METHOD FOR TREATING AND EXAMINING A POWDER BY MEANS OF INSTRUMENTAL ANALYSIS AND USE

Abstract

The application relates to a method for treating and examining a powder by: generating two-dimensional tomographic representation of an initial small amount of powder granules of the powder; determining and outputting an initial powder granule structural parameter based on the two-dimensional tomographic representation of the initial small amount of powder; producing a solid body including a statistically validatable powder representation of a totality of the powder granules of the powder; tomographically representing the solid body, wherein at least one imaging parameter and/or at least one image recording setting is adjusted based on the initial powder granule structural parameter; and determining and outputting at least one characteristic value of the statistically validatable powder representation of the powder granules of the powder by evaluating the tomographic representation of the solid body.

Claims

1-33. (canceled)

34. A method for treating and examining a powder comprising: introducing powder granules of the powder into a liquid precursor stage of a solid body, wherein the powder granules are arranged in the solid body as a statistically validatable powder representation of the powder granules of the powder; isolating and distancing the powder granules of the statistically validatable powder representation from surrounding powder granules of the statistically validatable powder representation and homogeneously distributed in the precursor stage by isolating the introduced powder granules using one or more of dispersants, surfactants, ultrasound, mechanical agitation, and stirring; fixing a position of the isolated powder granules of the statistically validatable powder representation by one of transitioning and converting of the precursor stage of the solid body having the isolated powder granules distanced from the surrounding powder granules of the statistically validatable powder representation and homogeneously distributed in the precursor stage, into the solid body; graphically representing the solid body via a computed tomographic representation; and determining and outputting at least one characteristic value of the statistically validatable powder representation of the powder granules by evaluating the computed tomographic representation of the solid body.

35. The method according to claim 34, wherein at least one step of the method is repeated.

36. The method according to claim 34, wherein the statistically validatable powder representation includes sampling at least 100 powder granules and no more than 10,000,000 powder granules.

37. The method according to claim 34, wherein the at least one characteristic value is one of a volume, a surface area and a length.

38. The method according to claim 34, wherein the computed tomographic representation includes creation of a digital volume of the solid body.

39. The method according to claim 34, further comprising extracting impurities from the powder and examining one or more of the extracted impurities of the powder and remaining purified powder by weighing and by scanning electron microscopy examination.

40. The method according to claim 39, further comprising examining the extracted impurities as per one of the examination applied to the powder, parts of the examination applied to the powder, and one part of the examination applied to the powder, and at least a part of at least one of the examination applied to the powder by two-dimensional tomographic representation, whereby purification parameters can be determined.

41. The method according to claim 34, further comprising determining at least one macroscopic powder parameter selected from one or more of piling behavior, coloration of the powder, and a chemical component of the powder.

42. The method according to claim 34, further comprising: generating at least one two-dimensional tomographic representation of an initial small amount of powder granules of the powder; and determining and outputting at least one powder granule structural parameter based on the at least one two-dimensional tomographic representation, wherein the powder granule structural parameter is used to adjust a sample position for one or more of an imaging parameter and an image recording setting of the computed tomographic representation of the solid body.

43. The method according to claim 42, wherein the at least one powder granule structural parameter is an absorption behavior and at least one 3D imaging parameter is a source setting.

44. The method according to claim 42, wherein the at least one powder granule structural parameter is a particle size of the powder granules and at least one 3D imaging parameter is a detection resolution.

45. The method according to claim 42, wherein the at least one two-dimensional tomographic representation includes at least one magnified image representation of the powder granules of the initial small amount of powder granules.

46. The method according to claim 45, wherein one or more of form parameters and state parameters of the powder granules are obtained as the initial powder granule structural parameter based on the at least one magnified image representation.

47. The method according to claim 34, wherein ultrasound acts upon at least one precursor stage of the solid body during a production of the solid body.

48. The method according to claim 47, wherein the ultrasound acting upon the at least one precursor stage of the solid body occurs during which the at least one precursor stage is forming into the solid body.

