JPS59224445A - Piston - Google Patents

Abstract

PURPOSE:To join ceramic and metal by chemical reaction so as to strengthen the construction of junction therebetween, by fitting a metalized ceramic molded structure, whose outside part is coated to be brazed by a cast iron ring, cap, etc., to be mounted on a top surface of the crown part of a piston. CONSTITUTION:A ceramic molded structure 1a is fitted into the crown part of a piston and metalized in a ring shape. This structure provides the brazed part of a ceramic surface in the piston, forming a metalized part 1-m on the bottom surface of said structure. The ceramic molded structure 1a, on the bottom surface of which copper-copper molybdenum or the like is provided as a damping layer, is fitted onto an upper surface of the crown part 3 of a cast iron piston main unit 2a to be brazed and integrally formed with the cast iron piston main unit 2a by silver-copper eutectic crystal brazing. In this way, the construction of junction can be strengthened because ceramics and metal are joined by utilizing chemical reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ceramic-metal composite piston.

Pistons, which are the main components of internal combustion engines, are exposed to high temperatures and pressures and have strict requirements for heat resistance, but in order to reduce weight in small engines, pistons made of aluminum alloy instead of regular cast iron have been created. However, problems remained because the thermal properties such as heat resistance and heat insulation were inferior.

By the way, pistons using senmic materials have recently been considered, and by utilizing the heat shielding effect based on the low thermal conductivity of ceramic materials, it is possible to reduce heat loss during internal combustion engine operation, improve output, and use hydrocarbons. Although pistons can be expected to have various desirable performances such as reduced concentration and reduced fuel consumption, pistons made using the ceramic shrink-fit casting method that has been considered up to now tend to degrade when used for long periods of time in heating and cooling cycles. There is a risk that this may cause deformation or cracking, and a practical product has not yet been realized.

The present invention was made in view of this situation, and instead of bonding ceramic and metal through physical contact such as casting or shrink fitting as described above, it combines ceramic and metal using a chemical reaction. The present invention provides a piston for an internal combustion engine that has an extremely strong joint structure by joining the pistons together.

Next, the piston of the present invention will be explained with reference to the drawings.

FIG. 1 shows a ring-shaped metallized ceramic molded body 1a that is fitted into a clawan part of a piston.

The metallization forms a portion of the ceramic surface to be soldered in a piston, which will be described later, and here a metallization portion 1-m is provided on the lower surface. FIG. 2 shows that the metallized ceramic molded body 1a shown in FIG. 1 is fitted onto the upper surface of the crown portion 3 of the cast iron piston body 2a.
A buffer layer 4 of copper, copper-molybdenum, copper clad material, copper-invar copper clad material, iron/nickel 42 alloy, or conogly plate is placed on the lower surface of the ceramic molded body 1a. Cast iron piston body 2a
This is a piston that is integrated by soldering with silver-copper eutectic solder. Note that the brazed surface of the ceramic molded body 1a is a metalized surface, but it is omitted in FIG. Instead, it shows a metallized irregularly shaped ceramic molded body 1b with a cavity in the center of the upper part, and metallization i-m is formed in the range shown by the imaginary line on the outside corresponding to the brazed part when fitted to the piston. It is intended to provide

Figures 4, 5, 6, 7, 8, and 9 show the metallized irregularly shaped ceramic molded body 1b shown in Figure 3 being fitted onto the top surface of the crown portion of the piston body. The figure shows an example of a piston.

However, all metallized parts are omitted without being explicitly stated, but since they are soldered, they will be easily understood.

FIG. 4 shows a buffer layer such as a cylindrical copper plate having a length equal to the depth of the crown portion of the piston into which the irregularly shaped ceramic molded body 1b is fitted, on the outer cylindrical side surface of the irregularly shaped ceramic molded body 1b whose side surface is metallized. 4, and the metallized surface of the irregularly shaped ceramic molded body 1b existing inside and outside the molded body 1b and the cast iron body 2a of the piston are integrated by soldering 5 with a silver-copper eutectic brazing agent.

Fig. 5 shows an irregularly shaped ceramic molded body 1b whose entire outer surface is metallized, a buffer layer 4 made of a copper plate or the like having a matching shape is provided on the outer side, and the buffer layer 4 is fitted onto the top surface of the crown portion of the piston. 4 is integrated with the metallized surface of the irregularly shaped ceramic molded body 1b and the cast iron body 2a by soldering 5 using a silver-copper eutectic brazing agent.

