# US 12,179,421 B2 · Three-dimensional printing > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,179,421 B2 - Document ID: US12179421B2 - Status: Granted - Kind: B2 - Application number: 17/288,554 - Filed: 2019-04-27 - Published: 2022-02-10 - Granted: 2024-12-31 - Earliest claimed: 2019-04-27 - Assignees: Hewlett-Packard Development Company, L.P. - Applicants: Hewlett-Packard Development Company, L.P. - Inventors: James W. Stasiak; Garry D. Hinch; Timothy L. Weber - Web page: https://patentgrep.com/patent/US12179421B2 ## CPC - B29C 64/165: using a combination of solid and fluid materials, e.g. a powder selectively bound by a liquid binder, catalyst, inhibitor or energy absorber - B22F 1/0545: Dispersions or suspensions of nanosized particles - B22F 1/105: containing inorganic lubricating or binding agents, e.g. metal salts - B22F 3/1021: {Removal of binder or filler (removal of binder from ceramics C04B35/638)} - B22F 10/14: by jetting of binder onto a bed of metal powder - B22F 10/64: by thermal means (control of energy beam parameters for post heating B22F10/364) - B29C 64/209: Heads; Nozzles - B29C 64/245: Platforms or substrates (support structures intended to be sacrificed after manufacture B29C64/40) - B29C 64/295: Heating elements - B29C 64/371: using an environment other than air, e.g. inert gas - B33Y 10/00: Processes of additive manufacturing - B33Y 40/20: Post-treatment, e.g. curing, coating or polishing - B33Y 70/00: Materials specially adapted for additive manufacturing - B33Y 70/10: Composites of different types of material, e.g. mixtures of ceramics and polymers or mixtures of metals and biomaterials - C08K 3/38: Boron-containing compounds - C08L 101/00: Compositions of unspecified macromolecular compounds - B22F 12/13: to preheat the material - B22F 12/17: to heat the build chamber or platform - B22F 12/53: Nozzles - B22F 2301/205: Titanium, zirconium or hafnium - B22F 2301/255: Silver or gold - B22F 2301/35: Iron - B22F 2998/10: Processes characterised by the sequence of their steps - B29K 2995/0094: Geometrical properties - C08K 2003/385: {Binary compounds of nitrogen with boron} - Y02P 10/25: Process efficiency - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) - B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER - B33Y: ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING - C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09) - C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06) - B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract In an example three-dimensional printing method, individual layers of a metal-based build material are patterned, based on a 3D object model, with a binding agent to form an intermediate structure. A case-hardened portion of a 3D object is also patterned (based on the object model) by selectively depositing a hardening agent to deliver a predetermined concentration of a hardening element to at least one of the individual layers, wherein the individual layers are maintained below a vaporization temperature of the hardening agent during the selectively depositing. The intermediate structure is heated at a first rate to a temperature that aids in diffusion of the hardening element, and is held at the temperature for a predetermined time. The intermediate structure is cooled at a second rate. The intermediate structure, with the patterned case-hardened portion, is then sintered at a sintering temperature of the metal-based build material. ## Claims ### Claim 1 A method for three-dimensional printing, comprising: based on a 3D object model, patterning individual layers of a metal-based build material with a binding agent to form an intermediate structure; heating the intermediate structure to form a 3D object; and case-hardening a predetermined depth of at least a portion of the 3D object by: cooling the 3D object to a first temperature that is below a vaporization temperature of a hardening agent to be selectively applied to at least a portion of the 3D object; selectively depositing, using an inkjet printhead, the hardening agent to a surface of the 3D object to deliver a predetermined concentration of a hardening element to the at least the portion of the 3D object; heating the 3D object at a first rate to a second temperature that aids in diffusion of the hardening element; holding the 3D object at the second temperature for a predetermined time; and cooling the 3D object at a second rate. ### Claim 2 (depends on 1) The method as defined in claim 1 wherein the heating, the holding, and the cooling together are a thermal cycle, and wherein the method further comprises repeating the thermal cycle to create a gradient profile of the hardening element throughout the predetermined depth. ### Claim 3 (depends on 1) The method as defined in claim 1 wherein: the metal-based build material is a stainless steel, and the hardening element is selected from the group consisting of molybdenum, tungsten, and boron; and after the case-hardening, the method further comprises exposing the 3D object to a reducing atmosphere. ### Claim 4 (depends on 1) The method as defined in claim 1, further comprising selectively depositing, using a second inkjet printhead, a second hardening agent to deliver a second predetermined concentration of a second hardening element to the at least the portion of the 3D object. ### Claim 5 (depends on 1) The method as defined in claim 1 wherein one of: the metal-based build material is a stainless steel, and the hardening element is selected from the group consisting of carbon, molybdenum, tungsten, copper, and boron; or the metal-based build material is titanium, and the hardening element is gold. ### Claim 6 (depends on 5) The method as defined in claim 5 wherein the metal-based build material is the stainless steel and wherein the second temperature is an austenitic temperature of the stainless steel. ### Claim 7 (depends on 1) The method as defined in claim 1, further comprising controlling the inkjet printhead to selectively deposit the hardening agent over a number of printing passes. ### Claim 8 (depends on 7) The method as defined in claim 7, further comprising setting the number of printing passes based on the predetermined concentration of the hardening element to be delivered, a concentration of the hardening element in the hardening agent, a diffusion coefficient of the hardening element, and the predetermined time. ### Claim 9 (depends on 7) The method as defined in claim 7 wherein the number of printing passes includes an initial printing pass and at least one subsequent printing pass, and wherein the at least one subsequent printing pass replenishes the hardening element at a surface of the at least the portion of the 3D object for thermal diffusion into the predetermined depth.