KR102194420B1 - Ni-Cr-Fe-P based alloy powder for brazing having a low melting point and high corrosion resistance and a method for producing the same - Google Patents

Abstract

The present invention relates to a Ni-Cr-Fe-P-based brazing alloy powder having a low melting point and high corrosion resistance and a method for producing the same, and more specifically, 5 to 40% by weight of Cr, 5 to 30% by weight of Fe, Ni-Cr-Fe-P-based brazing alloy powder containing 5 to 20% by weight of P, remaining Ni and other inevitable impurities, and Ni-Cr-Fe-P-based brazing through a gas atomizing process As a method for producing molten alloy powder, the melting temperature is 1300 to 1650 °C, the molten metal nozzle diameter is 3 to 10 mm, and the gas injection pressure is 3 to 15 bar, which has a low melting point and high corrosion resistance Ni-Cr-Fe-P It relates to a method of manufacturing alloy powder for brazing system. The alloy powder according to the present invention has a low melting point compared to the existing products, so it acts advantageously to the bonding temperature in the post-treatment process, and by applying it to brazing, it can be used in various ways as a high-functional bonding material.

Description

Ni-Cr-Fe-P based alloy powder for brazing having a low melting point and high corrosion resistance and a method for producing the same}

The present invention relates to a Ni-Cr-Fe-P-based brazing alloy powder having a low melting point and high corrosion resistance, and a manufacturing method thereof.

Conventionally, in the fields of heat exchangers (EGR coolers) of automobile exhaust gas recirculation systems (EGR: Exhaust Gas Recirculation System) composed of various stainless steels, gas turbines and steam turbines composed of various heat-resistant alloys, various Fe-based Brazing of alloy materials and parts was performed.

Particularly, brazing joint parts used in environments with high corrosiveness such as exhaust gas, combustion gas, and steam are generally used as a brazing material using Ni-based alloy powder containing Cr, which has an effect of improving corrosion resistance. In addition, a brazing material containing B or P having an effect of lowering the melting point for the purpose of lowering the brazing temperature is also used. Commercial products include BNi-2 (Ni-Cr-B-Fe-Si) and BNi-7 (Ni-Cr-P).

As a prior patent, there is Korean Laid-Open Patent Publication No. 10-2012-0068028 of HOGANAS AB, the patent is Fe: Bal., Cr: 11 to 35% by weight, Ni: 0 to 30% by weight, Cu: 2 to 20% by weight, Si: 2 to 10% by weight, P: 4 to 10% by weight, Mn: It is composed of a range of 0 to 10% by weight, and has excellent wettability, high strength, and good corrosion resistance. Is known. However, the patent does not specifically describe the manufacturing method, and differs from the present invention in that it is an alloy composition based on Fe.

In addition, Korean Patent Publication No. 10-2017-0117573 of HOGANAS AB is Ni: bal., Cr: 20 to 35% by weight, Fe: 7 to 15% by weight, Si: 2.5 to 9% by weight %, Mo: It is composed of a range of 0 to 15% by weight, and is known to have excellent corrosion resistance. However, Ni-Cr-Fe-Si-Mo is a major element and differs from the present invention in P, which is a major fluidity improvement factor.

In addition, commercialized products include BNi-2 (Ni-Cr-B-Fe-Si) and BNi-7 (Ni-Cr-P), but in the case of BNI-2, B is used as an essential element to improve fluidity. In addition, BNI-7 is different from the present invention because Fe, which is an element for improving bonding strength and reducing cost, is omitted.

The brazing material must have an appropriate melting point to meet the appropriate brazing temperature required for post-treatment work. To this end, in the case of alloy composition design, it is necessary to manage the melting point displayed during various heating, and the object of the present invention is a nickel-based alloy powder for brazing use that has high corrosion resistance and economical efficiency while having a low melting point by properly combining several elements. And it is to provide a manufacturing method thereof.

To this end, the present invention is a nickel-chromium-iron-phosphorus (Ni-Cr-Fe-P)-based brazing alloy powder, 5 to 40% by weight of Cr, 5 to 30% by weight of Fe, 5 to 20% by weight It provides Ni-Cr-Fe-P-based brazing alloy powder containing P, the balance of Ni and other inevitable impurities.

