Densification of Metal BJT Parts with Fine Grains Coated with Fine Powder

Binder jetting (BJT) metal additive manufacturing uses binder to bind metal powders and build metal parts. Binder jetting has low equipment costs and is highly scalable. However, parts printed by BJT process are difficult to be high density. Conventional densification methods require high temperatures and long sintering hours, but this method results in larger grains and lower strength. Therefore, both densification and fine grains are necessary. This study discusses how pre-sintered body at low temperatures was manufactured, and hot isostatic pressing (HIP) them. However, a pre-sintered body at low temperatures has interconnected open pores. If there were interconnected open pores, HIP can't ensure density. To solve this problem, this study attempted to eliminate the interconnected open pores by coating them with slurry using fine powder. The fine powder on the surface was densified and eliminated interconnected open pores. As a result, a high-density and fine-grained specimen was obtained.