49. A method for treating and examining a powder comprising: introducing powder granules of the powder into a liquid precursor stage of a solid body, wherein the powder granules are arranged in the solid body as a statistically validatable powder representation of the powder granules of the powder, wherein the statistically validatable powder representation includes sampling at least 100 powder granules and no more than 10,000,000 powder granules; isolating and distancing the powder granules of the statistically validatable powder representation from surrounding powder granules of the statistically validatable powder representation and homogeneously distributed in the precursor stage by isolating the introduced powder granules using one or more of dispersants, surfactants, ultrasound, mechanical agitation, and stirring, wherein during a production of the solid body ultrasound acts upon the precursor stage of the solid body; fixing a position of the isolated powder granules of the statistically validatable powder representation by one of transitioning and converting of the precursor stage of the solid body having the isolated powder granules distanced from the surrounding powder granules of the statistically validatable powder representation and homogeneously distributed in the precursor stage, into the solid body; graphically representing the solid body via a computed tomographic representation; and determining and outputting at least one characteristic value of the statistically validatable powder representation of the powder granules by evaluating the computed tomographic representation of the solid body.

50. The method according to claim 49, wherein a two-dimensional tomographic representation of an initial powder granule structural parameter includes at least one magnified image representation of the powder granules of an initial small amount of powder granules.

51. The method according to claim 50, wherein one or more of form parameters and state parameters of the powder granules are obtained as the initial powder granule structural parameter based on the at least one magnified image representation.

52. The method according to claim 49, further comprising extracting impurities from the powder and examining one or more of the extracted impurities of the powder and remaining purified powder by weighing and by scanning electron microscopy examination.

53. A method for treating and examining a powder comprising: introducing powder granules of the powder into a liquid precursor stage of a solid body, wherein the powder granules are arranged in the solid body as a statistically validatable powder representation of the powder granules of the powder; isolating and distancing the powder granules of the statistically validatable powder representation from surrounding powder granules of the statistically validatable powder representation and homogeneously distributed in the precursor stage by isolating the introduced powder granules using one or more of dispersants, surfactants, ultrasound, mechanical agitation, and stirring; fixing a position of the isolated powder granules of the statistically validatable powder representation by one of transitioning and converting of the precursor stage of the solid body having the isolated powder granules distanced from the surrounding powder granules of the statistically validatable powder representation and homogeneously distributed in the precursor stage, into the solid body; graphically representing the solid body via a computed tomographic representation; extracting impurities from the powder and examining one or more of the extracted impurities of the powder and remaining purified powder by weighing and by scanning electron microscopy examination; and determining and outputting at least one characteristic value of the statistically validatable powder representation of the powder granules by evaluating the computed tomographic representation of the solid body.

Description

[0133] The invention will be described in greater detail in the following on the basis of an exemplary embodiment referencing the figures. Thereby shown are:

[0134] FIG. 1 a schematic representation of a method for treating and examining a powder by means of instrumental analysis

[0135] FIG. 2 a schematic representation of a method for producing a solid body

[0136] FIG. 3 a 2D sectional image extraction and 3D image synthesis based on 2D sectional views for creating a digital volume and selecting a partial volume of the digital volume

[0137] FIG. 4a an overview of 2D sectional views and resulting digital volume of a solid body according to a prior art method

[0138] FIG. 4b an overview of 2D sectional views and resulting digital volume of a solid body according to a method pursuant to the invention

[0139] FIG. 5 an overview of different partial digital volumes of a digital volume of a solid body according to a method pursuant to the invention

[0140] FIG. 5a a large partial digital volume

[0141] FIG. 5b a medium-sized partial digital volume

[0142] FIG. 5c a small partial digital volume

[0143] FIG. 6 3D image synthesis of isolated powder granules

[0144] FIG. 7 a scanning electron microscope (SEM) image of a 2D powder granule preparation

[0145] FIG. 8 a partial digital volume corresponding to a thin cross-section perpendicular to the rotational axis of the solid body of 10 mm in diameter

[0146] The following description uses the same reference numerals for components of equal and equivalent effect.

[0147] FIG. 1 shows a schematic representation of a method 1 for treating and examining a metallic/metal alloy-based powder by means of instrumental analysis according to one inventive exemplary embodiment. The method is applicable for imaging all metals. The densities thereby correspond to ordinary metals from magnesium (1.7 g/cm.sup.3) to medium (22.6 g/cm.sup.3) and/or generally larger 1.5 g/cm.sup.3.

[0148] Commercially available powders with a mean particle size between 10 and 100 μm can thereby be treated and examined.

