Synthesis And Research Of Functionalized Polyacrylate Binder For Metal Powder Injection Molding

Metal powder injection molding is a new net technology of powder metallurgy.The binder is the key component for the feedstock of metal powder injection molding.The interaction between the binder and the metal powder has a significant influence on the homogeneity,fluidity,molded shape retention,powder loading and properties of the sample after degreasing and sintering.The functionalized polyacrylate binders were studied in this article.The main contents were summarized as follows:By analyzing the possible groups on the surface of 17-4PH metal powder,the functionalized polyacrylate binders of different molecular weights was designed and synthesized.Methyl methacrylate and butyl acrylate were designed as backbone.Glycidyl methacrylate,hydroxyethyl methacrylate and methacrylate were designed as functional monomers.Skeleton ratio,the amount of functional groups and the melt viscosity were optimized to obtain the optimal formula for the functionalized polyacrylate binder.The effect of the interaction between the functionalized polyacrylate binder and the metal powder on the fluidity of the feedstock,the shape retention of the green body,the powder loading and the properties of the sample after degreasing and sintering were investigated.It was found that the fluidity of the feedstock increased with the interaction between the binder and the metal powder increasing at the same powder loading.The same is true of the rheological index n and the viscous flow activation energy E.The hydroxyl-functionalized binder had the best fluidity and the composite rheological index was 1.5 times the reference binder.At the different powder loadings,the critical powder loading of the feedstock increased with the interaction between binder and metal powder increasing.The hydroxyl-functionalized binder had a critical powder loading of 56 vol.%to 58 vol.%,an increasing of 2 vol.%over the reference binder.The properties of the samples after degreasing and sintering were tested.The results showed that with the increasing of the interaction between the binder and the metal powder,the volume shrinkage of the samples decreased,the porosity decreased,the relative density increased,the bending strength increased,and the degreasing rate decreased.