Performance Improvement Of Iron-based Powder Metallurgy Parts

To improve mechanical properties of iron-based powder metallurgy products, thispaper utilizes atomized iron powder with size of100meshes added with minor copperpowder with size of200meshes, different sizes of iron-based powder, and zinc stearatereplaced by wax powder. After pressing and sintering, sample parts with variouscompositions were produced. Mechanical properties of the parts were obtained andmicrostructures were observed. An optimal composition ratio for enhancing propertiesof iron-based powder metallurgy products was acquired.1) Atomized iron powder with size of100meshes was added with minor copperpowder with size of200meshes. After pressing and sintering, sample parts wereproduced with various copper compositions. Mechanical properties of the parts wereobtained via tensile testing and hardness testing, as well as density measurement. Thefracture topography of the samples was examined by SEM. An optimal proportion ofcopper composition was proposed to obtain the best mechanical properties. The resultshows that, adding minor copper powder with size of200meshes can improvemechanical properties, and the optimal adding ratio is1%.2) Atomized iron powder with size of100meshes was added with iron powderwith size of325meshes. After pressing and sintering, sample parts were produced withvarious coarse/fine powder ratios. Mechanical properties of the parts were obtained viaseveral tests, including tensile test, hardness testing, and density measurement. Thefracture topography of the samples was examined by SEM. The result shows that, theamount of0.5%iron powder with size of325meshes can improve hardness.3) By detecting mechanical properties of parts with adding zinc stearate and adding polyglycolic class wax powder, including tensile test, hardness testing, anddensity measurement. The result shows that, compared with the original lubricantzinc stearate, wax powder can not only improve mechanical properties but alsoimprove the microstructure of the parts. The wax powder becoming volatile in thesintering process did not release any harmful substances, being not residual in the parts.The amount of wax powder existed an optimal level for the parts. The result shows that,the amount of0.5%can improve the performance of the parts. If the addition of waxpowder was too little or too much, it will bring negative effects to the properties of theparts.Innovations of this dissertation:(i) Both adding iron powder with size of325meshes or minor copper powder with size of200meshes to iron-based parts can fillpores of iron powders and improve pressing and sintering, further improving theperformance of the products.(ii) Using wax powder instead of zinc stearate aslubricant and releasing agent can not only improve the performance of iron-basedpowder metallurgy products and also act as an environmentally friendly lubricant. Thewax powder does not contain heavy metal salt, and it can keep good demoldingproperties and edge retention. It can completely be vaporized, and does not leaveharmful substances in the process of production.