TW593779B - Anodization of Ti-rich titanium aluminide for use in high-temperature environments - Google Patents

Abstract

A method to make the surface of Ti-rich titanium aluminides less reactive chemically is disclosed. In particular, this treatment improves oxidation resistance of Ti-rich titanium aluminides at high temperature. According to the invention, anodization of Ti-rich titanium aluminides in a solution containing phosphoric and silicate solution can substantially reduce the oxidation rate. One can use this process to anodize the blades of a gas turbine, the valve of car engine, or other Ti-rich titanium aluminide structures intended for use in high-temperature environment.

Description

V. Description of the invention (1) Background of the invention: < Industrial advantage due to titanium | Lu density), so as in aircraft and so on. However, its high-titanium-aluminum-metal solid salt is resistant to a phosphoric acid solution, and the titanium-aluminum-based intermetallic T is referred to as T).嗝 人 你 N / dish also has a high specific strength (strength / high -2: in the structure that requires high temperature strength for movement, 2: cattle, turbine bow 丨, blades, air cores of car engines) oxidation resistance is not Jia has always been the bottleneck of use. The 纟 invention is mainly to increase the high-temperature oxidation resistance of titanium-aluminum-based metal by anodic treatment with silicic acid, which is more suitable for 鬲 temperature environment. The invention belongs to a titanium-aluminum intermetal containing a ThAl phase, (A + metal and r-TiAl intermetal.) In addition to using alloy design to improve the high-temperature oxidation resistance of titanium metal, the surface modification can also be used. Quality, such as plasma sprayed surface or ion implantation, to improve the high temperature oxidation resistance of titanium aluminum alloy. US Patent No. 5,118,581 (patent date: June 2, 1992) using oxidation Shi Xi and alumina, sprayed into a glass coating on the surface of titanium aluminum alloy, can improve the high temperature oxidation resistance of titanium aluminum alloy. US Patent No. 5,6 4 5, 303 (patent date: December 1,997) Utilizing 85% by weight phosphoric acid, drying at about 150 ° C and sintering above 500 ° C can effectively improve the oxidation resistance of titanium aluminum alloy at 800 ° C. US Patent No. 5, 695, 827 (patent date: December 1999) The implantation of aluminum, oxygen, argon, boron, nitrogen, and phosphorus ions into the surface of titanium-aluminum metal by ion implantation can improve the titanium-aluminum High temperature oxidation resistance of metal. Among them, titanium-based metal implanted with ion implantation

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Thermo-oxidation, thermo-oxidation titanium aluminum is good at high temperature oxidation resistance, and has metal as the main (that is, the richest technical properties. Therefore, it is beneficial to add an intermetallic surface to make the temperature oxidation resistance. This resistance Oxidation (Wu Xikan, the method of ability ", its θ is also prepared to invest in poor, shiny. Only the above-mentioned titanium-aluminum-based metal, titanium-aluminum-based metal surgery 0 can know the element of phosphorus. The use of surface production _ process not only can k Yang wood Rong, the Republic of China is easy to operate, and Chen's previous use of A-Ti3Al) has not yet been a titanium alloy. It can be improved in an acid-filled solution, and the inert film with good coating at the anode can effectively improve the titanium-aluminum dielectric. "Improving the titanium high temperature metal patent No. 0881 1 9290 while the workpieces are processed at the same time, the technology is still protected. All titanium aluminum alloys based on the γ-TiAl phase are more effective to improve the high temperature oxygen resistance. ≪ This technology is intended to solve Problems > The use of ion implantation or plasma spray high temperature oxidation properties, but its equipment investment is also poor because of its poor coverage, so for uniform implantation. And the use of phosphoric acid coating, low investment, etc. Its operating time is poor. For the use of the surface of the linoleic acid solution, the surface has a good coating property. This process can not only improve effectively, but also has a small investment in equipment, easy operation, and luster. The properties, but the improvement is very limited. Although this special coating method can improve the size of titanium-aluminum-metal, the operation is more complicated, and the cost is higher; The workpiece with a more complex shape cannot be fired uniformly. Although it has good coverage and long equipment, And in the quality of the processed workpiece, anodized titanium-aluminum-metal surface inert film is used to improve its high-temperature resistance to high-temperature oxidation resistance of titanium-metal and high-temperature oxidation resistance. At the same time, the processed workpiece still retains the high-temperature oxidation resistance of gold I Lu Jijie metal Is used in the addition of oxalic acid m

