Wear-resistant Stellite6 / WC laser cladding composite coating and preparation method thereof

Abstract

The invention provides a wear-resistant Stellite6 / WC laser cladding composite coating and a preparation method thereof.The preparation method comprises the following steps that 1, Stellite6 cobalt-based alloy powder and WC powder are weighed to obtain composite powder, and the mass of the WC powder accounts for 2.5-10% of the mass of the composite powder; 2, the surface of a to-be-treated base body is pretreated, and a sample base body is obtained; and step 3, preparing a laser cladding coating on a sample matrix by using the obtained composite powder to obtain the wear-resistant Stellite6 / WC laser cladding composite coating. The wear resistance of the surface of the blade can be effectively improved, the service life of the blade is prolonged, and the requirements of the turbine blade under severe working conditions are met.

Description

Technical Field

[0001] The invention belongs to the technical field of laser cladding coatings and relates to a wear-resistant Stellite 6 / WC laser cladding composite coating and a preparation method thereof. Background Art

[0002] Steam turbines are the core equipment of thermal power generation. During the manufacturing process, the blade materials may have defects such as inclusions, pores, cracks, etc. These defects may expand during use and cause damage to the blade surface. In addition, they will be subjected to harsh environments such as high temperature, high speed and high pressure during operation. Long-term use will cause wear and fatigue, and the blade surface will gradually lose material, and wear and cracks will appear. The last-stage long blades work in the wet steam area for a long time. The working medium in the cooling system is usually water or steam, which may contain suspended particles, bubbles or other corrosive substances. When these substances pass through the cooling system, they will collide and scour with the blade surface, causing water erosion on the blade surface, and hit the moving blades in the form of water droplets at a certain angle and very fast speed, causing damage to the moving blades. The impact and scouring of suspended particles or bubbles in the cooling water gradually causes the blade surface to wear and corrode.

[0003] Cobalt-based alloys have broad application prospects in the field of metal surface modification and remanufacturing because of their excellent high temperature performance, thermal fatigue performance, and excellent low friction and wear resistance. This is due to the hcp crystal structure formed by the cobalt element, which has a low stacking fault energy and is difficult to slip, so it is not easy to be damaged by friction. After machining, the surface of the Stellite alloy material is smooth, with excellent wear resistance and low friction coefficient, which effectively reduces the damage and wear stress to the material. Therefore, it is particularly suitable for application scenarios such as valve seals and turbine blades that often face friction and wear. Although the Stellite6 alloy cladding layer has good hardness and wear resistance, considering the use requirements of turbine blades under harsh working conditions, the use of only the Stellite6 alloy cladding layer will only increase the service life of the blade surface to a limited extent. In order to further improve the performance of the blade surface, composite coating technology can be considered. As a hard phase particle, WC has the characteristics of high hardness, high melting point and strong wear resistance, and is often used to mix with metal alloy powder to prepare composite coatings. In the composite coating, WC can act as a reinforcing phase and interact with the metal alloy to improve the hardness, wear resistance and strength of the coating, thereby improving the wear resistance of the blade surface, extending the service life of the blade, and meeting the requirements of turbine blades under harsh working conditions.

[0004] Laser cladding technology is a technology that uses laser irradiation to modify the surface of materials. It can repair damage to the metal surface and enhance its performance for remanufacturing. It has been widely used in many engineering practices. Summary of the invention

[0005] The purpose of the present invention is to provide a wear-resistant Stellite6 / WC laser cladding composite coating and a preparation method thereof, so as to solve the defect of short life of existing turbine impellers under harsh working conditions; the present invention adopts laser cladding technology to prepare Stellite6 / WC composite coating on Q235 steel plate substrate to obtain a wear-resistant surface with higher strength, greater hardness and better wear resistance, thereby extending the life of related components.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is: The present invention provides a method for preparing a wear-resistant Stellite 6 / WC laser cladding composite coating, comprising the following steps: Step 1, weighing Stellite 6 cobalt-based alloy powder and WC powder to obtain composite powder, wherein the mass of WC powder is 2.5-10% of the mass of the composite powder; Step 2, pretreating the surface of the substrate to be treated to obtain a sample substrate; Step 3, using the obtained composite powder to prepare a laser cladding coating on the sample substrate to obtain a wear-resistant Stellite6 / WC laser cladding composite coating.

[0007] Preferably, in step 1, the mass of the WC powder is 10% of the mass of the composite powder.

[0008] Preferably, in step 1, the weighed Stellite 6 cobalt-based alloy powder and WC powder are vacuum dried and then vibrated and mixed to obtain a composite powder.

