CN111270198A - Ion nitriding method for titanium alloy - Google Patents

Abstract

The invention discloses a titanium alloy ion nitriding method, which relates to the technical field of surface treatment. It includes placing the workpiece in a plasma nitriding furnace, feeding nitriding gas, controlling the nitriding voltage to be 500-700V, controlling the temperature in the plasma nitriding furnace to slowly rise to 750-950°C, the air pressure to 500-1500Pa, and keeping the temperature at 500-1500Pa. The required thickness of the infiltrating layer is obtained; the nitriding gas includes nitrogen-containing gas, hydrogen, argon and an infiltration agent, and the infiltration agent includes at least one of rare earth oxide, oxygen-containing gas and carbon-containing gas. The nitriding method provided by the invention has the characteristics of fast penetrating speed, reducing nitriding temperature, thick nitriding layer, high hardness, good wear resistance and small deformation of workpiece.

Description

A kind of titanium alloy ion nitriding method

technical field

The invention relates to the technical field of surface treatment, in particular to a method for ion nitriding of titanium alloys.

Background technique

Titanium and titanium alloys have excellent comprehensive properties and are widely used in aerospace and automotive fields. However, titanium alloys have low surface hardness and poor wear resistance, which limit the wide application of titanium alloys. Ion nitriding is a commonly used surface treatment method, which can obtain a surface with a thick layer and high surface hardness. At present, the commonly used ion nitriding treatment methods have the defects of slow nitriding speed, long nitriding time, and high temperature during nitriding, which affect the structure and properties of the workpiece.

In view of this, the present invention is proposed.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a titanium alloy ion nitriding method to solve the above-mentioned technical problems.

The present invention is realized in this way:

A titanium alloy ion nitriding method, which comprises placing a workpiece in a plasma nitriding furnace, feeding a nitriding gas, controlling the nitriding voltage to be 500-700V, and controlling the temperature in the plasma nitriding furnace to slowly rise to 750-950 ℃, the air pressure is 500-1500Pa, and the required thickness of the infiltrating layer can be obtained by heat preservation; the nitriding gas includes nitrogen-containing gas, hydrogen, argon and infiltration agent, and the infiltration agent includes rare earth oxide, oxygen-containing gas and carbon-containing gas. at least one of.

In the present invention, the nitriding temperature of the titanium alloy can be significantly reduced by adding the infiltration catalyst into the nitriding gas, the infiltration rate can be increased, the deformation of the workpiece can be reduced, and at the same time, titanium with good toughness, high hardness, good wear resistance and good corrosion resistance can be obtained. Alloy layer.

The rare earth oxides in the infiltration catalyst can refine the grains of the infiltration layer, purify the grain boundaries, increase the infiltration rate, and obtain the infiltration layer structure with good toughness and high hardness.

The oxygen-containing gas in the infiltration catalyst can accelerate the infiltration rate, reduce the ion infiltration temperature, and increase the thickness of the infiltration layer, and the formed titanium oxide helps to improve the wear resistance and corrosion resistance of the infiltration layer.

The carbon-containing gas in the infiltration catalyst can accelerate the infiltration rate and form a carbon-containing phase on the surface of the titanium alloy, which is beneficial to improve the wear resistance of the infiltration layer.

After the nitriding gas is introduced, by controlling the nitriding voltage and gas pressure, the temperature in the ion nitriding furnace is gradually increased to a specified temperature, and then the temperature is maintained at this temperature. At this temperature, a layer of nitrogen is formed on the surface of the titanium alloy. Compared with other surface modification layers, the nitride layer has the advantages of strong bonding force between the infiltrating layer and the substrate, and it is not easy to fall off during the friction process. In addition, the infiltration layer can significantly improve the microhardness of the titanium alloy surface and improve the wear resistance of the titanium alloy.

The gradient of heating is related to the size of the workpiece. The larger the workpiece, the slower the heating rate and the longer the heating time. On the contrary, the heating time is shorter.

In a preferred embodiment of the present invention, the nitriding gas contains the following components by volume percentage: 5-50% of hydrogen, 10-30% of argon, 0.5-40% of infiltration agent, and the balance of nitrogen gas.

Under the above-mentioned nitriding gas percentage conditions, a titanium alloy infiltrated layer with good toughness, high hardness, good wear resistance and good corrosion resistance can be quickly prepared on the surface of the titanium alloy.

