A method of powder-fed laser cladding

Abstract

The application relates to the technical field of metal surface processing, in particular to a powder feeding type laser cladding method.The method comprises the following steps: filling a gas with a set pressure into a powder feeding device powder bin, so that a to-be-cladded powder enters a powder feeding head of the powder feeding device; the included angle between the powder feeding head and the horizontal plane normal is controlled, the to-be-cladded powder is sprayed to a to-be-cladded substrate surface through the powder feeding head, so that the to-be-cladded powder is attached to at least part of the to-be-cladded substrate surface, and a to-be-laser-cladded layer is obtained; wherein the included angle between the to-be-cladded substrate surface normal and the horizontal plane normal is greater than or equal to 120 ο ; the surface of the to-be-laser-cladded layer containing the to-be-cladded powder is melted and a molten pool is formed through laser, and then is cooled and solidified to obtain a cladded layer.The application solves the technical problem that large parts cannot be moved for on-site processing, and that a large-angle to-be-cladded substrate surface (the included angle between the to-be-cladded substrate surface normal and the horizontal plane normal is too large) cannot be subjected to laser cladding.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal surface processing, in particular to a powder feeding type laser cladding method. BACKGROUND

[0002] The powder feeding type laser cladding is also called laser cladding or laser coating, which is a new surface modification technology. It forms a metallurgical bonded additive cladding layer on the surface of the base layer by adding cladding material on the surface of the base material and using high-energy-density laser beam to melt the cladding material together with the thin layer on the surface of the base material.

[0003] At present, for the powder feeding type laser cladding of large parts which need to be processed on site and cannot be moved, and the large-angle cladding substrate surface (the angle between the normal of the cladding substrate surface and the normal of the horizontal plane is too large), the powder feeding type laser cladding is still not formed a special and effective process method due to the limitation of cladding technology and operation method.

[0004] The powder feeding type laser cladding of the large-angle cladding substrate surface is carried out by using the conventional method. On the one hand, due to the large angle, it is not possible to pre-powder, on the other hand, the powder scatters in the powder feeding process due to the action of gravity, resulting in low powder acquisition rate of the molten pool, low utilization rate, and the cladding layer is too thin, so the powder feeding type laser cladding of the large-angle cladding substrate surface cannot be completed. SUMMARY

[0005] The present application provides a powder feeding type laser cladding method to solve the technical problem that the large-angle cladding substrate surface (the angle between the normal of the cladding substrate surface and the normal of the horizontal plane is too large) of large parts which need to be processed on site and cannot be moved cannot be laser cladded in the prior art.

[0006] In a first aspect, the present application provides a powder feeding type laser cladding method, which comprises:

[0007] A gas with a set pressure is filled into a powder tank of a powder feeding device to make the cladding powder enter a powder feeding head of the powder tank of the powder feeding device;

[0008] The angle between the powder feeding head and the normal of the horizontal plane is controlled, the cladding powder is sprayed to the cladding substrate surface by the powder feeding head, so that the cladding powder is attached to at least part of the surface of the cladding substrate to obtain a laser cladding layer; wherein the angle between the normal of the cladding substrate surface and the normal of the horizontal plane is ≥120 ο ;

[0009] The surface of the laser cladding layer containing the cladding powder is melted by laser to form a molten pool, and then cooled and solidified to obtain a cladding layer.

[0010] Optionally, the angle between the normal of the cladding substrate surface and the normal of the horizontal plane is 120 ο ~180ο .

[0011] Optionally, the set pressure is 0.3MPa-2MPa.

[0012] Optionally, the included angle between the powder feeding head and the normal of the horizontal plane is 10 ο -20 ο .

[0013] Optionally, the gas includes at least one of argon, nitrogen, carbon dioxide.

[0014] Optionally, the powder to be cladded includes an adhesive and a raw material.

[0015] Optionally, the powder to be cladded includes an adhesive, an auxiliary agent and a raw material.

[0016] Optionally, the raw material includes at least one of ceramic powder, alloy powder.

[0017] Optionally, the adhesive includes at least one of epoxy adhesive, acrylate adhesive, silicate, sulfate.

[0018] Optionally, the auxiliary agent includes at least one of alcohol, acetone, rosin.

[0019] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0020] The powder feeding type laser cladding method provided by the embodiment of the present application uses a gas with a certain pressure to spray the powder to be cladded to the large-angle surface of the substrate to be cladded through the powder feeding head at a certain angle, and laser cladding is performed at the same time. The advantage is that the large-angle surface of the substrate to be cladded can be directly laser cladded on site, which not only avoids the scattering of the powder due to the gravity in the powder feeding process, but also avoids the phenomenon of low powder yield, low utilization rate and too thin cladding layer of the laser cladding molten pool on the large-angle surface of the substrate to be cladded. In summary, the technical problem that the large-angle surface of the substrate to be cladded cannot be laser cladded because the large-scale parts cannot be moved and processed on site in the prior art is solved. BRIEF DESCRIPTION OF DRAWINGS

[0021] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the present application and, together with the specification, serve to explain the principles of the application.

