JPS6024941A - Heat-insulating laminated part - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-insulating laminate component having a mechanically and thermally strong ceramic coating and having a heat-insulating interfacial layer interposed therebetween.

Conventionally, gasoline engines, diesel engines, etc. have been constructed of metal members such as cast iron and aluminum alloy. However, recently, from the perspective of energy conservation, research has been actively conducted to reduce the large heat loss caused by engine exhaust and cooling, and to increase the thermal efficiency of engines. Many methods have been proposed using ceramics alone or composite structures made of ceramics and metals laminated.

However, in either case, ceramics used alone or used for ceramic-metal shrink fitting, bolting, caulking, etc., are made into high-strength components, so the preparation of the starting raw materials, molding and sintering conditions, and sintering Extremely advanced and precise manufacturing techniques are required, including finishing the body. This results in a significant increase in cost, and it is necessary to make the layer of the ceramic member considerably thicker in order to further improve the heat insulation effect. Generally, due to the large difference in coefficient of thermal expansion between ceramics and metal components, cracks and peeling may occur due to gaps between the combined metal components, rattling, and thermal strain under product temperature conditions. It is easy to use, and therefore has poor reliability, and there are still many problems in practical application.

The present invention solves these conventional problems,
The purpose of the present invention is to provide a highly reliable heat-insulating laminate component using a relatively simple manufacturing process without requiring sophisticated manufacturing technology.

The present invention will be explained in detail below with reference to the drawings.

As shown in the figure, the present invention provides a metal porous body (also F: r,
A heat insulating interface layer 3 made of ceramic is interposed, and the mutually overlapping surfaces are fixed with a fused layer by metal soldering or a chemical bonding layer 4 of chromium oxide produced by firing chromic acid, and the outer side of the metal member 2 is A ceramic coating 5 chemically bonded with thermally sprayed ceramics and/or chromium oxide is applied to the surface. In this way, an effective heat insulating effect can be obtained by the relatively porous heat insulating interface layer 3 and the ceramic coating layer 5, and in addition, the heat resistance of the surface of the metal member 2 can be improved.
The wear-resistant ceramic coating layer 5 is a relatively thin coating and has a two-stage structure with the interface layer 3, which can greatly alleviate thermal shock and temperature gradients. The metal used for this purpose may be an iron-based alloy or an aluminum-based alloy, such as cast iron, carbon steel, or aluminum alloy casting.

Further, the metal member 2 coated with the ceramic 5 is made of iron or an iron-based alloy, and can be made of, for example, cast iron, carbon steel, stainless steel, heat-resistant steel, or the like.

Next, the ceramic 5 coated on the outer surface of the metal member 2 made of the iron-based alloy is a thermal sprayed ceramic and/or a ceramic chemically bonded with chromium oxide, such as stabilized and partially stabilized ZrO2, CaZrOa.
, 8rZr03, MgZrO3, Y2Zr20y, etc., by plasma spraying. Ceramic coatings chemically bonded with chromium oxide can also be coated with various heat-resistant oxides, such as ZrO.
2,8102, A11.03, 'rioz, CaZrO
3. 5 to 20 parts by weight of fine powder of one or more oxides selected from oxides such as MgZrO3 with a specific gravity of 1.5 to 1
．． In addition to 100 parts by weight of an aqueous solution of 70H20r04, a slurry that was thoroughly mixed using a ball mill was added to the metal member 2.
A ceramic coating chemically bonded to chromium oxide is applied to one side of the coating and heat-treated at 450 to 650°C.This coating and heat treatment are repeated to reduce the thickness of the coating. Since the plasma sprayed layer is essentially porous, the plasma sprayed coating can be coated with the slurry containing HaCrOt and heat treated to reduce porosity and strengthen the coating. A more favorable coating can be obtained.