[0149] A powder sample 3; i.e. a small amount of the powder, is drawn from the totality of the powder 2 for examination by means of macroscopic and chemical analysis. Said powder sample 3 is supplied to the macroscopic and/or chemical analysis. The chemical analysis yields the chemical components 13 which are present in the powder, or of which the powder partially consists respectively, including the non-metal content (N, C, O, H), as well as an oxide content. To that end, the powder of sample 3 is melted and solidified into a planar flat body and the planar flat body then subjected to X-ray fluorescence spectroscopic analysis. The macroscopy returns macroscopic powder parameters 12, including a Hausner factor, a degree of corrosion and a degree of oxidation. The completion of the macroscopy and/or the chemical analysis represents a process control point 11. When the chemical components 13 and/or macroscopic powder parameters 12 correspond to the specifications and/or indicate that the powder is capable of being processed, following comparison with a database, the method is continued.

[0150] Upon continuation of the method, an initial small amount 4 is drawn from the totality of the powder 2 and subjected to scanning electron microscopic examination. To that end, the particles of the initial small amount 4 are deposited onto an adhesive carbon pad and supplied to a scanning electron microscope (SEM). The scanning electron microscopic examination provides initial powder granule structural parameters, including initial sphericity, initial powder granule volume as well as initial powder granule length. The completion of the SEM examination represents another process control point at which the method is either continued or terminated based on the initial powder granule structural parameters. Upon continuation of the method, the initial powder granule structural parameters 14 are supplied to a computed tomography apparatus CT, whereby the measurement parameters and other settings of the computed tomography apparatus CT are adjusted based on the initial powder granule structural parameters 14 to the effect of the detector position and/or sample position and/or source settings altering for instance the emission power so as to minimize the noise and to maximize the resolution. The emission power, thus the number of photons emitted from the source, is optimized for implementing the computed tomographic method relative to the desired noise. As the noise increases, deviations in diameter and form values increase. Keeping the noise as low as possible for these values is therefore the goal. On the other hand, a desired resolution and thereby associated low noise competes with economical implementation of the method. For geometric dimensions such as for instance the powder granule diameter and/or powder granule length, a high resolution increases the measurement accuracy whereas it induces measurement deviations in form measurements such as sphericity. Therefore, the initial powder granule structural parameters are used for setting the computed tomographic apparatus CT so as to optimize the noise and the resolution for the examination of the respective powder. The settings and adjustments in the computed tomography apparatus ensue automatically.

[0151] Alternatively to terminating the method when the macroscopic powder parameters 12 and/or the chemical components 13 and/or the initial powder granule structural parameters 14 do not correspond to the specifications at a process control point 11 and/or would cause the method to be terminated after comparison with a corresponding database, the powder, the totality of the powder 2 and/or the powder sample 3 and/or initial small amount 4 and/or the statistically validatable powder representation 5 is supplied to a purification step 16. Sieving removes substances mechanically input into the powder but also oversized powder granules. These separated components of the powder are weighed and compared to the weight of the agitated powder in order to determine a degree of contamination. These impurities, or inputs and/or oversized powder granules respectively, are also supplied to the (not shown) method steps described here. The powder is thereafter fed back to macroscopic and/or chemical analysis again in order to re-determine the macroscopic powder parameters and/or chemical components and/or initial powder granule structural parameters. These parameters of the purified powder determine the continuation and/or termination and/or a further purification step of the method at process control point 11. This thereby yields a recursive opportunity for further purifying the powder until ultimately positively passing the process control point 11 and the method being continued. When the macroscopic powder parameters 12, the chemical components 13 and the initial powder granule structural parameters 14 induce a continuance of the method at process control points 11, a statistically validatable powder representation 5 is drawn from the totality of the powder 2. A solid body 10 is produced therefrom (see FIG. 2). Said solid body 10 is conveyed to a computed tomography apparatus CT and further characteristic values 20 including particle size, particle size distribution, sphericity, form factor distribution, HDP as well as particle surface properties determined by means of computed tomography and output (see FIG. 3 and FIG. 6).

