JPH037629B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention applies to machines having toughness and rigidity, such as internal combustion engines such as gasoline engines, diesel engines, and gas turbines, as well as rotating shafts, coupling mechanisms, connecting rods, cams, blades, and sliding members of compressors, precision machine tools, etc. It relates to a composite structure whose parts are made of ceramic and metal. In recent years, with the aim of improving fuel efficiency, reducing weight, improving durability, and conserving resources, we have been developing combustion chamber parts for diesel and gasoline engines, rotor blades for gas turbines, exhaust rotor blades for turbochargers, internal combustion engines, and compressors. Machine parts that require toughness and rigidity, such as cams, camshafts, connecting rods, crankshafts, sliding members, and rotating shafts of precision machine tools, are manufactured using wear-resistant and impact-resistant materials such as silicon nitride, silicon carbide, and zirconia. If you simply replace it with a ceramic material that has excellent properties, ceramic will bend, have lower tensile strength than metal, and lack toughness and rigidity, so it will easily break when subjected to strong impact or torsional strength, making it impractical There were some shortcomings. The present invention aims to solve this problem. That is, the composite structure used in the mechanical component of the present invention includes a rod-shaped, plate-shaped, or tubular reinforcing member made of a high-melting point metal and having a larger coefficient of thermal expansion and/or Young's modulus than the ceramic base material, in a ceramic base material. By arranging them concentrically and burying them by simultaneous sintering, compressive stress is applied to the ceramic to obtain a composite structure with high toughness and rigidity. As described above, the present invention is characterized in that a metal having a higher coefficient of thermal expansion than ceramic and having a high melting point is disposed within an unfired ceramic base material and buried by simultaneous sintering, or a metal having a Young's modulus higher than that of ceramic material and having a high Melting point metals are similarly sintered to embed them, or metal reinforcing members having both of the above properties are embedded by sintering at the same time, and compressive stress is applied to the ceramic through simultaneous sintering. Add. As a result, the ceramic is not subjected to any external force until the stress becomes zero, so that the strength against the external force is improved by that much, and the fracture strength of the ceramic can be improved. Ceramic base materials applied to the present invention generally include silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), silicon carbide (SiC), zirconia (ZrO ₂ ), and alumina (Al ₂ ), which have relatively high impact resistance. It is a sintered body such as O ₃ ), SiAlON (Si-Al-ON), and has the characteristics shown in Table 1. These ceramics are sintered by conventional methods such as reaction, normal pressure, and hot pressing, and are shaped by appropriately selecting the sintering method and reinforcing member in order to apply effective compressive stress. Next, the reinforcing member is made of a material with a high melting point that does not cause abnormalities at the sintering temperature of the ceramic mentioned above, and is made of a single metal such as tungsten, molybdenum, or tantalum, or a W-Mo alloy (5 to 50% W) or a Ta-W alloy (1 ~10%W)W-
Ir alloy (1~30% Ir), W-Cu-Ni alloy (1~5%
%Cu, 15%Ni (W) and other alloys are useful. A preferred combination of the ceramic base material and reinforcing member is as follows. (1) Si ₃ N ₄ (reactive, normal pressure, hot press) and all the metal materials listed above can be used, and compressive stress can be applied depending on at least one of the characteristics of thermal expansion coefficient and Young's modulus. (2) AlN (normal pressure hot press) and Mo, Ta, Ta-
W material can be used, and compressive stress is added due to the difference in thermal expansion coefficient. (3) SiC (reaction, normal pressure, hot press) and Mo,
Ta and Ta-W materials can be used, and compressive stress is added due to the difference in thermal expansion coefficient. (4) ZrO ₂ (normal pressure), W, and Mo materials can be used, and compressive stress is added by Young's modulus. (5) Al ₂ O ₃ (normal pressure), W, and Mo materials can be used, and compressive stress is added by Young's modulus. etc. are preferable.

