrogen group, and is in contact with a steel material which is a material to be heat-treated. Therefore, on the surface of the roll, an oxide or iron powder generated on the surface of the steel material reacts with the surface of the roll to adhere, thereby causing such accumulation to form a so-called pickup. When the surface of the steel sheet which is the material to be heat-treated is generated by the surface flaw, the steel sheet is inferior in quality. In addition, in order to avoid such a decrease in quality, when the inclusion occurs, the operation is stopped, and the roll of the roll is replaced, which causes damage to productivity. 〃 In order to solve this problem, a technique for using a carbon-based material, that is, a carbon material on a roll surface, has been proposed. For example, a so-called carbonaceous roll using a graphite carbon material is disclosed in Japanese Laid-Open Patent Publication No. Hei. No. Hei. The ratio of the carbonaceous rolls to the steel rolls or the ceramic layers formed on the surface -5 - 1355422

The inclusion resistance is good. That is, it is difficult to react with the surface oxide of the steel sheet. Further, since the surface of the roll is worn by contact with the steel sheet, it is difficult to adhere not only to foreign matter, but also has an advantage of being easily detached even if it adheres. On the other hand, the case where the carbon material is used as a furnace roll of a heat treatment furnace is an important factor for ensuring oxidation resistance. In the case of a carbon-based material, a carbon-based material is disclosed as a means for improving the oxidation resistance, and it is disclosed that the furnace is lightly immersed in cerium oxide or the like. Further, Japanese Laid-Open Patent Publication No. 2000-45037 discloses a heat treatment furnace roll which is subjected to slurry coating and heat treatment on a carbon substrate to have a roll shell forming a tantalum carbide-carbon composite layer. The carbonaceous roller' maintains the above-described characteristics or lubricity peculiar to the carbon material, and also has oxidation resistance and wear resistance of niobium carbide. DISCLOSURE OF INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION However, in the above-mentioned carbonaceous roller, there is room for improvement in the improvement of the life of the roller due to the occurrence of a pickup flaw during long-term use. Despite this, the improvement in the resistance to inclusion has not been successful since the development of carbonaceous rolls. Further, the oxidation resistance of the carbonaceous roll disclosed in JP-A-2000-45037 or JP-A-60-92427, and the effect of improving wear resistance (3) 1355422 are also limited. The present invention has been made in view of the above problems, and it is an object of the present invention to provide a carbon material for a roll that can improve the life of a roll as compared with a conventional carbon roll, and a roll using the carbon material. Further, it is an object of the invention to provide a method of using a furnace roll which does not cause heat generation for inclusions for a long period of time. Q [Solutions of the problem] The inventors of the present invention investigated the phenomenon of inclusions in the carbonaceous rolls, and as a result, the following institutions were explained. In the conventional carbon material, the large-diameter pores (stoxnate or pore) are many, so that the oxide formed on the surface of the steel sheet or the carbon particles desorbed from the light surface of the carbonaceous material in the heat treatment enters the pores by foreign matter. This foreign matter comes into contact with the steel sheet in the heat treatment, so that the oxide on the surface of the steel sheet is mixed, and the foreign matter starts to grow. Further, the conventional carbonaceous roller is soft, and even if the carbon layer of the roller is worn, foreign matter such as oxide which invades the surface of the roller is continuously buried in the carbonaceous roller. As a result, the foreign matter continues to grow while being buried in the carbonaceous roller. Based on the above findings, the inventors of the present invention have found that the maximum diameter of the pores in the carbon material used as the material for the furnace roll is reduced, and the hardness of the carbon material is set to the correct range, thereby preventing the occurrence of inclusions. On the other hand, in order to ensure the oxidation resistance, there is a method of impregnating a substance having oxidation resistance from pores in the pore surface from the surface of the carbonaceous roll, as disclosed in Japanese Patent Laid-Open No. 60-92427. However, in order to reduce the maximum diameter of the gas -7-(4) 1355422 hole, the carbon material is made dense, and the impregnation layer can be formed only in the shallower region of the surface portion of the furnace roll. Therefore, it has been difficult to manufacture a furnace roll which is subjected to immersion treatment from the surface layer to a sufficiently deep position for the purpose of long-term roll life. Further, the technique disclosed in Japanese Laid-Open Patent Publication No. 2000-4 5 03 7 can obtain a deepening of the oxidation resistant layer as compared with the usual impregnation, but it is still insufficient. Therefore, 'and further strengthen the results of the review, found that the starting material of carbon contains .S i carbide 'B carbide, B nitride, S i nitride, T i boride ' Zr boride ' A1 oxide, One or two or more kinds of Si oxide and Ti oxide are sequentially cast, and a carbon material is produced by burning and graphitization, which can greatly improve the inclusion resistance. At the same time, it has excellent oxidation resistance and is a true insight. The present invention has been completed based on the above-mentioned insights, and the gist thereof is as follows. 