Method of treating surface of Ti-Al alloy and Ti-Al alloy obtained by the same

A surface treatment, ti-al technology, applied in the direction of metal material coating process, coating, solid diffusion coating, etc., can solve the problems that have not been raised, high temperature corrosion resistance, oxidation resistance degradation, etc., to achieve improved resistance High temperature oxidation resistance, effect of improving high temperature oxidation resistance

Inactive Publication Date: 2010-08-11
AIR WATER INC
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  • Abstract
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Problems solved by technology

[0003] However, the above-mentioned Ti-Al-based alloy has a problem that it is superior in oxidation resistance at a temperature of 800° C. or lower than ordinary Ti alloys and the like, but when it exceeds 800° C., the oxidation resistance rapidly deteriorates.
However, the mixed atmosphere containing halogen and oxygen is highly corrosive, and when it is heated to a high temperature of 700-1125°C for treatment, at least the reaction furnace wall material for this treatment needs to have high high-temperature corrosion resistance
Therefore, as a result, the following problems occur: In addition to the high cost of the processing equipment, frequent replacement of the furnace wall material is required, and the processing is not suitable for mass production.
[0024] As described above, in order to improve the high-temperature oxidation resistance of Ti-Al alloys, it is considered that in the oxide layer formed in a high-temperature oxidizing atmosphere, especially uniform Al with low oxygen permeability 2 o 3 Coating the surface of the Ti-Al alloy base material with a film is the most effective method, but there are a lot of research publications and patent documents on this method, but it is especially aimed at making strong improvements in productivity and mass production. means of reporting but did not present

Method used

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  • Method of treating surface of Ti-Al alloy and Ti-Al alloy obtained by the same

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0048] Sponge titanium (sponge titanium) with a purity of 99.8% and aluminum with a purity of 99.99% were weighed to form the target composition, and a melting furnace was used to vacuum exhaust once to reach 10 -4 After Torr or more, it was melted and solidified in an Ar gas atmosphere to produce an ingot (Ti-48 atomic % Al). A plate-shaped test piece of 30 mm×10 mm×3 mm was cut out from the ingot, and the surface of the test piece was polished with No. 1000 SiC paper, and then ultrasonically cleaned in acetone to obtain a test piece.

[0049] With this test piece as embodiment A~E, by containing 2 volume % of NF 3 gas, balance by N 2 In the fluorine source gas atmosphere composed of gas and impurity gas, the method of maintaining at 200-400° C. for 5-120 minutes was used to prepare the test piece subjected to the fluorine-concentrated treatment. The thickness of the fluorine-concentrated layer and the maximum concentration of F are measured using ESCA (X-ray photoelectron ...

Embodiment 2

[0056] In order to investigate the influence of the highest F concentration in the fluorine-concentrated layer, the same test piece as in Example 1 was produced, and the concentration of the fluorine gas in the atmosphere was changed to make the thickness of the fluorine-concentrated layer equal. The highest F concentration in the fluorine-intensified layer varies and so is handled. The test piece of embodiment F is in the NF containing 3 volume % 3 gas, balance by N 2 In the fluorine source gas atmosphere composed of gas and impurity gas, it was kept at 350°C for 60 minutes. In addition, the test piece of Comparative Example C was made of NF containing 30% by volume. 3 gas, balance by N 2 In a fluorine source gas atmosphere composed of fluorine gas and impurity gas, the temperature was kept at 350° C. for 60 minutes. Thereafter, the same oxidation test as in Example 1 was performed at 1000° C.×100 hr (in air). The results are shown in Table 2.

[0057] Table 2

[0058] ...

Embodiment 3

[0064] In order to investigate the influence of the Al content of the Ti-Al alloy, the raw material was weighed so that the Al content was 15 atomic %, 30 atomic %, 45 atomic %, and 55 atomic %, so that the raw material reached the target composition as in Example 1, It was melted and solidified to produce an ingot, and a plate-shaped test piece of 30 mm×10 mm×3 mm was cut out, and then the surface was ground and ultrasonically cleaned in acetone to obtain a test piece.

[0065] For these test pieces with different compositions, when containing 2% by volume of NF 3 gas, balance by N 2 In the fluorine source gas atmosphere composed of gas and impurity gas, the fluorine densification treatment was carried out at 300°C for 120 minutes, and then the oxidation test was carried out in the air at 1000°C for 100 hours. The results are shown in Table 3 below. In addition, the thickness of the fluorine-concentrated layer of the test pieces subjected to the fluorine-concentrated treatme...

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Abstract

A surface treatment method for improving the unsusceptibility of a Ti-Al alloy to oxidation at high temperatures in a manner suitable for mass production; and a Ti-Al alloy. A Ti-Al alloy base containing 15-55 at.% aluminum is held with heating in a gas atmosphere containing a fluorine source gas to form a fluorine-rich layer having a thickness of 0.1-10 [mu]m on the surface of the base. The fluorine-rich layer is regulated so as to have a maximum fluorine concentration of 2-35 at.%. When exposed to a high-temperature oxidizing atmosphere, this surface of the Ti-Al alloy base is coated with an Al2O3 coating film having extremely low oxygen permeability. This alloy hence has excellent unsusceptibility to high-temperature oxidation. Thus, the poor unsusceptibility to high-temperature oxidation which is a most serious defect of the Ti-Al alloy, which is lightweight and has a high high-temperature strength, can be improved in a manner suitable for mass production. The Ti-Al alloy thus treated can be advantageously used as, e.g., a turbine wheel for superchargers, engine bulb, or turbine blade for gas turbines.

Description

technical field [0001] The present invention relates to a surface treatment method for improving high-temperature oxidation resistance by forming a fluorine-concentrated layer on the surface of a Ti-Al alloy, and the obtained Ti-Al alloy. Background technique [0002] Ti-Al-based alloys have the characteristic that the strength of TiAl intermetallic compounds does not decrease even at a temperature of about 800° C., but rather increases, and thus is used as a high-temperature material. In addition, it has the characteristic that its specific gravity is smaller than that of Ti alone, and it is very lightweight compared to Ni-based superalloys such as Inconel 713C, which are widely used as heat-resistant metals, and its specific gravity is about 1 / 2 of that. Therefore, for example, it can be applied to turbocharging turbos and engine valves of automobiles, and can achieve high performance such as improvement of fuel consumption and responsiveness, and high-speed rotation of th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C8/08C22C14/00
CPCC23C8/80C23C8/06C23C8/08C22C14/00C22C21/003
Inventor 渡边崇则岩村英明西川晃司
Owner AIR WATER INC
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