In a preferred embodiment of the present invention, the nitriding gas contains the following components by volume percentage: 5-50% of hydrogen, 10-30% of argon, 0-10% of rare earth oxide, and 1% of oxygen-containing gas -40%, the balance is nitrogen-containing gas.

In a preferred embodiment of the application of the present invention, the nitriding gas contains the following components by volume percentage: 5-50% of hydrogen, 10-30% of argon, 0.5-10% of rare earth oxide, and 0% of oxygen-containing gas. -40%, carbon-containing gas 1-40%, the balance is nitrogen-containing gas.

In a preferred embodiment of the present invention, the nitriding gas contains the following components by volume percentage: 5-50% of hydrogen, 10-30% of argon, 0.5-10% of rare earth oxide, and 1% of oxygen-containing gas -40%, carbon-containing gas 0-40%, and the balance is nitrogen-containing gas.

In a preferred embodiment of the present invention, the nitriding gas contains the following components by volume percentage: 5-50% of hydrogen, 10-30% of argon, 0.5-10% of rare earth oxide, and 1% of oxygen-containing gas -40%, carbon-containing gas 1-40%, the balance is nitrogen-containing gas.

In a preferred embodiment of the present invention, the rare earth oxide is at least one of yttrium oxide, cerium oxide, and lanthanum oxide.

In other embodiments, the remaining rare earth oxides are also within the scope of the present invention.

In a preferred embodiment of the application of the present invention, the rare earth oxides introduced into the ion nitridation furnace are rare earth saturated solutions dissolved in organic solvents, and the volume percentage of rare earth oxides in the nitriding gas is rare earth saturated solutions The volume percentage after volatilization in the ion nitriding furnace.

In a preferred embodiment of the present invention, the above-mentioned organic solvent is anhydrous ethanol.

In the actual preparation, the rare earth oxide is placed in anhydrous ethanol, and the obtained saturated solution is used in an ion nitridation furnace until the precipitate is precipitated in the anhydrous ethanol.

In a preferred embodiment of the application of the present invention, the above-mentioned oxygen-containing gas is at least one of CO ₂ , N ₂ O and O ₂ .

In a preferred embodiment of the application of the present invention, the above-mentioned carbon-containing gas is at least one of methane, acetylene, propane and natural gas.

The natural gas may be commercially available natural gas.

In a preferred embodiment of the present invention, the above-mentioned nitrogen-containing gas is at least one of nitrogen gas and ammonia gas.

In a preferred embodiment of the application of the present invention, after the workpiece is placed in a plasma nitriding furnace, vacuum is first drawn, and then a gas with a hydrogen to argon ratio of 1:3 to 3:1 is introduced for sputtering cleaning. After jet cleaning, the nitriding gas is introduced.

In a preferred embodiment of the application of the present invention, the workpiece is degreasing, rust-removing and cleaning, dried and placed in an ion nitriding furnace, and evacuated until the vacuum degree of the plasma nitriding furnace is below 5Pa.

In a preferred embodiment of the present invention, the air pressure of the sputtering cleaning is 30-100Pa, the voltage is 500-1000V, and the sputtering cleaning time is 30-60min.

In other embodiments, before placing the workpiece into the ion nitriding furnace, it also includes degreasing, derusting and cleaning the workpiece, and then placing it in the ion nitriding furnace after drying.

The present invention has the following beneficial effects:

The invention provides a titanium alloy ion nitriding method. In the method, adding an infiltration agent to the nitriding gas can significantly reduce the nitriding temperature of the titanium alloy, increase the infiltration rate, reduce the deformation of the workpiece, and at the same time obtain good toughness and hardness. High, wear-resistant and corrosion-resistant titanium alloy layer. After the nitriding gas is introduced, by controlling the nitriding voltage and gas pressure, the temperature in the ion nitriding furnace is gradually increased to a specified temperature, and then the temperature is maintained at this temperature. At this temperature, a layer of nitrogen is formed on the surface of the titanium alloy. Compared with other surface modification layers, the nitride layer has the advantages of strong bonding force between the infiltrating layer and the substrate, and it is not easy to fall off during the friction process. In addition, the nitride infiltration layer can significantly improve the microhardness of the titanium alloy surface and improve the wear resistance of the titanium alloy.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore do not It should be regarded as a limitation of the scope, and for those of ordinary skill in the art, other related drawings can also be obtained according to these drawings without any creative effort.

