JP2933701B2 - Wear-resistant sliding member and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an engine component, a valve, a seal ring,
Wear-resistant sliding member excellent in wear resistance and seizure resistance of channel type or pin point type porous chrome plated sliding member used for high-speed moving sliding portion such as bearing, and method of manufacturing the same It is about.

(Prior art) Conventionally, sliding parts such as cylinder liners, piston rings, connecting rods, valves and valve guides of various engines such as gasoline engines and diesel engines are
Sliding members in which hard chrome plating is applied to metal members have been mainly used, but hard chrome plating has been used in automobiles, ships, and other vehicles at higher speeds and higher loads, and as fuel quality has deteriorated. Problems such as abnormal wear and seizure have occurred, and as a countermeasure, many methods of spray-coating ceramic or a composite material of metal and ceramic on a metal substrate have been proposed. As another method, a method in which a ceramic slurry is applied and heated and fired is proposed as an effective means for forming a wear-resistant sliding film (Japanese Patent Publication No.
64-3951).

(Problems to be Solved by the Invention) However, in this method, the heating and firing temperature after the application of the ceramic slurry is 300 ° C. at a high temperature of 370 to 500 ° C.
It is necessary to perform heat baking treatment for up to 60 minutes.
It may be repeated about once, and if such high temperature treatment is repeated, there is a problem that the hardness of the porous chromium plating layer is rapidly reduced, and there are also problems such as distortion and bending of the metal substrate. .

The present invention solves the above-mentioned problems, reduces the number of repetitions of the impregnation-heating and baking treatments, can lower the heating and baking temperature, and has improved durability such as abrasion resistance, seizure resistance and other properties, which is excellent in durability. It is an object of the present invention to provide a wear-resistant sliding member and a method for manufacturing the same.

(Means for Solving the Problems) As a result of repeated studies to solve the above problems and achieve the above object, the present inventor has found that the fine pores and / or the porous chrome plating layer coated on the surface of the metal substrate have been formed. The present invention has been found out that the object can be achieved by forming a ceramic film in which chromium oxide and phosphorous oxide are mixed on a crack portion and a surface, or a ceramic film in which ceramic particles are dispersed in a matrix thereof. Was completed. That is, the first embodiment of the present invention provides a ceramic film in which chromium oxide and phosphorus oxide are mixed on the surface of the fine pores and / or cracks of the porous chrome plating layer coated on the surface of the metal substrate, or A wear-resistant sliding member formed by forming a ceramic film in which ceramic particles are dispersed in a matrix in which chromium oxide and phosphorus oxide are mixed. A second embodiment is a porous chromium coated on a metal substrate surface. The third embodiment is a method for manufacturing a wear-resistant sliding member in which a plating layer is impregnated with an impregnating solution composed of a mixed solution of chromic acid and phosphoric acid and heated and fired at least once repeatedly. , On the porous chrome plating layer coated on the metal substrate surface, a mixed concentrated solution of chromic acid and phosphoric acid, Cr ₂ O ₃ , SiO ₂ , ZrO ₂ , Al ₂ O ₃ , SiC, Si ₂ N ₄ ,
LiF, impregnated with ceramic slurry comprising at least one member selected from among CaF _2, and heated and baked, then the process of mixing the impregnated heat calcining the impregnated solution comprising a concentrated solution of chromic acid and phosphoric acid A method for producing a wear-resistant sliding member that is repeatedly performed at least once.

In the present invention, the porous chromium plating applied to the metal substrate is conventionally performed as a channel type having a predetermined porosity, a pinpoint type or an intermediate type by a method generally performed on sliding members such as various engines. You can use what has been enforced.

Chromic acid is obtained by dissolving chromium trioxide in water,
Used as a concentrated aqueous solution adjusted to 1.65, phosphoric acid is 75
Commercial products with a concentration of ~ 88% can be used.

The mixed concentrated solution of chromic acid and phosphoric acid was prepared by adding an aqueous solution of chromic acid adjusted as described above to one molecular weight of phosphoric acid.
A mixture of 48 to 2.7 molecular weight, preferably 0.96
Use a mixture of ~ 1.36. In this mixed concentrated liquid, if the molecular weight ratio of chromic acid is less than 0.48, the viscosity becomes high, and the impregnation of fine pores and cracks formed in the porous chromium plating layer is not performed smoothly. Even if repeated, further increase in hardness can not be expected, and when the ratio of the molecular weight of chromic acid exceeds 2.7,
The catalytic effect of phosphoric acid is reduced, and a higher firing temperature is required. Of course, if the number of treatments is not increased, a ceramic film having desired properties is hardly obtained.