In addition, the present invention is a method for producing a Ni-Cr-Fe-P-based brazing alloy powder through a gas atomizing process, the melting temperature is 1300 to 1650 ℃, the molten metal nozzle diameter is 3 to 10 mm , The gas injection pressure provides a method for producing a Ni-Cr-Fe-P-based brazing alloy powder having a low melting point and high corrosion resistance of 3 to 15 bar.

The Ni-Cr-Fe-P based alloy powder for brazing according to the present invention has a low melting point and high corrosion resistance, and has a low melting point compared to similar products, thereby advantageously acting on the bonding temperature in the post-treatment process. In addition, as an alloy powder having a low melting point and high corrosion resistance according to the present invention, it is possible to utilize variously as a high-functional bonding material by applying it to brazing.

1 is a SEM micrograph of powder particles manufactured by a gas atomizing process according to the present invention.
2 is a TGA analysis data for the melting point affecting the junction temperature.
3 shows a comparative evaluation of corrosion resistance, since the brazing powder is used for parts of a heat exchanger exposed to a corrosive environment, and thus an optical micrograph according to the corrosion resistance test result is shown.

The present invention relates to a Ni-Cr-Fe-P-based brazing alloy powder having a low melting point and high corrosion resistance, and a method for manufacturing the same through a gas atomizing process having a specific condition.

Hereinafter, the present invention will be described in detail.

The present invention is a Ni-Cr-Fe-P-based brazing alloy powder, containing 5 to 40% by weight of Cr, 5 to 30% by weight of Fe, 5 to 20% by weight of P, the balance of Ni and other inevitable impurities It provides Ni-Cr-Fe-P based alloy powder for brazing.

The alloy powder of the present invention contains Ni, Cr, Fe and P as main compositions, and more specifically, 5 to 40% by weight of Cr, 5 to 30% by weight of Fe, 5 to 20% by weight of P, the balance It contains, or consists solely of, Ni and other unavoidable impurities. Among the above elements, Ni, which is a base, is preferably contained in an amount of 45% by weight or more, more preferably 55% by weight or more. In addition, the alloy powder may optionally contain an element contributing to the fluidity of at least one of Si and Sn.

The alloy powder contains Cr in the range of 5% to 40% by weight for corrosion resistance in addition to Ni as the base, preferably 10% to 35% by weight, more preferably 20% to 30% by weight Include. When the Cr content is less than 5% by weight, sufficient corrosion resistance improvement cannot be expected, and when the content exceeds 40% by weight, it is preferable to include it in the above range because it adversely affects various properties such as strength during post-treatment.

In the alloy powder of the present invention, Fe is included in the range of 5% to 30% by weight, preferably 6% to 20% by weight, more preferably 7% to 13% by weight. If the content of Fe is less than 5% by weight, there is no significant economic advantage through sufficient strength improvement and replacement of expensive Ni material during post-treatment. If the content exceeds 30% by weight, economical efficiency is secured. Increasing the temperature causes an increase in the cost of the brazing process and adversely affects corrosion resistance.

In the alloy powder of the present invention, P is included in the range of 5 to 20% by weight, preferably 8% to 17% by weight, more preferably 10% to 15% by weight. When the content is less than 5% by weight, a sufficient melting point drop is not achieved, and thus, fluidity is deteriorated in the post-treatment bonding process. In addition, when the content exceeds 20% by weight, the fluidity is improved, but excessive fluidity in the post-treatment bonding process causes a problem of deteriorating the bonding strength of the bonding surface.

Optionally, the alloy powder of the present invention may contain at least one element of Si and Sn as elements contributing to strength and fluidity, and at least one element of Si and Sn is included in the range of 1% to 5% by weight, It is preferably included in the range of 1.5% to 4.5% by weight, more preferably 2% to 4% by weight. If the content is less than 1% by weight, sufficient strength and fluidity cannot be expected during post-treatment, and when the content exceeds 5% by weight, strength and fluidity are improved, but in the case of Si, due to the formation of silicide on the surface. It is not preferable because the inclusion remains and strength reduction problems may occur. On the other hand, in the case of using one or more elements of Si and Sn that affect fluidity, it is preferable to adjust the amount used in relation to P, and generally 6% by weight ≤ (one or more elements of Si and Sn) + P ≤ 25 % By weight is used, and preferably 8% by weight <(one or more elements of Si and Sn) + P <20% by weight is used.