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

[0023] Figure 1 A flowchart of a powder feeding type laser cladding method provided by an embodiment of the present application;

[0024] Figure 2 A micrograph of a cladding layer provided by Embodiment 1 of the present application;

[0025] Figure 3 A macrograph of a cladding layer provided by Embodiment 1 of the present application. DETAILED DESCRIPTION

[0026] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without any creative effort fall within the scope of protection of the present application.

[0027] The various embodiments of the present application can exist in the form of a range; it should be understood that the description in the form of a range is merely for the convenience and brevity, and should not be understood as a hard limitation on the scope of the present application; therefore, it should be considered that the described range has specifically disclosed all possible sub-ranges and single values within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the described range, such as 1, 2, 3, 4, 5 and 6, which applies to any range. In addition, whenever a numerical range is indicated in this document, it refers to any cited number (fraction or integer) within the indicated range.

[0028] In the present application, the orientation words such as "upper" and "lower" are specifically the directions of the drawing surface in the drawings unless otherwise stated. In addition, in the description of the present application, the terms "include", "contain" and the like mean "include but not limited to". In the present text, the relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. In the present text, the "and / or" describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent the cases of A alone, A and B together, and B alone. Wherein A and B can be singular or plural. In the present text, "at least one" means one or more, and "multiple" means two or more. "At least one", "at least one of the following" or the like means any combination of the items, including single item or any combination of multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can represent a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, wherein a, b, and c can be single or multiple.

[0029] Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or prepared by existing methods.

[0030] In a first aspect, the present application provides a powder feeding type laser cladding method, please refer to Figure 1 , the method comprises:

[0031] S1, a gas with a set pressure is filled into a powder tank of a powder feeding device, so that the to-be-cladded powder enters a powder feeding head of the powder tank of the powder feeding device;

[0032] S2, the included angle between the powder feeding head and the horizontal normal is controlled, the to-be-cladded powder is sprayed to the surface of the to-be-cladded substrate through the powder feeding head, so that the to-be-cladded powder is attached to at least part of the surface of the to-be-cladded substrate, and a to-be-laser-cladded layer is obtained; wherein the included angle between the normal of the surface of the to-be-cladded substrate and the horizontal normal is ≥120 ο ;

[0033] S3, the surface of the to-be-laser-cladded layer containing the to-be-cladded powder is melted and a molten pool is formed by laser, and then cooled and solidified to obtain a cladding layer.

[0034] In the embodiments of the present application, the "normal" indicates the direction of the normal line, which is perpendicular to the tangent direction, i.e. the direction of the tangent line. The above method is suitable for laser cladding of a large part which needs to be processed on site and cannot be moved, and laser cladding of a large-angle to-be-cladded substrate surface (the angle between the normal of the to-be-cladded substrate surface and the normal of the horizontal plane is greater than or equal to 120 ο ) which cannot be processed on site. The technical problem of the large-angle to-be-cladded substrate surface which cannot be processed on site is solved. Referring to Figure 2 the microstructure diagram of the cladding layer provided by the present application, Figure 3 the macrostructure diagram of the cladding layer provided by the present application, it can be seen that the cladding layer formed by the powder feeding type laser cladding method provided by the embodiments of the present application has good formability, and the surface is flat and uniform.

[0035] In some embodiments, the angle between the normal of the to-be-cladded substrate surface and the normal of the horizontal plane is 120 ο ~ 180 ο .

[0036] Specifically, the angle between the normal of the to-be-cladded substrate surface and the normal of the horizontal plane can be 120 ο , 130 ο , 140 ο , 150 ο , 160 ο , 170 ο , 180 ο , etc. Figure 2 The angle between the normal of the to-be-cladded substrate surface and the normal of the horizontal plane provided by the embodiments of the present application is 180 ο , the microstructure diagram of the cladding layer formed thereby, Figure 2 it can be seen that the overall cladding layer has a relatively thick and uniform thickness; Figure 3 The angle between the normal of the to-be-cladded substrate surface and the normal of the horizontal plane provided by the embodiments of the present application is 180 ο , the macrostructure diagram of the cladding layer formed thereby, Figure 3 it can be seen that the surface of the overall cladding layer is relatively flat and has a uniform thickness.

[0037] In some embodiments, the set pressure is 0.3 MPa to 2 MPa.

[0038] The positive effect of the powder feeding gas filled into the powder tank of the powder feeding device is that it can ensure that the mixed raw material powder stably enters the powder feeding head from the powder tank and adheres to the to-be-cladded substrate surface. The mixed material is sprayed to the large-angle to-be-cladded substrate surface at a certain angle by the powder feeding head using the powder feeding gas at a certain pressure.