'I A carbon material for a furnace roll, which is a carbon material obtained by performing calcination and graphitization, and is characterized in that the maximum diameter of pores present in the carbon material is 0.2 mm or less, bulk specific gravity· ) is 1.55 to 2.00 g/cm3, the degree of graphitization is 0.5 or more, and the Shore hardness is 40 or more, less than 70. Further, Fe which is an inevitable impurity is 0.010% by mass or less, and alkali The metal (alkali metal) element is 0,010 mass, and the amount is less than or equal to one. (5) 1355422 2. The carbon used for the furnace roll as described in (.1), which further contains: Si carbide, B carbide 'B nitride, S i nitride, T i boride, ζ Γ boron The compound, the yttrium oxide, the Si oxide and the Ti oxide, or a mixture of two or more, is 3 to 50% by mass in total. 3. A furnace roll for a heat treatment furnace, characterized by having a shell having a carbon material as described in (1) or (2) at least on the surface. Further, it is not necessary for the body of the roll to be completely the carbon material, and the stomach carbon material has at least a surface. A method of using a furnace roll, characterized in that the steel sheet described in (3) is used to transport steel sheets at a high temperature of 700 ° C or higher. BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. <Carbon Material> 〇 The carbon material of the present invention is usually produced in the following order. Carbonaceous raw materials, for example, natural graphite, carbon black, anthracite 'coke, etc. are pulverized, and used as a starting material. The starting material is mixed with tar, asphalt or resin which is a binder, and is melted by compaction or extrusion to form a $- / ° followed by a calcination step and a graphitization treatment. The step, or, as the case may be, the surface high purity step becomes a carbon material (calcined. graphitized carbon material). The calcination can be carried out in a known temperature range, for example, at about 7 Torr to 130 (the graphitization treatment can also be carried out in a well-known temperature range, for example, at about 25 Torr to -9-(6) 1355422 3000 ° C. Before the forming, one or more of Si carbide, B carbide, B nitride, Si nitride, Ti boride, Zr boride, A1 oxide 'Si oxide and Ti oxide are added to the total of 3~ 50. The mass% may be mixed. Among the carbon materials obtained, the residual part is C and the unavoidable impurities. The important impurities are as follows. φ The characteristics of the carbon material of the present invention are subjected to the final step (graphitization step) Or the high-purification step), the maximum diameter of the pores present in the carbon material is 〇.2 mm or less, the bulk specific gravity is 1.55 to 2.00 g/cm3, the degree of graphite is 〇·5 or more, and the hardness of the ear is Hs. 40 or more, less than 70, and further, as an unavoidable impurity, Fe is 0.010% by mass or less, and an alkali metal element is 0.010% by mass or less. Hereinafter, the reason for limiting the respective requirements will be described. • The maximum diameter of the pores: 0.2 mm or less φ The maximum diameter of the pores in the carbon material is an important requirement in the present invention. When the maximum diameter of the pores exceeds 0.2 mm, the porosity of the pores becomes very high. Therefore, the maximum diameter of the pores can be 0.2 mm or less, and 0.1 mm. The following is preferable, and further preferably 〇. 5 mm or less. Here, the diameter of the pores is regarded as the longest diameter of the carbon material by using a scanning electron microscope (SEM) to observe the pores. In the present invention, the pore diameter is measured by the following method. Using a SEM, the 2.5 mm x 3 mm field of view is observed over 5 fields of view, and the longest diameter is measured for each of the observed pores. The diameter distribution of the pores is determined -10 - (7) 1355422, which is the largest 〇 table with a maximum standard deviation of 3 times (3σ) than the average .. The figure is used in the carbonaceous light of the present invention. The carbon material is organized by SEM photo 'Fig. 2 The carbon material used in the conventional furnace is used to observe the photograph of the structure. In the conventional carbon material, there are large pores (in the black portion). In contrast, the carbon material of the present invention shows that the pores are present. Figure The maximum diameter of the pores is 〇.19 mm, which is 〇. 46 mm in the figure. In addition, the maximum particle diameter of the starting material is preferably 0 mm or less, so that the maximum particle diameter of the starting material is 0 mm or less. The diameter adjustment is performed by smashing the subsequent screening. Further, the particle size of the additive such as the S i carbide described later may be 0.5 mm or less. Further, the diameter of the pore is 0.1 mm or less. When the initial maximum particle size is 0.10mm or less, 'the maximum pore diameter is less than 0.05mm', the maximum particle size of the starting material is less than mm5mm. On the other hand, the maximum particle size of the starting material is insufficient. 