Fig. 1 is the sectional topography of the titanium alloy nitrided layer prepared in Example 5;

Fig. 2 is the XRD pattern of the titanium alloy nitrided layer prepared in Example 4 and the XRD pattern of the titanium alloy nitrided layer prepared in the comparative example;

3 is a cross-sectional hardness gradient diagram of the nitrided layers prepared in Example 9 and Comparative Example.

Detailed ways

In order to make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not indicated in the examples, it is carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments used without the manufacturer's indication are conventional products that can be purchased from the market.

The features and performances of the present invention will be further described in detail below in conjunction with the embodiments.

Example 1

The present embodiment provides a titanium alloy ion nitriding method, which includes the following steps:

(1) Degreasing, derusting and cleaning the TC4 titanium alloy workpiece;

(2) Put the dried workpiece into the ion nitriding furnace, and vacuumize to below 5Pa;

(3) The ratio of introducing hydrogen and argon is 1:2, the air pressure is 30Pa, the bias voltage is 500V, and the sputtering cleaning is 60min;

(4) The hydrogen content is 5%, the argon content is 10%, the yttrium oxide rare earth is 0.5%, the CO ₂ gas is 40%, and the balance is nitrogen. During nitriding, the voltage is 500-600V, the temperature in the furnace is slowly raised to 750°C, the heating rate is 2-5°C/min, the air pressure is 600-800Pa, and the temperature is kept for 12 hours. During nitriding, the temperature in the furnace is controlled to rise slowly to 750°C. During this process, the gas pressure and voltage of nitriding can be adaptively adjusted within the corresponding range. In fact, in the production process, in order to control the temperature in the heat preservation stage, the temperature during nitriding can be adjusted. Voltage and air pressure can be adjusted within the above ranges as required.

The thickness of the obtained nitrided layer reaches 218μm, the surface hardness HV is 919, a good hardness gradient is formed, and the wear rate is 4.07×10 ^-4 mm ³ /mN; the hardness of the matrix is 345HV, and the wear rate is 5.48×10 ^-4 mm ³ . /mN, the wear resistance after nitriding is 26% higher than that of the matrix.

Example 2

The present embodiment provides a titanium alloy ion nitriding method, which includes the following steps:

(1) Degreasing, derusting and cleaning the TC4 titanium alloy workpiece;

(2) Put the dried workpiece into the ion nitriding furnace, and vacuumize to below 5Pa;

(3) The volume ratio of hydrogen gas and argon gas is 1:1, the air pressure is 100Pa, the bias voltage is 1000V, and the sputtering cleaning is 30min;

(4) The hydrogen content is 10%, the argon content is 20%, the yttrium oxide rare earth is 3%, the _CO2 gas is 20%, and the balance is nitrogen. During nitriding, the voltage is 550-700V, the temperature is slowly raised to 850°C, the heating rate is 2-5°C/min, the air pressure is 1000-1500Pa, and the temperature is kept for 4 hours. During nitriding, the temperature in the furnace is controlled to rise slowly to 850°C, and the gas pressure and voltage of nitriding can be adaptively adjusted within the corresponding range during this process. In fact, in the production process, in order to keep the temperature in the heat preservation stage unchanged, the voltage and air pressure during nitriding can be adjusted within the above range as required.

The thickness of the obtained nitrided layer reaches 376 μm, the surface hardness HV is 959, a good hardness gradient is formed, and the wear rate is 2.14×10 ^-4 mm ³ /mN; the matrix hardness is 345HV, and the wear rate is 5.48×10 ^-4 mm ³ /mN, The wear resistance after nitriding is 61% higher than that of the matrix.

Example 3

The present embodiment provides a titanium alloy ion nitriding method, which includes the following steps:

(1) Degreasing, derusting and cleaning the TC4 titanium alloy workpiece;

(2) Put the dried workpiece into the ion nitriding furnace, and vacuumize to below 5Pa;

(3) The ratio of feeding hydrogen and argon is 2:1, the air pressure is 60Pa, the bias voltage is 800V, and the sputtering cleaning is 50min;

(4) The hydrogen content is 10%, the argon content is 10%, the rare earth lanthanum oxide is 3%, the N ₂ O gas is 40%, the propane gas is 1%, and the balance is ammonia gas. The voltage during nitriding is 550-650V, the temperature is slowly raised to 900°C, the heating rate is 2-5°C/min, the air pressure is 800-1000Pa, and the temperature is kept for 4 hours. During nitriding, the temperature in the furnace is controlled to rise slowly to 900°C, and the gas pressure and voltage of nitriding can be adaptively adjusted within the corresponding range during this process. In fact, in the production process, in order to keep the temperature in the heat preservation stage unchanged, the voltage and air pressure during nitriding can be adjusted within the above range as required.

