CN104684667A - Additive manufacturing of turbine components using multiple materials - Google Patents

Abstract

A method of additive manufacturing utilizing multiple materials. First (48), second (50) and third (52) adjacent powder layers and respective first (73) of adjacent final material (30, 44, 45) in a given section of part (20) , second (74) and third (75) area shapes are delivered onto the work surface (54A). The first powder may be a structural metal delivered in the cross-sectional shape of the airfoil base (30). The second powder may be a bond coat material delivered in the cross-sectional shape of the bond coat (45) on the substrate. The third powder may be a thermal barrier ceramic delivered in the cross-sectional shape of the thermal barrier coating (44). Specific laser intensities (69A, 69B) are applied to each layer to melt or sinter the layers. An integrated interface ( 57 , 77 , 80 ) may be formed between adjacent layers by gradient material overlap and/or interdigitation.

Description

Additive manufacturing of turbine components using multiple materials

This application requests U.S. Provisional Patent Application No. 61/710,995, filed October 08, 2012 (Attorney Docket 2012P24077US) and U.S. Provisional Patent Application No. 61/711,813, filed October 10, 2012 (Attorney 2012P24278US), both of which are incorporated herein by reference.

technical field

The present invention relates to additive layer manufacturing, and in particular to the fabrication of multi-material metal/ceramic gas turbine components by selective laser sintering and selective laser melting of adjacent powder layers of different materials.

Background technique

Selective layer additive manufacturing includes selective laser melting (SLM) and selective layer sintering (SLS) of powder beds to build up parts layer by layer to achieve net shape or near net shape. A powder bed of part final or precursor material is deposited on the work surface. Laser energy is selectively directed onto a powder bed that follows the shape of the cross-sectional area of the part, thereby forming a layer or piece of the part that then becomes the new working surface for the next layer. Conventionally, in a first step, a bed of powder is spread over the work surface, and then in a subsequent step, a laser defines or "brushes" the cross-sectional area of the part on the bed, for example by raster scanning.

A related process, often called micro-coating, deposits powder onto the part via a moving nozzle or other conveying device. The laser simultaneously melts the powder at the point of deposition, forming a bead of material on the part as the conveyor moves. Successive passes can build up one or more layers of material for repair or fabrication of components.

Description of drawings

In the following description the invention is explained on the basis of the accompanying drawings, which show:

Figure 1 is a cross-sectional view of a prior art gas turbine blade.

Figure 2 is a cross-sectional view of a powder delivery device forming adjacent layers of powder on a working surface.

Figure 3 is a cross-sectional view of a laser beam melting and sintering adjacent powder layers.

Figure 4 shows a pattern of scan paths for powder delivery and/or laser delivery parallel to the non-linear cross-sectional profile of the part.

Figure 5 shows an alternative scan pattern with parallel linear paths.

Figure 6 shows a scan path perpendicular or approximately perpendicular to the wall of the part.

Figure 7 shows the second sheet formed on the first sheet of the component.

Figure 8 shows adjacent powder layers deposited at different thicknesses.

Figure 9 shows an interlocking interface between adjacent materials.

Figure 10 is a flow diagram illustrating some aspects of an embodiment of the invention.

Detailed ways

The present invention has devised a method for the additive manufacturing of components having multiple adjacent materials with different properties. It uses strong bonding of adjacent materials, including metals to ceramics, to create a net or near-net shape. This is particularly advantageous in the manufacture of gas turbine components such as superalloy blades and airfoils with ceramic thermal barrier coatings. Such airfoils are difficult to manufacture because they have a complex shape with serpentine cooling channels lined with turbulators and film cooling holes.

1 is a transverse cross-sectional view of a typical gas turbine airfoil 20 having a leading edge 22, a trailing edge 24, a pressure side 26, a suction side 28, a metal matrix 30, cooling passages 32, dividing walls 34, turbulators 36 , film cooling exit hole 38 , cooling pin 40 and trailing edge exit hole 42 . The exterior of the airfoil base is coated with a ceramic thermal barrier coating 44 . A metallic bond coat 45 may be applied between the substrate and the thermal barrier coating. Turbulators are protrusions, dimples, ridges or depressions within cooling passage 32 that increase the surface area and mix the fluid boundary layer of coolant flow.