〇.〇2mm (the maximum diameter corresponds to about 0.01mm). Due to the preparation of raw materials, • The management cost of the steps increases, which is not good. If the cost can be increased, the maximum particle size of the starting material can be 0 · 〇 5 mm or more. • The specific gravity of the body: 1.55 to 2.00 g/cm3 In the present invention, in order to make the bulk specific gravity 1.55 g/cm3 or more, the carbon diameter is observed, and the diameter of the second largest sample material in the SEM sheet is a good pore. The density of the dense -11 - (8) 1355422 can be reduced by the number of pores that become the starting point of the inclusion. When the bulk specific gravity is less than 1.55 g/cm3, it becomes porous, and the number of pores which are the starting point of inclusion increases. Further, when the bulk specific gravity exceeds 2.00 g/cm3, the impact enthalpy is lowered, and when the carbon material is used as a furnace roll, there is a damage due to crack. Therefore, the specific gravity of the carbon material becomes 1.55 to 2 · 00 g/cm 3 . The specific gravity of the body can be controlled, for example, depending on the particle diameter of the starting material, the baking conditions, and the like, and the molding pressure at the time of molding can be controlled. 'D. Graphitization degree: 〇. 5 or more - The carbon material of the present invention is a graphite carbon material, and the degree of graphiteization after graphitization is required to be 0.5 or more. It is preferably 0.7 or more. When the degree of graphitization is less than 0.5, the material is softened to deteriorate the abrasion resistance of the carbon material, and the life of the furnace roll cannot be sufficiently ensured. This is not the case. When the pores are at the starting point of the inclusions, the carbon material around the pores is abraded, so that the growth rate of the inclusions becomes larger, and the inclusion resistance is deteriorated. Further, when the degree of graphitization is not sufficiently large, it is easy. The problem of oxidative wear is caused. In addition, the carbon material is classified into carbonaceous and graphite, but the degree of graphitization in the present invention means the ratio of the possession of graphite in the carbon material. In the present invention, by X Line back analysis to determine the layer spacing d ( 002 ) of the (002) plane, which is the degree of graphitization of d (〇〇2) = 3.354g + 3.44 (lg) g. The degree of graphitization, mainly in graphite The conditions of the treatment step (treatment temperature, treatment time) can be controlled after the setting. -12- 1355422 (9) • Hardness of the ear: 40 or more, less than 70. If the hardness of the ear after the graphitization is 40 or more, even in the case of The pores are oxides, foreign matter such as carbon particles invade, and the origin of inclusions is generated. Since the carbon around the carbon has sufficient hardness, the abrasion of the carbon material does not proceed, and since no foreign matter is buried in the carbon, the growth of the foreign matter can be suppressed. On the other hand, Xiao If the ear hardness Hs is too hard at 70 or more, if the foreign matter in the pores is invaded by the Q-hole, the foreign matter in the carbon material is completely infiltrated, and the foreign matter does not fall off from the carbon material, but continues to exist in the carbon material, and instead makes the clip resistant. The hysteresis is deteriorated. Therefore, the hardness Hs. is 40 or more and less than 70. • The hardness of the carbon material, for example, by the calcination-condition (temperature, time, etc.), is controlled by the particle size of the starting material. In addition, the molding conditions (forming method, pressure, etc.) can be adjusted. .Fe: 0.010 mass% or less, alkali metal element: 0.010 mass. /0 〇 or less. ^ Fe or alkali in carbon material When a metal element (Na or the like) is present as an impurity, the catalyst becomes a catalyst and promotes oxidation, so that the oxidation resistance is lowered. Therefore, each of the allowable reductions can be reduced to 0.010% by mass or less. To reduce the content of the elements. Further, it is possible to use a starting material having a high purity. Further, it is preferable to use an additive such as S i carbide described later in terms of management purity. In addition, it is also possible to make an alkaline earth metal (Ca, Mg, etc.) in a carbon material. Become 0.010 % Or less, preferably an amount of - the oxidation resistance of the carbon material of the present invention are also good, that it also further improve -13- 1355422 do) may contain the following additives. · Addition amount of one or more of Si carbide, B carbide, B nitride, Si nitride, Ti boride, Zr boride, A 1 oxide, Si oxide and Ti oxide: 3 to 50% by mass (optional)