Fig. 6 shows that a buffer layer 4 such as a copper plate is provided on the cylindrical outer surface of the irregularly shaped ceramic molded body 1b whose cylindrical side surface is metallized, and the inside thereof is covered with the metallized surface of the irregular shaped ceramic molded body 1b, and the outer side is further covered with a buffer layer 4. The cast iron ring 6 to be provided is soldered using a silver-copper eutectic brazing agent, and the surface of the cast iron ring 6 is subjected to arun-in treatment 7, and then the aluminum alloy 2b-Q casting that constitutes the piston body is applied. It is made up of a whole, and each layer is chemically bonded and integrated by waxing agent and alphine treatment.

FIG. 7 shows that a buffer layer 4 such as a copper-molybdenum-copper plate is provided adjacent to the metallized portion of the irregular shaped ceramic molded body 1b whose side and bottom surfaces are metallized, and the outside (Il
A U-shaped cast iron cap 6 is installed on each Jffi.
They are integrated by soldering 5 between them using silver-copper eutectic solder. Next, the outer surface of the cast iron cap 6 is subjected to Alfin treatment 7,
This shows an aluminum piston in which an aluminum alloy constituting the piston body 2b is cast around the outside of the piston body, and the two are firmly bonded chemically.

FIG. 8 shows that a buffer layer 4 made of copper or Kovar plate or the like is provided on the cylindrical side surface of an irregularly shaped ceramic molded body 1b whose side surface is metallized, the depth being equal to the groove of the crown portion into which the ceramic molded body is fitted. The inside of f: is the ceramic molded body 1b
The metallized surface and the outside of the cast iron piston body 2
a and a silver-copper eutectic solder 5 to integrate them.

Fig. 9 is almost the same as Fig. 8 above, but in Fig. 9, a buffer layer 4 such as a copper plate is provided on both the cylindrical side and bottom of the irregularly shaped ceramic, and both sides are soldered 5 with silver-copper eutectic solder. It is an integrated system.

Other parts that are the same as those in Area 8 are given the same numbers.

As described above, the present invention integrates a ceramic molded body onto the top surface of the crown portion of a piston by soldering by utilizing the metal film (metallization) strongly formed on the ceramic surface. If necessary, provide an easy-to-solder buffer layer such as copper or copper alloy, copper-based cladding material, iron/nickel 42 alloy, or metal plate, and solder it through this buffer layer. To provide a piston that realizes an integral connection, and furthermore, in the case of an aluminum alloy piston, a cast iron ring or a cast iron cap is provided on the outside of the ceramic molded body, the inner surface of which is soldered with a silver-copper eutectic solder, and the outer surface of the piston is soldered with a silver-copper eutectic solder. After being treated with Alfin, an aluminum alloy is cast as the piston body 2b, and the cast iron and the aluminum alloy are bonded using a chemical agent for Alfin treatment, thereby providing an aluminum piston in which each layer is firmly joined.

Then, when we install these pistons in an actual engine and look at the required strength of the ceramic and piston body, we find that:
If the force acting on the ceramic is mainly the inertial force of the vertical movement of the piston, the required strength is 100 kg at 400°C.
/(7) It was also confirmed in the sample of Example 1 that it is good if it is 2 or more.

Next, the most important point of the present invention is the use of a metalized ceramic molded body, and the ceramics used here include silicon nitrogen, Si3N, and silicon carbide, SiO.
, Ittria-stabilized zirconia and other materials with good heat resistance and strength are preferred. As a means of providing a metal layer on the surface, a vapor deposition method or an activated metal method is preferable.
These will be explained in detail below.

A Vapor Deposition Method Example 1 Group A of the periodic table (Ti, Zr.

A first gold ash layer consisting of one or more types selected from Hf) is provided, and gold ash from the iB group of the periodic table (cu, Ag.

A second metal layer made of one or more selected from Au) is provided to form a metal film, and a metallized ceramic molded body is obtained.

Example 2 Group IVA (Ti, Zr, Hf) of the periodic table (7) formed on the surface of a ceramic molded body by physical vapor deposition
Alternatively, a first metal layer made of one or more metals selected from the VIA group (Cir, Mo, W) is provided, and a multilayer of the iB group (Cir, Mo, W) is formed thereon by a physical vapor deposition method or a chemical plating method.
A second metal layer made of one or more selected from Cus, Ags, Au) is provided to form a metal film, and a metallized ceramic molded body is obtained.

Example 3 One or more types selected from Group VIA (Cr, Mo, W) or Group IB (Ou, Ag, Au) of the periodic table, formed on the surface of a ceramic molded body by physical vapor deposition. A metal film is formed to obtain a metallized ceramic molded body.