[0039] The positive effect of setting the pressure to 0.3-2 MPa is to ensure that the mixed raw material powder stably enters the powder feeding head from the powder bin and adheres to the surface of the substrate to be cladded. If the pressure is too small, the powder feeding amount will be too small, the cladding layer of the laser processing will be thin, and the forming quality will be poor. When the pressure is too large, the airflow will cause the mixed material to separate from the adhered surface of the substrate to be cladded, resulting in uneven distribution of the adhered powder and poor forming quality. Specifically, the atmospheric pressure in the powder bin of the powder feeding device can be 0.3 MPa, 0.8 MPa, 1.3 MPa, 1.8 MPa, etc.

[0040] In some embodiments, the angle between the powder feeding head and the normal of the horizontal plane is 10 ο -20 ο .

[0041] The positive effect of setting the angle between the powder feeding head and the normal of the horizontal plane to 10 ο -20 ο is to ensure that the mixed raw material powder can be stably sprayed onto the surface of the substrate to be cladded. If the angle between the powder feeding head and the normal of the surface of the substrate to be cladded is too small, the spraying effect of the mixed material will be poor due to gravity, and even the powder feeding head will be blocked. When the angle between the powder feeding head and the normal of the surface of the substrate to be cladded is too large, the adhesion effect of the mixed material will be poor, and the adhesion area on the surface of the substrate to be cladded will be uneven. Specifically, the angle between the powder feeding head and the normal of the horizontal plane can be 10 ο , 12 ο , 14 ο , 16 ο , 18 ο , 20 ο , etc.

[0042] In some embodiments, the gas includes at least one of argon, nitrogen, and carbon dioxide.

[0043] The positive effect of argon is to prevent oxidation of the raw material during laser processing, and to ensure that the mixed material has enough kinetic energy to reach the surface of the substrate to be cladded.

[0044] The positive effect of nitrogen is to prevent oxidation of the raw material during laser processing, and to ensure that the mixed material has enough kinetic energy to reach the surface of the substrate to be cladded.

[0045] The positive effect of carbon dioxide is to prevent oxidation of the raw material during laser processing, and to ensure that the mixed material has enough kinetic energy to reach the surface of the substrate to be cladded.

[0046] In some embodiments, the powder to be cladded includes a binder and a raw material.

[0047] The raw material is made to have viscosity by the adhesive, so that the mixed powder is attached to the surface of the substrate to be cladded. The adhesive is an organic or inorganic material with certain viscosity, which can provide certain viscosity to the raw material after mixing, so as to ensure that the raw material can be attached to the surface of the substrate to be cladded at any angle within a certain time. The material does not leave residual substances and defects under the condition of laser cladding, and does not reduce the performance of the formed organization of the raw material powder.

[0048] In some embodiments, the powder to be cladded comprises: an adhesive, an auxiliary agent and a raw material.

[0049] In the embodiments of the present application, the adhesive is added to the raw material, and an auxiliary agent can also be added according to the situation. The positive effect of the auxiliary agent is to improve the powder filling performance and reduce the difficulty of feeding the mixed state material. The material can avoid reducing the viscosity of the mixed material and the performance of the formed organization of the raw material powder to the greatest extent under the condition of powder feeding type laser cladding.

[0050] In some embodiments, the raw material comprises at least one of: ceramic powder, alloy powder.

[0051] The positive effect of the ceramic powder is to form a cladded layer with specific organization and performance. Specifically, the ceramic can be boron nitride

[0052] The positive effect of the alloy powder is to form a cladded layer with specific organization and performance. Specifically, the alloy can be high-chromium-content iron-based alloy powder

[0053] In some embodiments, the adhesive comprises at least one of: epoxy adhesive, acrylate adhesive, silicate, sulfate.

[0054] The positive effect of the epoxy adhesive is that it has certain viscosity, which can provide certain viscosity to the raw material after mixing, so as to ensure that the raw material can be attached to the surface of the substrate to be cladded at any angle within a certain time, and does not reduce the performance of the formed organization of the raw material powder under the condition of laser cladding.

[0055] The positive effect of the acrylate adhesive is that it has certain viscosity, which can provide certain viscosity to the raw material after mixing, so as to ensure that the raw material can be attached to the surface of the substrate to be cladded at any angle within a certain time, and does not reduce the performance of the formed organization of the raw material powder under the condition of laser cladding.

[0056] The positive effect of the silicate is that it has certain viscosity, which can provide certain viscosity to the raw material after mixing, so as to ensure that the raw material can be attached to the surface of the substrate to be cladded at any angle within a certain time, and does not reduce the performance of the formed organization of the raw material powder under the condition of laser cladding.

