Inter-Layer Bonding in 3D Printed Parts

A method for 3D printing multi-layer structures with improved interlayer adhesion to prevent delamination. The method involves creating cavities that cross multiple layers during printing and then filling the cavities with a second material to form rivets perpendicular to the layers. The rivets compress the surrounding layers as they cool and contract, increasing adhesion.

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Improving the tensile strength of 3D printed green bodies to prevent damage during transportation and handling prior to fusing. The method involves selectively applying an adhesion promoter containing multihydrazide compounds like adipic dihydrazide to the binder fluid used in 3D printing. The multihydrazide adhesion promoter enhances the bonding between layers of particulate build material when forming the green body.

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Method for manufacturing a three-dimensional shaped object with high adhesion between layers without using solvents. The method involves shaping a first layer, cutting it, heating it to a temperature below the resin's glass transition temperature, and then shaping subsequent layers on top. The heating step increases adhesion between the layers.

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Printing head for 3D printers that improves adhesion between layers of printed objects. The nozzle of the head includes a texturing member that protrudes from the main surface of the printed layer. These protrusions increase the contact surface area between layers, improving adhesion strength. The textured layer interfaces lock together better when subsequent layers are printed on top. The protrusions can be clamping features that grip the next layer.

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A method to improve interlayer adhesion in 3D printed objects made by fused material extrusion, e.g., FDM. The method involves extruding adjacent layers at different temperatures. The temperature difference between layers should be at least 5°C. This sequence of alternating temperatures enhances bonding between layers to improve the overall strength of the printed object. The layers are fused together after extrusion to form the final article.

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A feedstock for additive manufacturing that enables strong interlayer bonding in 3D printed objects. The feedstock contains removable capsules that, when extracted after printing, leave voids on the surface of the solidified layer. The voids are then filled by the next layer's material, forming mechanical interlocks between layers. This provides enhanced adhesion compared to regular printing.

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Directly printing thermoplastic structures onto composite parts made of fiber-reinforced thermoplastic prepreg tape or sheet. The method involves extruding molten thermoplastic feedstock through a printing head onto the composite part at a temperature higher than the matrix polymer melting point. The first layer melts and bonds the composite, then subsequent layers build the structure. The printed layers fuse together and co-mingle with the matrix polymer, creating a strong melt bond. This allows complex shapes to be formed on prepreg without needing additional adhesives or molds.

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Gradient nesting material for 3D printing with improved interlayer adhesion. The material consists of a core layer and a cladding layer. Polymerization occurs at the interface between the layers. The core layer contains a second polymer, a polymerization aid, and catalyst. The cladding layer contains a first polymer. The polymerization aid enables chemical bonding between the polymers at the interface, improving adhesion and preventing delamination. This allows 3D printing of dissimilar materials with better mechanical properties in all directions.

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Manufacturing method for substrate laminates with reduced voids and misalignment issues. The method involves applying a curable bonding material to the substrate surfaces, curing it to form a low modulus (10 GPa or less) bonding layer, then bonding the substrates through that layer. This prevents void formation and misalignment compared to using uncured bonding material.

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An improved method for layer-to-layer bonding in additive manufacturing ensures reliable, uniform bonding of new layers to previously processed layers. The method involves using a transparent substrate between the new uncured layer and the previously cured layer and curing the new layer by applying energy through the substrate to simultaneously cure and bond the new layer to the stack. A flexible pressure conveyance media is then applied to the substrate to uniformly compress the new layer onto the stack during curing.

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Composite structures with improved through-thickness toughness and crack resistance. The structures have interwoven belts with posts that interlock between belts to provide continuity through the thickness. The belts have a two-dimensional mesh with filaments in orthogonal directions. The posts extend from the mesh and interlock between belts to create a three-dimensional network. This network provides interlocking interfaces between adjacent layers that prevent crack propagation through the thickness. The belts can be positioned between layers of fiber bundles during composite fabrication to toughen the structure.