Thus, phosphoric acid itself forms a polymer structure from dehydration condensation and blending with metal ions, but has a reducing effect of chromic acid when mixed with chromic acid, and polymer bonds through chromium and oxygen. It takes a structure and forms a harder cured film.

In addition, as ceramic raw materials, SiO ₂ , ZrO ₂ , Al ₂ O ₃ , S
At least one selected from iC, Si ₂ N ₄ , LiF, CaF ₂ , and Cr ₂ O ₃ is used.
A powder having an average particle size of 10 μm or less, preferably 3 μm or less, is used.

The ceramic slurry is prepared by adding at least one of the ceramic raw materials to the mixed concentrated solution of chromic acid and phosphoric acid prepared as described above at a rate of 1.5 to 2.5 kg /, and sufficiently stirring the mixture. The order of mixing is not restricted).

According to the second embodiment, the ceramic film is formed by brushing and spraying the ceramic slurry prepared as described above on the fine pores and / or cracks and the surface of the porous chrome plating layer coated on the surface of the metal substrate. Coating, or can be impregnated by a dipping method or the like, preferably by a dipping method, in which case it can be carried out at normal pressure, but reduced pressure of 0.1 to 1 mmHg, or ^{2 to 4} kg / cm ²
It is preferable to hold for 5 to 10 minutes under the above pressure. Then, it is baked at 200 to 300 ° C. for 30 to 120 minutes to form a ceramic film. By repeating the impregnation-heating and baking treatment at least once, the fine pores of the porous chrome plating layer can be effectively sealed.

Further, the formation of the ceramic coating according to the third embodiment includes:
The pores and / or cracks of the porous chromium plating layer coated on the surface of the metal substrate and the surface thereof are impregnated with the above-mentioned ceramic slurry and heat-treated at 200 to 300 ° C. for 30 to 120 minutes. Then, the obtained ceramic coating is impregnated with the mixed concentrated solution of chromic acid and phosphoric acid prepared as described above by brush coating, spray coating, dipping method, etc., at 200 to 300 ° C.
Heating and baking for 30 to 150 minutes, this impregnation-heating and baking treatment is performed at least once, preferably 3 to 5 times repeatedly, and it is usually sufficient to repeat the treatment 5 times, and the ceramic coating is sufficient. Can be formed.

Thus, the fine pores of the porous chrome plating layer,
Furthermore, a ceramic film in which chromium oxide and phosphorus oxide are mixed on the plating surface, or a ceramic film in which ceramic particles are dispersed in a matrix thereof is formed, and the heating and firing temperature is as low as 200 to 300 ° C. Processing can be performed, and the number of times of processing is about five times. This effect is the effect of phosphoric acid as a catalyst for the low-temperature reduction of chromic acid, and furthermore, when CrO ₃ is converted to Cr ₂ O ₃ , a chemical change occurs with phosphoric acid and an organic oxidative bond, This is considered to be because it remains as a film and is an effective means for obtaining a hardening and filling effect of the ceramic film.

In addition, as a result of examining the ratio of the molecular weights of phosphorus oxide and chromium oxide with respect to the obtained ceramic coating, it was confirmed that the ratio of the molecular weight of chromic acid to phosphoric acid in the mixed concentrated liquid remained almost as it was. Was.

(Example) Next, an example of the present invention will be described.

Example 1) Preparation of mixed concentrated solution of chromic acid and phosphoric acid 100 m of chromic acid having a specific gravity of 1.65 prepared by dissolving CrO ₃ in water
l and commercially available 85% phosphoric acid (100 ml) were mixed and thoroughly mixed to prepare a mixed concentrated solution of chromic acid and phosphoric acid.

2) Preparation of ceramic slurry Cr ₂ O _{3 having} an average particle size of 1 μm and a particle size of 6 μm or less,
Using stabilized ZrO ₂ , α-Al ₂ O ₃ , CaF ₂ , 40 parts by weight of Cr ₂ O ₃ ,
10 parts by weight of stabilized ZrO _2, 10 parts by weight of α-Al ₂ O _{3, and} 10 parts by weight of CaF ₂ are mixed liquid concentrates of chromic acid and phosphoric acid prepared in 1) 15
Parts by weight and pulverized and mixed using an alumina ball mill for 40 hours to prepare a slurry.

3) Preparation of Metal Substrate A 24 mmφ × 6 mm disk was cast from cast iron (JIS G 5501 FC 350) and subjected to channel type porous chrome plating with a porosity of 30%.

4) -1 Formation of ceramic coating The porous chromium-plated metal substrate prepared in 3) was immersed in the concentrated solution of chromic acid and phosphoric acid prepared in 1), and kept at a reduced pressure of 0.1 mmHg for 5 minutes. Then, the pressure was returned to normal pressure, and the plate was allowed to stand for 5 minutes to impregnate and coat the surface together with the inside of the fine pores of the plating layer.