[0009] Preferably, the process parameters of vacuum drying are: Drying was carried out under argon atmosphere at 80 °C for 360 min; The process parameters of vibration mixing are: vibration frequency of 50 Hz and time of 4 h.

[0010] Preferably, in step 2, the surface of the substrate to be treated is pretreated, and the specific process includes: Ultrasonic cleaning is performed on the surface of the substrate to be treated to obtain a sample after cleaning; The cleaned sample is subjected to sandblasting to obtain a sandblasted sample; The sample after sandblasting is ultrasonically cleaned to obtain the sample matrix.

[0011] Preferably, the process parameters of ultrasonic cleaning are: The ultrasonic frequency was 90KHz and the time was 10min.

[0012] Preferably, in step 3, the obtained composite powder is used to prepare a laser cladding coating on a sample substrate to obtain a wear-resistant Stellite6 / WC laser cladding composite coating, and the specific process is: The obtained composite powder and sample matrix are placed in a laser cladding device; The laser cladding coating is prepared on the sample substrate using the preset process parameters of the single-pass cladding coating and the number of cladding layers.

[0013] Preferably, the overlap between each cladding coating and the previous cladding coating is 30%.

[0014] Preferably, the process parameters of a single-pass cladding coating are: The laser power is 1100W, the scanning speed is 480mm / min, and the powder output speed is 18.75g / min.

[0015] A wear-resistant Stellite 6 / WC laser cladding composite coating is prepared on a sample substrate by using the method described.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for preparing a wear-resistant Stellite6 / WC laser cladding composite coating. Stellite6 / WC cobalt-based alloy composite powder with excellent performance is clad on a Q235 substrate through laser cladding technology to prepare a composite coating with high hardness and high wear resistance. This method can effectively improve the wear resistance and abrasion resistance of the blade surface, extend the service life of the blade, and meet the requirements of turbine blades under harsh working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a preparation flow chart of a wear-resistant Stellite6 / WC laser cladding composite coating of the present invention; Figure 2 is a SEM image of the friction and wear of the sample obtained in Example 1 of the present invention; Figure 3 is a SEM image of the friction and wear of the sample obtained in Example 2 of the present invention; Figure 4 This is a SEM image of the friction and wear of the sample obtained in Example 3 of the present invention; Figure 5 This is the friction and wear SEM morphology of the sample obtained in Example 4 of the present invention. DETAILED DESCRIPTION

[0018] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0019] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0020] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0021] As used in the specification and appended claims of this application, the term "if" can be interpreted as "when" or "uponce" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "uponce it is determined" or "in response to determining" or "uponce [described condition or event] is detected" or "in response to detecting [described condition or event]", depending on the context.

[0022] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0023] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0024] The present application provides a method for preparing a wear-resistant Stellite6 / WC laser cladding composite coating, according to Figure 1 The specific steps shown are implemented: Step 1, weighing Stellite 6 cobalt-based alloy powder and WC (tungsten carbide) powder, the WC powder content is 2.5-10% of the mass of the composite powder; placing the weighed Stellite 6 cobalt-based alloy powder and WC powder in a vacuum drying oven for drying, the vacuum drying temperature is 80 ° C, the time is 360 minutes, and the drying is protected by argon atmosphere; then transferring to a special bottle for vibrating powder mixing, placing it on a vibrating powder mixer for sufficient vibration mixing to obtain composite powder A, the vibration frequency of the vibrating powder mixer is 50 Hz, and the time is 4 hours.

[0025] Step 2: Place the surface of the substrate to be laser clad on an ultrasonic cleaning machine for ultrasonic cleaning to remove surface oil and impurities. The ultrasonic cleaning frequency is 90 KHz and the time is 10 minutes. After the cleaning is completed, sample B is obtained.

[0026] Step 3, performing surface sandblasting on sample B in step 2, and cleaning the surface of the sample substrate with an ultrasonic cleaning machine after the sandblasting to obtain sample C, and the ultrasonic cleaning parameters are the same as those in step 2; Step 4: Place the composite powder A obtained in step 1 and the sample C obtained in step 3 in a laser cladding device to prepare a laser cladding coating. The parameters are: laser power 1100 W, scanning speed 480 mm / min, and powder output speed 18.75 g / min. The sample D obtained is a single-pass cladding coating.

[0027] Step 5, repeat step 4, with the overlap between each cladding layer and the previous one being 30%; repeat 30 times, and obtain sample F as a multi-cladding coating.