That is, an aqueous solution of E2Cr04 with a specific gravity of 1.6 to 1 nia or MgO or C
A small amount of heat-resistant oxide, such as stabilized ZrO2, TlO2, 5102, is added to a solution in which 0.1 to 0.4 mole of ttO is added or dissolved, or to an aqueous solution of H2CrOt with a specific gravity of 1.6 to 1.7.
, Al2os, CaZrO3, etc., a small amount of fine powder of one or more oxides, preferably 5 to 12
% by weight, mix well to prepare a slurry, and impregnate the pores of the thermal sprayed ceramic with this slurry.
Heat treatment is performed at 0 to 650°C, and this treatment is repeated several times to eliminate open pores in the coating layer.
And the film is strengthened. The thickness of the ceramic 5 coated on the metal member 2 is set to 50 to 250 μm in consideration of the thermal shock caused by the thermal energy of combustion gas, the thermal conductivity and thermal expansion characteristics of the ceramic, and based on experimental results.
Preferably it is about 130 μm.

Next, one of the members used for the heat insulating interface layer 3 is a metal porous body, such as a metal fiber sintered body, a metal mesh laminated sintered body, a metal powder sintered body, etc. These metal porous bodies are stainless steel fiber sintered bodies having an average pore diameter of 10 to 100 μm, a porosity of 40 to 75, preferably a maximum pore diameter of ω μm, and a porosity of about 50,
The strength of the sintered body is increased, and the metal surfaces 1 on both sides of the interface layer 3.
In terms of increasing the bonding strength with 3, it is best to use stainless steel fibers with reinforcing steel sintered on both sides.

Further, when the member used for the interface layer 3 is ceramic, for example, stabilized or partially stabilized ZrO2,0n (
For 100 parts by weight of fine powder of one or more oxides selected from Sr, Mg) Zr03, Y2 Z r20, etc.
The powder is formed by mixing one quantity of ZrC fine powder, and is made of ceramic which is well sintered at 1500°C or higher and has an apparent porosity of 10-20cm.Preferably, this sintered body is molded in the same manner as above. Add fine powder of oxide) to a concentrated aqueous solution of 12C'r04, and use the prepared slurry to impregnate the pores of the ceramic and heat treat it. Repeat this process 4 to 5 times to reduce the heat insulation properties. A high-strength ceramic interface layer is formed without any damage.

Furthermore, the metal used for the interface layer consisting of a metal-ceramic composite structure is a metal porous body, such as a stainless steel mesh laminate, a fiber sintered body, a stainless steel fiber felt, and the like. A material with a relatively large pore diameter and a bulk density of 40 to 70% is used. Ceramic raw materials may also contain refractory oxides, such as stabilized or partially stabilized Z
Add to 100 parts by weight of an aqueous solution of H2CrO with a specific gravity of 1.45 to 1.6 U) and add to 100 parts by weight of a powder of 1'm or more and 44 μm or less selected from R0g, Ca (Sr, Mg) Zr01, etc. A slurry is prepared by thoroughly mixing using a ball mill, and the slurry is impregnated and filled into the pores of the metal porous body, and after drying, heat treatment is performed at 450 to 650°C. By repeating this impregnation and heat treatment 6 to 8 times, an interfacial layer consisting of a strong heat-insulating composite structure is formed.

Next, the combination, combination, and bonding of each layer of the laminated structure component of the present invention will be explained in more detail with reference to examples.

Example 1 When the constituent material is a metal member made of carbon steel coated with ceramic spraying, the interface layer is a stainless steel fiber sintered body, and the metal base is an aluminum alloy casting, first, carbon steel 545C (JIS) is used.沁×(fund)×
A 2.5-piece specimen was prepared, both sides of which were roughened by 250 μm sandblasting, and 0.2 m of ZrO2 stabilized with 6 layers of CaO and 10 layers of UGO was placed on one side.
A ceramic coating is formed by Glazma spraying to a thickness of '
is.