The thickness of the obtained nitrided layer reaches 376 μm, the surface hardness HV is 1177, a good hardness gradient is formed, and the wear rate is 2.14×10 ^-4 mm ³ /mN; the matrix hardness is 345HV, and the wear rate is 5.48×10 ^-4 mm ³ /mN, The wear resistance after nitriding is 61% higher than that of the matrix.

Example 4

The present embodiment provides a titanium alloy ion nitriding method, which includes the following steps:

(1) Degreasing, derusting and cleaning the TC4 titanium alloy workpiece;

(2) Put the dried workpiece into the ion nitriding furnace, and vacuumize to below 5Pa;

(3) The ratio of hydrogen gas to argon gas is 1:3, the air pressure is 70Pa, the bias voltage is 900V, and the sputtering cleaning is 60min;

(4) The hydrogen content is 50%, the argon content is 15%, the rare earth cerium oxide is 5%, the _O2 gas is 1%, the acetylene gas is 1%, and the balance is nitrogen. During nitriding, the voltage is 500-650V, the temperature is slowly raised to 820°C, the heating rate is 2-5°C/min, the air pressure is 500-800Pa, and the temperature is kept for 8 hours. During nitriding, the temperature in the furnace is controlled to rise slowly to 820°C, and the gas pressure and voltage of nitriding can be adaptively adjusted within the corresponding range during this process. In fact, in the production process, in order to keep the temperature in the heat preservation stage unchanged, the voltage and air pressure during nitriding can be adjusted within the above range as required.

The thickness of the obtained nitrided layer reaches 248μm, the surface hardness HV is 973, a good hardness gradient is formed, and the wear rate is 3.21×10 ^-4 mm ³ /mN; the matrix hardness is 345HV, and the wear rate is 5.48×10 ^-4 mm ³ /mN, The wear resistance after nitriding is 41% higher than that of the matrix.

The XRD spectrum of the phase structure of the added infiltration agent obtained in this example is shown in FIG. 2 .

Example 5

The present embodiment provides a titanium alloy ion nitriding method, which includes the following steps:

(1) Degreasing, derusting and cleaning the TC4 titanium alloy workpiece;

(2) Put the dried workpiece into the ion nitriding furnace, and vacuumize to below 5Pa;

(3) The ratio of feeding hydrogen and argon is 3:1, the air pressure is 50Pa, the bias voltage is 700V, and the sputtering cleaning is 60min;

(4) The hydrogen content is 10%, the argon content is 30%, the N ₂ O gas is 20%, and the balance is nitrogen. During nitriding, the voltage is 550-650V, the temperature is slowly raised to 880°C, the heating rate is 2-5°C/min, the air pressure is 1000-1300Pa, and the temperature is kept for 4 hours. During nitriding, the temperature in the furnace is controlled to rise slowly to 880°C, and the gas pressure and voltage of nitriding can be adaptively adjusted within the corresponding range during this process. In fact, in the production process, in order to keep the temperature in the heat preservation stage unchanged, the voltage and air pressure during nitriding can be adjusted within the above range as required.

The thickness of the obtained nitrided layer reaches 234 μm, the surface hardness HV is 1095, a good hardness gradient is formed, the wear rate is 2.14×10 ^-4 mm ³ /mN; the hardness of the matrix is 345HV, and the wear rate is 5.48×10 ^-4 mm ³ /mN, The wear resistance after nitriding is 61% higher than that of the matrix.

The cross-sectional electron microscope image of the titanium alloy prepared in this example is shown in FIG. 1 .