Si carbide, B carbide, B nitride, Si nitride, Ti telluride, Zr boride, A1 oxide, Si oxide and Ti oxide are all substances having oxidation resistance due to inclusion in carbon materials. In this case, the oxidation consumption of the carbon material when used in a high φ temperature atmosphere can be suppressed. Further, since these substances are hard, they contribute to the hardening of the carbon material. When the total content is less than 3% by mass, the effect of improving oxidation resistance is not sufficient. On the other hand, when the total content is more than 50% by mass, the embrittlement is remarkably brittle and the toughness of the carbonaceous roll cannot be ensured. Therefore, the total addition amount of one or more of Si carbide, B carbide, B nitride, Si nitride, Ti boride, Zr boride, A1 oxide, Si oxide, and Ti oxide is 3 ~50% by mass. φ In addition, among the above, B nitride, B carbide, Si carbide and

The Si nitride, in particular, allows the glassy oxidation resistant film to be formed well on the surface and pores, so that the effect is high. The content of each additive can be adjusted in accordance with the amount of the starting material. The content can be confirmed by ICP (inductively coupled plasma) mass spectrometry, ICP luminescence analysis, ΕΡΜΑ (electron probe micro-analysis), EDX (energy dispersive X-ray) In the conventional impregnation technique, etc., the region having the oxidation resistant substance can be limited to the vicinity of the surface, and the use in the high temperature furnace causes the oxidation resistant substance. When it is sublimated, it loses its effect, so it has the problem of persistence of oxidation resistance. There are no such problems in the present invention, and oxidation resistance can be maintained for a very long time. <Rolling Roller> When the above carbon material is used as a furnace roll of a heat treatment furnace, the occurrence of inclusions is extremely reduced, and the life of the furnace roll can be extended. The furnace roll of the present invention is a furnace roll having a heat treatment furnace formed of the above-mentioned carbon material. Here, it is not necessary to be the carbonaceous roller until the axis of the body portion, and it is sufficient if the surface of the body portion can be covered to a certain extent. The thickness is preferably 20 mm or more depending on the application. In the method of manufacturing a furnace roll which is suitable from the viewpoint of workability, the carbon material is cut into a sleeve shape and embedded in a core of a roll shaft, and the furnace can be a furnace having the above-mentioned carbon material. Roller. Or, by processing a carbon material, it can be used as a furnace roll in the shape of a shaft. The manufacturing method is not limited to these. <Method of Using Furnace Roller> The above-described furnace roll of the present invention is suitably used as a furnace roll for a heat treatment furnace of a steel sheet. That is, the oxide attached to the surface of the steel sheet adheres to the furnace roll, and the inclusions can be suppressed for a long period of time, so that the life of the furnace roll can be greatly improved -15- (12) 1355422 In addition, in terms of the use temperature of the furnace roll, That is, the high temperature at 950 ° C or higher can also sufficiently improve the resistance to inclusion. The life is sufficiently increased, and the effect of the present invention is particularly exhibited, and it is in the temperature range of 700 to 1100 °C. Here, the use temperature of the furnace roll means the surface temperature of the roll, and is usually substantially the same as the temperature (in-furnace temperature) or the ambient temperature in the heat treatment furnace to which the roll is applied. The present invention can exert an effect irrespective of the use atmosphere (in-furnace atmosphere). Therefore, the atmosphere which is usually used for the heat treatment of the steel sheet, for example, _H2 and/or n2 is mainly contained (or contained), and in the atmosphere containing H20, etc., good results are obtained. [Embodiment] [Examples] (Example 1) The carbon raw material was formed by CIP (Cold Iso static Press) using a coke having a maximum particle diameter of 0.30 mm as a starting material, and baking was carried out. And graphitization treatment can obtain a carbon material having a degree of graphitization of 0.72, a hardness of Hs40, a maximum pore diameter of 0.20 mm, and a specific gravity of 1.78 g/cm3. Further, the Fe content as an inevitable impurity was 15 ppm, and the content of the metal element was 19 ppm (mainly Na and K, the same applies hereinafter). Next, a carbonaceous roll using this carbon material for the roll body portion was produced, and the carbonaceous roll was used as a furnace roll for an annealing furnace of a thin steel plate. The temperature in the