Preferred ceramic materials for the present invention have already been mentioned, including those with excellent heat resistance and thermal shock resistance, but in addition to these materials, aluminum + porcelain, mullite magnetic pieces, zircon porcelain, etc. can be used for the piston head. All ceramics can be applied if they withstand.

Next, the results of comparative tests made by preparing samples of Examples of the present invention and Comparative Examples will be shown.

Example 1 Pressure-sintered silicon nitride with a porosity of 1 and a silicon nitride content of 90% was processed as shown in Fig. 1 to form a ceramic molded body, and 1O-6To was deposited on the bottom surface by vacuum evaporation. In a vacuum of
A cladding material of (Q,,)-Mo(0,4)-Cu(0,3) is interposed as an intermediate layer and inserted into the crown part of the cast iron piston body, and the joint is made using silver and copper eutectic solder in a hydrogen furnace. Braze at 900°C in a pipe 4 as shown in Figure 2. Got a ton.

Example 2 A piston as shown in FIG. 2 was obtained in the same manner as in Example 1 using pressureless sintered silicon carbide having a porosity of 1% and a silicon carbide content of 0.5%.

To measure the strength of the joint, a horseshoe piston was fabricated and its tensile strength was measured.

In addition, in order to examine heat resistance and durability, we conducted a multi-heating-cooling cycle test of 500 cycles and 1,000 cycles of directly heating and cooling the seven-dimensional part of the piston using a commercially available Bunsen burner.
The temperatures at the joints during the cycle were both a maximum of 400°C and a minimum of 300°C.

In the comparative example, a 0.1N shrink-fitted plate was used without metallizing the ceramic, and it was attached to the crown of a cast iron piston and shrink-fitted at 500°C, and the burner test and tensile strength were measured in the same manner as described above.

These results are summarized in Table 1.

Example 3 A deformed ceramic molded body as shown in FIG. 3 was made using pressureless sintered silicon nitride having a porosity of 1% and a silicon nitride content of 90%, and its vertical outer surface was metallized.

For metallization, Ti i,
000 L, Or 1000 K, -0u5μ
A metalized irregular shaped ceramic was produced by sequentially depositing the following. This metallized irregularly shaped ceramic was fitted into the crown of a cast iron piston, a 0.5ηt thick Cu plate was interposed as a buffer layer, and brazed at 90°C in a hydrogen furnace using a silver-copper eutectic solder. A cast iron piston as shown in FIG. 4 was obtained.

In addition, a cast iron piston as shown in Fig. 5 was obtained by using deformed ceramic metallized by vapor deposition on the side and bottom surfaces in the same manner and brazing at 900°C in a hydrogen furnace using silver-copper eutectic solder. Ta.

Furthermore, using steamed metallized deformed ceramic on the side and bottom surfaces, a cast iron ring was brazed at 900'C in a hydrogen furnace with a Kovar plate interposed using a silver-copper eutectic solder, and then cast iron After the surface of the link is alpha-treated, it is cast with aluminum alloy (AOBA) and the sixth
An aluminum piston like the one shown above was obtained.

Example 4 Using ittria-stabilized zirconia with a porosity of 1° and a zirconia content of 90°, in the same manner as in Example 3,
A Z piston was manufactured as shown in FIGS. 4, 5 and 6. The pistons shown in Examples 3 and 4 were subjected to the same joint test as in Example 1, and then the pistons were processed and the joint strength was measured.

In a comparative example, a ceramic molded body made of 81% N4 was cast in an aluminum alloy (AOBA), and the bonding strength was measured after the molded body was cast with an aluminum alloy (AOBA).

These results are shown in Table 2.

Next, a ceramic molded body was obtained which was metallized using silicon nitride in the same manner as in Example 1, and using an Ou plate with a thickness of i rartt as an intermediate barrier layer, it was bonded with a silver-copper eutectic solder, as shown in Fig. 2. A cast iron piston was obtained, and its hot strength was determined at 100℃, 3
Measured at 00°C and 500°C.

According to the test results of each example and comparative example as described above, the piston of each example of the present invention is thermally stable up to 600°C.
It was also found that the conventional low-temperature casting method (luhiston) had superior performance by several orders of magnitude.

Group IV A of the periodic table (Ti, Zr.

Hf), vIA group (Or, Mo, W) metals are used in the first or second layer because they have good reactivity with the ceramic molded body, have good adhesion, and have high bonding strength. This is because the heat resistance after bonding is good.

