CN111945151A - Preparation method of Ti-Al-N-Nb quaternary coating - Google Patents
Preparation method of Ti-Al-N-Nb quaternary coating Download PDFInfo
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- CN111945151A CN111945151A CN202010727574.4A CN202010727574A CN111945151A CN 111945151 A CN111945151 A CN 111945151A CN 202010727574 A CN202010727574 A CN 202010727574A CN 111945151 A CN111945151 A CN 111945151A
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C24/00—Coating starting from inorganic powder
- C23C24/08—Coating starting from inorganic powder by application of heat or pressure and heat
- C23C24/10—Coating starting from inorganic powder by application of heat or pressure and heat with intermediate formation of a liquid phase in the layer
- C23C24/103—Coating with metallic material, i.e. metals or metal alloys, optionally comprising hard particles, e.g. oxides, carbides or nitrides
Abstract
The invention belongs to the technical field of preparation of high-temperature protective coatings, and particularly relates to a preparation method of a Ti-Al-N-Nb quaternary coating. The method is characterized in that laser is used as an energy source, powder feeding type laser rapid forming equipment is utilized, reasonable process parameters are set, commercially available Ti2AlNb powder is used as a raw material, the Ti-Al-N-Nb quaternary coating is directly obtained by melting and depositing on a forming substrate after sand blasting treatment, the obtained Ti-Al-N-Nb quaternary coating is compact and free of defects, and nitrides in the coating mainly exist in a dendritic crystal form. The process for preparing the Ti-Al-N-Nb quaternary coating does not need a die, and the coating has good forming quality, uniform structure and better comprehensive mechanical property.
Description
Technical Field
The invention belongs to the technical field of preparation of high-temperature protective coatings, relates to a powder feeding type laser rapid prototyping technology, and particularly relates to a preparation method of a Ti-Al-N-Nb quaternary coating.
Background
With the development of the manufacturing field, the requirements of people on metal performance are higher and higher. At present, surface strengthening technologies such as modification and coating are effective ways for prolonging the service life of metals on the premise of not reducing the overall performance of the metals. The nitride hard film layer has the potential of having the characteristics of high hardness, high wear resistance, high melting point, good thermal stability, excellent high-temperature strength, excellent chemical inertness and the like, is suitable for high-speed cutting of materials such as high-alloy steel, stainless steel, titanium alloy, nickel-based alloy and the like, has become a research hotspot at home and abroad, and is widely applied.
Nitride hard coatings that have become industrialized and widely used today are TiN coatings. The coating has good wear resistance and mechanical property, but when the using temperature reaches the critical oxidation temperature, the coating can be rapidly oxidized and failed, and then the protective capability is lost. The Ti-Al-N ternary coating overcomes the defect that the TiN coating cannot be continuously used under the high-temperature condition due to the characteristics of high oxidation temperature, good hot hardness, strong adhesive force, low thermal conductivity and the like. Based on the thought of solid solution strengthening and compound alloying, researchers consider that alloy elements (Nb, Cr, Zr, W, Hf, Ta, Y, Mo, V and the like) are added on the basis of Ti-Al-N ternary nitrides so as to obtain quaternary or even more-element nitride coatings, and based on the performances of different alloy elements, compared with Ti-Al-N ternary coatings, the coatings are improved in the aspects of film-substrate binding force, hardness, oxidation resistance, wear resistance and the like to different degrees.
However, there are few methods for preparing multi-element (more than four-element) nitride hard coatings in the prior art, and the coatings are formed by the ion deposition principle. Such as:
the patent (201310515573.3) is characterized in that a multi-arc ion plating technology is adopted to prepare the titanium aluminum nitride niobium nitrogen gradient hard reaction film. The method adopts the main principle that the cathode target material is evaporated by adopting electric arc discharge, and evaporated ions are deposited on the surface of a base material to form a film. The method can control the formation of the coating by adjusting the size of the external magnetic field, and has the advantages of high film forming speed, high coating density and high film-substrate binding force. But the process is limited by the vacuum environment, the size and shape of the product are limited, and the surface finish of the coating is low.