Example 6

The present embodiment provides a titanium alloy ion nitriding method, which includes the following steps:

(1) Degreasing, derusting and cleaning the TC4 titanium alloy workpiece;

(2) Put the dried workpiece into the ion nitriding furnace, and vacuumize to below 5Pa;

(3) The ratio of feeding hydrogen and argon is 1:1, the air pressure is 40Pa, the bias voltage is 800V, and the sputtering cleaning is 60min;

(4) The hydrogen content is 10%, the argon content is 20%, the yttrium oxide rare earth is 10%, the methane gas is 8%, and the balance is nitrogen. During nitriding, the voltage is 550-650V, the temperature is slowly raised to 900°C, the heating rate is 2-5°C/min, the air pressure is 800-1000Pa, and the temperature is kept for 4 hours. During nitriding, the temperature in the furnace is controlled to rise slowly to 900°C, and the gas pressure and voltage of nitriding can be adaptively adjusted within the corresponding range during this process. In fact, in the production process, in order to keep the temperature in the heat preservation stage unchanged, the voltage and air pressure during nitriding can be adjusted within the above range as required.

The thickness of the obtained nitrided layer reaches 90 μm, the surface hardness HV is 1013, a good hardness gradient is formed, the wear rate is 3.36×10 ^-4 mm ³ /mN; the hardness of the matrix is 345HV, and the wear rate is 5.48×10 ^-4 mm ³ /mN, The wear resistance after nitriding is 38% higher than that of the matrix.

Example 7

The present embodiment provides a titanium alloy ion nitriding method, which includes the following steps:

(1) Degrease, derust and clean the TC4 titanium alloy workpiece, and activate it by pickling;

(2) Put the dried workpiece into the ion nitriding furnace, and vacuumize to below 5Pa;

(3) The ratio of feeding hydrogen and argon is 1:1, the air pressure is 30Pa, the bias voltage is 800V, and the sputtering cleaning is 60min;

(4) The hydrogen content is 20%, the argon content is 20%, the yttrium oxide rare earth is 1%, the natural gas is 20%, and the balance is nitrogen. During nitriding, the voltage is 550-650V, the temperature is slowly raised to 950°C, the heating rate is 2-5°C/min, the air pressure is 600-900Pa, and the temperature is kept for 4 hours. Among them, natural gas is the gas with methane as the main component purchased in the market. During nitriding, the temperature in the furnace is controlled to rise slowly to 950°C, and the gas pressure and voltage of nitriding can be adaptively adjusted within the corresponding range during this process. In fact, in the production process, in order to keep the temperature in the heat preservation stage unchanged, the voltage and air pressure during nitriding can be adjusted within the above range as required.

The thickness of the obtained nitrided layer reaches 81 μm, the surface hardness HV is 925, a good hardness gradient is formed, the wear rate is 1.63×10 ^-4 mm ³ /mN; the hardness of the matrix is 345HV, and the wear rate is 5.48×10 ^-4 mm ³ /mN, The wear resistance after nitriding is 70% higher than that of the matrix.

Example 8

The present embodiment provides a titanium alloy ion nitriding method, which includes the following steps:

(1) Degrease, derust and clean the TC4 titanium alloy workpiece, and activate it by pickling;

(2) Put the dried workpiece into the ion nitriding furnace, and vacuumize to below 5Pa;

(3) The ratio of feeding hydrogen and argon is 1:1, the air pressure is 60Pa, the bias voltage is 800V, and the sputtering cleaning is 60min;

(4) The hydrogen content is 20%, the argon content is 15%, the rare earth yttrium oxide is 1%, the CO ₂ is 7%, and the balance is nitrogen. During nitriding, the voltage is 530-650V, the temperature is slowly raised to 800°C, the air pressure is 1000-1300Pa, and the temperature is kept for 10 hours. During nitriding, the temperature in the furnace is controlled to rise slowly to 800°C, and the gas pressure and voltage of nitriding can be adaptively adjusted within the corresponding range during this process. In fact, in the production process, in order to keep the temperature in the heat preservation stage unchanged, the voltage and air pressure during nitriding can be adjusted within the above range as required.

The thickness of the obtained nitrided layer reaches 450 μm, the surface hardness HV is 1028, a good hardness gradient is formed, the wear rate is 4.07×10 ^-4 mm ³ /mN; the hardness of the matrix is 345HV, and the wear rate is 5.48×10 ^-4 mm ³ /mN, The wear resistance after nitriding is 26% higher than that of the matrix.