[0028] Example 1 A method for preparing a wear-resistant Stellite6 / WC laser cladding composite coating specifically includes the following steps: Step 1: Composite powder prefabrication Weigh Stellite6 cobalt-based alloy powder and WC powder, the WC powder content is 2.5% of the mass of the composite powder; place the weighed Stellite6 cobalt-based alloy powder and WC powder in a vacuum drying oven for drying, the vacuum drying temperature is 80°C, the time is 360 minutes, and the drying is protected by argon atmosphere; then transfer to a special bottle for vibrating powder mixing, place it on a vibrating powder mixer for sufficient vibration mixing to obtain composite powder A, the vibration frequency of the vibrating powder mixer is 50Hz, and the time is 4h. ; Step 2: Clean the substrate surface The surface of the substrate to be laser clad was placed on an ultrasonic cleaning machine for ultrasonic cleaning to remove surface oil and impurities. The ultrasonic cleaning frequency was 90 KHz and the time was 10 min. After the cleaning was completed, sample B was obtained.

[0029] Step 3: Sandblast and clean the substrate surface The surface of sample B in step 2 is subjected to sandblasting treatment, and after the sandblasting is completed, the surface of the sample substrate is cleaned with an ultrasonic cleaning machine to obtain sample C, and the ultrasonic cleaning parameters are the same as those in step 2; Step 4: Single-pass cladding layer preparation The composite powder A obtained in step 1 and the sample C obtained in step 3 were placed in a laser cladding device to prepare a laser cladding coating, and the parameters were laser power of 1100 W, scanning speed of 480 mm / min, and powder output speed of 18.75 g / min. The sample D obtained was a single-pass cladding coating.

[0030] Step 5: Preparation of multiple cladding layers Repeat step 4, with the overlap between each cladding layer and the previous one being 30%; repeat 30 times, and obtain sample F as a multi-cladding coating.

[0031] The SEM appearance of the friction and wear prepared in Example 1 of the present invention is as follows: Figure 2 As shown in the results, it can be seen that there are obvious plowing grooves and a large amount of wear debris in the composite cladding layer with 2.5% WC added.

[0032] Example 2 A method for preparing a wear-resistant Stellite6 / WC laser cladding composite coating specifically includes the following steps: Step 1: Composite powder prefabrication Weigh Stellite6 cobalt-based alloy powder and WC powder, the WC powder content is 5% of the composite powder mass; place the weighed Stellite6 cobalt-based alloy powder and WC powder in a vacuum drying oven for drying, the vacuum drying temperature is 80°C, the time is 360 minutes, and the drying is protected by argon atmosphere; then transfer to a special bottle for vibrating powder mixing, place it on a vibrating powder mixer for sufficient vibration mixing to obtain composite powder A, the vibration frequency of the vibrating powder mixer is 50Hz, and the time is 4h. ; Step 2: Clean the substrate surface The surface of the substrate to be laser clad was placed on an ultrasonic cleaning machine for ultrasonic cleaning to remove surface oil and impurities. The ultrasonic cleaning frequency was 90 KHz and the time was 10 min. After the cleaning was completed, sample B was obtained.

[0033] Step 3: Sandblast and clean the substrate surface The surface of sample B in step 2 is subjected to sandblasting treatment, and after the sandblasting is completed, the surface of the sample substrate is cleaned with an ultrasonic cleaning machine to obtain sample C, and the ultrasonic cleaning parameters are the same as those in step 2; Step 4: Single-pass cladding layer preparation The composite powder A obtained in step 1 and the sample C obtained in step 3 were placed in a laser cladding device to prepare a laser cladding coating, and the parameters were laser power of 1100 W, scanning speed of 480 mm / min, and powder output speed of 18.75 g / min. The sample D obtained was a single-pass cladding coating.

[0034] Step 5: Preparation of multiple cladding layers Repeat step 4, with the overlap between each cladding layer and the previous one being 30%; repeat 30 times, and obtain sample F as a multi-cladding coating.

[0035] The SEM appearance of the friction and wear prepared in Example 2 of the present invention is as follows: Figure 3 As shown in the results, it can be seen that the number of furrows in the 5% WC composite cladding layer is reduced, and large areas of spalling pits and pits appear.