Moreover, the reason why IB group (Cu, Ag, Au) was selected for the outermost layer is that it has good melting properties with various brazing agents, and good soldering can be obtained. Of course, it is recognized that the adhesion tk of the ceramic y is acceptable even if a gold FA film is formed using the 4i l B group as the first layer.

In the present invention, the physical vapor deposition method refers to an ion beam method, a sputtering method, a resistance heating method, etc., and although the thickness of the vapor deposited film is limited depending on the vapor deposition equipment, preferably I
For group B, it may be several thousand, and for others, it may be several hundred.

B. Activated metal method The activated metal method is an effective alternative to the vapor deposition method, and is achieved by the following method.

(1) T1 or Zr and A on the surface of the ceramic molded body
A method of heating at 800° C. to 1,200° C. in a non-oxidizing atmosphere.

(2) Place Ti foil or Zr foil and at least one wax foil of Ag, Ou (7) on the surface of the ceramic molded body and heat at 800°C to 1.200°C in a non-oxidizing atmosphere.
A method of heating and bonding at ℃.

When a metallized layer is formed on a predetermined surface of a ceramic molded body using such a method, Ti or Zr diffuses into the ceramic and chemically combines with the oxygen atoms and nitrogen atoms in the ceramic to form an integral body. It is possible to maintain one's sexuality.

Example 5 Pressure-sintered silicon nitride with a porosity of 1 and a silicon nitride content of 90 was processed as shown in Figure 3, and the side surface of the ceramic was KM'6kq.
bQT15%, 1g69qb, C! u26%notsa0
．． After installing the 05mu foil, a Cu plate (thickness 0.5yr
rm), then a Ag-Cu eutectic solder was installed between the cast iron pistons, and 10"-' T(+rr
A cast iron piston as shown in FIG. 8 was obtained by heating on a heating table at 1,000° C. for 30 minutes in a vacuum.

Example 6 A cast iron piston was prepared by applying the same vacuum heat bonding to the side and bottom surfaces of similar ceramics using Ti-Ag-Gu foil, Cu plate, and Ag-Cu eutectic solder in exactly the same manner as in Example 5. I got it.

After conducting the same burner test as in Example 1 for these, pistons were processed and their joint strength was measured.

The results are 9 as shown in Table 6.

3 As can be seen from these results, a ceramic molded body with a strong metallized layer can be obtained by the activation area method as well as by the vapor deposition method, so the various effects of the piston using this method are no different from those by the vapor deposition method. .

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing an example of a metallized ceramic molded body used in the present invention, FIG. 2 is a partial vertical cross-sectional view showing an example of the structure of a piston of the present invention using this, and FIG. FIGS. 4 to 9 are vertical cross-sectional views showing other examples of the metallized ceramic molded body used in the present invention, and partial vertical cross-sectional views showing structural examples of the piston of the present invention using the same. . 1a: Metallized ring-shaped ceramic molded body 1b: Metallized irregular-shaped ceramic molded body 1-m:
Metallized part 2a: Cast iron piston body 2b Nialuminum alloy piston body 3: Crown part 4: Buffer layer 5: Brazing 6: V3 iron ring, cast iron cap 7: Alfin processing agent Patent attorney Mamoru Takeuchi 26

Claims (1)

[Scope of Claims] (1) Cast iron or aluminum, characterized in that a metallized ceramic molded body is fitted onto the upper surface of the crown portion of the piston and integrated with the piston body by brazing directly or indirectly. Piston (2) A metallized ceramic molded body is covered with a cast iron ring or a cast iron cap on a part or all of its outer side and soldered to it, and an aluminum alloy forming the piston body is integrated into this by being cast. Aluminum piston (3) A metallized ceramic molded body is fitted onto the top surface of the crown part of the piston, a metal buffer layer is provided between it and the piston body, and both sides of the metallized ceramic body are soldered to 19. Cast iron or aluminum piston characterized by being integrated (4) The metal used for the buffer layer is copper, copper-molybdenum-copper clad material, copper-invar copper clad material, iron/nickel 42 alloy or Kovar. Cast iron or aluminum piston (5) according to claim 3, which is a plate; Claim 1, 2 or 3, wherein the ceramic metallization is applied by vapor deposition or activated metal ash. Piston (6) as described in Section 6: The ceramic is yttoria-stabilized zirconia,
Claims 1 and 2 are silicon nitride and silicon carbide.
Piston (7) according to claim 1 or 3, wherein the brazing agent is a silver-copper eutectic solder Piston (8) according to claim 1, 2, or 3 Bonding strength by brazing is 11001 (/c) at 400℃
The piston according to claim 1, 2 or 3, which has an IR of 2 or more.