阅读说明：本技术 一种钛合金低温氧氮化超硬超厚渗层及其制备方法和应用 (Titanium alloy low-temperature oxynitride superhard super-thick infiltrated layer and preparation method and application thereof ) 是由 牛云松 杨延格 王海峰 朱圣龙 于 2020-12-04 设计创作，主要内容包括：本发明公开了一种钛合金低温氧氮化超硬超厚渗层及其制备方法和应用,属于金属材料表面处理技术领域。在钛合金部件表面上,通过低温等离子渗氧及后续的等离子氧氮化处理复合处理方案,获得表面超硬且渗层超厚的耐磨耐腐蚀氧氮化渗层。所述复合处理工艺控制温度在620～650℃范围内,渗层的表面硬度在Hv-(0.05)1100～2900范围内,表面化合物层厚度在5～20微米之间,渗层深度可达300微米。该工艺能够解决钛合金部件表面耐磨性较差,硬度较低的复合表面处理工艺技术,更因较低的工艺处理温度防止复杂钛合金部件的大幅度变形,可以避免高温等离子氮化处理过程中基材发生的相转变,保证钛合金原本的基材力学性能。(The invention discloses a titanium alloy low-temperature oxynitride superhard super-thick infiltrated layer as well as a preparation method and application thereof, belonging to the technical field of surface treatment of metal materials. On the surface of the titanium alloy part, a wear-resistant corrosion-resistant oxynitriding layer with super-hard surface and super-thick diffusion layer is obtained through a low-temperature plasma oxygen permeation and subsequent plasma oxynitriding treatment composite treatment scheme. The temperature of the composite treatment process is controlled within the range of 620-650 ℃, and the surface hardness of the infiltrated layer is Hv 0.05 1100-2900, the thickness of the surface compound layer is 5-20 μm, and the depth of the penetrated layer can reach 300 μm. The process can solve the problems of poor surface wear resistance and low hardness of the titanium alloy part by using a composite surface treatment process technology, prevent the complex titanium alloy part from being greatly deformed due to low process treatment temperature, avoid phase transformation of the base material in the high-temperature plasma nitriding treatment process and ensure the original mechanical property of the base material of the titanium alloy.)

1. A preparation method of a titanium alloy low-temperature oxynitride superhard super-thick infiltrated layer is characterized by comprising the following steps of: the method takes titanium alloy as a substrate material, and sequentially carries out a composite treatment process of plasma oxygen permeation and plasma oxynitriding technologies under a low-temperature condition, so as to obtain a wear-resistant and corrosion-resistant oxynitriding layer with ultrahigh hardness and an ultra-thick permeation layer on the surface of the titanium alloy; the temperature of the composite treatment process is controlled within the range of 620-650 ℃.

2. The method for preparing a titanium alloy low-temperature oxynitrided superhard super-thick infiltrated layer according to claim 1, wherein: the method specifically comprises the following steps:

(1) putting a cleaned titanium alloy workpiece into a furnace cavity of a plasma nitriding furnace, vacuumizing a vacuum chamber to 1-5 Pa, introducing oxygen-nitrogen mixed gas and argon gas at the same time, heating to 620-650 ℃, and preserving heat for 2-3 hours, wherein the flow rate of the oxygen-nitrogen mixed gas is 50-100 ml/min, and the flow rate of the argon gas is 30-300 ml/min;

(2) further introducing high-purity nitrogen with the flow rate of 400-600 ml/min, and continuously preserving heat within the range of 620-650 ℃ for 1.5-7 hours; cooling to room temperature with the furnace and taking out.

3. The method for preparing a titanium alloy low-temperature oxynitrided superhard super-thick infiltrated layer according to claim 2, wherein: the oxygen-nitrogen mixed gas is formed by mixing oxygen and nitrogen according to the volume ratio of 1 (4-10).