furnace of the annealing furnace was 1000 ° C, and the atmosphere in the furnace was N2. However, in this annealing furnace, 365 days are used, and no inclusions occur, and no abnormal oxidation consumption or cracking occurs. -16- (13) 1355422 In addition, the measurement method of the D-shaped test machine JIS B 7727 (1993 edition) is measured in accordance with JIS Z2246 (1992 edition). . (Example 2) The carbon raw material was obtained by using coke having a maximum particle diameter of 〇.10 rnm as a starting material, and performing CIP forming 'calcination and graphitization to obtain graphitization 0 degree 〇.76, hardness Hs55, maximum diameter of pores. O.lOmm, carbon material with a specific gravity of 1.8〇g/cm3. Further, as an inevitable impurity, the content of Fe is 5 ppm, and the content of the alkali metal element is 丨6ρριη. Then, a carbonaceous roll having the carbon material used for the roll body portion was produced, and the carbonaceous roll was used as a furnace roll for an annealing furnace of a thin steel plate. The annealing furnace was the same as in Example 1, and the furnace temperature was 10 ° C. The atmosphere in the furnace was N2. Then, in this annealing furnace, 365 days were used, and no inclusions occurred, and there was no oxidation consumption and cracking of the abnormal f. Q.. (Example 3) 'Carbon raw material system' uses coke having a maximum particle diameter of 0.05 mm as a starting material, performs CIP molding, and performs calcination and graphitization to obtain a graphitization degree of 0.80, a hardness of Hs55, and a maximum pore diameter. A carbon material having a diameter of 0.05 mm and a specific gravity of 1.85 g/cm3. The content of Fe as an inevitable impurity was 10 ppm, and the content of the metal was 15 ppm. Then, this carbon material was produced for use in a roll body carbonaceous roll, and the carbon roll was used as a roll of an annealing furnace for a steel sheet. The temperature inside the furnace of the annealing furnace is 1 000 ° C, so that the atmosphere in the furnace is N2. Then, using this annealing furnace to make 甩3 65, no inclusions occurred, and -17- (14) 1355422, there is no abnormal oxidation consumption, cracking. (Example 4) A carbon raw material was obtained by using coke having a maximum particle diameter of 〇30 mmi as a starting material, and B4C (maximum particle diameter: 0.15 mm) and SiC (maximum particle diameter: 0.26 mm) were added thereto, and CIP molding was carried out to carry out baking. And graphitization to obtain a carbon material having a degree of graphitization 〇·73, a hardness Hs40, a maximum diameter of the pores of 0.20 mm, and a body weight of 1.82 g/cm3. The degree of graphitization herein means the ratio of graphite in the carbon other than the additive (B4C, SiC). The content of B4C after the graphitization treatment was 10% by mass, and the content of SiC was 8% by mass. Further, 'the content of Fe as an inevitable impurity was 16 ppm, and the content of an alkali metal element was 13 ppm. Then, a carbonaceous roll using this carbon material for the roll body portion was produced. This carbonaceous roll was used as a furnace roll for an annealing furnace of a steel sheet. The temperature in the furnace of the annealing furnace was 1 000 ° C, and the atmosphere in the furnace was N2. Then, in this annealing furnace, the occurrence of no inclusions was carried out on the 73th day, and there was no abnormal oxidation Q consumption. The crack occurred. (Example 5) A carbon raw material was obtained by using coke having a maximum particle diameter of 0.10 mm as a starting material, and ZrB2 (maximum particle diameter 〇.3〇mm) and SiC (maximum particle diameter 0.15 mm) were added thereto to perform CIP molding. Calcination and graphitization were carried out to obtain a carbon material having a degree of graphitization 〇70, a hardness Hs55, a maximum diameter of pores, i〇mm, and a specific gravity of 1.86 g/cm3. The degree of graphitization herein means the ratio of graphite in the carbon other than the additive (ZrB2' SiC). After the graphitization treatment, the content of -18-(15) 1355422 ΖγΒ2 was 10% by mass, and the content of SiC was 30% by mass. Further, the content of Fe as an inevitable impurity was 30 ppm, and the content of the metal element was 26 ppm. Then, a carbonaceous roll using this carbon material for the body of the roll was produced. This carbonaceous roller is used as a furnace roll for an annealing furnace of a steel sheet. The annealing furnace was the same as in Example 1, and the furnace temperature was 1000 1, and the furnace atmosphere was N2. Then, in this annealing furnace, the use of 730 days, no inclusions occurred, and there was no abnormal oxidation consumption, and cracking occurred. Ο (Example 6) The carbon raw material was obtained by using coke having a maximum particle diameter of 0.30 mm as a starting material '', and TiB2 (maximum particle diameter 〇.30 mm) was added thereto, and CIP molding was carried out to carry out baking and graphitization treatment. A carbon material having a degree of graphitization of 0.76, a hardness of Hs40, a maximum diameter of the pores of 0.20 mm, and a bulk specific gravity of 1.78 g/cm3 was obtained. The content of