Method of manufacturing monolithic cellular carrier for catalytic exhaust gas neutralizers and carrier manufactured by this method

FIELD: gas treatment catalysts.

SUBSTANCE: invention, in particular, relates to internal combustion engine exhaust gas neutralizers. Method of invention comprises rolling refractory metallic tape into block by way of overlapping its smooth and corrugated sides to form channels, performing ultrasound-assisted chemical cleaning of thus rolled tape in alkali solution followed by joining alternate layers of metallic tape with each other by diffusion welding in vacuo within a range of 5·10-5-1·10-5 mm Hg using stepwise heating to 1250 ± 10°ะก and isothermal exposure to this temperature for 12-17 min to form monolithic structure consisting of triangular and trapezoidal channel at density up to 600 channels per 1 inch2. Invention further describes carrier for catalytic exhaust gas neutralizers representing monolithic metallic structure in the form of cylindrical block or block with oval cross-section, which block consists of parallel channels, 200-600 per 1 inch2, density of channels varying along the cross-section of carrier: from center and extending to 0.55 0,7 diameter if cylindrical block or large axis of oval cross-section, density of channels is 400-600 per 1 inch2 and farther it decreases to 200 or 400 channel/inch2, respectively.

EFFECT: simplified manufacture technology and increased strength of monolithic cellular structure.

4 cl, 4 dwg, 1 tbl

 

The invention relates to a method of manufacturing a monolithic honeycomb carrier for catalytic converters of exhaust gases of internal combustion engines (ice) and the media for catalytic EXHAUST gas of the internal combustion engine obtained by this method.

Known metal block structure, for example a block of metal carriers catalyst for catalytic EXHAUST gas, which are folded in a roll or typed in the package at least partially structured metal sheets. Monolithic blocks is achieved by bonding the metal sheets interconnected by soldering or sintering, in particular by soldering solid or amorphous solder (also called high-temperature soldering), preferably at temperatures up to 1200°With vacuum. If necessary, the metal structure is also connected by soldering with cover (cowling) (EN 2184007, EN 2179097).

From the patent RU 2179097 C2, 27.06.2000 g, there is a method of manufacturing a cell element for catalytic exhaust gas, which consists of metal sheets, at least some of which are at least partially structured and which are folded in a roll or typed in the package with the formation of channels, and between adjacent metal plates which are provided solder gaps, at least casticin is filled connecting these metal sheets solder. According to well-known solution cell element made of sheet metal has the advantage that upon melting of the solder in the soldering process the initial tension of sheet metal in the casing is maintained. Another advantage of the proposed cell element is that the presence of the embossed projections improves the wetting of sheet metal solder.

The disadvantage of this method is the presence of undercuts the base metal at the border seam, which dramatically reduces the strength of the solder joints and affects the strength and durability of the entire monolithic metal structure. In addition, the currently used expensive amorphous alloys almost doubled the cost of the metal block design.

Known metal block structure, for example a block of metal carriers catalyst for catalytic EXHAUST gas, which are folded in a roll or typed in the package at least partially structured metal sheets, the design of which is to improve the efficiency of the catalyst and increasing the heat transfer varies considerably. For example, in the patent RU 2188325 C2, 27.08.2002, the carrier has an open front parcels of from 55 to 90% of the length of the channel, and provides more efficient heat transfer, however high temperatura welding of such products is much more difficult, and without it at a high level of vibration during operation using virtually impossible. To improve the efficiency of the decontamination process of the EXHAUST gas of the engine, in the patent RU 2182979 C2, 27.05.2002, the proposed design block the media from corrugated spirally wound tape, and the centerline of paired depressions and bumps previous and subsequent layers are at an angle up to 60°. The disadvantage of this design is to increase the back pressure in the exhaust system of the vehicle and reducing the strength of the brazed structure.