Example 9

The present embodiment provides a titanium alloy ion nitriding method, which includes the following steps:

(1) Degrease, derust and clean the TC4 titanium alloy workpiece, and activate it by pickling;

(2) Put the dried workpiece into the ion nitriding furnace, and vacuumize to below 5Pa;

(3) The ratio of introducing hydrogen and argon is 1:1, the air pressure is 50Pa, the bias voltage is 800V, and the sputtering cleaning is 60min;

(4) The hydrogen content is 30%, the argon content is 20%, the yttrium oxide rare earth is 1%, the _N2O is 5%, the methane is 3%, and the balance is nitrogen. During nitriding, the voltage is 530-650V, the temperature is slowly raised to 900°C, the air pressure is 800-1000Pa, and the temperature is kept for 5 hours. During nitriding, the temperature in the furnace is controlled to rise slowly to 900°C, and the gas pressure and voltage of nitriding can be adaptively adjusted within the corresponding range during this process. In fact, in the production process, in order to keep the temperature in the heat preservation stage unchanged, the voltage and air pressure during nitriding can be adjusted within the above range as required.

The thickness of the obtained nitrided layer reaches 217 μm, the surface hardness HV is 1197, a good hardness gradient is formed, and the wear rate is 1.71×10 ^-4 mm ³ /mN; the matrix hardness is 345HV, and the wear rate is 5.48×10 ^-4 mm ³ /mN. The wear resistance after nitriding is 69% higher than that of the matrix.

The cross-sectional hardness gradient obtained in this example is shown in FIG. 3 .

Example 10

The present embodiment provides a titanium alloy ion nitriding method, which includes the following steps:

(1) Degrease, derust and clean the TC4 titanium alloy workpiece, and activate it by pickling;

(2) Put the dried workpiece into the ion nitriding furnace, and vacuumize to below 5Pa;

(3) The ratio of introducing hydrogen and argon is 1:1, the air pressure is 50Pa, the bias voltage is 800V, and the sputtering cleaning is 60min;

(4) The hydrogen content is 20%, the argon content is 30%, the yttrium oxide rare earth is 3%, the methane is 20%, and the balance is nitrogen. During nitriding, the voltage is 530-650V, the temperature is slowly raised to 900°C, the air pressure is 700-900Pa, and the temperature is kept for 6 hours. During nitriding, the temperature in the furnace is controlled to rise slowly to 900°C, and the gas pressure and voltage of nitriding can be adaptively adjusted within the corresponding range during this process. In fact, in the production process, in order to keep the temperature in the heat preservation stage unchanged, the voltage and air pressure during nitriding can be adjusted within the above range as required.

The thickness of the obtained nitrided layer reaches 90 μm, the surface hardness HV is 1011, a good hardness gradient is formed, and the wear rate is 3.41×10 ^-4 mm ³ /mN; the matrix hardness is 345HV, and the wear rate is 5.48×10 ^-4 mm ³ /mN, The wear resistance after nitriding is 38% higher than that of the matrix.

Example 11

The present embodiment provides a titanium alloy ion nitriding method, which includes the following steps:

(1) Degrease, derust and clean the TC4 titanium alloy workpiece, and activate it by pickling;

(2) Put the dried workpiece into the ion nitriding furnace, and vacuumize to below 5Pa;

(3) The ratio of introducing hydrogen and argon is 1:1, the air pressure is 50Pa, the bias voltage is 800V, and the sputtering cleaning is 60min;

(4) The hydrogen content is 30%, the argon content is 20%, yttrium oxide rare earth 0.5%, cerium oxide rare earth 0.5%, N ₂ O 5%, methane 3%, and the balance is nitrogen. During nitriding, the voltage is 530-650V, the temperature is slowly raised to 900°C, the air pressure is 800-1000Pa, and the temperature is kept for 5 hours. During nitriding, the temperature in the furnace is controlled to rise slowly to 900°C, and the gas pressure and voltage of nitriding can be adaptively adjusted within the corresponding range during this process. In fact, in the production process, in order to keep the temperature in the heat preservation stage unchanged, the voltage and air pressure during nitriding can be adjusted within the above range as required.