Separately, as above, IIC C! 3 parts by weight of ZrOs+ powder of 1011 m or less stabilized by ao-+MgO and 3 parts of 8102 powder of 5 μm or less were added to 12
00 parts by weight of cr04 aqueous solution], grind and mix for 24 hours using a ball mill to prepare a slurry, and add about 15 parts of the above thermal sprayed ceramic coated steel plate to the slurry.
The slurry was soaked in the pores of the film for 1 minute, and the excess slurry adhering to the surface of the film was wiped off.
The apparent porosity of the thermal sprayed ceramic coating is 1 inch or less, and the bonding strength with the metal member is 390 mm. It was reinforced to Kf/cm2 or more (measured by a tensile strength test using an epoxy resin adhesive and peeled off at the resin adhesive surface). Note that the surface of the steel sheet opposite to the ceramic coating needs to be bonded to a metallic interface layer as described below, so masking tape is pasted on that surface before the slurry treatment is performed, and the slurry-treated material is After drying, the tape can be peeled off and bonded in the next step. Note that masking may be performed with a polystyrene resin paint instead of the tape. This decomposes and disappears during heat treatment.

51) x 50 x 4 mm as a heat insulating interface layer
A commercially available stainless steel fiber sintered body having a porosity of about 50 was used. This type of sintered body may also have reinforcing gold copper sintered on both sides at the same time. The thermal conductivity of the interface layer used was approximately 0.008 Ca1l/cm·5ec-'C (value measured by hot wire method).

The bare surface of the carbon steel plate was coated with about 0% of a brazing agent made of fine powder of pure copper made into a paste with a 20ts solution of nitrocellulose.
．． The stainless steel fiber sintered body is layered on top of the coating, and a heavy film of about 50Of is placed from above, and it is heated to about 1125F in a reducing atmosphere of butane conversion gas (008 to 10OF). Brazing joints were performed at ℃.

Next, the bonded body and the metal base are bonded.

JISAC' is used as aluminum alloy casting for monetary base.
5A (commercially available Y alloy), 50 x 50 x 10 pieces, was used. AA on this base surface! - Laying a thin plate of 8i-based aluminum solder ('.rxsBAao Aimushi), then
The interfacial layer of the above bonded body was applied on top of the adhesive, and a heavy sheet of about 500 tons was placed on top, and heated to 560°C in an electric furnace under a reducing atmosphere to perform soldering and heat insulation. We made a prototype of a laminated product. It is also possible to produce such a combination of laminated products by first joining each metal layer using a metal brazing filler metal, and then in the subsequent process strengthening the coating by ceramic spray coating and chemical bonding of chromium oxide. is obtained. Further, when an iron-based alloy is used as a substitute for the aluminum alloy substrate, the interface layers can be simultaneously bonded using pure copper solder. The thermal conductivity of the laminated parts in this case is 0.007 to 0.006 Ca4/cm
-sec・6C, the performance was sufficiently satisfactory.

Example 2 In the case of a heat-insulating laminate component consisting of a metal member having a ceramic coating chemically bonded with chromium oxide, a ceramic heat-insulating interface layer, and a metal base, spheroidal graphite cast iron (JIS, FCD40) and blades were used as the metal members. ×(support)×2.3m
Using a plate of
510 parts of 5 μm or less for 100 parts by weight of a concentrated aqueous solution of
2 powder, 3 parts by weight of Al2O3 powder of 5 μm or less, and melt-stabilized Zr
A slurry prepared by adding 9 parts by weight of O2 powder of 10 μm or less and pulverizing and mixing for 24 hours using a ball mill was applied, and after drying, heat treatment was performed at 550°C for about 20 minutes, and the above application and heat treatment were repeated 5 times. I did it. HQCrO in the slurry during this treatment.

was decomposed and converted to CrCl3-+ Cr2O3, which strongly chemically bonded with the coexisting 5in2, Al2O3, 2102 particles and cast iron, forming a ceramic coating with a thickness of about 120 μm.

Next, in order to further increase the bonding strength of this coating, the specific gravity is 1.
65 H, lCr0. The sample was immersed in a simple concentrated aqueous solution for 10 minutes, dried, and then heat treated at 550° C.I.C., and the immersion and heat treatment in this solution were repeated twice.

