Debinding and sintering properties of titanium alloys prepared by powder injection molding

Complex shaped titanium alloy parts with the high-precision and high performance were prepared by powder injection molding (PIM) technology. High powder loading titanium alloy feedstock by catalytic debinding was prepared by the multi-granularity powders and the multi-component binder with polyformaldehyde (POM) as the main component, the titanium alloy parts were obtained by vacuum sintering. The influencing factors of the catalytic debinding process and the influence of feedstocks ratio on the properties of the sintered samples were studied. The results show that, when the mass proportion of the large (D₅₀=25.28 μm), medium (D₅₀=16.75 μm), and small (D₅₀=12.66 μm) particles is 17:6:2, the tap density of the mixed titanium alloy powders is as high as 55%. Moreover, the better catalytic debinding process of the feedstock is as follows: the debinding temperature is 120 ℃, the nitrogen feed rate is 120 cm³·min⁻¹, the feed rate of nitric acid gas is 1.5 cm³·min⁻¹, the debinding time is 6 h, and the binder removal rate is 85%. Furthermore, by using the controlling technology of the impurity content in the whole process, the relative density of the titanium alloy products can reach 95.9%, the tensile strength is 933 MPa, the bending strength is 1282 MPa, the elongation is 7.5%, and the mass fraction of C and O is 0.10% and 0.21%, respectively.