Research On Powder Injection Molding Of Pure Titanium Porous Filter Cartridge

The titanium-based porous materials are novel materials used for structural andfunctional applications. Due to combining the excellent properties of titanium andtitanium alloys with good characteristics of metallic foams, the titanium-based porousmaterials are widely used in many fields. However, because of the high processingcosts and difficulties in forming, the development and application are confined. Metalpowder injection molding is a novel near net-shape technology, which has a uniqueadvantage of forming complex parts, increasing production efficiency and reducingcosts. In this paper, pure titanium powder was used for the preparation of porous filtercartridge with powder injection molding. And pore morphology and mechanicalproperties of pure titanium porous filter cartridge were researched.In this paper, the mold of porous filter cartridge was designed and manufactured.Injection molding feedstock with good rheological properties was successfullyprepared. The binder was a multiple-component thermoplastic system consisting ofPW, PP and SA. Feedstock was injected to obtain porous filter cartridge green parts.The bending strength and compressive strength of green parts was researched tooptimize the process parameters. After repeated experiment, it was found that when thepowder loadings in the MIM feedstock was55vol%, the green parts injected by it wasbetter. Besides, more reasonable MIM process parameters were found. Theseparameters are the injection temperature of190oC, the injection pressure of40~100MPa and the cold time of15~20s.Thermal debinding of the porous filter cartridge was researched. By the use ofX-ray diffraction (XRD) and electronic differential system (EDS), the processparameters in thermal debinding were optimized. It is found that when the debindingtemperature is600oC, the debinding effect is better. Moreover the heating rate hasgreat effect on quality of defatted green parts. And when the heating rate is0.5oC/min,the quality of defatted green parts is better. Besides, The bending strength andcompressive strength of defatted green parts was researched. The result shows that thebending strength is7.4MPa and the compressive strength is5.1MPa.Then, the defatted green parts of the porous filter cartridge were sintered in a hightemperature furnace, in Ar atmosphere. It is found that the sintering parameters has great effect on quality of the porous filter cartridge. In the process of sintering, with theincreasing of sintering temperature, the density of the porous filter cartridge rise, whilethe porosity decrease. Besides, with the increasing of sintering temperature, thebending strength and compressive strength of defatted green parts rise, too. And whenthe sintering temperature is1000oC, the porosity is32.28%.At the same time thebending strength and compressive strength of defatted green parts is65MPa and60MPa.At last, by analysis of connection technology of the porous filter cartridge, theprocess parameters in it were optimized. Connection interface were researched by theuse of SEM and the bending strength. The result shows the bending strength ofconnection interface is40MPa.