Method for improving hot corrosion resistance of Co-Al-W high temperature alloy by utilizing pre-oxidation

A high-temperature alloy, co-al-w technology, applied in the direction of metal material coating process, coating, solid-state diffusion coating, etc., can solve the problem that the alloy matrix cannot be protected for a long time, the oxide layer is easily corroded by secondary corrosion, and the oxide layer is damaged structure and other issues, to improve the thermal corrosion resistance, avoid further corrosion, and reduce the thickness of the corrosion layer

Active Publication Date: 2019-01-04
NORTHEASTERN UNIV
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Problems solved by technology

A large number of experiments have shown that at 75% Na 2 SO 4 In +25% NaCl medium, the corrosion layer of the Ni-based superalloy still falls off after pre-oxidation treatment, or a large number of cracks appear in the corrosion layer after 100 hours of corrosion, which cannot protect the alloy matrix for a long time; because the corrosion medium can destroy the structure of the oxide layer, the oxide layer is easy to Being corroded twice, it is difficult to find a pre-oxidation layer that can exist stably in the corrosive medium, which limits the application of pre-oxidation technology in Co-Al-W superalloys, and the effect is not good, leading to widespread research in the prior art The direction is still in the field of coating

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  • Method for improving hot corrosion resistance of Co-Al-W high temperature alloy by utilizing pre-oxidation
  • Method for improving hot corrosion resistance of Co-Al-W high temperature alloy by utilizing pre-oxidation
  • Method for improving hot corrosion resistance of Co-Al-W high temperature alloy by utilizing pre-oxidation

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Embodiment 1

[0028] Taking the cobalt-based superalloy shown in Table 1 as the material of the example, it is processed into a hot corrosion sample of 10mm×10mm×3mm by using a wire cutting machine tool, a grinding machine, etc. The hot corrosion samples were polished with 1000# sandpaper, cleaned with alcohol, dried and placed in a clean corundum crucible, and pre-oxidized at 950°C for 72 hours in a box-type resistance furnace.

[0029] The 800°C hot corrosion test was carried out on the pre-oxidized alloy and the non-pre-oxidized alloy, and the corrosion medium was 75wt.%Na 2 SO 4 +25 wt.% NaCl. Its corrosion kinetic curve is as follows figure 1 shown. It can be seen that the corrosion increase of the pre-oxidized alloy is greatly reduced. When corroded at 800℃, the average corrosion weight gain rate of the pre-oxidized alloy is about 17% of that of the non-pre-oxidized alloy, and the corrosion resistance of the alloy is significantly improved. figure 2 and image 3 Corrosion layer...

Embodiment 2

[0031] Same as embodiment 1 method. The 850°C hot corrosion test was carried out on the pre-oxidized alloy and the non-pre-oxidized alloy, and the corrosion medium was 75wt.%Na 2 SO 4 +25 wt.% NaCl. Its corrosion kinetic curve is as follows figure 1 shown. When corroded at 850℃, the corrosion increase of the pre-oxidized alloy is greatly reduced, and the average corrosion weight increase rate is about 14% of that of the non-preoxidized alloy, indicating that the corrosion resistance of the alloy has been significantly improved. Figure 4 and Figure 5 Corrosion layer cross section of pre-oxidized alloy and non-preoxidized alloy corroded at 850°C for 99h. The thickness of the corrosion layer of the pre-oxidized alloy is significantly smaller than that of the non-pre-oxidized alloy, and the structure of the pre-oxidized layer is dense after being corroded at 850 ° C for 99 hours. The continuous oxide layer prevents corrosive media such as O, S and Cl from entering the matri...

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Abstract

The invention discloses a method for improving hot corrosion resistance of Co-Al-W high temperature alloy by utilizing pre-oxidation. The method comprises the following steps: under atmospheric conditions, heating cobalt-based high temperature alloy to 950 DEG C and carrying out oxidation treatment for 50-100 hours to obtain a pre-oxidized layer with the thickness of 2-10 micrometers, wherein thethickness of an Al2O3 layer is 0.5-2 micrometers. The method disclosed by the invention has the advantages that the process is simple and the energy is saved. Compared with un-pre-oxidized alloy, thepre-oxidized alloy has the advantages that the pre-oxidized layer is structurally stable in a corrosive medium and the corrosive medium can be effectively prevented from entering the alloy matrix, sothat the corrosion weight gain of the alloy is significantly reduced by 80% or above and the hot corrosion resistance of the alloy is remarkably enhanced.

Description

technical field [0001] The invention relates to the technical field of metal corrosion protection, and mainly relates to a method for enhancing the thermal corrosion resistance of Co-Al-W superalloys. Background technique [0002] In 2006, Sato et al. discovered Co in Co-based alloys 3 (Al,W)-γ′ phase. Unlike traditional cobalt-based superalloys, the discovery of the γ′ phase means a transformation of the alloy strengthening method, which is similar to that of nickel-based superalloys and can greatly increase the high-temperature strength of cobalt-based alloys. Therefore, the γ′ phase-strengthened cobalt-based superalloy is called a new type of cobalt-based superalloy. [0003] Under high temperature conditions, the strength of the γ′ phase-strengthened cobalt-based superalloy is relatively high, which has met the strength requirements of hot-end components such as industrial gas turbines. When superalloys are in service, superalloys are often eroded by corrosive media s...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C8/02C23C8/10
CPCC23C8/02C23C8/10
Inventor 王磊高博宋秀刘杨
Owner NORTHEASTERN UNIV
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