Preparation method of high-temperature coating based on metal core

Abstract

According to the preparation method of the high-temperature coating based on the metal core, the mixture of the glass ceramic particles and the glass fibers is sprayed on the surface of the titanium alloy metal core in a relatively low room temperature environment, so that the influence of temperature on the surface structure of the titanium alloy can be avoided; the glass ceramic particles and the glass fibers are mixed and the overall stress structure of the titanium alloy metal core in the extrusion state is changed, under the action of airflow pressure, the mixture of the glass ceramic particles and the glass fibers can be easily attached to the surface of the titanium alloy metal core with low hardness, the generated coating has high ductility, the embrittlement risk generated under the pressure can be effectively prevented, and the service life of the titanium alloy metal core is prolonged. And the hardness of the alloy can reach HV 0.03 and reach 800-1500.

Description

Technical Field

[0001] The invention discloses a method for preparing a high-temperature coating based on a metal core, and belongs to the technical field of processing and manufacturing high-temperature alloy disc forgings. Background Art

[0002] Ceramic matrix composites (CMC) are ideal substitutes for high-temperature alloys, with lower density, higher heat resistance and oxidation resistance. After adding advanced ceramic components, its application range exceeds many traditional materials and shows excellent comprehensive performance. In the field of aviation engines, CMC can promote the temperature rise of turbine intake air, thereby improving engine efficiency; at the same time, it can reduce structural density, thereby improving aircraft thrust-to-weight ratio. In the aerospace industry, CMC can be used as "ablative material" to manufacture thermal structural components of near-space vehicles and reusable spacecraft. With the growth of energy needs and the development of aerospace technology, the total market demand for CMC is rising rapidly. Summary of the invention

[0003] The present invention is designed to address the problems existing in the above-mentioned prior art and provides a method for preparing a high-temperature coating based on a metal core. Its purpose is to use glass fiber as a wear-resistant and high-temperature resistant surface reinforcement material to prepare a high-temperature coating on the surface of titanium alloy shaft components, thereby solving the shortcomings of titanium alloy shaft components that are not resistant to high temperatures and wear, and enabling them to be used as structural materials for helicopter transmission components.

[0004] To achieve the above purpose, the technical solution of the present invention is as follows:

[0005] The method for preparing a high-temperature coating based on a metal core proposed by the present invention comprises the following steps:

[0006] Step 1: Prepare a titanium alloy metal core and use mechanical processing to make its surface roughness reach 0.3, then use gasoline and alcohol to fully clean the surface for later use;

[0007] Step 2: At 0°C, using an ultrasonic device, glass ceramic particles and glass fibers are mixed in an alcohol solution, wherein the mass ratio of the glass ceramic particles to the glass fibers is 1:1. After mixing, the glass ceramic particles are wrapped with glass fibers and present a cluster shape;

[0008] Step 3: Mix the glass ceramic particles-glass fiber mixture with compressed air and helium, and evenly cold spray it on the surface of the titanium alloy metal core. The spraying pressure is 100-500MP. When the spraying thickness reaches 0.5-1mm, stop spraying. The ambient temperature of the entire spraying process is below 0°C.

[0009] In the cold spraying of step 3, the glass ceramic particles-glass fiber mixture is mixed with compressed air and helium through a gas mixer, the gas mixer has three inlets and one outlet, the inlets are respectively input with compressed air, helium and the glass ceramic particles and glass fiber mixture, wherein the flow ratio of compressed air to helium is 1:2, and the outlet outputs compressed air, helium and the glass ceramic particles and glass fiber mixture, and the output temperature does not exceed 0°C;

[0010] A pneumatic gas mixer is used to spray compressed air, helium (cooling effect, absorbing the heat generated by the collision) and a mixed mixture of glass-ceramic particles and glass fibers onto the circumferential surface of the titanium alloy metal core. Due to the presence of a certain pressure during spraying and the fact that the titanium alloy metal core has not been subjected to quenching and tempering heat treatment, the surface hardness is limited, so that the glass-ceramic particles and glass fiber mixture can adhere to the surface of the titanium alloy metal core. During the spraying process, some ceramic particles are embedded in the shallow surface of the titanium alloy metal core, and some glass fibers are broken and also penetrate into the shallow surface of the titanium alloy metal core.

[0011] Step 4: Under the condition of constant ambient temperature, the cold-sprayed titanium alloy metal core is reciprocatedly rolled, and the single-pass rolling reduction is not greater than 0.2 mm, until the surface roughness of the titanium alloy metal core is not less than 0.6, so that the glass fiber is broken, and the glass ceramic particles are embedded below the surface of the titanium alloy metal core under the action of pressure; at this time, most of the ceramic particles are embedded in the shallow surface and deep surface of the titanium alloy metal core, and most of the glass fibers are broken and penetrate into the shallow surface and deep surface of the titanium alloy metal core;

[0012] Step 5. Place the titanium alloy metal core into a vacuum furnace for heating. The vacuum furnace uses induction heating to instantly heat the titanium alloy metal core. The heating rate is not less than 500°C / s, the heating temperature is 1500-2000°C, and the insulation time is not more than 3s. At this time, the glass fiber melts. After the insulation is completed, it is quickly cooled to form a glass-like high-temperature coating on the surface / shallow surface / deep surface of the titanium alloy metal core.

