De-powdering of green samples using freezing method for additive manufacturing
A method for producing an article and a system associated with the method are provided. The method includes providing a green part, cooling the green part to a temperature below the freezing point of the ink to form a hardened mass and loosely-attached powder particles, and removing the loosely-attached powder particles. The green part includes powder particles, an ink, and optionally a binder. The loosely-attached powder particles removed from the green part may be recycled and reused.
1 . A method for producing an article, comprising the following steps:
(a) providing a green part, wherein the green part comprises powder particles, an ink, and optionally a binder;
(b) cooling the green part to a temperature below the freezing point of the ink to form a hardened mass having loosely-attached powder particles;
(c) de-powdering the hardened mass to remove the loosely-attached powder particles from the hardened mass; and
(d) collecting the loosely-attached powder particles that are removed from the hardened mass.
2 . The method according to claim 1 , further comprising the following step:
(d) sintering the hardened mass.
3 . The method according to claim 1 , wherein the powder particles are temperature-sensitive materials.
4 . The method according to claim 1 , wherein the powder particles are selected from the group consisting of zeolite, metal-organic frameworks (MOFs), a metal, a ceramic material, a pharmaceutical drug material and any combination thereof.
5 . The method according to claim 4 , wherein the powder particles comprise a composite comprising the zeolite and the MOFs.
6 . The method according to claim 4 , wherein the MOFs are selected from the group consisting of ZIF-8, MIL-100, IRMOF-1, M-MOF-74, CPO-27-M, DMOF-1 and any combination thereof and the zeolite are selected from the group consisting of Zeolite 4A, Zeolite 3A, Zeolite 13X, Zeolite Ca-A and any combination thereof.
7 . The method according to claim 1 , wherein the ink is selected from the group consisting of deionized water, an alcohol, or any combination thereof.
8 . The method according to claim 1 , wherein the binder is selected from the group consisting of bentonite clay, kaolin, silica and any combination thereof.
9 . The method according to claim 1 , wherein the size of the powder particles is in the range from 2 μm to 100 μm.
10 . The method according to claim 1 , wherein the temperature of cooling in step b) is at least 5° C. less than the freezing point of the ink.
11 . The method according to claim 1 , wherein the loosely-attached powder particles removed in step (c) have one or more of the following properties substantially the same as the powder particles in step (a): chemical structure, chemical composition, crystalline structure, powder shape, powder size and powder spreadability.
12 . The method according to claim 1 , wherein the loosely-attached powder particles collected in step ((d)) are recycled.
13 . The method according to claim 1 , wherein the green part is formed by three-dimensional printing, powder pressing or injection molding.
14 . The method according to claim 13 , wherein the three-dimensional printing is inkjet printing, binder jet printing or extrusion printing.
15 . The method according to claim 1 , further comprises: forming a layer of the powder particles and applying a mixture comprising the ink to a predetermined region of the layer of the powder particles.
16 . The method according to claim 15 , wherein the binder is admixed with the powder particles to form the layer of the powder particles.
17 . The method according to claim 15 , wherein the binder is admixed with the ink to form the mixture.
18 . The method according to claim 2 , wherein the powder particles in the hardened mass are bonded to form a sintered article.
19 . The method according to claim 18 , wherein the article is a porous sintered article.
20 . The method according to claim 2 , wherein the ink is removed in step (d).