TiB2 after the graphitization treatment was 15% by mass. Further, the content of Fe as an inevitable impurity was 60 ppm, and the content of an alkali metal element was 30 ppm. Then, a carbonaceous roll using this carbon material for the body of the roll was produced. This carbonaceous roll was used as a furnace roll for an annealing furnace of a steel sheet. The temperature inside the furnace of the annealing furnace is 100 (TC, the atmosphere in the furnace is N2. Then, the annealing furnace is used for 730 days, no inclusions are generated, and no abnormal oxidation consumption occurs, and cracking occurs. (Example 7 The carbon raw material is made of coke having a maximum particle diameter of 〇30 mm as a starting material, and ZrB2 (maximum particle diameter of 0.18 mm) is used for forming, and -19-(16) 1355422 CIP is formed, and calcination and graphite are carried out. A carbon material having a degree of graphitization of 0.74, a hardness of Hs40, a maximum diameter of pores of 0.20 mm, and a specific gravity of 1.80 g/cm3 was obtained by chemical treatment. The content of ZrB2 after graphitization was 20% by mass. Further, as Fe of inevitable impurities The content of 45 ppm and the content of the alkali metal element are 16 ppm. Then, a carbonaceous roll using this carbon material for the body of the roll is prepared. This carbonaceous roll is used as a furnace roll for an annealing furnace of a steel sheet. The internal temperature is l〇〇〇°C, and the atmosphere in the furnace is N2. Then, the annealing furnace is used for 73 0 days, no inclusions occur, and there is no abnormal oxidation. Consumption 'cracking occurs. Example 8). The carbon raw material is a coke having a maximum particle diameter of 〇30 mm. As a starting material, Al2〇3 (maximum particle diameter: 0.20 mm) was added for this purpose, and CIP molding was carried out, and calcination and graphitization were carried out to obtain a graphitization degree of 0.72, a hardness of Hs40, a maximum diameter of pores of 0.20 mm, and a specific gravity of 1.82 g. /cm3 of carbon material 3. The content of Al2〇3 after graphitization is 35% by mass. Further, the content of Fe as an unavoidable impurity is 35 ppm, and the content of an alkali metal element is 60 ppm. The carbon material is used for the carbonaceous roll of the roll body. The carbonaceous roll is used as the furnace roll of the annealing furnace of the thin steel plate. The temperature inside the furnace of the annealing furnace is l〇〇〇°C, and the atmosphere in the furnace is N2. Then, With this annealing furnace, 7+30 days, no inclusions occurred, and no abnormal oxidation consumption occurred, and cracking did not occur. (Example 9) -20 - * (17) ' 1355422 Carbon raw material made the largest grain A coke having a diameter of 0.30 mm was used as a starting material, and Si 2 (maximum particle diameter 〇.i 〇 mm) was added for casting, and calcination and graphitization were carried out to obtain a graphitization degree of 0.81 and a hardness of Hs40'. The maximum diameter of the pores is 〇.2〇mm, and the carbon content of the body specific gravity is KMg/cn^. The content of SiO 2 after the graphitization treatment was 40% by mass. Further, the content of Fe as an unavoidable impurity was 50 ppm, and the content of the metal element was 15 ppm. Then, the carbon material used for the carbon material in the roll body was produced. 0 Roller. This carbonaceous roll is used as the furnace roll of the annealing furnace of the thin steel plate. The temperature inside the furnace of the annealing furnace is l〇〇〇°C, and the atmosphere in the furnace is N2. Then, the furnace is used for 730 days. No inclusions occur, and there is no abnormal oxidation consumption. • The occurrence of cracks. (Comparative Example 1) 'The starting material used was coke with a maximum particle size of 0.6 mm, treated with CIP, formed, calcined and graphitized to obtain a degree of graphitization of 0.7, hardness () Hs55, maximum diameter of pores 〇. 25mm, carbon material with a specific gravity of 1.70g/cm3. The content of Fe as a no-avoidance impurity was 13 ppm, and the content of alkali metal was 13 ppm. Then, a carbonaceous roll using this carbon material for the roll body portion was produced, and the carbonaceous material was used as a furnace roll for an annealing furnace of a steel sheet. The annealing furnace was the same as in Example 1, the temperature in the furnace was 100 ° C, and the atmosphere in the furnace was N2. Then, the annealing furnace was used for 90 days, and the continuous use of the above was a difficult state due to the occurrence of inclusions. One