[0013] During implementation, the ratio of the length to the diameter of the titanium alloy metal core in step one is 5:1 to 7:1, and the titanium alloy metal core is obtained by an extrusion process, and the titanium alloy metal core after extrusion is not subjected to any tempering or stress relief heat treatment.

[0014] During implementation, in step one, the surface roughness of the two end faces and the circumferential surface of the titanium alloy metal core is firstly increased to 0.8 by mechanical processing, and then the surface roughness of the two end faces and the circumferential surface of the titanium alloy metal core is increased to 0.3 by rolling.

[0015] During implementation, in step 2, the glass ceramic particles are composed of WC with a particle size of 0.05-0.1 mm, and the glass fibers are composed of SiN with a diameter of 0.01-0.05 mm and a length of 0.1-0.5 mm.

[0016] During the implementation, during the cold spraying in step three, the titanium alloy metal core rotates around the central axis at a rotation speed of 10 to 100 rad / s.

[0017] During implementation, in step 4, the cold spinning action causes the glass ceramic particles to be embedded 0.1-0.5 mm below the surface of the titanium alloy metal core.

[0018] During implementation, in step five, the rapid cooling is performed by using helium as a medium for instant cooling.

[0019] The technical solution of the present invention realizes complete plastic deformation of metal powder particles on the metal surface and completes the multi-layer gradient structure through the above-mentioned pressure application method and combination thereof. The beneficial technical effects are as follows:

[0020] 1. By spraying the mixture of glass ceramic particles and glass fibers on the surface of the titanium alloy metal core at a relatively low room temperature, the influence of temperature on the surface structure of the titanium alloy and the change of the overall stress structure of the titanium alloy metal core under the extrusion state can be avoided. Under the action of air flow pressure, the mixture of glass ceramic particles and glass fibers can be easily attached to the surface of the titanium alloy metal core with low hardness. The resulting coating is highly ductile and can effectively prevent the risk of embrittlement under pressure. Its hardness can reach HV0.03 and reach 800-1500.

[0021] Second, this technical solution adopts the method of spraying first and then heating. The entire titanium alloy metal core is subjected to a tempering and stress relief heat treatment, so that the performance of the reinforced fiber layer on the titanium alloy surface and the titanium alloy matrix are better matched. During the heat treatment process, instant heating-short-term heat preservation-instant cooling ensures that excessive temperature only has a greater effect on the glass fiber and will not have a significant impact on the titanium alloy matrix;

[0022] 3. Glass-ceramic particles are embedded more and deeper into the surface of the titanium alloy metal core than glass fibers, which plays a certain role in heat insulation during the hot cabin process and also enables the surface of the titanium alloy metal core to achieve stepped strength. DETAILED DESCRIPTION

[0023] The technical solution of the present invention will be further described in detail below in conjunction with embodiments:

[0024] The steps of preparing a high-temperature coating on the surface of a titanium alloy bar using the technical solution of the present invention are as follows:

[0025] Step 1: prepare a titanium alloy metal core. First, use mechanical processing to make the surface roughness of the two end faces and the circumferential surface of the titanium alloy metal core reach 0.8, and then use rolling to increase the surface roughness of the two end faces and the circumferential surface of the titanium alloy metal core to 0.3, and then use gasoline and alcohol to fully clean the surface for use;

[0026] The ratio of the length to the diameter of the titanium alloy metal core is 5:1 to 7:1, and the titanium alloy metal core is obtained by an extrusion process, and the titanium alloy metal core after extrusion is not subjected to any tempering or stress relief heat treatment;

[0027] Step 2: Under 0°C, using an ultrasonic device, glass ceramic particles and glass fibers are mixed in an alcohol solution, wherein the mass ratio of the glass ceramic particles to the glass fibers is 1:1, the glass ceramic particles are composed of WC, with a particle size of 0.05-0.1 mm, and the glass fibers are composed of SiN, with a diameter of 0.01-0.05 mm and a length of 0.1-0.5 mm. After mixing, the glass ceramic particles are wrapped with glass fibers and present a cluster shape;

[0028] Step 3: Mix the glass ceramic particle-glass fiber mixture with compressed air and helium, and evenly cold spray it on the surface of the titanium alloy metal core. During the cold spraying process, the titanium alloy metal core rotates around the central axis at a speed of 10 to 100 rad / s and a spraying pressure of 100 to 500 MP. When the spraying thickness reaches 0.5 to 1 mm, the spraying is stopped. The ambient temperature of the entire spraying process is below 0°C.

