Sinterable separation material in additive manufacturing

Abstract

According to one aspect, embodiments of the invention provide a method of 3D printing, comprising depositing a model material in successive layers to form a part, the model material being a metal composite including greater than 50% by volume metal powder and less than 50% by volume a first removable binder, depositing the model material in successive layers to form a support structure adjacent the part, depositing a sinterable separation material between a surface of the part and a surface of the support structure, the sinterable separation material formed from 10-40% by volume ceramic powder and greater than 50% by volume a second removable binder, debinding the first removable binder of the model material and the second removable binder of the sinterable separation material, and sintering the part, the support structure, and the sinterable separation material at a temperature profile that sinters the model material and the sinterable separation material.

What is claimed is: 
     
         1 - 28 . (canceled) 
     
     
         29 . A method of additively manufacturing an object, the method comprising:
 depositing a composite including a metal particulate filler and a debindable matrix in successive layers to form a densification linking platform, densification linking supports, and a densification linking part, at least a portion of the successive layers of the object having at least one wall substantially enclosing an interior volume of a part;   forming a debinding acceleration structure having interconnected chambers and a plurality of access channels that penetrate one or more of the at least one wall exposing the composite, such that when exposed to a fluid debinder during a debinding process, the exposed composite forms a brown part including the debound densification linking platform, the debound densification linking supports, and the debound densification linking part;   debinding the composite including penetrating the fluid debinder into the debinding acceleration structure through the plurality of access channels to debind the matrix from within the interior volume of the densification linking platform, the densification linking supports, or the part; and   sintering, during a sintering process, the brown part assembly to densify at a rate substantially common throughout the brown part assembly to form the object.   
     
     
         30 . The method of  claim 29 , further comprising connecting a portion of the plurality of access channels to a pressurized supply of debinding fluid to force debinding fluid through the portion of the plurality of access channels. 
     
     
         31 . The method of  claim 29 , wherein the step of forming the interconnected chambers and the plurality of access channels that penetrate the one or more of the at least one wall exposing the composite of the debinding acceleration structure comprises fluidly interconnecting a plurality of honeycomb cavities. 
     
     
         32 . The method of  claim 29 , further comprising forming the debinding acceleration structure in additive layers, wherein at least one of the plurality of access channels spans a plurality of the additive layers. 
     
     
         33 . The method of  claim 29 , further comprising:
 depositing one or more part release layers between the densification linking supports and the part with a release composite comprising a ceramic particulate filler and a binder; and   forming a routing channel through the part release layer and to at least one of the plurality of access channels that permits the fluid debinder to flow through the one or more part release layers to the densification linking supports.   
     
     
         34 . The method of  claim 29 , wherein the step of debinding comprises cyclically filling and draining the debinding acceleration structure using a fluid debinder, thereby repeatedly immersing the densification linking platform, the densification linking supports, and the part, as well as filling and draining the interconnected chambers, to form the brown part assembly. 
     
     
         35 . The method of  claim 29 , wherein the step of debinding comprises holding the densification linking platform, the densification linking supports, and the part immersed in the debinding chamber for a dwell time that permits the fluid debinder to flow through the plurality of access channels. 
     
     
         36 . The method of  claim 29 , wherein the step of debinding comprises penetrating the fluid debinder throughout the interconnected chambers to debind the matrix from within the interconnected chambers. 
     
     
         37 . The method of  claim 29 , wherein interconnections between the interconnected chambers have a cross sectional area of less than 1% of a surface area of the interior volume of the densification linking platform, the densification linking supports, or the part. 
     
     
         38 . The method of  claim 29 , wherein depositing the composite in successive layers to form the debinding acceleration structure comprises depositing the composite within the interior volume of the densification linking supports connected to lateral sides of the part. 
     
     
         39 . A method of additively manufacturing an object, the method comprising:
 receiving, by a controller, a first tool path for a first layer of a part, wherein the received first tool path comprises a perimeter contour segment in the first layer;   receiving, by the controller, a second tool path for a second layer of the part, wherein the received second tool path comprises a parallel segment adjacent to the perimeter contour segment;   depositing a composite comprising a polymer-based matrix and a powdered sinterable metal in a pattern that follows the perimeter contour segment of the received first tool path to produce a perimeter path of the composite;   depositing the composite in a pattern that follows the parallel segment of the received second tool path in a retrograde direction with respect to the perimeter path to produce a stress-offsetting adjacent path of the composite,   depositing the composite in a pattern that follows the parallel segment of the received second tool path to produce a stress-offsetting retrograde adjacent path of the composite, wherein the perimeter path and the stress-offsetting adjacent path are deposited in retrograde directions with respect to one another such that directions of residual stress within the polymer-based binder of the composite are opposite in the perimeter path and the stress-offsetting retrograde adjacent path.   
     
