STRUCTURE FOR MANUFACTURING CAST ARTICLE

Abstract

A structure for manufacturing a cast article includes an organic component, at least a portion thereof being an organic fiber. The structure has a mass reduction rate of 1 mass % or greater to less than 20 mass % when heated under nitrogen atmosphere at 1000 C. for 30 minutes. The cast-article-manufacturing structure includes an inorganic particle. The cast-article-manufacturing structure includes, as the inorganic particle, a first inorganic particle having a predetermined shape and/or physical property, and a second inorganic particle having a predetermined shape and/or physical property different from the first inorganic particle. In addition thereto or instead thereof, the cast-article-manufacturing structure has a maximum bending stress of 9 MPa or greater measured in conformity with JIS K7017, and a bending strain of 0.6% or greater at the maximum bending stress.

Claims

1. A structure for manufacturing a cast article, the structure comprising: an organic component; and an inorganic particle on a surface of the structure, the inorganic particle including at least a first inorganic particle, wherein: at least a portion of the organic component is an organic fiber dispersed on the surface of the structure and in an interior of the structure, the inorganic particle is in the interior of the structure, the structure has a mass reduction rate of 1 mass % or greater to less than 20 mass % when heated under nitrogen atmosphere at 1,000 C. for 30 minutes, the structure has a maximum bending stress of 9 MPa or greater measured in conformity with JIS K7017, and the structure has a bending strain of 0.6% or greater at the maximum bending stress.

2. The structure for manufacturing a cast article according to claim 1, wherein the maximum bending stress is 9 MPa or greater and 50 MPa or less, and the bending strain at the maximum bending stress is 0.65% or greater and 8% or less.

3. The structure for manufacturing a cast article according to claim 1, wherein the inorganic particle includes a second inorganic particle, the first inorganic particle is not a layered particle, and the second inorganic particle is a layered particle.

4. The structure for manufacturing a cast article according to claim 1, further comprising another organic component other than the organic fiber.

5. The structure for manufacturing a cast article according to claim 1, wherein the first inorganic particle is spherical, and an average particle size of the first inorganic particle is 1 m or greater and 1,000 m or less.

6. The structure for manufacturing a cast article according to claim 1, wherein the inorganic particle has a melting point of 1,200 C. or higher and 2,500 C. or lower.

7. The structure for manufacturing a cast article according to claim 1, wherein the mass reduction rate is 1 mass % or greater and less than 15 mass %.

8. The structure for manufacturing a cast article according to claim 1, wherein the first inorganic particle includes mullite.

9. The structure for manufacturing a cast article according to claim 1, wherein the inorganic particle includes one or two or more selected from aluminum oxide, silicon dioxide, and iron oxide.

10. The structure for manufacturing a cast article according to claim 1, wherein the inorganic particle is one or more types selected from spherical particles and/or layered particles.

11. The structure for manufacturing a cast article according to claim 1, wherein 50 pieces or more and 300 pieces or fewer of the organic fiber are present per 100 mm.sup.2 on the surface of the structure for manufacturing the cast article.

12. The structure for manufacturing a cast article according to claim 1, wherein the organic fiber on the surface of the structure for manufacturing the case article has an average fiber length of 0.5 mm or greater and 7 mm or less.

13. The structure for manufacturing a cast article according to claim 1, wherein the organic fiber on the surface of the structure for manufacturing the case article has an average fiber diameter of less than 40 m and 8 m or greater.

14. The structure for manufacturing a cast article according to claim 13, wherein a ratio of the average fiber length of the organic fiber to the average fiber diameter of the organic fiber present on the surface is 10 or greater and 260 or less.

15. The structure for manufacturing a cast article according to claim 1, wherein the organic fiber includes one or plural selected from pulp fiber, fiber including polyester resin, and/or fiber including aramid resin.

16. The structure for manufacturing a cast article according to claim 1, wherein the structure for manufacturing the cast article has a thickness of 0.2 mm or greater and 10 mm or less.