Figure 2 shows a method and apparatus for placing first, second and third adjacent powder layers 48, 50, 52 in the first, second and third adjacent The respective first, second and third cross-sectional area shapes of the final material are delivered onto the working surface 54A. For example, the first powder layer 48 may be a structural metal delivered in the shape of the regions of the airfoil base 30 shown in FIG. 1 . The second powder layer 50 may be a bond coat conveyed adjacent to the first powder 48 in the shape of a region of the bond coat 45 ( FIG. 1 ) on the substrate. The third powder layer 52 may be a thermal barrier ceramic conveyed adjacent to the second powder in the shape of a region of the thermal barrier coating 44 ( FIG. 1 ).

The interface 56 between the first and second powder layers may be conveyed such that an overlap region 57 is formed which provides a material gradient transition between two adjacent powder layers 48 , 50 . The interface 58 between the second and third powders 50, 52 can be conveyed such that an engineered mechanical interlock is formed, such as interleaved fingers (shown later) that alternately protrude from the second and third powders. . The powder delivery device 60 may have one or more nozzles 62 that deliver a powder spray 64 to a focal point 66 .

The powder delivery device 60 can include multi-axis motion 61 relative to the working surface 54A so that the nozzle can follow a non-linear cross-sectional profile in a given horizontal plane, can be moved to different planes or distances relative to the working surface 54A, and can be moved at varying Conveying powder at an angle. The axis may be implemented by movement of the table 55 and/or the powder delivery device 60 via rails and rotary bearings under computer control. Powder delivery parameters such as nozzle translation velocity, mass delivery rate, and spray angle can be predetermined by discrete particle modeling simulations to optimize the final tablet geometry. After spraying, the powder can be compacted and fixed by means of, for example, electromagnetic energy and/or mechanical or acoustic vibrations before laser heating.

The powder can be wetted with water, alcohol, sizing agents or binders before or during spraying so that the powder retains the desired shape until the laser melts or sinters it into a bonded sheet of the part. As described more fully in co-pending U.S. Patent Application Publication US 2013/0140278A1 (Attorney Docket No. 2012P22347US), which is incorporated herein by reference, flux materials can be included with powder materials to facilitate cladding process.

FIG. 3 shows a method and a device for melting and/or sintering different powder layers 48 , 50 , 52 with respective different laser energies. For example, base superalloy powder 48 and bond coat powder 58 may be melted with first and second laser energies, and ceramic thermal barrier powder 52 may be sintered with a third laser energy that only partially melts the ceramic particles. The different laser energies 69A, 69B may be provided by a single laser emitter 68A with variable output, or by multiple laser emitters 68A, 68B with different outputs for different powder layers. The laser emitter can include multi-axis motion 70 relative to the work surface 54A such that it can follow a non-linear cross-sectional profile in a given plane, can be moved to different planes or distances relative to the work surface 54A, and can be positioned and directed laser beam to obtain the desired angle and spot size.

FIG. 4 shows the pattern of paths 72 following the non-linear cross-sectional shape profiles 73 , 74 , 75 of the component 20 . The powder delivery focal point 66 of FIG. 2 can be controlled to follow such a path. This scanning pattern 72 parallel to the cross-sectional shape profile allows for changing the powder type for each powder layer 48 , 50 , 52 .

Laser energy 69A-B ( FIG. 3 ) may also follow a non-linear scan path such as 72 of FIG. 4 . This path type minimizes the number of changes in laser intensity for different powder materials. The first laser energy may be directed to follow the contour of the cross-sectional shape 73 of the first powder layer 48, the second laser energy may be directed to follow the contour of the cross-sectional shape 74 of the second powder layer 50, and the third laser energy may be directed to follow the contour of the cross-sectional shape 75 of the third powder layer 52 . Cycling of the laser may be turned off when the laser passes over areas that are intended to remain as voids in the formed part, such as film cooling holes 38 .

FIG. 5 shows an alternative scan pattern with parallel linear paths 74 of laser energy. Figure 6 shows a path 76 that is perpendicular or approximately perpendicular to the wall of the component. In addition to the off/on cycles for the void 38, the patterns 74 and 76 may also require changing the laser intensity each time the interface 56, 58 of the different powder layers is crossed. The spacing of the scans 72, 74, 76 depends on the laser beam width or spot size at the powder surface. Multiple laser emitters can be used together to create a wider swath to reduce the number of scans. The width of the laser beam(s) can be adjusted by varying the distance of the emitter from the work surface, and/or the size and shape of the beam can be adjusted to better define the part with adjustable lenses, mirrors or gobos small, sharp or curved components, such as fillets, without scanning pitch and spot size.

