RU2493934C1 - Method of producing refractory highly porous permeable alloys - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to powder metallurgy, particularly, to production of refractory highly porous permeable cellular alloys. It maybe used production of bulk high-temperature catalyst carriers, high-temperature gas and melts filters. Surface of biller from the alloy of highly porous mesh-cellular-structure nickel or ferronickel is processed by composition of polymer binder and foundry alloy by airless spraying at pressure. Proposed composition contains polymer binder based on 20%-solution of colloxylin in white spirit and foundry alloy containing the following components at their following ratio in wt %: chromium - 50-52, aluminium - 18-20, iron - 25-28. Then, drying and sintering are performed at 1220-1250°C in reducing or inert atmosphere in tight container to be cooled in atmosphere of reducing or inert gas.

EFFECT: higher heat resistance, suitable for operation in oxidising atmosphere at 700-1000°C.

10 cl, 2 tbl, 8 ex

Description

The claimed invention relates to powder metallurgy, in particular, to methods for producing heat-resistant high-porous permeable cellular alloys, and can be used to obtain block high-temperature catalyst supports, high-temperature gas filters and melts.

The closest technical solution to the claimed invention is a method comprising treating the surface of a foam nickel blank with dimensions 300 × 150 × 1.9 mm in 1% solution of polyvinylpyrrolidone followed by dusting with ligature powder in a vibrating device, while the composition of the ligature "Inconel 625" contains the ingredients the following ratio, wt.%: chromium - 22.4; molybdenum - 10; iron - 4.8; cobalt - 0.3; niobium - 3.8; carbon - 0.1; nickel - 58.6. Next, the preform is treated with a suspension of amide wax (ethyleneamide stearic acid) with an average granule size of 30 μm in an amount of 2% by weight of the preform, and the melting point of the amide wax is 140-145 ° C. Then the preform is dried and sintered at a temperature of 1220-1250 ° C in a reducing or inert atmosphere (see patent US 2008/0148940 "Method for fabricating an open-porous metal foam body, metal foam body", filing date 08/22/2007, publication date June 26, 2008).

The disadvantages of this method are the high complexity of the process, the inability to use foam nickel blanks with complex geometry, as well as the use of the multi-component composition of the ligature in the implementation of the method.

The technical result to which the claimed invention is directed is the possibility of implementing a method using workpieces with complex geometry, simplifying the composition of the ligature, reducing the complexity of the process and obtaining a highly porous, permeable cellular alloy having increased heat resistance, suitable for use in an oxidizing atmosphere at temperatures up to 700 -1000 ° C.

The specified technical result is achieved in that a method for producing a heat-resistant highly porous permeable alloy, comprising treating the surface of the workpiece with a polymer binder and ligature composition, drying and sintering at 1220-1250 ° C in a reducing or inert atmosphere, according to the invention, an alloy of highly porous nickel is used as a material for the workpiece mesh-cellular structure with open porosity or ferronickel, surface treatment is carried out by airless spraying under pressure, while lzuyut polymeric binder composition based on 20% collodion solution in mineral spirits and ligatures containing the following ratio of components, wt%: chromium - 50-52;. aluminum - 18-20; iron - 25-28, drying and sintering is carried out in an airtight container, which is then cooled in a reducing or inert gas.

The viscosity of the polymer binder is not more than 40-60 seconds.

45-60 wt.% Ligatures are used for surface treatment, the rest is the polymer binder.

The average grain size of the ligature powder is 25 μm.

The open porosity of the sample material is 85-96%.

Drying in a stream of reducing or inert gas is carried out mainly at a temperature of 1250-1260 ° C for 6 hours.

The surface treatment of the workpiece is carried out at a pressure of not more than 100 bar.

To implement the method, preforms of various sizes, shapes and pores per inch (PPI) are used.

The full production cycle is 18 hours.

This method allows you to apply a given amount of the polymer composition with an alloying component on the surface of the workpiece with a uniform distribution over the entire surface.

In addition, this method significantly reduces the process, since it does not require pre-treatment of the workpiece with an adhesive composition, removal of excess adhesive composition, as well as vibration powder and treatment with amide wax.

Technical solutions that coincide with the totality of the essential features of the claimed invention have not been identified, which allows us to conclude that the claimed invention meets such a patentability condition as “novelty”.

The claimed essential features that predetermine the receipt of the specified technical result, do not explicitly follow from the prior art, which allows us to conclude that the claimed invention meets such a patentability condition as "inventive step".

The patentability condition "industrial applicability" is confirmed by the example of a specific implementation.

The implementation of the proposed method for producing heat-resistant highly porous permeable alloy is confirmed by examples of specific performance.

Example 1

To implement the method of producing a highly porous heat-resistant alloy, a highly porous permeable nickel blank (sample No. 1) with an average cell diameter of 2.1 mm, a density of 0.63 g / cm ³ , PPI 30 and dimensions of 500 × 500 × 10 mm was used. Prepared 20% solution of colloxylin and ligature in an amount of 55% wt. placed in a container equipped with a mixer, fed into a GRACO airless spraying system, and applied to a workpiece under a pressure of 100 bar. The weight of the applied composition was 24-26 wt.%. Next, the preform was dried at a temperature of 25 ° C for 20 minutes and placed in a container, which was sealed and transferred to a muffle furnace. Then, a reducing or inert gas current was supplied, increasing the temperature to 1250-1260 ° C, and sintered for 6 hours. After the end of the sintering operation, the container was slowly cooled in a reducing or inert gas medium, and then a preform was removed from it.

Example 2

A method of obtaining a heat-resistant highly porous permeable alloy was carried out using a workpiece, for which the material was used VPNM based on ferronickel (sample No. 2) in the form of a plate with a size of 450 × 500 × 10, density 0.7 g / cm ³ , cell diameter 1 9 mm and PPI 30.