Example 12

The present embodiment provides a titanium alloy ion nitriding method, which includes the following steps:

(1) Degrease, derust and clean the TC4 titanium alloy workpiece, and activate it by pickling;

(2) Put the dried workpiece into the ion nitriding furnace, and vacuumize to below 5Pa;

(3) The ratio of introducing hydrogen and argon is 1:1, the air pressure is 50Pa, the bias voltage is 800V, and the sputtering cleaning is 60min;

(4) The hydrogen content is 30%, the argon content is 20%, yttrium oxide rare earth 1%, N ₂ O 3%, CO ₂ 2%, methane 3%, and the balance is nitrogen. During nitriding, the voltage is 530-650V, the temperature is slowly raised to 900°C, the air pressure is 800-1000Pa, and the temperature is kept for 5 hours. During nitriding, the temperature in the furnace is controlled to rise slowly to 900°C, and the gas pressure and voltage of nitriding can be adaptively adjusted within the corresponding range during this process. In fact, in the production process, in order to keep the temperature in the heat preservation stage unchanged, the voltage and air pressure during nitriding can be adjusted within the above range as required.

Example 13

The present embodiment provides a titanium alloy ion nitriding method, which includes the following steps:

(1) Degrease, derust and clean the TC4 titanium alloy workpiece, and activate it by pickling;

(2) Put the dried workpiece into the ion nitriding furnace, and vacuumize to below 5Pa;

(3) The ratio of introducing hydrogen and argon is 1:1, the air pressure is 50Pa, the bias voltage is 800V, and the sputtering cleaning is 60min;

(4) The hydrogen content is 20%, the argon content is 30%, the yttrium oxide rare earth is 3%, the methane is 5%, the propane is 5%, and the balance is nitrogen. During nitriding, the voltage is 530-650V, the temperature is slowly raised to 900°C, the air pressure is 700-900Pa, and the temperature is kept for 6 hours. During nitriding, the temperature in the furnace is controlled to rise slowly to 900°C, and the gas pressure and voltage of nitriding can be adaptively adjusted within the corresponding range during this process. In fact, in the production process, in order to keep the temperature in the heat preservation stage unchanged, the voltage and air pressure during nitriding can be adjusted within the above range as required.

Example 14

The present embodiment provides a titanium alloy ion nitriding method, which includes the following steps:

(1) Degrease, derust and clean the TC4 titanium alloy workpiece, and activate it by pickling;

(2) Put the dried workpiece into the ion nitriding furnace, and vacuumize to below 5Pa;

(3) The ratio of feeding hydrogen and argon is 1:1, the air pressure is 60Pa, the bias voltage is 800V, and the sputtering cleaning is 60min;

(4) The hydrogen content is 20%, the argon content is 15%, the yttrium oxide rare earth is 1%, the _CO2 is 7%, the nitrogen gas is 30%, and the ammonia gas is 27%. During nitriding, the voltage is 530-650V, the temperature is slowly raised to 800°C, the air pressure is 1000-1300Pa, and the temperature is kept for 10 hours. During nitriding, the temperature in the furnace is controlled to rise slowly to 800°C, and the gas pressure and voltage of nitriding can be adaptively adjusted within the corresponding range during this process. In fact, in the production process, in order to keep the temperature in the heat preservation stage unchanged, the voltage and air pressure during nitriding can be adjusted within the above range as required.

Comparative Example 1

The difference between this example and Example 2 is that no infiltration catalyst is added, that is, in step (4), the hydrogen content is 10%, the argon content is 20%, and the balance is nitrogen. In nitriding, the voltage is 550-700V, the temperature is slowly raised to 850°C, the heating rate is 2-5°C/min, the air pressure is 800-1500Pa, and the temperature is kept for 4 hours.

The thickness of the obtained nitriding layer is 62 microns, the surface hardness is HV950, and the wear rate is 5.19×10 ^-4 mm ³ /mN; the hardness of the substrate is 345HV, and the wear rate is 5.48×10 ^-4 mm ³ /mN. The wear resistance after nitriding is higher than that of the substrate. 5%.

Comparative Example 2

The difference between this example and Example 4 is that no infiltration catalyst is added, that is, in step (4), the hydrogen content is 50%, the argon content is 15%, and the balance is nitrogen. During nitriding, the voltage is 500-650V, the temperature is slowly raised to 820°C, the heating rate is 2-5°C/min, the air pressure is 500-800Pa, and the temperature is kept for 8 hours.

The XRD pattern of the phase structure obtained in this example without the addition of the infiltration agent is shown in FIG. 2 , and the XRD pattern of the surface of the substrate of the TC4 titanium alloy workpiece is shown in FIG. 2 . It can be seen from Fig. 2 that adding an infiltrating agent to the nitriding gas can increase the surface nitride content of the nitride infiltration layer.