Figure 7 shows the first cured sheet 74 of the component providing a new working surface 54B onto which the powder layers 48, 50, 52 of the second sheet 76 of the component are applied.

Figure 8 shows powder layers 48, 50, 52 conveyed at different heights depending on their respective processing shrinkage to achieve a final uniform sheet thickness. The powder of the first and second adjacent layers 48, 50 may be deposited in the overlap region 57 such that the powder overlaps in the gradient material transition. The overlapping width may eg be at least 0.2 mm. The powder of the second and third adjacent layers 50, 52 may also be deposited in the overlap region 77 so that the powder overlaps in the gradient material transition. The overlap width may eg be at least 0.2 mm or 0.4 mm, or as much as 1 mm or as much as 2 mm.

Figure 9 shows the interface between the second and third layers 50, 52 formed with engineered interlocking features 80, such as staggered profiles, formed from the adhesive 3D interweaving fingers in which laminated layers 50 and ceramic layers 52 protrude alternately. Such interlocking mechanical interfaces may be provided instead of or in addition to the gradient material regions 77 shown in FIG. 8 . Cracks 82 may be formed in ceramic layer 52 for operational strain relief by turning off/on laser energy cycling as the laser energy scans ceramic layer 52 . Hollow ceramic balls 84 may be included in the material of ceramic layer 52 to reduce thermal conductivity. Inclusion of hollow ceramic spheres in thermal barrier layer 52 permanently reduces its thermal conductivity, since spherical voids do not suffer from reduction due to operational sintering.

Figure 10 is a flowchart illustrating a method 84 of aspects of an embodiment of the invention, comprising the following steps:

86． A plurality of adjacent powder layers of respective different materials are delivered onto the work surface in respective area shapes representing a given cross-section of the multi-material part.

88． Overlapping at least two of adjacent powder layers to form a gradient material transition region between the at least two adjacent powder layers.

90． Specific laser energy is applied to each powder layer to melt or sinter the layers, wherein at least two of the layers respectively receive different laser intensities.

92． Repeat from step 86 for successive sections to manufacture the part by selective layer additive manufacturing.

In some embodiments, the inclusion of nanoscale ceramic particles can reduce the sintering temperature of the ceramic layer by as much as 350°C. This can facilitate co-sintering and bonding of the metal and ceramic layers. The reduction in temperature occurs in particular when the ceramic powder comprises at least 2% and up to 100% by volume of particles having an average diameter of less than 100 nm, and it occurs in particular when the particles have an average diameter of less than 50 nm. The present method allows sintering by only partially melting such nanoparticles. This is not possible when applying ceramic coatings with thermal spray techniques, which tend to completely melt the smaller particles.

Nickel-based superalloys used in high temperature gas turbine components are typically strengthened by a gamma-major precipitated phase within a gamma-phase matrix. The properties of these superalloys that allow them to be durable in high temperature environments also make them difficult to manufacture and repair. However, it can be produced and bonded to adjacent layers of different materials, including ceramics, by the methods described herein. Casting of gas turbine blades with serpentine passages with turbulators and film-cooled exit holes is difficult and expensive. The method reduces costs while more completely joining layers of different materials. This allows for the production of complete multi-material components such as turbine blades in one process, instead of casting superalloy blades and then coating them in a separate process such as thermal spraying.

While various embodiments of the invention have been shown and described herein, it is evident that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions may be made without departing from the invention herein. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims.

Claims (20)

1., for making a method for parts, comprise the following steps:

By multiple adjacent powder layers of respective different dusty materials to represent that the respective region shape of the respective final material in the given section of many material components is transported on working surface;

By at least two overlaps in adjacent powder bed, to form material gradient district between described at least two adjacent powder beds;

First laser energy of the first intensity is applied to the first powder bed in described powder bed, and the second laser energy of the second different laser intensity is applied to the second powder bed in described powder bed; And

Section in succession for described parts repeats from supplying step, to manufacture described parts.

2. the method for claim 1, wherein, described first powder bed comprises metal, described second powder comprises ceramic with heat resistance, described first laser energy is directed to follow more than first scanning pattern parallel with the non-linear periphery of described first powder bed, and described second laser energy is directed to follow more than second scanning pattern parallel with the non-linear periphery of described second powder bed.

3. method as claimed in claim 2, also comprises: the circulation opening and closing described first and second laser energies while following described first and second scanning patterns, to form the passage through the described first and second final materials.