The closest known similar solution is the method of manufacturing a monolithic honeycomb carrier for catalytic EXHAUST gas of internal combustion engine from heat-resistant metal tape coiled in a block by imposing smooth and corrugated parts with the formation of channels, cleaning metal strip with subsequent connection of alternating layers of tape to each other in a monolithic design (EN 2135339 C1, 27.08.1999). According to the method of the monolithic honeycomb carrier for catalytic EXHAUST gas of internal combustion engine is a monolithic structure in the form of a cylindrical block or block with an oval cross-section of the interconnected alternating smooth and corrugated metal strips. According to the method of cleaning metal strips the block is carried out in vacuum in the cleaning chamber when the feed is heated to 200° With inert gas, and the monolithic blocks is achieved by connecting alternating layers interconnected by sintering at temperatures up to 1200°s, then the blocks are transported into the cooling chamber. The advantage of this method is the continuity of the process, however, the manufacturing process requires special expensive equipment and the most effective for metal strips having on the surface a minimum amount of grease. The complexity of using sintering method for manufacturing honeycomb structures associated with qualitative removing grease from the capillaries formed between the smooth and corrugated (structured) tape in contact with the unit manufacturer. In the manufacture of these designs use a metal tape, containing on the surface, a significant amount of fat and mechanical impurities, greatly complicates the process of removing grease vacuum and mechanical inclusions (strain hardening), remaining on the surface, lead to changes in the chemical composition of the surface layer of the alloy, which in turn reduces the heat resistance and strength characteristics of the structure. In addition, large volumes of gas emissions generated in the process of degreasing in a vacuum, require disposal, i.e. additional equipment for the doji is as toxic components of exhaust gases. In particular, the process is hampered by the production of blocks with the number of cells more than 400 pieces per square inch.

Based on the foregoing, the present invention was based on the task to provide a method of manufacturing a monolithic honeycomb carrier for catalytic EXHAUST gas of internal combustion engines, which would allow to simplify the technology, to improve the durability of the monolithic honeycomb structures, to produce a carrier having an effective density distribution channels in the cross section of the carrier, and to reduce the cost of the product.

To solve the problem proposed by the present method of manufacturing a monolithic honeycomb carrier for catalytic EXHAUST gas of internal combustion engine from heat-resistant metal tape, clotting in the block by applying a smooth and corrugated parts with the formation of channels, cleaning metal strip block chemically with ultrasound with subsequent connection of alternating layers of tape to each other in a monolithic structure by diffusion welding in vacuum in the range of 5·10-5-1·10-5mm Hg at step heating to a temperature of 1250+/-10°and isothermal exposure for 12-17 minutes Chemical treatment is carried out in an alkaline solution at a pH of 11.5 to 12.5 at a temperature of 40-60°With application of ultrasound with a frequency of 20-25 kHz.

Before the its in accordance with the present invention a monolithic honeycomb carrier for catalytic EXHAUST gas of internal combustion engines, manufactured in the above way, is a monolithic structure in the form of a cylindrical block or block with an oval cross-section of the interconnected alternating smooth and corrugated metal strips consisting of parallel channels of triangular or trapezoidal shape with a density of from 200 to 600 pieces per square inch at various density over the cross section of the media. While the media has the following density channel cross-section: - from the centre 400 or 600 pieces per square inch in the range from 0.55 to 0.7 of the diameter of the cylindrical block or from 0.55 to 0.7 of the length of the major axis of the block oval cross - hereinafter referred to respectively as 200 or 400 pieces per square inch.

Cleaning out the metal tape unit using chemical treatment with ultrasound allows easy enough to remove greasy stains. Of particular importance is the ability of ultrasonic vibrations to penetrate into narrow slits, pores, cleaning them with other methods do not give good results. Because ultrasonic cleaning is mainly due to mechanical vibrations, the composition of the working fluid has a lower value than conventional chemical degreasing. Therefore, when using alkaline solutions, the concentration can be significantly reduced, which allows the use of alkaline solutions with a pH of 11.5 to 12.5.

Diffusion connection metal strips do not require expensive solders, protects the metal from oxidation at high temperatures and improves the quality of the weld when welding in vacuum, thereby to provide high quality products, reliability, allows to increase the resource.

The essence of the proposed method of manufacturing a monolithic metal honeycomb carrier is as follows.

Modular construction - monolithic honeycomb carrier is a corrugated and a smooth steel tape brand HU (GOST 12766.2-90), wound spirally in a cylindrical block, a block with an oval cross-section or placed in another way with pre-stress in the shell of stainless steel sheet, for example, the brand 18CR10NITI, resulting in a cellular structure consisting of parallel channels of triangular or trapezoidal shape, with a density of channels in the media section up to 600 BHP. Monolithic honeycomb carrier is subjected to chemical treatment in an alkaline solution at a pH of 11.5 to 12.5 at a temperature of 40-60°With application of ultrasound with a frequency of 20-25 kHz, washed in distilled water and dried in air at a temperature of 100-120°that allows to obtain a high degree of surface cleaning tape, sufficient for diffusion welding in vacuum.