Example 3

When carrying out the method, a highly porous mesh-based nickel-based mesh material (sample No. 3) in the form of a cone with a base diameter of 150 mm and a height of 350 mm, a density of 0.65 g / cm ³ , a cell diameter of 2.1 mm and PPI was used as a preform twenty.

Example 4

As a blank, we used VPNM based on ferronickel (sample No. 4) in the form of a hollow cylinder with a diameter of 50 mm, a length of 145 mm, a wall thickness of 5 mm, a density of 0.7 g / cm ³ , a cell diameter of 1.9 mm, and PPI 50.

Example 5

As a preform, we used HPMP based on nickel in the form of a truncated cone with a base diameter of 100 mm, an upper * - + ---------- with a diameter of 30 mm and a height of 210 mm, a density of 0.38 g / cm ³ , and a diameter 0.8 mm cells and PPI100.

To study the advantages of the alloy obtained by the claimed method, the following studies were conducted.

The inventive samples under No. 1-5 and control samples No. 6, 7, made of foam nickel and ferronickel, respectively, using a digital milliometer {GOM-802}, the electrical resistance was measured and the resistivity was calculated.

Then, samples taken from samples Nos. 1–5 were heated on a NENZSCH STA 449C Jupiter thermal analyzer to a temperature of 1250 ° C. Thermograms were used to determine the temperatures of the onset of active oxidation of alloys made by the claimed method and control samples made of nickel and ferronickel.

The results obtained are presented in Table 1.

Table 1 Specific electrical resistance of the samples and the temperature of the onset of active oxidation No. Name of material Heat treatment mode Specific electric resistance of the matrix, Ohm · m · 10 ^-6 Active oxidation onset temperature, ° C one Nickel coated with a ligature powder of the claimed composition: chromium - 52%, aluminum - 20%, iron - 8% Example 1. 1250 ° C 6 hours 0.39 ± 0.02 950 ± 10 2 0.32 ± 0.02 925 ± 10 3 0.40 ± 0.02 955 ± 10 four 0.31 ± 0.02 920 ± 10 5 0.43 ± 0.02 940 ± 10 6 Nickel No heat treatment 0.086 ± 0.008 550 ± 10 7 Ferronickel No heat treatment 0.076 ± 0.007 510 ± 10

As follows from Table 1, the electrical resistivity of the matrix for samples No. 1-5 is higher than for control samples No. 6 and 7 made of nickel and ferronickel, respectively. In addition, the temperature of the onset of active oxidation in samples obtained by the claimed method is also higher. From a comparative analysis of the resistivities and temperatures of the onset of rapid oxidation of samples No. 1-5, it is seen that the saturation of the matrix of highly porous permeable nickel and ferronickel coated with ligature powder of the proposed composition has passed to a sufficient degree.

In addition, to confirm the industrial applicability of the claimed method on an industrial scale, a pilot batch of a highly porous heat-resistant nickel-based alloy was manufactured.

Example 8

The methodology of Example 1 was repeated, except that nickel-based HPLM (sample No. 8) in the form of a plate 500 × 500 × 10 in size, with a density of 0.63 g / cm ³ , and a cell diameter of 2.1 mm was used as a blank. and PPI 30 in an amount of 40 pcs. (100 l).

From 8 samples obtained according to example 8, a batch of 5 pieces was randomly selected and the main quality indicators were determined. The results obtained are presented in Table 2.

table 2 Quality indicators of a pilot industrial batch of highly porous heat-resistant nickel-based alloy No. Name of material The mass of the applied ligature, kg Heat treatment mode Specific electric resistance of the matrix, Ohm · m · 10 ^-6 Active oxidation onset temperature, ° C 8 Nickel coated with a ligature powder of the claimed composition: chromium - 52%, aluminum - 20%, iron - 8% 11.8 (24.6%) temperature 1250 ° C; time - 6 hours 0.38 ± 0.02 945 ± 10

The claimed invention allows to obtain a highly efficient heat-resistant highly porous permeable alloy, in terms of performance exceeding the known solutions.

Claims (10)

1. A method of obtaining a heat-resistant highly porous permeable alloy, comprising treating the surface of the workpiece with a polymer binder and ligature composition, drying and sintering 1220-1250 ° CC in a reducing or inert atmosphere, characterized in that a highly porous nickel mesh-like structure is used as the material for the workpiece with open porosity or ferronickel, surface treatment is carried out by airless spraying under pressure, while using a composition of a polymer binder based on 20% - solution of colloxylin in white spirit and a ligature containing components in the following ratio, wt.%: chromium 50-52, aluminum 18-20, iron 25-28, drying and sintering is carried out in an airtight container, which is then cooled in a reducing or inert gas. 2. The method according to claim 1, characterized in that the viscosity of the polymer binder is not more than 40-60 s. 3. The method according to claim 1, characterized in that for surface treatment use a composition containing 45-60 wt.% Ligatures, the rest of the polymer binder. 4. The method according to claim 1, characterized in that the average grain size of the ligature is 25 microns. 5. The method according to claim 1, characterized in that the porosity of the sample material is 85-96%. 6. The method according to claim 1, characterized in that the drying and sintering is carried out in a reducing or inert gas, mainly at a temperature of 1250 ° C. 7. The method according to claim 1, characterized in that the drying and sintering is performed for 6 hours 8. The method according to claim 1, characterized in that the surface treatment of the workpiece is carried out at a pressure of not more than 100 bar. 9. The method according to claim 1, characterized in that use blanks of various sizes, shapes and pores per inch (PPI). 10. The method according to claim 1, characterized in that the time of the full production cycle is 18 hours