4. method as claimed in claim 2, also comprises: the circulation opening and closing described second laser energy while following the second scanning pattern, to form strain relief crack in the described second final material.

5. the method for claim 1, also comprise: described working surface make to have staggered profile betwixt by the first and second dusty materials are transported to and between the described first and second final materials, form mechanical interlocking interface, forming the staggered finger through described interface.

6. the method for claim 1, also comprise: with the first and second respective thickness, described first and second powder beds are deposited on described working surface, and pre-determine described respective laser energy described powder bed to be reduced to the uniform thickness of the described final material in described given section.

7. the method for claim 1, also comprise: by being provided described first and second laser energies by the laser beam along linear scan Route guiding in succession, each linear scan path is process on described first and second powder beds, and comprises: change the intensity of described laser beam along each scanning pattern to provide described first and second intensity.

8. the product formed by the method for claim 1.

9. make a method for parts, comprise the following steps:

The respective first, second, and third region shape respective powder of first, second, and third adjacent layer of materials different separately being represented given many material profile of described parts to combine is transported on working surface;

Wherein, described first powder bed comprises structural metal material, and described second powder bed comprises adhesive coatings material, and described 3rd powder bed comprises ceramic with heat resistance;

Specific laser energy is applied to each described powder bed to melt or to sinter described layer, wherein, at least two in described layer receive different laser intensities respectively; And

Section is in succession repeated from supplying step, carrys out manufacture component to add manufacture by selective layer.

10. method as claimed in claim 9, also comprises: follow with the scanning pattern of the respective profile parallel of described region shape while open and close the circulation of described laser energy, to form passage in described parts.

11. methods as claimed in claim 9, also comprise: guide the first laser energy to follow the scanning pattern with the profile parallel of described first shape, guide the second laser energy to follow the scanning pattern with the profile parallel of described second shape, and guide the 3rd laser energy to follow the scanning pattern with the profile parallel of described 3rd shape.

12. methods as claimed in claim 11, also comprise: the circulation opening and closing described 3rd laser energy, to form strain relief crack in described ceramic with heat resistance.

13. methods as claimed in claim 11, also comprise: by by described second and the 3rd powder be transported to and described working surface makes to have staggered profile therebetween and between described second and third layer, form mechanical interlocking interface, in described interface, form staggered finger.

14. methods as claimed in claim 9, also comprise: make described first and second powder overlaps reach at least 0.2 mm, form functionally gradient material (FGM) district.

15. methods as claimed in claim 11, also comprise: make described second powder and the 3rd powder overlap reach at least 0.4 mm, form functionally gradient material (FGM) district.

16. methods as claimed in claim 11, also comprise: with the first and second respective different-thickness, described first and third layer are deposited on described working surface, and each self-strength of predefined described laser energy is to be reduced to uniform material thickness by three powder beds.

17. methods as claimed in claim 11, also comprise: provide described first, second, and third laser energy by by the laser beam guided along line in succession, every bar line is process on described first, second, and third layer, and comprises: change the intensity of described laser beam along every bar line to provide specific energy for by each powder bed of described line process.

18. 1 kinds of methods making gas turbine engine component, comprise the following steps:

First, second, and third adjacent powder layer is transported on working surface with the first, second, and third respective region shape of the adjacent final material of first, second, and third in the given section of described parts;

Wherein, described first material comprises structural metal, and described second material comprises adhesive coatings metal, and described 3rd material comprises ceramic with heat resistance;

Use the first and second respective laser energies by described first and second powder beds fusings, and use the 3rd laser energy only partly to be melted by described 3rd powder bed, wherein, solidify to form the new sheet face of adjacent final material; And

Repeat from supplying step for section in succession, to manufacture the parts of the described structural metal with porous ceramics thermal barrier coatings;

Wherein, described first laser energy is directed with the profile following described first shape, and described second laser energy is directed with the profile following described second shape, and described 3rd laser energy is directed with the profile following described 3rd shape.

19. methods as claimed in claim 18, also comprise:

Make described first and second powder overlaps reach at least 0.2 mm, between described first and second layers, form functionally gradient material (FGM) interface; And

By by described second and the 3rd powder be transported to and described working surface make to have staggered profile therebetween and between described second and third layer, forms mechanical interlocking interface, form the staggered finger through described interface.

20. 1 kinds of products formed by method as claimed in claim 19.