Page 6 593779 V. Description of the invention (3) The surface of the titanium-aluminum-based metal is anodized in the phosphoric acid solution of the salt to further improve the high-temperature oxidation resistance of the titanium-based metal. 〈Simplified description of the diagram〉 The following is a brief description of the diagram of the present invention. The first diagram is a 50 g / L (, 4 wt.%) Phosphoric acid aqueous solution at 18 ° C, with different Relationship between weight increase per unit area and high-temperature oxidation time of a2-Ti3Al (atomic ratio) 'after anodizing for 45 minutes under high temperature (800 ° C) air oxidation. Figure 2 shows the addition of silicates of different concentrations to a 50 g / L aqueous solution of acetic acid at 18 ° C for 45 minutes at a constant voltage of 400 V. The A-TisAl was anodized at high temperature ( The relationship between the weight increase per unit area and the high-temperature oxidation time during air oxidation at 80 ° C. 图 3 is an aqueous solution of 50 g / L scalylic acid + 30 g / L oxalate at 18. The relationship between the weight increase per unit area and the high-temperature oxidation time of α2-Τ "Α1 after anodizing at 45 ° C for different minutes at a constant voltage. The picture shows (% + r) _Ti6 () Al4 () after anodizing at 45 ° C for 45 minutes in a 50 g / L phosphoric acid aqueous solution at 18.0 ° C in a high ✓ dish (800 ° C). ) The graph of the relationship between the weight increase per unit area and the high-temperature oxidation time during the oxidation of working gas. Figure 5 shows the addition of 50 g / L phosphoric acid solution at different concentrations of sodium silicate at 18 ° C at 300 ° C. (Α 2 + 7) after V constant voltage anodizing-'At high temperature (80.00 air oxidation, the weight increase per unit area and high temperature oxidation Inter-relationship diagram.

593779 5. Description of the invention (4) Figure 6 shows (% + τ) -Ti6QAl40 after anodizing at different constant voltages in an aqueous solution of 50 g / L phosphoric acid + 10 g / L silicate at 18 ° C. A graph showing the relationship between the weight increase per unit area and the high-temperature oxidation time when the air is oxidized at a local temperature (800 ° C). Figure 7 shows (a2 + r) -Ti6 () Al4 () after anodizing at different constant voltages in an aqueous solution of 50g / L phosphoric acid + 30g / L silicate at 18 ° C. The relationship between the weight increase per unit area and the high temperature oxidation time when the temperature (800 ° c) air is oxidized. Figure 8 shows (% + r) -Ti53Al47 after anodizing at 45 ° C for 45 minutes in a 50 g / L dish acid aqueous solution at 18 ° C at different temperatures. 〇The graph of the relationship between the weight increase per unit area and the high temperature oxidation time during air oxidation. Figure 9 is a solution of silicate with different concentrations in 50,000 Å filled with acid at 18 ° C at 30 ° C. (A2 + 7) -Ti53Al47 'after anodizing at a constant voltage of 45V for 45 minutes under high temperature (800) air oxidation, the relationship between the weight increase per unit area and the high temperature oxidation time. —Figure 10 shows the 18 times, in an aqueous solution of 50 g / L phosphoric acid + 30 g / L silicate, at different constant voltages, after 45 minutes of anodic treatment (A + =), —TyAl47, at high temperature (8 00 ° c) air The relationship between the increase in weight per unit area and the high-temperature oxidation time during oxidation. <Example> Three types of alloys: α2 phase-titanium alloy phase-titanium-aluminum alloy were selected. It is a material. Α 2 + γ-phase-titanium This invention is applicable to these titanium aluminum alloys

Page 8 593779 V. Description of the invention (5) By vacuum arc remelting (VAR) of pure titanium (such as 9 9 9. 98wt%) to make ingots with the required composition, mask: and pure aluminum (such as 1150 ° C, 75hrs) vacuum homogenization heat treatment :: Intermediate and high temperature (such as using X-ray diffraction patterns to confirm its crystal structure. After its furnace is cooled to room temperature, Rifa can also formulate the titanium-aluminum alloy with the required composition Metals, alloys, alloys, powder metallurgy, etc. After cutting, such as vacuum induction remelting, platinum electrodes are used (others such as Ming alloys, copper alloys, aluminum alloys, and aluminum alloys, ^ α σ σ gold or other non-reactive inert Electrode 4 is also available), the distance between the% electrode and the cathode is 5 volts, temperature, and phosphoric acid + silicate concentrated electrode treatment pair (a9 + r). The t-metal and ~ phase-titanium Ming-Metal (T 13 A 1) oxidation resistance improvement at the south temperature. The high-temperature oxidation resistance was evaluated by taking it at 800 intervals in the air at a fixed interval. Air-cooled to room temperature for electronic days to evaluate its high-temperature oxidation resistance: milk is obtained from the weight increase of the early area &lt; Example β &gt; ^ 2-T "Α1 test piece at 18. : In a 50g / L phosphoric acid solution, the higher the external voltage, the rougher the surface of the test piece. This increase in voltage will increase the temperature of the compound and increase the ability of the phosphoric acid to dissolve the oxide film. The first is to oxidize Tijl in an 18 t 50g / L phosphoric acid aqueous solution at different constant voltages, and then oxidize it with high-temperature (80.000 air), and take the weight increase per unit area in summer. Relation diagram with high temperature oxidation time. Obviously, the high temperature oxidation of α2-T "A 1 can be slowed down by anodic treatment in phosphoric acid solution. The higher the constant voltage of anodic treatment, the more