[0036] Example 3 A method for preparing a wear-resistant Stellite6 / WC laser cladding composite coating specifically includes the following steps: Step 1: Composite powder prefabrication Weigh Stellite6 cobalt-based alloy powder and WC powder, the WC powder content is 7.5% of the mass of the composite powder; place the weighed Stellite6 cobalt-based alloy powder and WC powder in a vacuum drying oven for drying, the vacuum drying temperature is 80°C, the time is 360 minutes, and the drying is protected by argon atmosphere; then transfer to a special bottle for vibrating powder mixing, place it on a vibrating powder mixer for sufficient vibration mixing to obtain composite powder A, the vibration frequency of the vibrating powder mixer is 50Hz, and the time is 4h. ; Step 2: Clean the substrate surface The surface of the substrate to be laser clad was placed on an ultrasonic cleaning machine for ultrasonic cleaning to remove surface oil and impurities. The ultrasonic cleaning frequency was 90 KHz and the time was 10 min. After the cleaning was completed, sample B was obtained.

[0037] Step 3: Sandblast and clean the substrate surface The surface of sample B in step 2 is subjected to sandblasting treatment, and after the sandblasting is completed, the surface of the sample substrate is cleaned with an ultrasonic cleaning machine to obtain sample C, and the ultrasonic cleaning parameters are the same as those in step 2; Step 4: Single-pass cladding layer preparation The composite powder A obtained in step 1 and the sample C obtained in step 3 were placed in a laser cladding device to prepare a laser cladding coating, and the parameters were laser power of 1100 W, scanning speed of 480 mm / min, and powder output speed of 18.75 g / min. The sample D obtained was a single-pass cladding coating.

[0038] Step 5: Preparation of multiple cladding layers Repeat step 4, with the overlap between each cladding layer and the previous one being 30%; repeat 30 times, and obtain sample F as a multi-cladding coating.

[0039] The SEM appearance of the friction and wear prepared in Example 3 of the present invention is as follows: Figure 4 As shown in the results, it can be seen that in the 7.5% composite cladding layer, there are no obvious plowing grooves, the spalling pits are reduced, and the microstructure of the cladding layer is refined.

[0040] Example 4 A method for preparing a wear-resistant Stellite6 / WC laser cladding composite coating specifically includes the following steps: Step 1: Composite powder prefabrication Weigh Stellite6 cobalt-based alloy powder and WC powder, the WC powder content is 10% of the mass of the composite powder; place the weighed Stellite6 cobalt-based alloy powder and WC powder in a vacuum drying oven for drying, the vacuum drying temperature is 80°C, the time is 360 minutes, and the drying is protected by argon atmosphere; then transfer to a special bottle for vibrating powder mixing, place it on a vibrating powder mixer for sufficient vibration mixing to obtain composite powder A, the vibration frequency of the vibrating powder mixer is 50Hz, and the time is 4h. ; Step 2: Clean the substrate surface The surface of the substrate to be laser clad was placed on an ultrasonic cleaning machine for ultrasonic cleaning to remove surface oil and impurities. The ultrasonic cleaning frequency was 90 KHz and the time was 10 min. After the cleaning was completed, sample B was obtained.

[0041] Step 3: Sandblast and clean the substrate surface The surface of sample B in step 2 is subjected to sandblasting treatment, and after the sandblasting is completed, the surface of the sample substrate is cleaned with an ultrasonic cleaning machine to obtain sample C, and the ultrasonic cleaning parameters are the same as those in step 2; Step 4: Single-pass cladding layer preparation The composite powder A obtained in step 1 and the sample C obtained in step 3 were placed in a laser cladding device to prepare a laser cladding coating, and the parameters were laser power of 1100 W, scanning speed of 480 mm / min, and powder output speed of 18.75 g / min. The sample D obtained was a single-pass cladding coating.

[0042] Step 5: Preparation of multiple cladding layers Repeat step 4, with the overlap between each cladding layer and the previous one being 30%; repeat 30 times, and obtain sample F as a multi-cladding coating.

[0043] The SEM appearance of the friction and wear prepared in Example 4 of the present invention is as follows: Figure 4 As shown in the results, it can be seen that there are no obvious plowing grooves in the 10% composite cladding layer, fewer spalling pits, and the hardness and wear resistance are significantly improved.

[0044] The mechanical properties of the wear-resistant Stellite 6 / WC laser cladding composite coating prepared by the present invention are further illustrated by experiments.