     
         40 . The method of  claim 39 , wherein stresses within the stress-offsetting adjacent path are continuously adjacent to, parallel to, and opposite to at least 90 percent of stresses within the perimeter path. 
     
     
         41 . The method of  claim 39 , further comprising debinding the polymer-based matrix sufficient to form a shape-retaining brown part. 
     
     
         42 . The method of  claim 41 , further comprising sintering the shape-retaining brown part to densify the part as neighboring metal particles throughout the shape-retaining brown part undergo atomic diffusion, wherein the deposition of the composite positions residual stresses within the polymer-based binder in opposing directions in the perimeter path and the stress-offsetting adjacent path and reduces part twist caused by stress and relaxation of polymer chains in the composite. 
     
     
         43 . The method of  claim 39 , wherein the second tool path is continuously adjacent to and parallel to at least 90 percent of a length of the first tool path within an adjacent layer. 
     
     
         44 . The method of  claim 39 , further comprising depositing the composite in a pattern along a direction changing tool path segment, wherein the direction changing tool path segment is a reflex angle continuation joining the first tool path and the second tool path within a same layer. 
     
     
         45 . The method of  claim 39 , further comprising depositing the composite to form sintering supports below the part. 
     
     
         46 . The method of  claim 39 , further comprising forming one or more release layers of a release composite including a ceramic particulate filler and a binder between the part and the sintering supports. 
     
     
         47 . The method of  claim 39 , wherein the step of debinding the polymer-based matrix sufficient to form the shape-retaining brown part comprises debinding the polymer-based matrix of the part and the sintering supports. 
     
     
         48 . The method of  claim 46 , further comprising debinding the binder of the one or more release layers, thereby allowing a ceramic particulate that facilitates release of the part from the sintering supports to remain; and
 sintering, during a sintering process, the part and the sintering supports to densify at a rate substantially common throughout and to powderize the one or more release layers.   
     
     
         49 . The method of  claim 48 , further comprising forming a densification linking platform of the composite beneath the part and the sintering supports. 
     
     
         50 . The method of  claim 39 , further comprising tacking the densification linking platform to the part at a plurality of positions dispersed about an exterior of the part to substantially counteract a friction force between the shape-retaining brown assembly and a surface beneath the densification linking platform. 
     
     
         51 . The method of  claim 49 , wherein forming the densification linking platform comprises forming the densification linking platform to be horizontally larger than the part and having a cross-sectional area with no concavities. 
     
     
         52 . The method of  claim 49 , wherein forming the densification linking platform comprises forming the densification linking platform having a horizontal plane larger than a largest horizontal plane of the part. 
     
     
         53 . The method of  claim 49 , wherein forming the densification linking platform comprises forming the densification linking platform having a cross-sectional area with a convex shape. 
     
     
         54 . The method of  claim 53 , wherein forming the densification linking platform comprises the forming the densification linking platform having the cross-sectional area with the convex shape being a polygon substantially free of concavities. 
     
     
         55 . The method of  claim 52 , wherein forming the densification linking platform comprises forming the densification linking platform having a cross-sectional area having a centroid aligned with that of the part above. 
     
     
         56 . The method of  claim 52 , further comprising forming a sliding release layer below the densification linking platform of equal or larger surface area than a bottom of the densification linking platform that reduces lateral resistance between the densification linking platform and a surface beneath the densification linking platform. 
     
     
         57 . The method of  claim 39 , further comprising forming separable interconnected sintering supports to a side of the part by forming separable attachment protrusions of the composite between the sintering supports and the side of the part. 
     
     
         58 . The method of  claim 57 , further comprising connecting the interconnected sintering supports to the densification linking platform using connections of the composite of greater cross-sectional area than the separable attachment protrusions. 
     
     
         59 . The method of  claim 39 , further comprising forming soluble support structures including a soluble binder, the soluble support structures resisting downward forces during the forming of the part. 
     
     
         60 . The method of  claim 59 , further comprising, prior to sintering the shape-retaining brown part assembly, debinding the soluble binder of the soluble support structures. 
     
     
         61 . The method of  claim 39 , further comprising:
 forming a lateral support shell of the composite following at least a portion of a lateral contour of the part; and   connecting the lateral support shell to the lateral contour of the part by forming separable attachment protrusions of the composite between the lateral support shell and the part.   
     
     
         62 . The method of  claim 48 , further comprising separating the part from the sintering supports along the powderized one or more release layers. 
     