The Ni-Cr-Fe-P-based brazing alloy powder according to the present invention may contain other inevitable impurities in a very small amount. Other inevitable impurities do not affect the properties of the Ni-Cr-Fe-P-based brazing alloy powder having a low melting point and high corrosion resistance according to the present invention.

The Ni-Cr-Fe-P-based brazing alloy powder according to the present invention has a melting point of 800 to 1,100°C, preferably 840 to 970°C. Therefore, it exhibits the same effect as a generally used brazing welding material, and has a lower melting point, and is a brazing alloy powder suitable for a low melting point.

In addition, the Ni-Cr-Fe-P-based brazing alloy powder according to the present invention exhibits excellent corrosion resistance in which very little corrosion or corrosion sites are hardly observed on the surface under conditions of pH 1 to 2. Therefore, it is suitable as a brazing material for applications such as automotive EGR cooler parts that require high corrosion resistance.

In the present invention, raw material powders are prepared using a gas atomizing process, which is an industrial powder manufacturing process by blending raw materials having the above alloy composition.

More specifically, the Ni-Cr-Fe-P-based brazing alloy powder according to the present invention is manufactured through a gas atomizing process, a melting temperature of 1300 to 1650 °C, a molten metal nozzle of 3 to 10 mm A Ni-Cr-Fe-P-based brazing alloy powder having a low melting point and high corrosion resistance was prepared using a gas injection pressure of a diameter of 3 to 15 bar.

For example, the Ni-Cr-Fe-P-based brazing alloy powder according to the present invention is a gas atomizer that is an industrial powder manufacturing apparatus after mixing the raw material having the alloy composition according to the present invention in an appropriate ratio in consideration of the purpose. (Gas atomizer) was prepared by spraying gas with a melting temperature of 1300 to 1650 ℃, a molten metal nozzle diameter of 3 to 10 mm, and a gas injection pressure of about 3 to 15 Bar, and then sufficiently cooled through a cooling time of 0 to 24 Hr. Next, it can be manufactured through a method of first classifying into 100 meshes and performing second classifying by particle size according to the characteristics required by the demander.

At this time, for a uniform composition of the alloy powder, the melting temperature is suitably in the range of 1300 to 1650°C, preferably 1350 to 1550°C, more preferably 1400 to 1500°C. It is difficult to obtain a uniform dissolution composition at a temperature of less than 1300°C, and if it exceeds 1650°C, economical efficiency is deteriorated due to problems such as an increase in dissolution cost due to overtemperature.

On the other hand, when the tapping operation according to gas atomizing, an appropriate spray nozzle is required for spraying, and in the present invention, the molten metal nozzle diameter is 3 to 10 mm, preferably 4 to 9 mm, more preferably 5 to 8 Use the mm range. If a nozzle diameter of less than 4 mm is used, the molten metal is clogged and the operation is not performed smoothly. If it exceeds 10 mm, the yield decreases and economic efficiency is poor due to the formation of coarse powder due to excessive molten metal stems.

In addition, the gas injection pressure during tapping is 3 to 15 Bar, but preferably in the range of 5 to 10 bar. If the bar is less than 3 bar, the yield decreases due to the generation of coarse powder than the required particle size, and when it exceeds 15 bar, the powder finer than the required particle size is generated, which causes poor mass productivity.

In addition, after spraying, an appropriate cooling time is required, and after sufficiently cooling through 0 to 24 Hr, preferably 6 to 18 Hr, the particle size is classified according to the characteristics required by the customer after the first classification into 100 mesh. Conduct the 2nd classification.

In the case of using the method according to the present invention, the production yield can be improved through the control of an appropriate molten metal temperature and powder particle size for securing a uniform composition, and an alloy powder suitable for a low melting point of a uniform composition can be obtained.

Hereinafter, the present invention will be described in detail by examples. However, the following examples are for illustrating the present invention, and the contents of the present invention are not limited by the following examples.

Example

The present invention will be described according to the following examples.

(Examples 1 to 21 and Comparative Examples 1 to 12)

After each of the alloy powders was prepared using the above gas atomizing manufacturing method using the composition ratios shown in Table 1, physical properties were evaluated.

