# US 2010/0167909 A1 · Hot axial pressing method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2010/0167909 A1 - Document ID: US20100167909A1 - Status: Published application - Kind: A1 - Application number: 12/519,583 - Filed: 2007-12-19 - Published: 2010-07-01 - Earliest claimed: 2006-12-20 - Assignees: Koninklijke Philips Electronics N. V. - Inventors: Guenter ZEITLER; Herbert SCHREINEMACHER; Cornelis R. RONDA - Web page: https://patentgrep.com/patent/US20100167909A1 ## CPC - C04B 35/645: Pressure sintering - B30B 15/0017: {Deairing means} - C04B 35/547: based on sulfides or selenides {or tellurides} - C04B 2235/3224: Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide - C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE - B30B: PRESSES IN GENERAL (producing ultra-high pressure or ultra-high pressure and high temperature to effect modifications of a substance, e.g. for making artificial diamonds B01J3/00 ){(compressing means for refuse receptacles B65F1/1405)} ## Abstract A hot axial pressing method for sintering a ceramic powder, particularly doped Gd2O2S, comprise the step of placing a first porous body (7), the ceramic powder (9) and a second porous body (7) into a mould shell (5) supported by a support (13, 14). The ceramic powder (9) is located between the porous bodies (7). Gaseous components are evacuated from the ceramic powder (9) up to an ambient pressure of less than 0.8 bar. The porous body (7) and the ceramic powder (9) are heated to a maximum temperature of at least 900° C. and are applied to a pressure up to a maximum pressure of at least 75 Mpa. According to the invention the variation in time of the heating step and the variation in time of the pressure applying step is adjusted to each other such that the mould shell 5 is held by the porous bodies (7) and/or the ceramic powder (9) in a state where the mould shell (5) and the support (13, 14) are disconnected with respect to each other. ## Claims ### Claim 1 A hot axial pressing method for sintering a ceramic powder comprising the steps of: placing a first porous body, the ceramic powder and a second porous body into a mould shell supported by a support, wherein the ceramic powder is located between the first porous body and the second porous body, evacuate gaseous components from the ceramic powder up to an ambient pressure of less than 0.8 bar, heating the porous bodies and the ceramic powder up to a temperature of about 900° C. and applying a pressure to the porous bodies and the ceramic powder to about 75 MPa, whereby the method comprises the step of: disconnecting the mould shell and the support, wherein the variation in time of the heating step and the variation in time of the pressure applying step are adjusted to each other such that the mould shell is held by the porous bodies and/or the ceramic powder in a disconnected state with respect to the support. ### Claim 2 (depends on 1) The method according to claim 1, wherein a lubricant, is provided on the mould shell such that the friction between the mould shell and the ceramic powder and between the mould shell and the porous bodies is reduced. ### Claim 3 (depends on 1) The method according to claim 1, wherein at least a first stack and a second stack are provided, wherein each stack comprises the ceramic powder provided between the porous bodies, the first stack and the second stack are placed into two different mould shells and each mould shell is held in the disconnected state. ### Claim 4 (depends on 3) The method according to claim 3, wherein a spacer element is provided between the first stack and second stack for encapsulating a stack in its mould shell, wherein the spacer element comprises a stopper element for limiting the relative movement of the mould shell with respect to the spacer element. ### Claim 5 (depends on 4) The method according to claim 4, wherein the geometry of the spacer element and the thermal expansion coefficient of the material used for the spacer element is chosen such that in the disconnected state of the mould shell a friction force for holding the mould shell by the ceramic powder and/or the porous bodies is lower than without the spacer element but higher than in the state before applying pressure. ### Claim 6 (depends on 4) The method according to claim 4, wherein the spacer element is connected to a temperature control means for adjusting the temperature of the spacer element and/or to a clamping means for clamping the mould shell to the spacer element. ### Claim 7 (depends on 1) The method according to claim 1, wherein the support is used as heat radiation protection. ### Claim 8 (depends on 1) A ceramic material producible by a method according to claim 1. ### Claim 9 (depends on 8) The ceramic material according to claim 8, wherein the ceramic material comprises particularly at least 99.9% (weight proportion) doped Gd2O2S. ### Claim 10 (depends on 8) A computer tomography scanner comprising a ceramic wafer made of a ceramic material according to claim 8.