Both the patent (CN201711182033.2) and the patent (CN201410046151.0) adopt magnetron sputtering technology to respectively prepare TiAlVN and TiAlCrN multi-component coatings. The main principle of magnetron sputtering is that under the low-pressure environment, electrons collide with working gas through the action of an electric field to form high-energy particles, and the high-energy particles bombard a target material to sputter atoms so as to deposit the atoms on a substrate to obtain a coating. The coating obtained by the method has good uniformity, controllable surface smoothness and thickness, high deposition rate and good film-substrate bonding force, but is similar to the multi-arc ion plating method, the process needs to be carried out in a low-pressure closed environment, the size and the shape of the product are limited, and the thickness of the coating is thin.
Therefore, it is necessary to develop a method for preparing a multi-element (quaternary or higher) nitride hard coating layer that can solve the above problems.
Disclosure of Invention
Aiming at the problems, the invention provides a method for preparing a Ti-Al-N-Nb quaternary coating by taking a high-energy laser beam as a heat source.
In order to solve the technical problem, the technical scheme of the invention is as follows:
a preparation method of a Ti-Al-N-Nb quaternary coating is characterized in that Ti2AlNb powder is used as a raw material, a powder feeding type laser forming technology is adopted to prepare the Ti-Al-N-Nb quaternary coating, nitrides in the coating mainly exist in a dendritic crystal form, and the preparation process comprises the following steps:
step one, carrying out sand blasting treatment on a substrate;
secondly, placing Ti2AlNb powder with uniform granularity in a powder feeder of a laser rapid prototyping system, and taking mixed gas of nitrogen and argon in a certain proportion as powder carrying gas and protective gas;
step three, coaxially sending out the laser and the powder, synchronously moving the laser and the powder, scanning the laser and the powder for one pass in one direction, melting the Ti2AlNb powder on a forming substrate to form a molten pool under the action of the laser, and reacting the molten pool with nitrogen; the molten pool is solidified along with the forward movement of the powder and the laser to form a coating of one pass;
fourthly, the coaxial heads of the powder and the laser move for one pass interval along the coating direction vertical to the third step, and the third step is repeated to obtain another pass of coating;
and step five, repeating the step four until the Ti-Al-N-Nb quaternary coating with the required area is prepared, and taking out the coating after the temperature of the coating is reduced to room temperature to obtain the alloy with the Ti-Al-N-Nb quaternary coating on the surface.
And in the second step, the nitrogen in the mixed gas accounts for 20-80%.
Preferably, the average grain diameter of the Ti2AlNb powder in the second step is 50-100 μm.
Preferably, the flow rate of the powder-carrying airflow in the third step is 5-10L/min, and the flow rate of the protective airflow is 10-30L/min.
Preferably, the powder feeding rate in the third step is 5-15 g/min.
Preferably, the laser power in the third step is 500-1500W, the laser is in a defocused state, the defocused distance is 3-15 mm, and the laser scanning speed is 800-1500 mm/min.
Preferably, the distance between the fourth passes in the step is 0.2-0.6 mm.
Preferably, the Ti2AlNb powder in step two is obtained by sieving commercially available Ti2AlNb powder through a metal sieve.