In the case of the melting point, an ingot specimen was collected and measured using a TGA analysis method.For corrosion resistance, aqua regia (nitric acid 1: hydrochloric acid 1: distilled water 1 ratio) was prepared and the surface of the ingot specimen for each alloy Was corroded (immersed for 18 hrs) and the degree of corrosion was observed with the naked eye using an optical microscope.

division Ni Cr
(weight%) P
(weight%) Fe
(weight%) Si
(weight%) Sn
(weight%) B
(weight%) Melting point
(℃) Corrosion resistance Remark Example 1 Bal. 25 6 10 968 O Good Example 2 Bal. 25 12 10 956 O Good Example 3 Bal. 25 18 10 956 O Good Example 4 Bal. 25 12 7 955 O Good Example 5 Bal. 25 12 15 992 O Increase in melting point Example 6 Bal. 25 12 28 1001 O Increase in melting point Example 7 Bal. 7 12 10 971 Δ Surface corrosion,
Good Example 8 Bal. 20 12 10 962 O Good Example 9 Bal. 38 12 10 965 O Good Example 10 Bal. 25 6 10 2 964 O Good Example 11 Bal. 25 12 10 2 958 O Good Example 12 Bal. 25 18 10 2 957 O Good Example 13 Bal. 25 12 10 One 957 O Good Example 14 Bal. 25 12 10 3 951 O Good Example 15 Bal. 25 12 10 5 947 O Good Example 16 Bal. 7 12 10 2 959 Δ Good Example 17 Bal. 20 12 10 2 958 O Good Example 18 Bal. 38 12 10 2 959 O Good Example 19 Bal. 25 12 10 One 957 O Good Example 20 Bal. 25 12 10 3 955 O Good Example 21 Bal. 25 12 10 5 951 O Good Comparative Example 1 Bal. 3 12 10 984 X Surface corrosion, increasing melting point Comparative Example 2 Bal. 45 12 10 1056 O Increase in melting point Comparative Example 3 Bal. 25 3 10 987 O Increase in melting point Comparative Example 4 Bal. 25 25 10 979 O Increase in melting point Comparative Example 5 Bal. 25 12 35 1100 O Increase in melting point Comparative Example 6
(BNi-2) Bal. 7 3 5 3 970 X Surface corrosion, increasing melting point Comparative Example 7 Bal. 3 12 10 2 978 X Surface corrosion Comparative Example 8 Bal. 45 12 10 2 982 O Increase in melting point Comparative Example 9 Bal. 25 3 10 2 988 O Increase in melting point Comparative Example 10 Bal. 25 2 10 2 984 O Increase in melting point Comparative Example 11 Bal. 25 15 10 15 989 O Increase in melting point Comparative Example 12 Bal. 25 1399 O Increase in melting point

＊Criteria for evaluation of corrosion resistance (observation of surface corrosion after 18 hours immersion in aqua regia, OM)-Large amount of surface corrosion (X), surface local corrosion (Δ), no surface corrosion (O)

As can be seen in the tables of Examples 1 to 21 and Comparative Examples 1 to 12, the examples according to the present invention showed a result having a low melting point and high corrosion resistance.

More specifically, in the case of Example 15, a low melting point of 947° C. and surface corrosion were not observed. On the other hand, in the case of Comparative Example 6, a melting point of 970 °C and surface corrosion occurred.

In addition, as in the case of Comparative Example 12, when the P component and the Si component were not added, the melting point was remarkably increased and the melting point was significantly higher than that of 1050° C., which can be used as the bonding temperature of the brazing material.

On the other hand, in the case of Example 2, it was confirmed that the P component and the Fe component were contained, so that the melting point was lowered and corrosion resistance was also good compared to Comparative Example 12.

In addition, in the case of Example 15, a specimen containing a Si component along with a P component and an Fe component showed superior corrosion resistance evaluation and low melting point temperature results than that of a commercial product (Comparative Example 6).

In addition, after manufacturing the alloy powder by variously changing the manufacturing conditions as shown in Table 2 below, the degree of deviation from the target component value was confirmed through a component analyzer (ICP) in order to confirm the deviation of the highly volatile P component, The yield was evaluated and the results are shown in Table 2 below.