-21 - (18) 1355422 (Comparative Example 2) The starting material was coke with a maximum particle size of 0.13 mm, and CIP molding was carried out, and calcination and graphitization were carried out to obtain a graphitization degree of 0.78, a hardness of Hs75, and a maximum diameter of the pores of 0.10. Mm, carbon material with a specific gravity of 1.79 g/cm3. The content of Fe as an inevitable impurity was 14 pPm, and the content of alkali metal was 18 ppm. Then, a carbonaceous roll in which the carbon material is used in the roll body portion is produced, and the carbonaceous roll is used as a roll of an annealing furnace for a steel sheet. The annealing furnace was the same as in Example 1, and the furnace temperature was 1000 ° C, and the furnace atmosphere was N2. Then, when the annealing furnace is used for 90 days, the continuous use of these or the like becomes difficult due to the occurrence of inclusions. (Comparative Example 3) The starting material was a coke having a maximum particle diameter of 1.0 mm, and was subjected to extrusion molding, calcination and graphitization to obtain a graphitization degree of 0.68, a hardness of Hs20, and a maximum diameter of the pores of 5050 mm. Carbon material with a specific gravity of 1.62g/cm3. As an inevitable impurity, the Fe content is 13 ppm, and the alkali metal content is 18 ppm. Then, a carbonaceous roll using this carbon material for the roll body portion was produced, and this carbonaceous roll was used as a furnace roll for an annealing furnace of a steel sheet. The annealing furnace was the same as in Example 1, the furnace temperature was 10 00 ° C, and the atmosphere in the furnace was N 2 . Then, when the annealing furnace was used for 30 days, the continuous use of the above became a difficult state due to the occurrence of inclusions. (Comparative Example 4) -22- 1355422 (19) The starting material was extruded using coke having a maximum particle diameter of 1.0 mm, and calcined and graphitized to obtain a degree of graphitization of 0·73, and the hardness of Hs20' was the largest. A carbon material having a diameter of 50.50 mm and a specific gravity of 1.68 g/cm3. The content of Fe as an inevitable impurity was 5 2 ppm, and the content of an alkali metal element was 30 ppm. Then, a carbonaceous roll using this carbon material for the body of the roll was produced. This carbonaceous roll is used as an annealing furnace for thin steel sheets. The annealing furnace was the same as in Example 1, the furnace temperature was 1 000 ° C, and the furnace atmosphere was N2. Then, when it is used in this annealing furnace, inclusions occur on the 30th day, and the thickness is reduced due to oxidation consumption on the 580th day (thick-ness re(iuce.d) and inclusions, so that the above continuous use In the state of difficulty. (Comparative Example 5) The starting material was cast using a coke having a maximum particle diameter of 0.10 mm, and calcination and stone 'inking treatment were performed to obtain a degree of graphitization of 0.76, hardness 〇Hs55, and pores. A carbon material having a maximum diameter of 0.10 mm and a specific gravity of 1.78 g/cm 3 . The content of Fe as an inevitable impurity is 5 1 ppm, and the content of an alkali metal element is _31 ppm. Then, the carbon material is used for a roll. The carbonaceous roll of the body is used as the furnace roll of the annealing furnace of the steel sheet. The annealing furnace is the same as in the first embodiment, the temperature in the furnace is 100 ° C, and the atmosphere in the furnace is N2. Then, When the annealing furnace was used for 580 days, the thickness reduction was severe due to oxidation consumption, and the above-mentioned continuous use became difficult. (Example 1 0) -23- (20) 1355422 The starting materials described in Table 1 ( The maximum particle size is suitably adjusted between 0.025~0.70riim), which can be used as needed Adding an oxidation-resistant additive (the maximum particle size can be suitably adjusted between 0.050 and 0.50 mm), and after performing CIP molding, calcination and graphitization are carried out to obtain a carbon material. The maximum diameter of the obtained carbon material pores, the hardness Hs, The degree of graphitization, bulk specific gravity, content of Fe alkali metal elements (mainly Na and K) and oxidation resistance additives are shown in Table 1. In addition, regarding sample No. 20, the forming system was extruded into a crucible. The carbonaceous material ii is used to make the carbonaceous material used in the roll body of the roll, and the carbonaceous roll is used as a furnace roll for the annealing furnace of the steel sheet. In addition, the thickness of the carbonaceous roll is made into a thickness. The 25mm bushing is embedded in the heat-resistant steel roller shaft.

No. 18 can process the carbon material itself into a roll type. · The normal atmosphere is used in the annealing furnace, and the furnace temperature is 1000 °c. The inclusion resistance and oxidation resistance of each of the rolls were evaluated as follows. Index of resistance to inclusion: J 1 = number of days of use: in the case of less than .90 夹 there is inclusion, 2 = less than 180 days and less than 180 days of inclusion, 3 = more than 180 曰 less than 380 days of inclusion, 4 = There are inclusions with more than 3 80 days. Oxidation resistance index: 380 days after use weight / pre-use weight evaluation as described below (even if inclusions on the way continue to be used for evaluation until 380 )) 1 = less than 80% ’ -24-

Oh I355422~ — (21) 2 = 8 Ο % is less than 9 Ο %, 3 = 9 Ο % is less than 9 5 %, . 4 = 9 5 % or more. The evaluation results in each furnace roll are shown in Table 1. The furnace roll which satisfies the requirements of the present invention exhibits excellent resistance to inclusion and oxidation resistance.