593779 V. Description of the invention (6) The high-temperature oxidation resistance properties of the titanium-aluminum-intermediate metal in the α2 phase after physical treatment tend to be better. However, the results of its South-temperature oxidation cycle test are still not good. After the air oxidation at 800 ° C for seventy hours, in addition to the dark black protective oxide film on the surface of the test piece, a peeling white oxide film will also appear. . Figure 2 shows -Ti3Ai after adding silicates at different concentrations to an aqueous phosphoric acid solution at 18 ° C for 45 minutes at a constant voltage of 40 0V. Compared with the high temperature oxidation results shown in Figure 1, it can be seen that the addition of silicate can effectively improve its high temperature oxidation resistance. Figure 3 is a 50 ° / L dish acid + 30g / L sodium silicate solution, anodized at different constant voltages, and then treated with T'A1 at a constant temperature at 800 ° C. When the applied voltage range is 300V ~ A dark black oxide layer with good high-temperature oxidation resistance between 400V, because there is no peeling of the oxide layer at a high temperature oxidation test for 70 hours, and its oxidation rate follows the quadratic reaction rate formula, where w is the unit area Weight gain, t is the oxidation time, and κ is the parabolic Oxide rate constant. [Ρ · Kofstad, High Temperature Corrosion, Elsevier Applied Science Pub · Ltd 1988, p. 164]. Therefore, the formula ( 1) The calculated Kp value of the voltage at 35v is 0.0001 74 mg2 / cm4hr, and the Kp value of the test piece without anodizing is about 0.2798 mg2 / cm4hr or more (this is from TGA The approximate results obtained by the constant temperature oxidation and test, because the surface oxide layer peeling is very serious for the cyclic oxidation test), the slope (κ) of the equation (1) is improved by 1κ

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160. The test film with anodized 300v ~ 400V in 50g / L phosphoric acid + 30g / L sodium silicate solution at 18 ° C has the best oxidation resistance. <Example 2> T16OAl40 test piece in 50 g / L phosphoric acid solution at 18 ° C, the higher the applied voltage, the rougher the surface of the test piece, the weight increase of the unit area of the test piece after 45min of anodization, will also It increases as the applied voltage increases. And when the anode treatment is more than 200V, sparks will appear on the surface of the test piece. Figure 4 shows the different constant voltages in a 50 g / L phosphoric acid aqueous solution at 18 ° C. (R) -TUk after anodizing for 45 minutes, the relationship between the weight increase per unit area and the high-temperature oxidation time when air oxidation at high temperature (0 ° C). It can be seen from the figure that its oxidation resistance will increase with the increase of the anode treatment voltage (100V-400V). The 400v effect is the best. The Kp value of 400V is 0.0 0 0236 mg2 / cm4hr, and the improvement degree is 1/1400. From the SEM metallographic chart, it can be found that the surface of the 400 v test piece has not changed much before and after heating ', and needle-shaped Al 2 O 3 oxide is formed on the surface after heating for 70 hr. A picture five, and seven are (A + 9) _Ti6QAl4 () titanium | Lu Jie metal, respectively, the concentration of sodium silicate was added to 50 g / L phosphoric acid aqueous solution, anodized at a constant voltage of 300 v And in an aqueous solution of 50 g / L phosphoric acid + 10 g / L silicate, anodized at different constant voltages, and in an aqueous solution of 50 g / L phosphoric acid + 30 g / L silicate , Three different surface treatments, such as different constant voltage anodization, == The result of the relationship between the weight increase per unit area and the high temperature oxidation time at high temperature (800 ° C air oxidation. The Kp value is calculated to compare to Xing 乂'In a 50 g / L phosphoric acid + 30 g / L sodium silicate solution, the effect of applying a voltage of 300 V is better, and its Kp value is 0.00166 mg / cm4hr, the degree of improvement is 1 / 2080, comparing the results in Figure 4, we can see that adding silicate can further improve