4. A titanium alloy low temperature oxynitrided ultra hard super thick carburized layer prepared by the method of any one of claims 1 to 3, characterized in that: the surface hardness of the infiltrated layer is Hv_0.051100 to 2900; the infiltration layer comprises a surface compound layer and an oxynitride diffusion layer from outside to inside, the thickness of the surface compound layer is 5-20 micrometers, and the depth of the whole infiltration layer can reach 300 micrometers; the surface compound layer contains TiO₂TiN and Ti₂And (4) N phase.

5. The use of a titanium alloy low temperature oxynitrided superhard ultrathick infiltrated layer as claimed in claim 4, wherein: the titanium alloy low-temperature oxynitride superhard super-thick infiltrated layer is applied to titanium alloy workpieces of various grades or the surface of the titanium alloy workpiece obtained by a laser additive manufacturing process.

The technical field is as follows:

the invention relates to a surface treatment technology of a metal material, in particular to a titanium alloy low-temperature oxynitriding superhard super-thick infiltrated layer and a preparation method and application thereof.

Background art:

titanium and titanium alloy have excellent comprehensive performance and are widely applied to the fields of aerospace, automobiles, medical use and the like. However, the titanium alloy has low surface hardness and poor wear resistance, and the application range of the titanium alloy is greatly limited. Plasma nitriding is a commonly used surface treatment method, and a nitrided layer having high surface hardness can be obtained.

However, two phases of titanium alloys exist generally, and most of the titanium alloys have a phase transition temperature of alpha + beta/beta, which means that at a certain temperature, the titanium alloy undergoes phase transition and the related mechanical properties of the titanium alloy change. The invention patent ZL 201910621221.3 indicates that the ion nitriding temperature of the titanium alloy is 870-. Similarly, the chinese patent ZL 202010234027.2 also raises the nitriding temperature to 750 ℃, even 950 ℃, the base material has phase transition, and the mechanical properties will be reduced. In addition, for a workpiece with higher requirement on dimensional accuracy control, if the workpiece is raised to above 700 ℃, the workpiece can be seriously deformed and is directly scrapped. In addition, low temperature nitriding can also occur, and in the invention patent 201910983906.2 of China, the temperature adopted in the embodiment 1 is 600 ℃, the nitriding time reaches 10 hours, the thickness of the infiltrated layer is only 20 microns, and although the deformation of the matrix can be ensured to be small at the temperature, the infiltrated layer depth is shallow, and the service life is short.

The invention content is as follows:

the invention aims to provide a titanium alloy low-temperature oxynitriding superhard super-thick infiltrated layer as well as a preparation method and application thereof.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a preparation method of a titanium alloy low-temperature oxynitride superhard super-thick infiltrated layer is characterized in that a titanium alloy is used as a substrate material, and a composite treatment process of plasma oxygen permeation and plasma oxynitriding technologies is sequentially carried out under a low-temperature condition, so that a wear-resistant and corrosion-resistant oxynitride infiltrated layer with ultrahigh hardness and super-thick infiltrated layer is obtained on the surface of the titanium alloy; the temperature of the composite treatment process is controlled within the range of 620-650 ℃. The method specifically comprises the following steps:

(1) putting a cleaned titanium alloy workpiece into a furnace cavity of a plasma nitriding furnace, vacuumizing a vacuum chamber to 1-5 Pa, introducing oxygen-nitrogen mixed gas and argon gas at the same time, heating to 620-650 ℃, and preserving heat for 2-3 hours, wherein the flow rate of the oxygen-nitrogen mixed gas is 50-100 ml/min, and the flow rate of the argon gas is 30-300 ml/min; the oxygen-nitrogen mixed gas is formed by mixing oxygen and nitrogen according to the volume ratio of 1 (4-10).

(2) Further introducing high-purity nitrogen with the flow rate of 400-600 ml/min, and continuously preserving heat within the range of 620-650 ℃ for 1.5-7 hours; cooling to room temperature with the furnace and taking out.