[0152] A dispersant 500 is added to the statistically validatable powder representation 5 and the latter is introduced 200a into a liquid precursor stage 17 of a solid body 10 which comprises a first component 300 of a two-component resin to produce 200 a solid body 10 as depicted in FIG. 2. The powder granules 43 of the statistically validatable powder representation 5 are not arranged in a statistically distributed manner in the liquid precursor stage 17 since they bind together by interaction and tend to agglomerate. Although there already are isolated powder granules 44a caused by the dispersant, they are mostly still in the form of agglomerations 44b in the liquid precursor. Moreover, the powder granules 44 are not distributed homogeneously in the liquid precursor stage 17. For this reason, the liquid precursor stage 17 is subjected to application 200b of ultrasound 70 and simultaneously agitated along a main direction of agitation 600. This thereby increases the statistical mean powder granule spacing 18. The application of the ultrasound 70 as well as the agitating along a main direction of agitation 600 ceases once the particles are isolated. Curing 200c of the liquid precursor stage 17 then follows through the addition of a second component of a two-component resin 400. The solid body 10 thereby forms 200d as a result.

[0153] The solid body 10 is conveyed to a computed tomography apparatus CT (also see FIG. 1) and, as depicted in FIG. 3, is imaged in a digital volume 100a by means of 3D imaging 30. The solid body 10 is to that end rotated about a rotational axis 19 in one direction of rotation 51 while 2D radiographic X-ray projections 42 are generated along 2D sectional view planes 41 perpendicular 41a to the rotational axis 19 and parallel 41b, 41c to the rotational axis 19. A so-called 2D extraction 40 is therefore conducted. In computed tomography, the absorption differences of sample depth (y) are projected onto the xy-plane. The 2D radiographic X-ray projections 42 thusly extracted contain 2D powder granule projections 45. Subsequently and/or simultaneously, the 2D radiographic X-ray projections 42 to a digital volume 100a along a 3D image synthesis direction 52 which corresponds to the direction of rotation 51 in actual space, are assembled into a 3D image (digital volume). This digital volume 100a contains 3D powder granule representations 46 (3D images of the powder granules). These 3D powder granule representations 46 are thus 3D images of spherical powder granules 80a and aspherical powder granules 80b as well as 3D images of powder granules having a hollow space 80c. A partial digital volume 100b is thereafter selected 60 from partial digital volume 100a and isolated.

[0154] FIG. 4a shows a digital volume 100a according to a prior art method. FIG. 4b shows a digital volume 100a according to an inventive method for comparison. Shown for illustrative purposes are 2D radiographic X-ray projections perpendicular 42a to rotational axis 19 as well as 2D radiographic X-ray projections parallel 42b, 42c to rotational axis 19 and a digital volume 100a resulting from the 3D synthesis.

[0155] FIG. 5 shows a partial digital volume 100b using the same sample in FIG. 5a, FIG. 5b and FIG. 5c. Starting from FIG. 5a, the partial digital volume 100b reduces through FIG. 5b to FIG. 5c, whereby the particles are shown more clearly and further details become visible such as 3D image representations of isolated spherical powder granules 46a as well as aspherical powder granules 46b. Having information in a digital partial volume 100b allows conclusions to be drawn as to whether powder granules which appear agglomerated 46c are actually isolated or only partially overlap in the image representation due to being arranged on a virtually identical line of sight only in the 2D image representation of the three-dimensional partial digital volume 100b. The particles 46c are therefore also to be identified as isolated particles in the method.

[0156] These 3D image representations of the powder granules 80 can subsequently be viewed in isolation 700, as shown in FIG. 6. FIG. 6 shows 2D powder granule projections perpendicular 45a to the rotational axis 19 of the solid body 10 as well as 2D powder granule sectional views parallel 45b, 45c to the rotational axis 19 of the solid body 10. FIG. 6 comparatively shows a 3D image of a spherical powder granule 80a, a 3D image of an aspherical powder granule 80b and a 3D image of powder granule having a hollow space 80c. The characteristic values 20 such as sphericity, surface properties, powder granule length, powder granule diameter, etc. can be educed from these 3D images of the powder granules 80.

[0157] FIG. 7 shows a scanning electron micrograph (SEM) of a powder granule 43 of a statistically validatable powder representation after 2D thin-layer preparation. The powder granule 43 exhibits textured/rough surface areas 47 and smooth surface areas as well satellite adhesion 49. Initial powder granule structural parameters 14 are moreover determined, including an initial sphericity, an initial powder granule volume, an initial powder granule length, an initial surface quality, an initial satellite adhesion probability, etc.