【table】

[Table] The present invention will be described below based on embodiments shown in the drawings. FIG. 1 shows an embodiment of the present invention applied to mechanical parts such as a rotating shaft, a camshaft, and a connecting rod.
2 is a rod-shaped ceramic base material, and 2 is a reinforcing member buried concentrically inside the base material. Further, FIG. 2 shows an embodiment in which a plurality of reinforcing members 2 are embedded. Next, a suitable manufacturing method will be described. For example, in the case of embedding a W wire in a sintered body mainly composed of Si ₃ N ₄ , Japanese Patent Laid-Open No. 104972/1983 and Japanese Patent Laid-open No. 55-1982 by the same applicant. Publication No. 109275, Japanese Unexamined Patent Publication No. 54-34311
The one disclosed in the publication is used. The composition of silicon nitride includes approximately 65% by weight or more of Si ₃ N ₄ , ZrO ₂ , Ta ₂ O ₅ , Al ₂ O ₃ and MgO, CaO,
The remaining amount is a sintering aid consisting of one or more types of alkaline earth metal compounds such as BaO and SrO, for example.
90% by weight of 1μ Si ₃ N ₄ powder, 5% by weight of 2μ ZrO ₂ powder, and 5% by weight of 0.5μ MgO powder (hereinafter commercially available) were mixed, and an organic binder (such as methyl cellulose) was added by a conventional method. The raw material powder prepared by
Rubber press molding is performed at a predetermined pressure, and the molded body is heated to 500°C in an _N2 atmosphere to remove the organic binder, and then sintered at 1700°C for 60 minutes in a _N2 atmosphere at 1 atm. . Alternatively, the above-mentioned Si ₃ N ₄ raw material powder is made into a slurry, and after holding a reinforcing member at a predetermined position in a mold, the slurry is cast-molded and similarly sintered by a conventional method. Furthermore, those having a relatively simple shape are sintered by hot pressing. Note that the ceramic material is not limited to this example.
The combination of the ceramic material and reinforcing member described above is selected depending on the specifications of the mechanical parts to which it is applied. FIG. 3 shows an example of a mechanical part applied to a cam, a sliding member, etc., in which a tubular reinforcing member 12 is embedded in a cylindrical ceramic base material 11 having an inner hole 13 by simultaneous sintering. It is something. For example, when embedding a reinforcing member in a sintered body mainly composed of silicon carbide, the SiC sintered body may be used in Japanese Patent Application Laid-open No. 50-7860, Japanese Patent Laid-Open No. 1110499, filed by the same applicant, Those disclosed in JP-A-53-121810 and the like can be used. For example, 0.3 to SiC powder
A silicon carbide sintered body formed by mixing and molding 3.0 parts by weight of boron or a boron compound equivalent to boron and 0.1 to 6.0 parts by weight of carbon or a carbonaceous compound equivalent to carbon and sintering it to 80% or more of the theoretical density. . in particular,
α-SiC powder with an average particle size of 0.3 μ or less and 0.5% by weight of B ₄ C powder are dispersed in an acetone solution containing 6% by weight of phenolic resin based on the SiC powder and wet mixed. A predetermined amount of dried and prepared SiC raw material powder is filled into a mold and pressed in advance, a Mo wire is placed on top of it, and a predetermined amount of SiC raw material powder is placed on top of the SiC raw material powder, which is further filled with a predetermined amount, then press-molded into a predetermined shape, and heated at 800℃ in a vacuum. Calcinate to obtain a calcined compact. This calcined body is sintered at 1800 to 2100°C for 60 minutes in an Ar atmosphere to produce a silicon carbide sintered body with a reinforcing member embedded therein. FIG. 4 shows an embodiment of the present invention applied to rotor blades of gas turbines, turbochargers, etc. 21 is a blade made of, for example, a silicon nitride sintered body, 22 is a reinforcing member made of, for example, a Ta-W alloy material embedded therein by simultaneous sintering, 23 is a rotor, and 24 is a hub. Although the rotor is not shown, it is possible to use a rotor in which a reinforcing member is similarly embedded inside the rotor based on the embodiment shown in FIG. Now, a slurry of Si ₃ N ₄ raw powder was prepared by placing a plurality of Ta-W alloy wires in a mold and casting the slurry.
Similarly, a blade is manufactured by sintering in an N ₂ atmosphere using a conventional method. Although examples of the present invention applied to main mechanical parts have been given above, the present invention is not limited to these examples only, and the composite structure of the present invention can be applied to mechanical parts that require toughness and rigidity. The body can be applied effectively. As described above, the composite structure of the present invention has a reinforcing member made of a metal having a higher thermal expansion coefficient and/or Young's modulus than the ceramic and having a higher melting point embedded in the ceramic base material by simultaneous sintering. By effectively applying compressive stress to ceramics, it is possible to create composite structures with high toughness and high rigidity, which can be applied to mechanical parts that require these characteristics to greatly improve their durability. can improve sexual performance.

[Brief explanation of the drawing]

Fig. 1 shows a first embodiment of the present invention, Fig. 1a is a longitudinal cross-sectional view of the rotating shaft, and Fig. 1b is the A-
The sectional view taken along section A, FIG. 2, is the same sectional view as FIG. 1b, and shows a second embodiment of the present invention. Fig. 3 shows a third embodiment of the present invention, Fig. 3a is a longitudinal sectional view of the sliding member, Fig. 3b is a sectional view taken along line B-B, and Fig. 4 is a sectional view of the sliding member. FIG. 4a is a front view of the rotor blade, and FIG. 4b is a perspective view of the main part thereof.

Claims (1)

[Claims] 1 A rod-shaped, plate-shaped, or tubular reinforcing member made of a high-melting point metal and having a larger coefficient of thermal expansion and/or Young's modulus than the ceramic base material is arranged concentrically within the ceramic base material, A composite structure used for mechanical parts that is simultaneously buried by sintering.