The surface hardness of the titanium alloy low-temperature oxynitride superhard super-thick diffusion layer prepared by the method is Hv_0.051100 to 2900; the infiltration layer comprises a surface compound layer and an oxynitride diffusion layer from outside to inside, the thickness of the surface compound layer is 5-20 micrometers, and the depth of the whole infiltration layer can reach 300 micrometers; the surface compound layer contains TiO₂TiN and Ti₂And (4) N phase.

The titanium alloy low-temperature oxynitride superhard super-thick infiltrated layer is applied to titanium alloy workpieces of various grades or the surface of the titanium alloy workpiece obtained by a laser additive manufacturing process.

The invention has the advantages and beneficial effects that:

1. according to the invention, the corrosion-resistant and wear-resistant oxynitriding tough infiltrated layer is obtained by corrosion-resistant and wear-resistant oxynitriding treatment, so that an oxynitriding infiltrated layer with ultra-thick infiltrated layer and ultra-high surface hardness can be obtained at the low temperature of 620-650 ℃, the phase structure of any titanium alloy base material is not changed, the mechanical property of the base material is ensured, and the wear-resistant and corrosion-resistant properties of the surface of the titanium alloy are improved.

2. The invention adopts a conventional plasma nitriding heat treatment furnace, can realize low-temperature oxynitriding treatment by non-conventional process improvement, avoids the situation of large-amplitude deformation of a base material, is convenient for mass production, is easy to control the product quality, and has simple required equipment and less investment.

3. The corrosion-resistant oxynitriding toughness layer prepared by the invention has excellent comprehensive performance and the toughness of the toughness layerDegree in Hv_0.05The thickness of the tough layer is adjustable within the range of 1100-2900 and within the range of 100-500 microns. The main advantages of such a corrosion resistant oxynitriding robust layer are: (1) the bonding strength between the toughness layer and the substrate is high; (2) the interface has slower gradient hardness to inhibit the cracking of a permeable layer; (3) the surface strength is ultrahigh, and the ductility, toughness and corrosion resistance are good; (4) superior fatigue resistance.

Description of the drawings:

fig. 1 is a photograph showing the cross-sectional hardness of a cast TC4 titanium alloy after oxynitridation.

Fig. 2 shows the cross-sectional hardness gradient distribution of the cast TC4 titanium alloy after the oxynitridation treatment.

Fig. 3 is a photograph of cross-sectional hardness of a TC4 titanium alloy after oxynitridation by laser additive manufacturing.

The specific implementation mode is as follows:

the invention is described in detail below with reference to the figures and examples.

Example 1

Removing oil stains on the surface, ultrasonically cleaning in an acetone organic solvent for 10 minutes, putting the dried cast TC4 titanium alloy workpiece into a plasma heat treatment furnace, vacuumizing a vacuum chamber to be lower than 10Pa, and introducing oxygen-nitrogen mixed gas, wherein the volume ratio of oxygen to nitrogen is 1:6, and the total flow of the oxygen-nitrogen mixed gas is 70 ml/min; introducing argon gas with the flow rate of 200ml/min, applying negative bias to the workpiece, gradually increasing the negative bias from 0V to 800V at a constant speed, and carrying out plasma bombardment cleaning for 20 minutes; then, the temperature of the workpiece is gradually increased to 640 ℃ through ion bombardment, and the temperature is kept for 120 minutes; and introducing nitrogen again, keeping the temperature at 640 ℃ for 6 hours at the flow rate of 500ml/min, cooling to room temperature along with the furnace, and taking out, thereby obtaining the ultrahard and ultrathick oxynitrided infiltrated layer on the surface of the cast TC4 titanium alloy. The sample surface comprises a material comprising TiO₂TiN and Ti₂A compound layer of N phase, and an oxynitride diffusion layer. Surface hardness of the infiltrated layer is Hv_0.052728 and the depth of the infiltrated layer is as shown in FIG. 1, and the total infiltrated layer thickness is about 274 microns. FIG. 2 is a hardness gradient distribution of a infiltrated layer.