17. A method regarding a structure for manufacturing a cast article, comprising: providing the structure for manufacturing the cast article; and using the structure for manufacturing the cast article, wherein: the structure for manufacturing the cast article includes: an organic component, and an inorganic particle on a surface of the structure, the inorganic particle including at least a first inorganic particle, at least a portion of the organic component is an organic fiber dispersed on the surface of the structure and in an interior of the structure, the inorganic particle is in the interior of the structure, the structure has a mass reduction rate of 1 mass % or greater to less than 20 mass % when heated under nitrogen atmosphere at 1,000 C. for 30 minutes, the structure has a maximum bending stress of 9 MPa or greater measured in conformity with JIS K7017, and the structure has a bending strain of 0.6% or greater at the maximum bending stress.

18. The method according to claim 17, further comprising another organic component other than the organic fiber, wherein the maximum bending stress is 9 MPa or greater and 50 MPa or less, the bending strain at the maximum bending stress is 0.65% or greater and 8% or less, the inorganic particle has a melting point of 1,200 C. or higher and 2,500 C. or lower, and an average particle size of the first inorganic particle is 1 m or greater and 1,000 m or less.

19. The method according to claim 17, wherein the inorganic particle includes a second inorganic particle, and each of the first inorganic particle and the second inorganic particle is one or more types selected from spherical particles and layered particles.

20. The method according to claim 19, wherein the inorganic particle includes one or two or more selected from aluminum oxide, silicon dioxide, and iron oxide.

Description

EXAMPLES

[0203] The present invention will be described in further detail below by way of examples. The scope of the present invention is, however, not limited by the examples.

Example 1

[0204] As for the organic components, an organic fiber (mechanical pulp) and a thermosetting resin (phenolic resin; resol) were used. Mullite (spherical; average particle size: 30 m) was used as first inorganic particles, and layered clay mineral particles (montmorillonite; Kunipia F from Kunimine Industries Co., Ltd.; average particle size: 145 m) were used as second inorganic particles.

[0205] In addition, PAN-based carbon fiber (PYROFIL TR03 CM A4G from Mitsubishi Chemical Corporation) was used as inorganic fiber.

[0206] These materials were mixed according to the proportions shown in Table 1 below, to prepare a structure precursor, and cast-article-manufacturing structures were manufactured according to the aforementioned method. As regards the shapes of the obtained cast-article-manufacturing structures, two types of structures were produced: a flat plate-shaped structure having a thickness of 2 mm; and a cylindrical structure having an outer diameter of 50 mm, length of 300 mm, and thickness of 2 mm. It should be noted that the flat plate-shaped cast-article-manufacturing structure was used to perform the later-described evaluations on the maximum bending stress, the bending strain at the maximum bending stress, the mass reduction rate, and the average fiber length and average fiber diameter on the structure surface; whereas the cylindrical cast-article-manufacturing structure was used to perform the later-described evaluations on the handleability of the structure, casting, and surface properties of the cast article's surface after casting.

[0207] The amount of water added was 50 parts by mass to 100 parts by mass of the mixture. The heating temperature and heating time of the structure precursor were 140 C. for 10 minutes, and the pressure in the shaping step was 5 MPa.

[0208] In the Table, Total of Organic Components refers to the contents of the organic components in the cast-article-manufacturing structure. In this Example, the structures were not subjected to treatment such as coating, and thus had no surface layer.

Example 2

[0209] As the organic fiber, a fiber including aramid resin (Kevlar (registered trademark) Cut Fiber from Toray Industries, Inc.; aramid resin: 100 mass %) was used instead of mechanical pulp, and no inorganic fiber was used. Other than the above, the materials were mixed according to the proportions shown s in Table 1 below, and a cast-article-manufacturing structure was manufactured in the same manner as in Example 1.

Example 3

[0210] As the organic fiber, waste newspaper pulp, obtained by taking out pulp fiber from waste newspaper by beating in water, was used instead of mechanical pulp. Other than the above, the materials were mixed according to the proportions shown in Table 1 below, and a cast-article-manufacturing structure was manufactured in the same manner as in Example 1.