[0029] In the cold spraying of step 3, the glass ceramic particles-glass fiber mixture is mixed with compressed air and helium through a gas mixer, the gas mixer has three inlets and one outlet, the inlets are respectively input with compressed air, helium and the glass ceramic particles and glass fiber mixture, wherein the flow ratio of compressed air to helium is 1:2, and the outlet outputs compressed air, helium and the glass ceramic particles and glass fiber mixture, and the output temperature does not exceed 0°C;

[0030] Step 4: Under the condition of constant ambient temperature, the cold-sprayed titanium alloy metal core is reciprocatedly rolled, and the rolling reduction of a single pass is not greater than 0.2 mm, until the surface roughness of the titanium alloy metal core is not less than 0.6, so that the glass fiber is broken, and the glass ceramic particles are embedded 0.1-0.5 mm below the surface of the titanium alloy metal core under the action of pressure;

[0031] Step 5. Place the titanium alloy metal core into a vacuum furnace for heating. The vacuum furnace uses induction heating to instantly heat the titanium alloy metal core. The heating rate is not less than 500°C / s, the heating temperature is 1500-2000°C, and the insulation time is not more than 3s. At this time, the glass fiber melts. After the insulation is completed, helium is used as the medium for instant cooling to form a glass-like high-temperature coating on the surface / shallow surface / deep surface of the titanium alloy metal core.

Claims

1. A method for preparing a high-temperature coating based on a metal core, characterized in that: The steps of this method are as follows: Step 1: Prepare a titanium alloy metal core and machine it to a surface roughness of 0.3, then use gasoline and alcohol to fully clean the surface for later use; Step 2: At 0°C, using an ultrasonic device, glass ceramic particles and glass fibers are mixed in an alcohol solution, wherein the mass ratio of the glass ceramic particles to the glass fibers is 1:

1. After mixing, the glass ceramic particles are wrapped with glass fibers and present a cluster shape; Step 3: Mix the glass ceramic particle-glass fiber mixture with compressed air and helium, and evenly cold spray it on the surface of the titanium alloy metal core. The spraying pressure is 100-500MPa. When the spraying thickness reaches 0.5-1mm, stop spraying. The ambient temperature of the entire spraying process is below 0°C. Step 4: Under the condition of constant ambient temperature, the cold-sprayed titanium alloy metal core is reciprocatedly rolled, and the rolling reduction of a single pass is not greater than 0.2 mm, until the surface roughness of the titanium alloy metal core is not less than 0.6, so that the glass fiber is broken, and the glass ceramic particles are embedded below the surface of the titanium alloy metal core under the action of pressure; Step 5. Place the titanium alloy metal core into a vacuum furnace for heating. The vacuum furnace uses induction heating to instantly heat the titanium alloy metal core. The heating rate is not less than 500°C / s, the heating temperature is 1500-2000°C, and the insulation time is not more than 3s. At this time, the glass fiber melts. After the insulation is completed, it is quickly cooled to form a glass-like high-temperature coating on the surface / shallow surface / deep surface of the titanium alloy metal core.

2. The method for preparing a high-temperature coating based on a metal core according to claim 1, characterized in that: The ratio of the length to the diameter of the titanium alloy metal core in step 1 is 5:1 to 7:

1. The titanium alloy metal core is obtained by an extrusion process, and the titanium alloy metal core after extrusion is not subjected to any tempering or stress relief heat treatment.

3. The method for preparing a high temperature coating based on a metal core according to claim 1, characterized in that: In step 1, the surface roughness of the two end faces and the circumferential surface of the titanium alloy metal core is firstly increased to 0.8 by mechanical processing, and then the surface roughness of the two end faces and the circumferential surface of the titanium alloy metal core is increased to 0.3 by rolling.

4. The method for preparing a high temperature coating based on a metal core according to claim 1, characterized in that: In step 2, the glass ceramic particles are composed of WC with a particle size of 0.05-0.1 mm, and the glass fibers are composed of SiN with a diameter of 0.01-0.05 mm and a length of 0.1-0.5 mm.

5. The method for preparing a high-temperature coating based on a metal core according to claim 1, characterized in that: In the cold spraying of step three, the mixing of the glass ceramic particles-glass fiber mixture with compressed air and helium is completed by a gas mixer. The gas mixer has three inlets and one outlet. The inlets input compressed air, helium and the glass ceramic particles and glass fiber mixture respectively, wherein the flow ratio of compressed air to helium is 1:2, and the outlet outputs compressed air, helium and the glass ceramic particles and glass fiber mixture, and the output temperature does not exceed 0°C.

6. The method for preparing a high temperature coating based on a metal core according to claim 1, characterized in that: During the cold spraying in step 3, the titanium alloy metal core rotates around the central axis at a rotation speed of 10 to 100 rad / s.

7. The method for preparing a high temperature coating based on a metal core according to claim 1, characterized in that: In step 4, the cold spinning action causes the glass ceramic particles to be embedded 0.1-0.5 mm below the surface of the titanium alloy metal core.

8. The method for preparing a high temperature coating based on a metal core according to claim 1, characterized in that: In step five, the rapid cooling is performed by using helium as a medium for instant cooling.