Example 2

Removing oil stain on the surface, and ultrasonically cleaning in acetone organic solvent for 10 minutesThen, placing the dried TC4 titanium alloy workpiece manufactured by laser additive manufacturing into a plasma heat treatment furnace, vacuumizing a vacuum chamber to be lower than 10Pa, introducing oxygen-nitrogen mixed gas, wherein the volume ratio of oxygen to nitrogen is 1:5, and the total flow is 60 ml/min; introducing argon gas with the flow rate of 150ml/min, applying negative bias to the workpiece, gradually increasing the negative bias from 0V to 800V at constant speed, and performing plasma bombardment cleaning for 20 minutes; then, the temperature of the workpiece is gradually increased to 630 ℃ through ion bombardment, and the temperature is kept for 120 minutes; and introducing nitrogen again, keeping the temperature at 630 ℃ for 4 hours at the flow rate of 400ml/min, cooling to room temperature along with the furnace, and taking out, thereby obtaining the ultrahard and ultrathick oxynitrided infiltrated layer on the surface of the TC4 titanium alloy manufactured by laser additive manufacturing. The sample surface comprises a material comprising TiO₂TiN and Ti₂A compound layer of N phase, and an oxynitride diffusion layer. Surface hardness of the infiltrated layer is Hv_0.051152 and the percolated depth is as shown in figure 3, the total percolated thickness is about 108 microns.

Example 3

Removing oil stains on the surface, ultrasonically cleaning in an acetone organic solvent for 10 minutes, putting the dried cast TC6 titanium alloy workpiece into a plasma heat treatment furnace, vacuumizing a vacuum chamber to be lower than 10Pa, and introducing oxygen-nitrogen mixed gas, wherein the volume ratio of oxygen to nitrogen is 1:10, and the total flow is 100 ml/min; introducing argon gas with the flow rate of 100ml/min, applying negative bias to the workpiece, gradually increasing the negative bias from 0V to 800V at a constant speed, and carrying out plasma bombardment cleaning for 30 minutes; then, the temperature of the workpiece is gradually raised to 650 ℃ through ion bombardment, and the temperature is kept for 120 minutes; and introducing nitrogen again, keeping the temperature at 650 ℃ for 1.5 hours at the flow rate of 550ml/min, then cooling to room temperature along with the furnace, and taking out, thereby obtaining the ultrahard and ultrathick oxynitrided infiltrated layer on the surface of the cast TC6 titanium alloy. The sample surface comprises a material comprising TiO₂TiN and Ti₂A compound layer of N phase, and an oxynitride diffusion layer. Surface hardness of the infiltrated layer is Hv_0.051643 and a total percolated layer thickness of about 60 microns.

Example 4

Removing oil stains on the surface, ultrasonically cleaning in an acetone organic solvent for 10 minutes, putting the dried cast TA2 titanium alloy workpiece into a plasma heat treatment furnace, and vacuumizingVacuumizing the chamber to below 10Pa, introducing oxygen-nitrogen mixed gas, wherein the volume ratio of oxygen to nitrogen is 1:4, and the total flow is 50 ml/min; introducing argon gas with the flow rate of 300ml/min, applying negative bias to the workpiece, gradually increasing the negative bias from 0V to 800V at constant speed, and carrying out plasma bombardment cleaning for 10 minutes; then, the temperature of the workpiece is gradually increased to 620 ℃ through ion bombardment, and the temperature is kept for 120 minutes; and introducing nitrogen again, wherein the flow rate is 600ml/min, keeping the temperature at 620 ℃ for 6.5 hours, then cooling to room temperature along with the furnace, and taking out, thereby obtaining the ultrahard and ultrathick oxynitrided infiltrated layer on the surface of the cast TA2 titanium alloy. The sample surface comprises a material comprising TiO₂TiN and Ti₂A compound layer of N phase, and an oxynitride diffusion layer. Surface hardness of the infiltrated layer is Hv_0.052871 the total strike-through thickness is about 300 microns.