Comparative Example 3

The difference between this example and Example 9 is that no infiltration catalyst is added, that is, in step (4), the hydrogen content is 30%, the argon content is 20%, and the balance is nitrogen. During nitriding, the voltage is 530-650V, the temperature is slowly raised to 900°C, the air pressure is 800-1000Pa, and the temperature is kept for 5 hours.

The cross-sectional hardness gradient of the nitriding layer obtained in this example without the addition of the infiltration agent is shown in Figure 3. It can be seen from Figure 3 that the hardness of the cross-section of the nitrided layer with the addition of the infiltration agent in Example 9 is higher than that without the addition of the infiltration agent. Nitriding layer section hardness.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A titanium alloy ion nitriding method is characterized by comprising the steps of placing a titanium alloy workpiece in a plasma nitriding furnace, introducing nitriding gas, controlling the nitriding voltage to be 500-; the nitriding gas comprises a nitrogen-containing gas, hydrogen, argon, and a promoter comprising at least one of a rare earth oxide, an oxygen-containing gas, and a carbon-containing gas.

2. The method for ion nitriding of titanium alloys according to claim 1, wherein said nitriding gas comprises the following components in volume percent: 5-50% of hydrogen, 10-30% of argon, 0.5-40% of a catalyst penetration agent and the balance of nitrogen-containing gas;

preferably, the nitriding gas contains the following components in percentage by volume: 5-50% of hydrogen, 10-30% of argon, 0-10% of rare earth oxide, 1-40% of oxygen-containing gas and the balance of nitrogen-containing gas;

preferably, the nitriding gas contains the following components in percentage by volume: 5-50% of hydrogen, 10-30% of argon, 0.5-10% of rare earth oxide, 0-40% of oxygen-containing gas, 1-40% of carbon-containing gas and the balance of nitrogen-containing gas;

preferably, the nitriding gas contains the following components in percentage by volume: 5-50% of hydrogen, 10-30% of argon, 0.5-10% of rare earth oxide, 1-40% of oxygen-containing gas, 0-40% of carbon-containing gas and the balance of nitrogen-containing gas;

preferably, the nitriding gas contains the following components in percentage by volume: 5-50% of hydrogen, 10-30% of argon, 0.5-10% of rare earth oxide, 1-40% of oxygen-containing gas, 1-40% of carbon-containing gas and the balance of nitrogen-containing gas.

3. The method for ion nitriding of titanium alloy according to claim 1 or 2, wherein the rare earth oxide is at least one of yttrium oxide, cerium oxide, and lanthanum oxide.

4. The method for ion nitriding titanium alloy according to claim 3, wherein the rare earth oxide introduced into the ion nitriding furnace is a saturated rare earth solution dissolved in an organic solvent, and the volume percentage of the rare earth oxide in the nitriding gas is the volume percentage of the saturated rare earth solution after volatilization in the ion nitriding furnace;

preferably, the organic solvent is absolute ethyl alcohol.

5. Method for ion nitriding of titanium alloys according to claim 1 or 2, characterized in that said oxygen containing gas is CO₂、N₂O and O₂At least one of (1).

6. The method for ion nitriding of titanium alloy according to claim 2, wherein the carbon-containing gas is at least one of methane, acetylene, propane, and natural gas.

7. The method for ion nitriding titanium alloy according to claim 2, wherein the nitrogen-containing gas is at least one of nitrogen gas and ammonia gas.

8. A titanium alloy ion nitriding method according to claim 2, characterized in that after the workpiece is placed in the plasma nitriding furnace, vacuum is first applied, then sputter cleaning is performed by introducing a gas having a hydrogen to argon ratio of 1:3 to 3:1, and then nitrogen-permeated gas is introduced after sputter cleaning.

9. A titanium alloy ion nitriding method according to claim 8, characterized in that the work piece is cleaned for oil removal and rust removal, dried and then placed into the ion nitriding furnace, and vacuumized until the vacuum degree of the plasma nitriding furnace is below 5 Pa.

10. The method for ion nitriding of titanium alloy according to claim 8, wherein the pressure of the sputter cleaning is 30-100Pa, the voltage is 500-1000V, and the time of the sputter cleaning is 30-60 min.

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