[0158] FIG. 8 shows a partial digital volume 100b, wherein the dimensioning represents the total diameter of the cylindrical digital volume 100a and the viewing direction corresponds to the rotational axis 19 of the solid body 10.

[0159] Preferably, the highest CT resolution is 0.5 μm. This can be continuously increased upwards.

Cited Non-Patent Literature

[0160] Mostafaei et al. 2018 “Comparison of characterization methods for differently atomized nickel-based alloy 625 powders,” Amir Moustafaei, Colleen Hilla, Erica L. Stevens, Peeyush Nandwana, Amy M. Elliot, Markus Chmielus, Powder Technology, 333, 180-192, 2018

[0161] It is to be noted at this point that all the above-described components are claimed as essential to the invention on their own and in any combination, in particular the specifics illustrated in the figures. Modifications thereof are familiar to the person skilled in the art.

LIST OF REFERENCE NUMERALS

[0162] 1 method for treating and examining a powder by means of instrumental analysis [0163] 2 powder totality [0164] 3 powder sample, small amount of powder for the powder examination by means of macroscopy and chemical analysis [0165] 4 initial small amount [0166] 5 statistically validatable powder representation [0167] 6 two-dimensional SEM representation [0168] 10 solid body [0169] 11 process control point [0170] 12 macroscopic powder parameters: Hausner factor, degree of corrosion, degree of oxidation [0171] 13 chemical components: non-metal content (N, C, O, H), oxide content [0172] 14 initial powder granule structural parameters: sphericity, powder granule volume, powder granule length [0173] 15 particle size, particle size distribution, sphericity, form factor distribution, HDP, particle surface property [0174] 16 purification [0175] 17 liquid precursor of solid body [0176] 18 powder granule spacing [0177] 19 rotational axis [0178] 20 characteristic values [0179] 30 3D imaging of the solid body [0180] 40 2D extraction [0181] 41a 2D projection planes, perpendicular to rotational axis [0182] 41b, 41c, . . . 2D projection planes, along/parallel to rotational axis [0183] 42a 2D radiographic X-ray projections, perpendicular to rotational axis [0184] 42b, 42c, . . . 2D radiographic X-ray projections, along/parallel to rotational axis [0185] 43 powder granule in statistically validatable powder representation [0186] 44 powder granule [0187] 44a isolated powder granule [0188] 44b powder granule agglomeration [0189] 45 2D powder granule projection [0190] 45a 2D powder granule projection, perpendicular to rotational axis [0191] 45a, 45b, . . . 2D powder granule projection, along/parallel to rotational axis [0192] 46 3D powder granule representation=3D powder granule image [0193] 46a 3D image of a spherical isolated particle in a partial volume [0194] 46b 3D image of an aspherical isolated particle in a partial volume [0195] 46c 3D image of two isolated particles albeit on a similar visual axis and therefore partially overlapping [0196] 47 rough surface [0197] 48 smooth surface [0198] 49 satellite [0199] 50 3D image synthesis from 2D sectional views [0200] 51 solid body direction of rotation [0201] 52 2D projection composition for 3D image synthesis [0202] 60 selection of partial digital volume from a digital volume [0203] 70 ultrasound [0204] 80a 3D image of a spherical powder granule [0205] 80b 3D image of an aspherical powder granule [0206] 80c 3D image of a powder granule with hollow space [0207] 100a digital volume of the solid body [0208] 100b partial digital volume of a solid body digital volume [0209] 200 production of a solid body [0210] 200a mixing of a solid body liquid precursor [0211] 200b application of ultrasound to solid body liquid precursor [0212] 200c curing the liquid precursor into a solid body [0213] 200d completion of solid body curing [0214] 300 first component of a two-component resin [0215] 400 second component of a two-component resin [0216] 500 dispersant [0217] 600 main direction of agitation of an agitating means [0218] 700 isolated view of 3D image representations of powder granules for determining further characteristic values [0219] Macroscopy piling behavior analysis [0220] Chem. Ana. chemical analysis [0221] SEM scanning electron microscopy [0222] CT computed tomography