The inventive method allows to reduce the cost monolithic metal carrier by reducing the amount of used material tape, and thus reduce the cost of bulk catalyst and Converter as a whole while maintaining its efficiency, and to increase the durability of the metallic structure of the media, which will increase the service life of the Converter.

The effectiveness of the proposed method high temperature vacuum welding can be illustrated by the following examples, in which the investigated samples of cylindrical block media No. 1-3, processed and dried according to the method described above.

Sample size - diameter 50 mm, height - 90 mm

Samples 1, 2, 3, 4, 5 - the Number of channels in the cross section of the unit: the distance from the centre equal to 0.55 diameter of 400 per square inch, then 200 pieces per square inch;

Sample 6. The number of channels in the cross section of the unit: the distance from the centre equal to 0.55 diameter of 600 pieces per square inch, then 400 pieces per square inch.

The choice of the optimal temperature regime of the process of diffusion welding for samples No. 1 to 6 is carried out in the following sequence:

- the unit is installed on a molybdenum-style vacuum oven at equal distances from the heater;

- in the chamber of the vacuum furnace to create the vacuum is not worse than 5x10-5mm Hg;

- included heating VA is wumei furnace;

the heating rate is set:

- in the range of temperatures from 20°With up to 1000° - 20°/min

- in the range of temperatures from 1000°With up to 1250°C - 10°/min

- isothermal aging carry out:

sample 1 is at a temperature of 1150°C - 15 min,

sample 2 is at a temperature of 1200°C - 15 min (prototype)

samples 3 and 6 at a temperature of 1250°C - 15 min,

sample 4 is at a temperature of 1250°S - 20 min,

sample 5 is at a temperature of 1250° - 10 minutes

- heat oven off;

- cooling is carried out in vacuum with the natural cooling rate of the furnace to a temperature of 60°then the furnace chamber open and remove the sample for the subsequent operations.

The criterion for the quality of construction is the formation of a weld zone in places of contact of the components. The study of the microstructure of the samples in the connection zone of the cellular elements of the design carried out by metallographic techniques optical microscope "Neophot-21" when you increase up to 500x.

It should be noted that the research quality of a welded joint of sample 4 was not carried out, because visual inspection it was discovered the breach block design due to softening of the material of the tape.

In the study of samples 1, 2 (the prototype) and 5 revealed that more than 50% of the nodes welded elements not supremacy is formed, and the connection did not happen. In other cases, the contact area is small, since the welded area is small (see Illustrations, Fig 1, 2).

The study of the microstructure of samples 3 and 6 showed that the welding process has passed 100% of the nodes, and the weld zone has a significant size with the formation of common beans (see Illustrations, Fig 3, 4).

Thus, the optimal regime vacuum welding for the manufacture of a monolithic honeycomb carrier according to the invention, is the following mode: - temperature from 1250+/-10°C, the holding time is 12-17 minutes, a vacuum of about 5·10-5-1·10-5mm Hg

To study the effectiveness of a combined structure of the media were prepared with a full-sized samples of block metal carrier oval displacement of 0.786 DM3manufactured by the present method:

Comparative sample - number of channels in the cross section of 400 per square inch - Serial Converter;

The sample And the number of channels on the distance from the centre equal to 0.7 of the length of the major axis of the block oval - 400 pieces per square inch, then 200 pieces per square inch - Converter No. 1;

Sample B is the number of channels on the distance from the centre equal to 0.55 length of the major axis of the block oval - 400 pieces square inch, then 200 pieces square inch - Converter No. 2;

Sample - the number of channels on the distance from the center, equally the m 0.5 the length of the major axis of the block oval - 400 square inch, then 200 pieces square inch - Neutralizer No. 3;

Sample G is the number of channels on the distance from the center, equal to 0.8 of the length of the major axis of the block oval - 400 pieces square inch, then 200 pieces square inch - Neutralizer No. 4.