No. Maximum diameter of the starting material pores (mm) Hs Graphitization degree specific gravity (g/cm3) Inclusion resistance index... Oxidation resistance mm*** Fe (mass%) Alkali metal elements (total) (mass% Oxidation resistance (mass%) 1 Coke 0.30 55 0.60 1.75 0.004 0.004 - 1 3 2 Coke 0.25 55 0.60 1.75 0.004 0.004 - 1 3 3 Coke 0.20 55 0.60 1.75 0.004 0.004 - 3 3 4 Coke 0.15 55 0.60 1.75 0.004 0.004 -- 3 3 ^ 5 Coke 0.10 55 0.60 1.75 0.004 0.004 - 4 3 6 Coke 0.05 55 0.60 1.75 0.004 0.004 - 4 3 Ί ' Coke 0.02 55 0.60 1.75 0.004 0.004 - 4 3 8 Coke 0.10 30 0.60 1.75 0.004 0.004 - 2 3 9 Coke 0.10 40 0.60 1.75 0.004 0.004 - 4 3 10 Coke 0.10 70 0.60 1.75 0.004 0.004 - 4 3 11 Coke 0.10 80 0.60 1.75 0.004 0.004 - 2 3, 12 Coke 0.10 55 0.60 1.75 0.004 0.008 - 4 3 13 Coke 0.10 . 55 0.60 1.75 0.004 0.011 - 4 1 14 Coke 0.10 55 .0.60 1.60 0.004 0.004 - 4 3 A 15 Coke 0.10 55 0.60 1.95 0.004 0.004 - 4 3 16 Coke 0.10 55 0.60 1.75 0.008 0.004 - 4 3 17 Coke 0.10 55 0.55 1.75 0.00 4 0.004 - 4 3 18 Mix ** 0.10 55 0.60 1.75 0.004 0.004 Si3N4: 5% 4 4 19 Coke 0.10 55 0.60 1.75 0.004 0.004 BN: 10%, BC: 10% 4 4 20* Coke 0.20 45 0.60 1.75 0.004 0.004 - 3 3' table

Forming means: extrusion *) Mixed raw materials: carbon black = 30mass% + natural graphite = 70mass% ***) Adhesion resistance index: the number of days of use before inclusion, less than 1 = 90 days, 2 = 90 days Less than 180 days, 3 = 180 days or less, less than 3 80 days, 4 = 3 80 days or more &quot;**) oxidation resistance index; after use weight / before use weight is less than 1 = 80%, 2 = 80% or more Less than 90%, 3 = 90% or more and less than 95%, 4 = 95% or more - 25 - (22) (22) 135542 According to the carbon material for a furnace roll or the furnace roll of the present invention, the carbon particles can be prevented from falling off And the intrusion of the oxide from the steel sheet into the carbon material can suppress the formation of the inclusion starting point. Further, by the high hardness of the carbon material, even if the inclusion starting point is formed, the carbon material itself is not worn, and the growth of the inclusion starting point can be prevented from being buried in the carbon material. Therefore, the inclusion resistance can be greatly improved. Further, the oxidation resistance additive can be sufficiently ensured by the inclusion of the oxidation resistant additive in the carbon material. Further, according to the method of using the furnace roll of the present invention, no inclusions are generated over a long period of time, and the consumption of the rolls due to oxidation can be suppressed as needed, so that the life of the rolls can be further improved. Industrial Applicability The furnace roll of the present invention does not cause any occurrence of inclusions over a long period of time, and since the consumption of the rolls due to oxidation can be suppressed, the life of the rolls can be remarkably improved. In particular, in the heat treatment of the steel sheet, annealing conditions of h2 and N2 as main components in a high-temperature atmosphere containing 700 ° C or more (particularly 950 ° C or more) of the fine H20 can be suitably used. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a photograph of a structure observed by SEM of a carbonaceous roller of the present invention. Fig. 2 is a photograph of the structure of a conventional carbonaceous roller observed with S E Μ. -26-

Claims (1)

|I355422 η) X. Patent application scope* !· A carbon material for the furnace roll, which is subjected to baking and graphitization - a carbon material, characterized in that the maximum diameter of the pores present in the carbon material is 0.2mm or less, the bulk specific gravity is 1.55 to 2.00g/cm3, the degree of graphitization is 0.5 or more, and the Shore hardness is 40 or more, less than 70, and φ is an inevitable impurity. (incidental impurity) Fe is. 〇.〇1〇% by mass or less 'alkali metal' element is 0.010 quality 衅% or less. 2. The carbon material for a furnace roll according to the first aspect of the patent application, which further comprises: S 丨 carbide 'B carbide, B nitride 'S i nitride, Ti nord, Zr boride, A1 oxide One or more of the Si oxide and the Ti oxide are in a total amount of 3 to 50% by mass. The present invention is characterized in that it has a shell having at least a carbon material as described in the first or second aspect of the patent application. A method of using a furnace roll, characterized in that the steel sheet is conveyed at a high temperature of 700 ° C or higher by a furnace roll as described in the patent application. -27-