Then, it was heated and baked at 280 ° C. for 60 minutes. This impregnation-heating and firing treatment was repeated three times to obtain a mixed ceramic film of chromium oxide and phosphorus oxide.

4) -2 Formation of ceramic coating The porous chromium-plated metal substrate prepared in 3) was immersed in the ceramic slurry prepared in 2), and 0.1 mmH
The pressure is maintained for 5 minutes under a reduced pressure of g, and the pressure is returned to the normal pressure and left for 7 minutes to fill the grooves and pits of the plating layer. Then, after drying at about 45 ° C. for 40 minutes, a heating and baking treatment was performed at 280 ° C. for 60 minutes in an electric furnace. Then, the mixed concentrated liquid of chromic acid and phosphoric acid prepared in 1) was used as an impregnating liquid, impregnated and adhered in the same manner as described above, and then fired at 280 ° C. for 60 minutes. This impregnation-heating and baking treatment was repeated five times, and the ratio of the molecular weights of chromium oxide and phosphorus oxide was 1: 1.
A ceramic film in which particles of Cr ₂ O ₃ , ZnO ₂ , Al ₂ O ₃ , and CaF ₂ were dispersed in the matrix of No. 18 was obtained.

5) Abrasion test An Ogoshi type test was performed in which the disk formed with the ceramic coating formed in 4) was rotated, and a fixed mating member was pressed against the disk to measure sliding friction. That is,
Using a cast iron (FCD) cylindrical pin (4mmφ) as the mating material,
A maximum load of 2.5 kgf (20 kgf / cm ^{2 of} surface pressure) was applied, and silicone oil was used as a lubricating oil. The speed of the friction part was 3 m / min.

The measurement results show that the specific friction was 5.8 × 10 ⁻⁸ mm ³ / kg for 4) -1.
Mm, the specific friction was 3.8 × 10 ⁻⁸ mm ³ / kg · mm in 4) -2.

Comparative Example 25 parts by weight of a concentrated chromic acid solution having a specific gravity of 1.7 and 30 parts by weight of pure chromic acid prepared in the same manner as in the example, and 40 parts by weight of Cr ₂ O ₃ , stable 10 parts by weight of ZrO _2, 10 parts by weight of α-Al ₂ O _{3 and} 10 parts by weight of CaF ₂ were mixed and impregnated with a ceramic slurry prepared in the same manner as in the example, at 460 ° C. Baked for 30 minutes, then impregnated with a concentrated solution of chromic acid with a specific gravity of 1.7,
The heating and firing treatment was performed five times to form a ceramic film.

An Ogoshi type test was performed on the obtained film in the same manner as in the example. As a result, the specific wear amount is 18.2 × 10 ^-8 mm ³ / kg
mm.

The specific wear of the coating obtained by repeating the impregnation-heating treatment 10 times was 2.6 × 10 ⁻⁸ mm ³ / kgmm, but distortion was generated in the base cast iron. It was recognized that.

(Effects of the Invention) In the present invention, a ceramic coating in which chromium oxide and phosphorous oxide are mixed or a ceramic coating in which ceramic particles are dispersed in a matrix thereof is formed on a porous chromium plating layer coated on the surface of a metal substrate. Because
If the hardness of the film is high, it is dense, it is extremely excellent in heat resistance and corrosion resistance, it can be processed at a low firing temperature of 200 to 300 ° C, and the number of times of impregnation liquid treatment is repeated about 5 times. Sufficient effects are recognized, such as being able to reduce deterioration and deformation of the base material and forming a firmly bonded ceramic film.

Claims (3)

(57) [Claims] 1. A ceramic film in which chromium oxide and phosphorus oxide are mixed on the surface of fine pores and / or cracks of a porous chromium plating layer coated on the surface of a metal substrate.
A wear-resistant sliding member comprising a ceramic film in which ceramic particles are dispersed in a matrix in which chromium oxide and phosphorus oxide are mixed. 2. A process of impregnating a porous chromium plating layer coated on a surface of a metal substrate with an impregnating solution comprising a concentrated solution of a mixture of chromic acid and phosphoric acid and heating and firing the same at least once. Of producing a wear-resistant sliding member. To 3. A porous chromium plating layer coated on the metal substrate surface, and the mixture concentrated solution of chromic acid and phosphoric acid, Cr ₂ O
₃ , impregnated with a ceramic slurry consisting of at least one selected from the group consisting of SiO ₂ , ZrO ₂ , Al ₂ O ₃ , SiC, Si ₂ N ₄ , LiF and CaF ₂ , and calcined by heating; A process of impregnating with an impregnating solution comprising a concentrated solution of a mixture of sulfuric acid and phosphoric acid and heating and sintering it at least once repeatedly.