The thermal conductivity value of the ceramic coating thus obtained is approximately 0.006 to 0.007 using the laser pulse method.
It was recognized that

The insulating ceramic interface layer contains CaO15 weight factor + Mgo
ZrO of 44 μm or less stabilized by IQ heavy leaf chip
2 powder too parts by weight, ZrC12 heavy bone part of 108m or less, CaCO35 parts by weight of 5mm or less, and M of less than μm
1500 g of mixed powder consisting of 50 parts by weight of ZrO3 powder
Pressure molded at KW/crrt2 and sintered at 1500'C. Its apparent porosity was 15.6%, and in order to strengthen this sintered body, the following treatment was performed. That is, for 100 parts by weight of an aqueous solution of H2CrO4 with a specific gravity of 1.55 as a reinforcing agent, 10 μm stabilized with 18% by weight of CaO
The following Z r02 powder 8 layers and S↓o of 5 μm or less
A slurry prepared by adding 12 parts by weight of powder No. 2 and grinding and mixing for 24 hours using a ball mill was used. The ceramic sintered body was immersed in this slurry, the slurry was impregnated into the pores of the ceramic under a reduced pressure of 1 mmHg, the temperature was raised at 4°C/min in an electric furnace, and heat treatment was performed at 650°C for about 30 min. This impregnation/
The heat treatment was repeated 6 times. The obtained ceramic interface layer has an apparent porosity of 2.3 yen and a thermal conductivity of 0.005 Ca17
cm -5ea-°C, and had satisfactory performance as a heat insulating interface layer.

Next, gray cast iron (JI Nippon FC35) was used as the metal base, and a method using chemical bonding of chromium oxide was used to bond this to the ceramic-coated spheroidal graphite cast iron member and the ceramic interface layer in a laminated manner. Run. This method is described in detail in Japanese Patent Application No. 58-61660 and Japanese Patent Application No. 58-61661. That is, the bonding agent contains CrO350
0f was hydraulically dissolved and the specific gravity was 1. H2Cr with fi5~1.7
A solution of O4 is made, and ZnO25S' and MgO are added to it.
Dissolve 50 f of powder, add water to make a solution with a specific gravity of 1.85, and add K to 500 f of this solution.
15 f of powder and 3 Of of 8102 powder of 5 μm or less were added, ground and mixed for 24 hours using a ball mill, and the binder was added to the 8-round cylinder 1. Ta.

The above ceramic-coated cast iron member and gray cast iron as the base (Fe12.50X50X51jll size)
and specific gravity 1 heated to 85°C as a pretreatment for bonding.
．． 450H2CrO, (7) immersed in an aqueous solution, about 15
The graphite exposed on both cast iron surfaces was removed by heating and holding at 85°C.

The slurry of the bonding agent was thoroughly applied using a brush to the bonding surfaces of the degraphitized gray cast iron base, the ceramic interface layer, and the ceramic-coated spheroidal graphite cast iron member, and after about 5 minutes, the bonding surfaces were bonded. The laminate was fixed with a thin wire, heated at 4°C/min using an electric furnace, and kept heated for about 30 min at 5fiO'C. The piece was cut to a size of 15 x 15 mm on the bonded surface, and a tensile test specimen was made using epoxy adhesive to measure the bond strength. As a result, it peeled off at the resin bonded part, and its strength was 385.
Kp/cWL'' or higher was observed.Also,
The thermal conductivity of the laminated part is 0.004 Cal 7cm
-sec ·°C.

[Brief explanation of drawings]

The figure is a sectional view showing the structure of the heat insulating laminate component of the present invention. ■...Metal base, 2...Metal member, 3...Interface layer, 4...Joining layer, 5...Ceramic coating Patent applicant Usui Kokusai Sangyo Co., Ltd. Agent 1) Yoshihisa [Akira]

Claims (2)

[Claims] (1) A heat insulating interface layer is interposed between the overlapping surfaces of a metal base made of an iron-based alloy or an aluminum alloy and a metal member made of iron or an iron-based alloy, and these mutual overlapping surfaces are bonded by metal soldering. It is fixed with a solder bonding layer or a chemical bonding layer of chromium oxide produced by firing chromic acid, and the outer surface of the metal part is coated with a ceramic coating that is thermally sprayed or chemically bonded with chromium oxide. A heat-insulating laminate component featuring: (2) The heat-insulating interface layer is a porous metal body, a ceramic, or a composite of metal and ceramics.
Insulating laminate parts as described in section.