Example 4

[0211] As for the organic components, mechanical pulp as organic fiber and a thermosetting resin (phenolic resin; resol) were used. Obsidian (Nice Catch Flour #330 (polyhedric) from Kinsei Matec Co., Ltd.) having an average particle size of 27 m was used as first inorganic particles. Obsidian contained aluminum oxide, silicon dioxide, and iron oxide.

[0212] In addition, PAN-based carbon fiber (PYROFIL TR03 CM A4G from Mitsubishi Chemical Corporation) was used as inorganic fiber.

[0213] Other than the above, the materials were mixed according to the proportions shown in Table 1 below, and a cast-article-manufacturing structure was manufactured in the same manner as in Example 1.

Example 5

[0214] As the organic fiber, a fiber including polyester resin (fiber diameter: 11 m; fiber length: 5 mm; polyester resin: 100 mass %) was used instead of mechanical pulp, and no inorganic fiber was used. Other than the above, the materials were mixed according to the proportions shown in Table 1 below, and a cast-article-manufacturing structure was manufactured in the same manner as in Example 1.

Example 6

[0215] As the organic fiber, a fiber including polyester resin (fiber diameter: 11 m; fiber length: 5 mm; polyester resin: 100 mass %) was used instead of mechanical pulp. Other than the above, the materials were mixed according to the proportions shown in Table 1 below, and a cast-article-manufacturing structure was manufactured in the same manner as in Example 1.

Comparative Example 1

[0216] No organic fiber was used as the organic component. Other than the above, the materials were mixed according to the proportions shown in Table 1 below, and a cast-article-manufacturing structure was manufactured in the same manner as in Example 1.

Comparative Example 2

[0217] As the organic component, only waste newspaper pulp was used, instead of the combination of mechanical pulp and waste newspaper pulp. Other than the above, the materials were mixed according to the proportions shown in Table 1 below, and a cast-article-manufacturing structure was manufactured in the same manner as in Example 1.

Evaluation of Maximum Bending Stress and Bending Strain at Maximum Bending Stress:

[0218] For each cast-article-manufacturing structure of the respective Examples and Comparative Examples, a plate-shaped measurement sample was obtained according to the aforementioned method. The maximum bending stress (MPa) and the bending strain (%) at the maximum bending stress of each sample were measured in conformity with the three-point bending test of JIS K7017. The maximum bending stress and the bending strain are indices of the toughness of the cast-article-manufacturing structure; the higher the values of the maximum bending stress and the bending strain, the higher the toughness of the structure and the better the handleability of the structure. The results are shown in Table 1.

Evaluation of Mass Reduction Rate:

[0219] The mass reduction rate in each cast-article-manufacturing structure of the respective Examples and Comparative Examples was evaluated using a thermogravimetric instrument (STA7200RV TG/DTA from Seiko Instruments Inc.). Each cast-article-manufacturing structure of the respective Examples and Comparative Examples was heated under nitrogen atmosphere from 30 C. to 1000 C. at a temperature-rise rate of 20 C./minute, and the changes in mass were measured as a function of temperature. The mass reduction rate (%) was calculated, with reference to the mass at 30 C. The results are shown in Table 1.

Evaluation of Average Fiber Length and Average Fiber Diameter on Structure Surface:

[0220] The average fiber length and the average fiber diameter of the organic fibers present on the surface of each cast-article-manufacturing structure of the respective Examples and Comparative Examples were evaluated according to the aforementioned method. The results are shown in Table 1.

Evaluation of Number of Fibers on Structure Surface:

[0221] The number of organic fibers it on the surface of each cast-article-manufacturing structure of the respective Examples and Comparative Examples was evaluated according to the aforementioned method. The results are shown in Table 1.