[0045] Take four samples: (I) The wear-resistant Stellite 6 / WC laser cladding composite coating prepared in Example 1 of the present invention has a WC content of 2.5%, which is sample 1; (ii) The wear-resistant Stellite6 / WC laser cladding composite coating prepared in Example 2 of the present invention has a WC content of 5%, which is Sample 2; the other contents are the same as those in Example 1 of the present invention and are not described in detail here; (III) The wear-resistant Stellite6 / WC laser cladding composite coating prepared in Example 3 of the present invention has a WC content of 7.5%, which is Sample 3; the other contents are the same as those in Example 1 of the present invention and will not be described in detail here; (IV) The wear-resistant Stellite6 / WC laser cladding composite coating prepared in Example 4 of the present invention has a WC content of 10%, which is sample 4; the other contents are the same as those in Example 1 of the present invention and are not described in detail here; From the results, it can be seen that with the increase of WC content, the number of plowing grooves and spalling pits decreases, the hardness is significantly improved, and the microstructure of the cladding layer shows the characteristics of refinement. With the increase of carbide phase between grain boundaries, this change effectively inhibits the sliding movement of dislocations on the surface of the cladding layer, thereby inducing strain hardening effect, increasing the resistance of the friction pair to press into the surface of the cladding layer, and correspondingly reducing the wear contact area. In addition, some residual unmelted WC particles gradually emerge to the surface layer, which effectively blocks the cutting action of the friction pair, changes the formation path of the plowing groove or directly prevents its formation, and provides an additional protective barrier for the cladding layer. Based on the above reasons, the cladding layer containing 10% WC exhibits the best wear resistance. In summary, the main wear mechanisms of the composite cladding layer can be attributed to abrasive wear and adhesive wear.

[0046] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for preparing a wear-resistant Stellite6 / WC laser cladding composite coating, characterized in that: The following steps are involved: Step 1, weighing Stellite 6 cobalt-based alloy powder and WC powder to obtain composite powder, wherein the mass of WC powder is 2.5-10% of the mass of the composite powder; Step 2, pretreating the surface of the substrate to be treated to obtain a sample substrate; Step 3, using the obtained composite powder to prepare a laser cladding coating on the sample substrate to obtain a wear-resistant Stellite6 / WC laser cladding composite coating.

2. The method for preparing a wear-resistant Stellite 6 / WC laser cladding composite coating according to claim 1, characterized in that: In step 1, the mass of the WC powder is 10% of the mass of the composite powder.

3. The method for preparing a wear-resistant Stellite 6 / WC laser cladding composite coating according to claim 1, characterized in that: In step 1, Stellite 6 cobalt-based alloy powder and WC powder are weighed and vacuum dried, and then vibrated and mixed to obtain composite powder.

4. The method for preparing a wear-resistant Stellite 6 / WC laser cladding composite coating according to claim 3, characterized in that: The process parameters for vacuum drying are: Drying was carried out under argon atmosphere at 80 °C for 360 min; The process parameters of vibration mixing are: vibration frequency of 50 Hz and time of 4 h.

5. The method for preparing a wear-resistant Stellite 6 / WC laser cladding composite coating according to claim 1, characterized in that: In step 2, the surface of the substrate to be treated is pretreated, and the specific process includes: Ultrasonic cleaning is performed on the surface of the substrate to be treated to obtain a sample after cleaning; The cleaned sample is subjected to sandblasting to obtain a sandblasted sample; The sample after sandblasting is ultrasonically cleaned to obtain the sample matrix.

6. The method for preparing a wear-resistant Stellite6 / WC laser cladding composite coating according to claim 5, characterized in that: Ultrasonic cleaning process parameters: The ultrasonic frequency was 90KHz and the time was 10min.

7. The method for preparing a wear-resistant Stellite 6 / WC laser cladding composite coating according to claim 1, characterized in that: In step 3, the obtained composite powder is used to prepare a laser cladding coating on the sample substrate to obtain a wear-resistant Stellite6 / WC laser cladding composite coating. The specific process is: The obtained composite powder and sample matrix are placed in a laser cladding device; The laser cladding coating is prepared on the sample substrate using the preset process parameters of the single-pass cladding coating and the number of cladding layers.

8. The method for preparing a wear-resistant Stellite 6 / WC laser cladding composite coating according to claim 7, characterized in that: The overlap between each cladding coating and the previous cladding coating is 30%.

9. The method for preparing a wear-resistant Stellite 6 / WC laser cladding composite coating according to claim 8, characterized in that: The process parameters of single-pass cladding coating are: The laser power is 1100W, the scanning speed is 480mm / min, and the powder output speed is 18.75g / min.

10. A wear-resistant Stellite6 / WC laser cladding composite coating, characterized in that: A wear-resistant Stellite 6 / WC laser cladding composite coating is prepared on a sample substrate using the method described in any one of claims 1 to 9.

Images