[0057] The positive effect of the sulfate is that it has certain viscosity, and can provide certain viscosity to the raw materials after mixing, so as to ensure that the raw materials can adhere to the surface of the substrate to be cladded at any angle within a certain time, and does not reduce the performance of the raw material powder forming organization under the condition of laser cladding.

[0058] In some embodiments, the auxiliary agent includes at least one of alcohol, acetone, and rosin.

[0059] The positive effect of the alcohol is to improve the powder filling performance, reduce the powder feeding difficulty of the mixed state material, and maximize the avoidance of reducing the viscosity of the mixed material and the performance of the raw material powder forming organization under the condition of powder feeding type laser cladding.

[0060] The positive effect of the acetone is to improve the powder filling performance, reduce the powder feeding difficulty of the mixed state material, and maximize the avoidance of reducing the viscosity of the mixed material and the performance of the raw material powder forming organization under the condition of powder feeding type laser cladding.

[0061] The positive effect of the rosin is to improve the powder filling performance, reduce the powder feeding difficulty of the mixed state material, and maximize the avoidance of reducing the viscosity of the mixed material and the performance of the raw material powder forming organization under the condition of powder feeding type laser cladding.

[0062] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and are not used to limit the scope of the present application. The experimental methods in the following examples are not specified, and are generally determined according to the national standards. If there is no corresponding national standard, the international standard, the conventional condition, or the condition suggested by the manufacturer is used.

[0063] Table 1 Composition of the powder to be cladded.

[0064] Serial number Raw material Binder Auxiliary agent Example 1 Ceramic powder and alloy powder Silicate Alcohol Example 2 Ceramic powder Epoxy resin Acetone Example 3 Alloy powder Acrylate Rosin Example 4 Ceramic powder and alloy powder Sulfate Alcohol Example 5 Ceramic powder and alloy powder Acrylate - Comparative example 1 Ceramic powder and alloy powder - Alcohol Comparative example 2 Ceramic powder and alloy powder Silicate Alcohol Comparative example 3 Ceramic powder and alloy powder Silicate Alcohol Comparative example 4 Ceramic powder and alloy powder Silicate Alcohol Comparative example 5 Ceramic powder and alloy powder Silicate Alcohol

[0065] Table 2 Process of powder feeding type laser cladding.

[0066]

[0067]

[0068] Table 3 Process forming property detection results of powder feeding type laser cladding.

[0069]

[0070] From Table 1, the composition of the mixed powder used in the powder feeding type laser cladding process in the embodiment of the present application can be seen. The mixed powder contains raw materials, binders and auxiliary agents, which are more conducive to the formation of the final cladding layer. From Table 2, the process of the powder feeding type laser cladding method can be seen. The powder feeding device powder bin is input with a gas of a certain pressure, and the included angle between the powder feeding head and the horizontal normal is set, which is conducive to successfully bonding the mixed powder on the surface of the substrate to be cladded (the included angle between the normal of the surface of the substrate to be cladded and the horizontal normal is 120 ο ~ 180 ο ). It should be noted that the laser melting of the mixed powder and the surface of the substrate to be cladded of a certain thickness to form a molten pool is completed at the same time. The laser melting of the mixed material before adhering to the surface of the substrate to be cladded or the melting of the mixed material into the molten pool will cause poor flatness of the cladding layer and uneven layer thickness. From Table 3, the process forming property test results of the powder feeding type laser cladding can be seen. The cladding layer formed by the powder feeding type laser cladding method of the embodiment of the present application has good forming property, and the surface is flat and uniform.

[0071] The above description is merely a specific implementation of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method of powder-fed laser cladding, characterized in that, The method is suitable for large parts which are processed on site and cannot be moved, and the method comprises the following steps: a gas with a set pressure is filled into a powder tank of a powder feeding device, so that a powder to be cladded enters a powder feeding head of the powder feeding device; an included angle between the powder feeding head and a horizontal plane normal is controlled, the powder to be cladded is sprayed to a surface of a substrate to be cladded by the powder feeding head, so that the powder to be cladded is attached to at least part of the surface of the substrate to be cladded, and a layer to be laser cladded is obtained; a surface of the layer to be laser cladded containing the powder to be cladded is melted and a molten pool is formed by laser, and then is cooled and solidified to obtain a cladded layer; The angle between the powder feeding head and the normal of the horizontal plane is 10 ο ~20 ο The to-be-cladded powder comprises an adhesive, an auxiliary agent and a raw material. The included angle between the normal of the surface to be cladded and the normal of the horizontal plane is 120 ο ~180 ο ; the gas comprises at least one of argon, nitrogen and carbon dioxide; the adhesive comprises at least one of an epoxy adhesive, an acrylate adhesive, a silicate and a sulfate; the raw material comprises at least one of a ceramic powder and an alloy powder.

2. The method of claim 1, wherein, the auxiliary agent comprises at least one of alcohol, acetone and rosin.

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