Method for molding aluminum and aluminum alloy powder

Abstract

A powder molding method of aluminum and aluminum alloy includes: preparing a feedstock by kneading aluminum powder, aluminum alloy powder, or aluminum composite powder containing a reinforcing material with a thermoplastic organic binder; molding the feedstock to a product having a complex shape via powder injection molding, compression molding, or extrusion molding; and then producing a high-density sintered body having relative density of at least 96% by performing debinding and sintering in a single heating process under an argon gas atmosphere.

1 . A powder molding method comprising:
 preparing a feedstock by kneading aluminum powder or aluminum alloy powder with a wax-based thermoplastic organic binder containing polyolefin copolymer having a carbonyl group;   molding the feedstock to obtain a molded body;   debinding the wax-based thermoplastic organic binder from the molded body to obtain a debound body; and   sintering the debound body under an argon gas atmosphere for densification.   
     
     
         2 . The powder molding method of  claim 1 , wherein the wax-based thermoplastic organic binder contains 3 to 30 wt % of the polyolefin copolymer having the carbonyl group in total 100 wt %. 
     
     
         3 . The powder molding method of  claim 1 , wherein the polyolefin copolymer having the carbonyl group is maleic anhydride grafted polyethylene. 
     
     
         4 . The powder molding method of  claim 1 , wherein an average diameter of the aluminum powder or aluminum alloy powder is from 1 to 20 μm. 
     
     
         5 . The powder molding method of  claim 1 , wherein an aluminum alloy in the aluminum alloy powder is a commercial aluminum alloy composition containing at least 0.5 wt % of magnesium and selected from the group consisting of Al—Cu—Mg—(Mn) series (AA2xxx), Al—Mg series (AA5xxx), Al—Mg—Si—Cu series (AA6xxx), Al—Zn—Mg—(Cu) series (AA7xxx), or a composition containing 0.5 to 8 wt % of magnesium, 0 to 8 wt % of zinc, 0.1 to 3 wt % of copper, 0 to 5 wt % of silicon, 0 to 5 wt % nickel, 0 to 0.3 wt % of iron, 0 to 1 wt % of manganese, 0 to 0.5 wt % of zirconium, 0 to 0.5 wt % of chromium, 0 to 2 wt % of silver, 0 to 0.5 wt % of scandium, 0 to 2 wt % of lithium, and the balance of aluminum in total 100 wt %. 
     
     
         6 . The powder molding method of  claim 1 , wherein the aluminum alloy powder is a prealloyed powder produced by atomization of alloy in molten state, or blended powder in which pure aluminum and another alloying element powder or master alloy powder for addition of another alloying element are mixed. 
     
     
         7 . The powder molding method of  claim 1 , wherein the aluminum powder or aluminum alloy powder further contains 0.1 to 3 wt % of tin in total 100 wt %. 
     
     
         8 . The powder molding method of  claim 1 , wherein the aluminum powder or aluminum alloy powder further contains 0.3 to 5 wt % of tin oxide in total 100 wt %. 
     
     
         9 . The powder molding method of  claim 1 , wherein the molding is performed via powder injection molding, warm compression molding, or warm powder extrusion. 
     
     
         10 . The powder molding method of  claim 1 , wherein the debinding is performed under an atmosphere of an argon gas flowing at a rate of 0.1 to 20 L/min. 
     
     
         11 . The powder molding method of  claim 1 , wherein the debinding comprises partial debinding via solvent extraction or supercritical fluid extraction, and thermal debinding under an argon gas atmosphere. 
     
     
         12 . The powder molding method of  claim 1 , wherein the sintering is performed under at atmosphere of an argon gas flowing at a rate of 0.1 to 20 L/min. 
     
     
         13 . The powder molding method of  claim 10 , wherein the dew point of the argon gas is lower than or equal to −40° C. 
     
     
         14 . The powder molding method of  claim 1 , wherein the debinding and the sintering are performed in a single step in a same furnace under an argon gas atmosphere to remove the wax-based thermoplastic organic binder from the molded body and sinter the debound body. 
     
     
         15 . The powder molding method of  claim 1 , wherein a sintering temperature of the molded body using the aluminum powder as a raw material is between 630° C. to 655° C. 
     
     
         16 . The powder molding method of  claim 1 , wherein a sintering temperature of the molded body using aluminum alloy powder containing an alloying element of 0.5 to 12 wt % in total 100 wt % as a raw material is within a temperature range from a solidus temperature to a temperature where a liquid phase is formed within 30 vol. % in total 100 vol. %. 
     
     
         17 . The powder molding method of  claim 1 , wherein the aluminum powder or aluminum alloy powder further contains at least one reinforcing material selected from the group consisting of carbide selected from SiC, B 4 C, TiC and WC, nitride selected from Si 3 N 4 , AlN, TiN, c-BN and h-BN, oxide selected from Al 2 O 3 , SiO 2 , Y 2 O 3 , fly ash, and ZrO 2 , sulfide including MoS 2 , boride including TiB 2 , hard cobalt alloy including T-800, powder, short fiber or whisker of a refractory metal such as W and Mo, polycarbon, graphite, carbon nanotube, graphene, and diamond. 
     
     
         18 . The powder molding method of  claim 17 , wherein an average diameter of the at least one reinforcing material is from 0.05 to 40 μm. 
     
     
         19 . The powder molding method of  claim 17 , wherein the at least one reinforcing material is contained in 0.1 to 30 wt % based on 100 wt % of the aluminum powder or aluminum alloy powder. 
     
     
         20 . A sintered body part produced by using aluminum powder, aluminum alloy powder, or aluminum-matrix composite material manufactured via the powder molding method of  claim 1 . 
     
     
         21 . The sintered body part of  claim 20 , being an impeller, a small turbine and a linear motion bearing end cap. 
     
     
         22 . (canceled) 
     
     
         23 . The powder molding method of  claim 11 , wherein the dew point of the argon gas is lower than or equal to −40° C. 
     
     
         24 . The powder molding method of  claim 12 , wherein the dew point of the argon gas is lower than or equal to −40° C.