593779 V. Description of Invention (8)

Vll: '): Tl6 () Al4i) High temperature oxidation resistance. It can be found from the sem metallographic diagram that needle-shaped A 丨 2 oxides appeared on the surface of the test piece with a %% oxidation. <Example 1> Figure 8 shows (Seven + Two) and -Ti53jU47 after anodizing at 45 ° C for 50 minutes in an aqueous 50 g / L phosphoric acid solution at 18 ° C, at a high temperature (80 〇〇〇 Air oxidation, the weight increase per unit area and the relationship between high temperature oxidation time. TkAiu test strip in 18 50 g / L phosphoric acid solution, the higher the applied voltage, the more the surface of the test piece Coarse k, when the voltage is increased, the temperature of the solution will rise, and the ability of the phosphoric acid / combined oxide film will be enhanced. When the anode treatment voltage is greater than 20%, sparks will appear on the surface of the test piece. Nine and Figure ten are (α2 + τ) —Ti53Al47 at 18 t, respectively, in the addition of the hexanox oxalate in 50 g / l scale acid aqueous solution, with a constant voltage of 300 v, After 45 minutes of anodic treatment, and at 18 ° C, in an aqueous solution of 50 g / L phosphoric acid + 3Og / L silicate, at different constant voltages, after 45 minutes of anodic treatment and other surface treatment, at high temperature (8 The results of the air oxidation test. Comparing the results in Fig. 8, it can be seen that the addition of silicate can further improve (α 2 + 7 ) -1 ^ 53 high-temperature oxidation resistance of human 147. In 18. (3 of 50/2/1 phosphoric acid + 10 § / 1 ^ Shixi k nano solution part 'with 2000V and 300V The effect is better, of which 300V

The Kp value was 0.00193 mg2 / cm4hr. In the part of 50g / L phosphoric acid + 30g / L sodium silicate solution, the effect of 200V and 400V is better. The Kp value of 400V is 2.352 X 1 (P mg2 / cm4hr. For comparison, the value of κρ is In 50 g / L phosphoric acid + 30 g / L ♦ sodium voltage applied the best effect of the voltage of 400 V, the degree of improvement reached 1/3180. From the above statistical analysis, at 50 g / L structural acid + 3 0 g / L sodium silicate solution

Page 12 593779 5. In the description of the invention (9), the high-temperature oxidation test at 8 0 ° C between 3 Ο Ο V ～ 4 〇 Ο V, the improvement degree of each metal Kp is as follows: α2-Τι3Α1 1/160 (a2 + 7) -Ti6〇A 14〇1 / 2 080 (α 2 + τ &quot;)-T i53 A 147 1/3180

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Claims (1)

593779 ——; /// &quot; '' 二 / \ 一 j: _ 六) —Shen Yingliu Fanfan I. 1. A titanium-rich aluminum-containing metal that contains the following steps: J 丄 / High temperature resistance to oxidation Method, at least to provide metal, especially titanium-rich side titanium aluminum metal, and in a phosphoric acid solution, or a solution of silicate added t, the titanium aluminum metal on the anode, at 0 ° C to At 28 ° C · 'and the anode operating voltage is 15 volts to 400 volts, the cathode is an I # 金 惠 _ chemically inert film on the surface of the titanium aluminum alloy. 2. The method according to item 1 of the scope of patent application, in which the above-mentioned "titanium inscription" of the cup is a 0 ^ 2 phase intermetal. 3. The method as described in item 1 of the patent scope of Shenlong, wherein the above-mentioned titanium-rich metal is an alpha 2 + 7 phase intermetal. 4. The method according to item 1 of the scope of patent application, wherein the above-mentioned anodized cathode is a platinum electrode. 5. The method according to item 1 of the scope of patent application, wherein the above-mentioned anodized electrolyte solution is a solution containing phosphorus and silicon. 6. The method according to item 5 of the scope of patent application, wherein the above-mentioned solution containing the filling and stone evening is a solution of phosphoric acid and water glass (silicate). 7. The method according to item 5 of the scope of patent application, wherein the optimal range of the concentration of the above-mentioned electrolyte solution is the optimal range of the concentration of phosphoric acid containing 0 g / L to / 500 g / L, water glass (silicate ) The optimal concentration range is 4 g / L g / L °