     
         63 . A method of additively manufacturing an object, the method comprising:
 forming a densification linking platform comprising successive layers of a composite, the composite comprising a metal particulate filler in a polymer-based binder matrix;   forming densification linking supports of successive layers of the composite above the densification linking platform;   forming a part of successive layers of the composite on the densification linking platform and densification linking supports;   depositing the composite along wall and infill toolpaths forming at least one walled structure having an internal volume in which infill structures are provided for one or more of the platform, supports, and part, at least a portion of the wall tool paths forming a plurality of access channels penetrating through the at least one walled structures into the internal volume.   
     
     
         64 . The method of  claim 63 , further comprising debinding the polymer-based binder matrix by flowing a fluid debinder around the densification linking platform, the densification linking supports, and the part through the plurality of access channels. 
     
     
         65 . The method of  claim 64 , wherein the step of debinding is sufficient to form a shape-retaining brown part assembly comprising a debound densification linking platform, debound densification linking supports, and a debound part. 
     
     
         66 . The method of  claim 65 , further comprising sintering the shape-retaining brown part assembly to densify the densification linking platform, the densification linking supports, and the part together at a same rate as neighboring metal particles throughout the shape-retaining brown part assembly undergo atomic diffusion. 
     
     
         67 . The method of  63 , further comprising interconnecting the densification linking supports to a side of the part by forming separable attachment protrusions of the composite between the densification linking supports and the side of the part. 
     
     
         68 . The method of  63 , further comprising forming a lateral densification linking support shell of the composite comprising forming a lateral contour of the part. 
     
     
         69 . The method of  claim 68 , further comprising connecting the lateral contour of the part by forming separable attachment protrusions of the composite between the lateral densification linking support shell to the part. 
     
     
         70 . The method of  63 , further comprising forming soluble support structures of a soluble binder, the soluble support structures resisting downward forces during the forming of the part. 
     
     
         71 . The method of  63 , further comprising, prior to sintering the shape-retaining brown part assembly, debinding the matrix sufficient to form a shape-retaining brown part assembly comprising the densification linking platform, the densification linking supports, and the part; and
 debinding the soluble binder of the soluble support structures.   
     
     
         72 . The method of  63 , further comprising forming one or more part release layers between the densification linking supports and the part with a release composite comprising a ceramic particulate filler and a binder. 
     
     
         73 . The method of  claim 72 , further comprising maintaining the one or more part release layers and shape-retaining brown part assembly as a unit during the debinding and during the sintering. 
     
     
         74 . The method of  claim 73 , further comprising after sintering, separating the one or more part release layers, the densification linking platform, and the densification linking supports from the part. 
     
     
         75 . The method of  63 , further comprising forming a plurality of distribution channels among the infill toolpaths. 
     
     
         76 . The method of  claim 75 , wherein a portion of the distribution channels of the plurality of distribution channels fluidly interconnect pairs of access channels. 
     
     
         77 . The method of  claim 76 , wherein a portion of the distribution channels of the plurality of distribution channels fluidly interconnect portions of the internal volume. 
     
     
         78 . The method of  claim 77 , wherein the portions of the internal volume comprise cells, cavities, and infill patterns. 
     
     
         79 . The method of  claim 78 , further comprising flowing the fluid debinder through the plurality of access channels, the plurality of distribution channels, and the internal volume to accelerate the debinding step. 
     
     
         80 . The method of  claim 79 , wherein flowing the fluid debinder further comprises releasing the flow of fluid debinder out through a portion of the plurality of access channels to accelerate the debinding. 
     
     
         81 . The method of  63 , further comprising surrounding the densification linking platform, the densification linking supports, and the part to accelerate the debinding. 
     
     
         82 . The method of  claim 81 , further comprising draining and replenishing a bath of the fluid debinder surrounding the densification linking platform, the densification linking supports, and the part to accelerate the debinding. 
     
     
         83 . The method of  claim 82 , further comprising draining and replenishing a supply of the debinding fluid entering the portion of the plurality of access channels to accelerate fluid flow and/or debinding. 
     
     
         84 . The method of  63 , wherein the step of depositing the composite to form the densification linking platform, the densification linking supports, and the part comprises forming adjacent toolpaths including a first toolpath along a perimeter patterned path and a second toolpath along a retrograde patterned path. 
     
     
         85 . The method of  claim 84 , wherein depositing the composite comprises depositing adjacent tool paths in a same layer in retrograde directions. 
     
     
         86 . The method of  claim 85 , wherein a centroid of a combined densification linking platform and connected densification linking supports is substantially aligned with a centroid of the part.