No. Alloy powder Melting temperature
(℃) Nozzle diameter
(mm) Injection pressure
(bar) Degree of deviation from target value of P component yield Remark 1 (Example) Example 2 1450 4 7 -One 84 Good 2 (Example) Example 2 1450 6 7 -One 94 Good 3 (Example) Example 2 1450 9 7 -One 82 Good 4 (Example) Example 2 1450 6 4 -One 96 Good 5 (Example) Example 2 1450 6 9 -One 86 Good 6 (Example) Example 2 1450 6 14 -One 84 Differential increment 7 (Example) Example 2 1320 6 7 0 89 Good 8 (Example) Example 2 1470 6 7 -One 92 Good 9 (Example) Example 2 1630 6 7 -2 94 Good 10 (Example) Example 11 1450 4 7 -One 82 Good 11 (Example) Example 11 1450 6 7 -One 91 Good 12 (Example) Example 11 1450 9 7 -One 81 Good 13 (Example) Example 11 1450 6 4 -One 93 Good 14 (Example) Example 11 1450 6 9 -One 82 Good 15 (Example) Example 11 1450 6 14 -One 82 Differential increment 16 (Example) Example 11 1320 6 7 0 86 Good 17 (Example) Example 11 1470 6 7 -One 90 Good 18 (Example) Example 11 1630 6 7 -3 90 Good 19 (Comparative Example) Example 2 1200 6 7 - 0 Molten metal cooling,
Nozzle clogged 20 (Comparative Example) Example 2 1750 6 7 -5 88 High temperature
Component volatilization 21 (Comparative Example) Example 2 1450 2 7 - 0 Nozzle clogged 22 (Comparative Example) Example 2 1450 12 7 -One 99 Coarse powder
produce 23 (Comparative Example) Example 2 1450 6 2 -One 97 Coarse powder
produce 24 (Comparative Example) Example 2 1450 6 17 -One 45 Undifferentiated and
Molten metal backflow 25 (Comparative) Comparative Example 6 1450 6 7 -One 72 Melt viscosity
increase

Above No. As can be seen through the comparison of 1 to 25, the examples according to the present invention showed excellent results in terms of the degree of deviation from the target value of the P component and the yield, while the comparative examples were melt cooling, nozzle clogging, component volatilization due to high temperature, It showed several problems, such as generation of coarse powder, micronization and backflow of molten metal, and increase in molten metal viscosity.

For example, No. 4 (Example) showed a difference of -1 and a yield of 96% in the P component target value due to factors such as oxidation, whereas No. 22 (Comparative Example) shows the result that ingot-shaped coarse powder was generated as the nozzle size increased.

Claims (8)

Ni-Cr-Fe-P-based brazing alloy powder,
20 to 38% by weight of Cr,
7 to 13% by weight of Fe,
6 to 18% by weight of P,
Ni-Cr-Fe-P-based brazing alloy powder containing the balance of Ni and other inevitable impurities. The method of claim 1,
Ni-Cr-Fe-P-based brazing alloy powder that further comprises at least one element of Si and Sn of 1 to 5% by weight. The method of claim 2,
Ni-Cr-Fe-P-based brazing alloy powder containing 6% by weight ≤ (one or more elements of Si and Sn) + P ≤ 25% by weight. The method according to any one of claims 1 to 3,
Ni-Cr-Fe-P based alloy powder for brazing, characterized in that it contains more than 45% by weight of Ni. As a method of manufacturing Ni-Cr-Fe-P based alloy powder for brazing through a gas atomizing process,
The Ni-Cr-Fe-P based alloy powder for brazing is
20 to 38% by weight of Cr,
7 to 13% by weight of Fe,
6 to 18% by weight of P,
Contains the balance Ni and other inevitable impurities,
The gas atomizing process has a melting temperature of 1300 to 1650°C, a molten metal nozzle diameter of 3 to 10 mm, and a gas injection pressure of 5 to 10 bar, which has a low melting point and high corrosion resistance. -P-based brazing alloy powder manufacturing method. The method of claim 5,
The melting temperature is 1350 to 1550 ℃ Ni-Cr-Fe-P-based method for producing an alloy powder for brazing. delete The method of claim 5,
The method for producing a Ni-Cr-Fe-P-based alloy powder for brazing further comprises 1 to 5% by weight of Si and Sn.

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