2012 Volume 76 Issue 8 Pages 515-520
A manufacturing technique for the modeling of titanium powder by indirect selective laser sintering (SLS) and magnesium infiltration was developed. The modeling powder used for the indirect SLS was prepared by coating 1.1 mass% nylon with titanium powder particles and then mixing 1.9 mass% phenol resin powder (<10 µm). The hardness of the modeling powder at 477 K was greater than that of A90 (durometer type A), and it was suitable for indirect SLS modeling. While the amounts of resin (nylon and phenol) were equal in both methods, unlike the use of nylon coating and phenol resin powder, which resulted in the formation of a sufficiently hard titanium powder, the use of nylon resin powder and phenol resin powder resulted in the formation of an insufficiently hard titanium powder.
The titanium powder preform and a magnesium ingot were then heated at 973 K, and the dense composite, consisting of titanium particles and infiltrated magnesium, was fabricated by the self-activation of the infiltrated molten magnesium. Microstructure analyses of the composites titanium, magnesium, and titanium-carbide (TiC) were conducted by XRD. We concluded that the formation of TiC was attributed to the formation of titanium and carbon during the decomposition of the phenol resin.
The density, hardness, and tensile strength of the obtained composites are 3.2, 60 HRB, and 241 MPa, respectively. The tensile strengths of the composites are significantly higher than those of the cast magnesium (106 MPa). We believe that a large increase in the tensile strength after infiltration was due to the sintered behavior of the titanium powder and the densification of magnesium infiltration. Thus, the infiltration of magnesium into the titanium powder preform can be considered as an effective method for manufacturing lightweight composites.