Evaluation of Handleability of Structure:

[0222] The handleability of each cast-article-manufacturing structure of the respective

[0223] Examples and Comparative Examples was evaluated according to the following method. Specifically, using a hand-held saw with rip teeth having a blade thickness of 1 mm, the structure was cut at a position 50 mm away from the structure's end face, and the length (mm) of the affected range, in which crazing, chipping, etc., occurred at the time of cutting, was measured from the cut end face. A shorter affected-range length indicates better handleability of the structure. The results are shown in Table 1 below.

Evaluation of Casting (Blowback Height):

[0224] Each cast-article-manufacturing structure of the respective Examples and Comparative Examples was used as a casting mold, and 25 kg of molten metal at 1 350 C. and including cast iron was poured into the casting mold in 20 seconds, to manufacture a cast article. At this time, the blowback height (mm) of molten metal from the end face of the pouring gate, through which the molten metal was poured, was measured. A lower blowback height indicates that gas produced from the cast-article-manufacturing structure when pouring the molten metal can be suppressed, which means that gas defects in cast articles can be reduced and the safety during casting operation is improved. The results are shown in Table 1 below.

Evaluation of Surface Properties on Cast Article's Surface:

[0225] Each cast-article-manufacturing structure of the respective Examples and Comparative Examples was used as a casting mold, and molten metal at 1 350 C. and including cast iron was poured into the casting mold, to manufacture a cast article. The area percentage of burn-on portions formed at this time was calculated, to evaluate the surface properties of the cast article's surface.

[0226] Specifically, on the cast article's surface in an area where the obtained cast article was in contact with the cast-article-manufacturing structure, portions where the poured molten metal has adhered by destroying the cast-article-manufacturing structure, as well as portions where sand inclusion originating from casting sand has adhered, were identified as burn-on portions, and the presence/absence of such burn-on portions and the regions thereof were determined by visual observation.

[0227] Next, for each region of burn-on portions determined according to the above method, a sheet material having a constant basis weight was cut so as to conform to the shape of each burn-on portion, and the sum total of the mass of the pieces cut out from the sheet material was divided by the basis weight of the sheet material, to calculate the area of the burn-on portions.

[0228] The cast article's surface area was found using a sheet material having a constant basis weight and covering the cast article's surface therewith such that the sheet material did not overlap, and the mass of the sheet material used for covering was divided by the basis weight of the sheet material, to calculate the cast article's surface area.

[0229] The area percentage of the burn-on portions was found by calculating the percentage (%) of the area of the burn-on portions with respect to the cast article's surface area.

[0230] A lower area percentage of the burn-on portions means that burn-on of the structure onto the cast article's surface can be reduced, thereby obtaining a cast article having excellent dimensional precision and surface smoothness. The results are shown in Table 1 below.

TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 Organic Organic fiber Pulp fiber [mass %] 0.5 5.0 0.5 components Fiber including aramid resin 3.0 [mass %] Fiber including polyester resin 3.0 [mass %] Average fiber length L1 [ m] 1.6 1.5 2.0 1.8 1.1 Average fiber diameter D [m] 30 13 30 30 11 Ratio: 1000 L1 [ ]/D [m] 53.3 115.4 66.7 60.0 100.0 Thermosetting resin Phenolic resin [mass %] 9.0 9.0 9.0 9.0 9.0 Total of organic components [mass %] 9.5 12.0 14.0 9.5 12.0 Inorganic First inorganic Mullite [mass %] 72.5 73.0 68.0 73.0 components particle Obsidian [mass %] 72.5 Shape Spherical Spherical Spherical Polyhedric Spherical Melting point [ C.] 1850 1850 1850 1340 1850 Second inorganic M onite [mass %] 15.0 15.0 15.0 15.0 15.0 particle Shape Layered Layered Layered Layered Layered Inorganic fiber Carbon fiber [mass %] 3.0 3.0 3.0 Average fiber length [mm] 1.5 2.0 1.3 Average fiber diameter [m] 7 7 7 Total of inorganic components [mass %] 90.5 88.0 86.0 90.5 85 Total of components [mass %] 100 100 100 100 100 Mass reduction amount [%] 5.78 8.01 9.69 6.53 8.57 Number of organic fibers present per 100 mm.sup.2 on surface of structure 2 100 or more 100 or more 100 or more 100 or more [pieces] JIS K7017: Maximum bending stress [MPa] 16.11 11.79 9.23 14.45 12.83 Three-point bending test Bending strain [%] at maximum 1.15 1.6 1.24 1.03 1.75 bending stress Evaluation of handicability of structure (affected-range length [mm]) 0.3 0.2 0.5 0.4 0.2 Evaluation of casting (blowback height [mm]) 100 90 120 110 100 Evaluation of surface properties on cast article's surface (area 1 1 2 2 1 percentage of burn-on portions [%]) Comparative Comparative Example 6 Example 1 Example 2 Organic Organic fiber Pulp fiber [mass %] 26.0 components Fiber including aramid resin [mass %] Fiber including polyester resin 2.0 [mass %] Average fiber length L1 [ m] 1.2 2.0 Average fiber diameter D [m] 11 30 Ratio: 1000 L1 [ ]/D [m] 109.1 66.7 Thermosetting resin Phenolic resin [mass %] 5.0 9.0 18.0 Total of organic components [mass %] 7.0 9.0 44.0 Inorganic First inorganic Mullite [mass %] 75.0 73.0 components particle Obsidian [mass %] 48.0 Shape Spherical Spherical Polyhedric Melting point [ C.] 1850 1850 1340 Second inorganic M onite [mass %] 15.0 15.0 particle Shape Layered Layerext Inorganic fiber Carbon fiber [mass %] 3.0 3.0 8.0 Average fiber length [mm] 1.3 1.3 2.0 Average fiber diameter [m] 7 7 7 Total of inorganic components [mass %] 93.0 93.0 56.0 Total of components [mass %] 100.0 100 100 Mass reduction amount [%] 5.32 5.54 29.37 Number of organic fibers present per 100 mm.sup.2 on surface of structure 100 or more 100 or more [pieces] IS K7017: Maximum bending stress [MPa] 18.20 21.30 11.92 Three-point bending test Bending strain [%] at maximum 0.68 0.55 1.11 bending stress Evaluation of handicability of structure (affected-range length [mm]) 0.0 0 0.2 Evaluation of casting (blowback height [mm]) 70 110 730 Evaluation of surface properties on cast article's surface (area 1 1 5 percentage of burn-on portions [%]) indicates data missing or illegible when filed

[0231] As shown in Table 1, the cast-article-manufacturing structures of the Examples include predetermined amounts of organic components including organic fiber; thus, the maximum bending stress and the bending strain are equal to or higher than predetermined values, showing that the structures have improved toughness, and due thereto, the structures' handleability is improved, compared to the Comparative Examples. Further, since the cast-article-manufacturing structures of the Examples include predetermined amounts of organic components including organic fiber, the mass reduction rate of the structures is equal to or below a predetermined value, showing that gas defects in the obtained cast articles can be reduced efficiently. Furthermore, the area percentage of burn-on portions in the cast-article-manufacturing structures of the Examples is equivalent to or less than that of the Comparative Examples, which shows that burn-on of the structure onto the cast article's surface is reduced effectively, and cast articles having excellent dimensional precision and surface smoothness can be obtained.

[0232] Therefore, the cast-article-manufacturing structure of the present invention has excellent handleability and can reduce gas defects in the obtained cast articles and burn-on on the cast article's surface.

[0233] Particularly, the cast-article-manufacturing structures of Examples 1, 3 and 4, which contain inorganic fiber together with a small amount of organic fiber, are capable of improving bending stress while suppressing the amount of gas production.

[0234] Further, the cast-article-manufacturing structure of Example 5 is capable of significantly suppressing the cost of manufacturing the structure while sufficiently satisfying the bending properties with organic fiber only.

INDUSTRIAL APPLICABILITY

[0235] The present invention can provide a cast-article-manufacturing structure that has excellent handleability and with which it is possible to reduce gas defects in cast articles and burn-on on the cast article's surface.