The invention has the beneficial effects that:
the invention adopts a powder feeding type laser rapid forming technology to prepare the Ti-Al-N-Nb quaternary coating. Ti2AlNb powder is used as a raw material, a mixed gas of nitrogen and argon in a certain proportion is used as a powder-carrying gas and a protective gas, and a reaction is carried out on the surface of a formed substrate under the action of laser, so that the Ti-Al-N-Nb quaternary coating is prepared. Because of the addition of the alloy element Nb, the hardness, the thermal stability, the film-substrate binding force and the wear resistance of the quaternary coating are all superior to those of the Ti-Al-N ternary coating. The substrate is subjected to sand blasting treatment, so that the surface cleanliness of the substrate can be improved, certain roughness can be obtained, the laser absorption rate is further improved, the film-substrate binding force is enhanced, and the service life of the coating is prolonged. In the preparation process, laser is used as a coating heat source, the coating and the matrix are metallurgically bonded, the film-matrix bonding force is high, the laser action area is small, the area which is difficult to process can be processed, the coating is suitable for components with complicated shapes, in addition, the thermal deformation of the substrate is small, and the problem of coating cracking after coating is relieved. The invention can control the surface nitridation by controlling the laser radiation condition, changing the laser condition (laser power, scanning speed, etc.) and the gas condition (nitrogen and argon proportion, gas flow rate, etc.). The nitrides in the coating are mainly present in the form of dendrites, are uniformly distributed, and because of the deep laser action depth, thicker coatings (up to several hundred micrometers) can be produced. The invention is based on the laser rapid forming technology, has high coating preparation efficiency, can be used for preparing coatings in atmospheric environment, and has wide application prospect.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Features of various aspects of embodiments of the invention will be described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these specific details. The following description of the embodiments is merely intended to better understand the present invention by illustrating examples thereof. The present invention is not limited to any particular arrangement or method provided below, but rather covers all product structures, any modifications, alterations, etc. of the method covered without departing from the spirit of the invention.
In the following description, well-known structures and techniques are not shown to avoid unnecessarily obscuring the present invention. The preparation method of the Ti-Al-N-Nb quaternary coating is specifically as follows.
Example 1
(1) Sieving commercially available Ti2AlNb powder by a metal sieve to obtain Ti2AlNb powder with the average particle size of 80 mu m;
(2) taking TC4 titanium alloy of 100mm multiplied by 5mm as a forming substrate, and carrying out sand blasting treatment on the substrate;
(3) placing the Ti2AlNb powder obtained in the step (1) in a powder feeder of a laser rapid prototyping system, and taking a mixed gas of nitrogen and argon in a certain proportion as a powder carrying gas and a protective gas, wherein the nitrogen content in the mixed gas is 60%, the powder carrying gas flow rate is 8L/min, and the protective gas flow rate is 25L/min;
(4) the laser and the powder are coaxially sent out and synchronously move, scanning is carried out only in one direction for one pass, the powder feeding speed is 10g/min, the laser power is 600W, the laser is in a defocusing state, the defocusing distance is 5mm, the laser scanning speed is 900mm/min, and under the action of the laser, the Ti2AlNb powder is melted on a forming substrate to form a molten pool and reacts with nitrogen. The molten pool is solidified along with the forward movement of the powder and the laser to form a coating;
(5) moving the coaxial heads of the powder and the laser along the coating direction vertical to the step (4) for a certain distance (namely, the pass interval), wherein the pass interval is 0.4mm, and repeating the step (4) to obtain another pass of coating;
(6) and (5) repeating the step (5) until the Ti-Al-N-Nb quaternary coating with the area of 100mm multiplied by 100mm is prepared, and removing the coating after the temperature of the coating is reduced to room temperature to obtain the TC4 titanium alloy with the Ti-Al-N-Nb coating on the surface.
Example 2
(1) Sieving commercially available Ti2AlNb powder by a metal sieve to obtain Ti2AlNb powder with the average grain size of 90 mu m;
(2) taking TC4 titanium alloy of 100mm multiplied by 5mm as a forming substrate, and carrying out sand blasting treatment on the substrate;
(3) placing the Ti2AlNb powder obtained in the step (1) in a powder feeder of a laser rapid prototyping system, and taking a mixed gas of nitrogen and argon in a certain proportion as a powder carrying gas and a protective gas, wherein the nitrogen content in the mixed gas is 40%, the powder carrying gas flow rate is 6L/min, and the protective gas flow rate is 20L/min;
(4) the laser and the powder are coaxially sent out and synchronously move, scanning is carried out in one direction only for one pass, the powder feeding speed is 7.5g/min, the laser power is 900W, the laser is in a defocusing state, the defocusing distance is 7mm, the laser scanning speed is 1000mm/min, and under the action of the laser, the Ti2AlNb powder is melted on a forming substrate to form a molten pool and reacts with nitrogen. The molten pool is solidified along with the forward movement of the powder and the laser to form a coating;
(5) moving the coaxial heads of the powder and the laser along the coating direction vertical to the step (4) for a certain distance (namely, the pass interval), wherein the pass interval is 0.3mm, and repeating the step (4) to obtain another pass of coating;
(6) and (5) repeating the step (5) until the Ti-Al-N-Nb quaternary coating with the area of 100mm multiplied by 100mm is prepared, and removing the coating after the temperature of the coating is reduced to room temperature to obtain the TC4 titanium alloy with the Ti-Al-N-Nb coating on the surface.