The catalytic coating was applied to the surface of the block carrier in a known manner according to the patent RU 2190470. Coating composition: Al2About3- 20 wt.%, SEO2to 1.9 wt.%, Pt - 0.1 wt.%, Rh - 0.02 wt.%, the rest is steel HUE.

Evaluation tests of the catalysts was carried out on the car VAZ-2110 (engine capacity of 1.5 liters, the power supply system - a distributed respectively according to the ECE Regulations No. 83-B, category M1. The test results are shown in table. According to test results, we can conclude that to reduce the cost of media is optimal density distribution channels unit within from 0.55 to 0.7 of the diameter of the cylindrical block or from 0.5 to 0.7 of the length of the major axis of the block oval cross-section. Increasing the density of channels to 0.8 of the length of the major axis of the block with oval section does not affect the efficiency of the Converter, and a decrease of less than 0.55 length of the major axis of the block oval cross section dramatically reduces the efficiency of the Converter.

The technical result of the present invention is to simplify the technology and improving the strength of the monolithic honeycomb structures used in the block when asked the media for catalytic exhaust gas of internal combustion engines.

Table

The results of the tests.
EquipmentDriving cycleCOCH+NOx
Converter # 1 and 4The effect of the neutralizer*93%87%
The neutralizer No. 2The effect of the neutralizer*91,5%85%
The neutralizer No. 3The effect of the neutralizer*81,5%76%
Serial ConverterThe effect of the neutralizer*87%90%
Note: * - averaged values 3-4 tests

1. A method of manufacturing a monolithic honeycomb carrier for catalytic exhaust gas of internal combustion engines of the metal heat-resistant tape comprising folding it into the block by applying a smooth and corrugated parts with the formation of channels, cleaning metal strip block with subsequent connection at elevated temperatures alternating layers of metal tape with each other in a monolithic structure, characterized in that the cleaning of metal ribbon conduct chemical treatment using ultratv the ka, and the connection alternating layers of metal strip is carried out by diffusion welding in vacuum in the range of 5·10-5-1·10-5mm Hg at step heating to a temperature of 1250±10°and isothermal exposure for 12-17 minutes

2. The method according to claim 1, characterized in that the chemical treatment is carried out in an alkaline solution at a pH of 11.5 to 12.5, a temperature of 40-60°With application of ultrasound with a frequency of 20-25 kHz.

3. Monolithic honeycomb carrier for catalytic exhaust gas of internal combustion engines, which is a metal structure in the form of a cylindrical block or block with an oval cross-section of the interconnected alternating smooth and corrugated metal strips, characterized in that it is manufactured according to claim 1 and consists of parallel channels of triangular or trapezoidal shape with a density of from 200 to 600 pieces per square inch under different density of channels in the cross section of the media.

4. Monolithic honeycomb carrier according to claim 3, characterized in that it has the following density of channels in the cross section of the media: from the centre 400 or 600 pieces per square inch in the range from 0.55 to 0.7 of the diameter of the cylindrical block or from 0.55 to 0.7 of the length of the major axis of the block oval cross - hereinafter referred to respectively as 200 or 400 pieces per square inch.



 

Same patents:

FIELD: production of honeycomb substrates for catalyst converters for two-wheeled or diesel vehicles.

SUBSTANCE: the invention is dealt with production of honeycomb substrates made out metal sheets piled or rolled in a package and minimized to the honeycomb elements used first of all as honeycomb substrates for catalyst converters in the systems of exhaust gas (EG) neutralization. There is a description of a honeycomb element (1) first of all as a honeycomb substrate for a catalyst converter for systems of two-wheeled vehicles exhaust gas neutralization. The honeycomb substrate for catalyst converter consists of some layers of metal sheets (2, 3) packed as a package or minimized in a roll, which are at least on separate sections are structured or profiled in such a manner, that they form for EG flowing channels (4). At that the metal sheets (2, 3) represent the sheets of high-quality steel of more than 0.08 mm thick with a share of aluminum from 6 up to 12 mass % multiplied by 0.02 mm and divide by "d" - thickness of the metal sheets (2, 3). The technical result - a possibility to use metal sheets depending on the share of aluminum in them and their thickness, that allows to use the sheets taken from production process of manufacture of a material subjected to a hot aluminization.

EFFECT: the invention ensures a possibility to use metal sheets for the purpose depending on the share of aluminum in them and their thickness.

5 cl, 1 dwg

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