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Method to improve bonding between layers of 3D printed polydicyclopentadiene (DCPD) devices. The method involves using a mixed solution containing both DCPD and a liquid epoxy monomer as the 3D printing material. During printing, the DCPD front-end polymerizes and cures at lower temperatures than the epoxy monomer. After printing, heat treatment causes the epoxy monomer to thermally polymerize and form a second network inside the DCPD layers, providing interlayer bonding. This double network structure significantly improves the interlayer bonding strength of 3D printed DCPD devices compared to using just DCPD.

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A 3D printing technique to improve the strength of printed parts in the thickness direction. The technique involves embedding adjacent layers of the printed structure into each other. This creates interlocking connections between layers that improves shear resistance compared to conventional layer-by-layer printing. The embedding is achieved by modifying the printing path to overlap adjacent layers during deposition. This allows the filament to be extruded into the gaps between layers of the previous print pass. The interlocking structure created by embedding adjacent layers helps prevent separation and shear failure in the thickness direction.

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Method to improve the interlayer performance of 3D printed fiber-reinforced resin composites by adding toughness films between the layers. The method involves fused deposition printing tough resin filaments between the fiber-reinforced resin layers to form thin films. This creates multi-phase interfaces that enhance strength and toughness. The toughness films can be made from short fiber, particle, nanotube, graphene, or high-toughness resins. The shape, position, thickness, and type of the films can be customized for different applications. Auxiliary heating and hot pressing are used to improve bonding strength. This allows targeted local or global reinforcement and toughening of printed parts.

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Method for performing additive manufacturing using a photocurable composition to form a three-dimensional part. The method involves providing a non-flowable photocurable composition in a reservoir, heating it to a temperature to make it flowable, and then exposing it to radiation to initiate polymerization. This allows the formation of a photoplastic material with improved properties compared to existing photopolymers.

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3D printing method to prevent interlayer mixing and rounding issues when forming laminated structures with different materials. The method involves providing separate objects and surrounding objects with a predetermined distance between them. This prevents mixing between layers during curing. The objects are formed by sequentially curing slurries. The surrounding objects are cured separately. The objects and surrounding objects can be separated after printing. This allows forming structures surrounded by different materials without mixing or rounding issues.

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3D printing electronics directly onto printed circuit boards (PCBs) without bending them by using an adhesive layer between the PCB and the 3D printed structure. The adhesive layer has cavities or a grid structure to provide stress relief and improve adhesion. This allows 3D printing on PCBs without causing board deformation. The adhesion layer prevents bending by dispersing stresses across the PCB surface. The cavities or grid structure in the adhesive layer provide stress relief to further prevent PCB deformation during 3D printing.

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3D printing of reinforced concrete structures using a process that allows for high-strength reinforcement without the need for complex and expensive formwork. The process involves printing layers of concrete with embedded reinforcement elements that are rigidly connected to adjacent layers. The reinforcement elements are printed in a way that they extend beyond the current layer and are connected to the next layer. This allows for continuous reinforcement throughout the structure.

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3D printing semi-crystalline and amorphous polymers with improved layer adhesion for 3D printed parts that have similar mechanical properties in all directions. The polymers have a low curing temperature (G'/G" junction point) below 140°C. This allows the layers to interpenetrate better during printing, resulting in stronger parts with better elastomer properties. The lower junction temperature prevents poor layer adhesion and Z-direction weakness. The lower hardening point improves printability. The lower junction temperature is achieved by blending polymers with different hardening points.

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Improving the bonding force between layers of fused deposition 3D printed polymer devices by adding low molecular weight polymer materials to the conventional high molecular weight polymer materials used for 3D printing. The low molecular weight polymer improves interlayer adhesion without significantly impacting the overall material properties. The method involves mixing a small amount of low molecular weight polymer (0.2-2 wt%) with the high molecular weight polymer, extruding the blended material into filament for 3D printing, and printing the composite material as normal.

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