According to the invention, the Ti-Al-N-Nb coating is formed by reacting nitrogen in the molten pool, the depth of the nitrided layer can be controlled by changing the laser conditions (laser power, scanning speed and the like) and the gas conditions (nitrogen-argon ratio, gas flow rate and the like), and the Ti-Al-N-Nb quaternary coating with the thickness of 180 mu m can be prepared in the embodiment.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive various equivalent modifications or substitutions within the technical scope of the present invention, and these modifications or substitutions should be covered within the scope of the present invention.
Claims (8)
1. A preparation method of a Ti-Al-N-Nb quaternary coating is characterized by comprising the following steps: the preparation method of the Ti-Al-N-Nb quaternary coating takes Ti2AlNb powder as a raw material, adopts the powder feeding type laser forming technology to prepare the Ti-Al-N-Nb quaternary coating, and comprises the following steps:
step one, carrying out sand blasting treatment on a substrate;
placing Ti2AlNb powder with uniform granularity in a powder feeder of a laser rapid prototyping system, and taking a mixed gas of nitrogen and argon as a powder carrying gas and a protective gas;
step three, coaxially sending out the laser and the powder, synchronously moving the laser and the powder, scanning the laser and the powder for one pass in one direction, melting the Ti2AlNb powder on a forming substrate to form a molten pool under the action of the laser, and reacting the molten pool with nitrogen; the molten pool is solidified along with the forward movement of the powder and the laser to form a coating of one pass;
fourthly, the coaxial heads of the powder and the laser move for one pass interval along the coating direction vertical to the third step, and the third step is repeated to obtain another pass of coating;
and step five, repeating the step four until the Ti-Al-N-Nb quaternary coating with the required area is prepared, and taking out the coating after the temperature of the coating is reduced to room temperature to obtain the alloy with the Ti-Al-N-Nb quaternary coating on the surface.
2. The method of preparing a Ti-Al-N-Nb quaternary coating according to claim 1, characterized in that: in the second step, the average grain diameter of the Ti2AlNb powder is 50-100 mu m.
3. The method of preparing a Ti-Al-N-Nb quaternary coating according to claim 1, characterized in that: and in the second step, the nitrogen in the mixed gas accounts for 20-80%.
4. The method of preparing a Ti-Al-N-Nb quaternary coating according to claim 1, characterized in that: in the third step, the flow speed of the powder-carrying airflow is 5-10L/min, and the flow speed of the protective airflow is 10-30L/min.
5. The method of preparing a Ti-Al-N-Nb quaternary coating according to claim 1, characterized in that: the powder feeding rate in the third step is 5-15 g/min.
6. The method of preparing a Ti-Al-N-Nb quaternary coating according to claim 1, characterized in that: in the third step, the laser power is 500-1500W, the laser is in an out-of-focus state, the out-of-focus distance is 3-15 mm, and the laser scanning speed is 800-1500 mm/min.
7. The method of preparing a Ti-Al-N-Nb quaternary coating according to claim 1, characterized in that: the fourth step is that the channel interval is 0.2-0.6 mm.
8. The method of preparing a Ti-Al-N-Nb quaternary coating according to claim 1, characterized in that: and in the second step, the Ti2AlNb powder is obtained by sieving commercially available Ti2AlNb powder through a metal sieve.
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