This study investigated the microstructure and high temperature oxidation properties of Fe-25Cr-20Ni-1.5Nb, HK30 alloy manufactured by metal injection molding (MIM) process. The powder used in MIM had a bi-modal size distribution of 0.11 and 9.19 μm and had a spherical shape. The initial powder consisted of γ-Fe and Cr23C6 phases. Microstructural observation of the manufactured (MIMed) HK30 alloy confirmed Cr23C6 along the grain boundary of the γ-Fe matrix, and NbC was distributed evenly on the grain boundary and in the grain. After a 24-hour high temperature oxidation test at air atmospheres of 1000, 1100 and 1200°C, the oxidation weight measured 0.72, 1.11 and 2.29 mg/cm,2 respectively. Cross-sectional observation of the oxidation specimen identified a dense Cr2O3 oxide layer at 1000°C condition, and the thickness of the oxide layer increased as the oxidation temperature increased. At 1100°C and 1200°C oxidation temperatures, Fe-rich oxide was also formed on the dense Cr2O3 oxide layer. Based on the above findings, this study identified the high-temperature oxidation mechanism of HK30 alloy manufactured by MIM.

In this study, the bio state of the alloy produced in the modified metal injection system was monitored after sintering. A new system operating with high gas pressure, far from the traditional injection model, has been established for material production. In this system, 316L stainless steel powders were molded using a PEG/PMMA/SA polymer recipe. During molding, approximately 60% 316L and 40% binder by volume were used. The samples obtained were sintered at different temperatures (1100-1300°C) after de-binding. Density measurement (Archimedes) and hardness tests (HV1) of the samples were measured as 6.74 g/cm3 and ~285 HV1, respectively. A potentiodynamic corrosion test was applied to monitor the effect of the amount of oxide in the structure of the 316L stainless steel produced. Corrosion tests were carried out in artificial body solutions. The corrosion rate was measured at the level of 17.08×10–3 mm/y. In terms of biocompatibility, a cytotoxicity test was applied to the samples and the life course of the bacteria was monitored. For the 316L alloys produced, the % vitality reached approximately 103%.