Net Shape HIP (NSHIP) process is the superior approach for both high performance and cost reduction compared to the castings and the forged materials machining. IHI has developed the NSHIP technology in order to incorporate NSHIP parts to the LE-9 engine turbopump for the H3 rocket which is under development by JAXA. In this article, the overview of the NSHIP technology development is introduced, which includes the FEM analysis model for the prediction of the final shape after the HIP sintering process, the establishment of manufacturing processes and the verification of the material properties. Based on these results, the NSHIP part development is proceeding to the next step, the turbopump and the engine testing which are currently performed.
Sr ferrite nanoparticles were synthesized by supercritical hydrothermal synthesis. The precursor as a raw material was prepared by neutralizing a solution of iron nitrate (III) and strontium nitrate with KOH. First, a batch type reactor was used to explore the condition (temperature and reaction time) to synthesize Sr ferrite. As a result, formation of Sr ferrite was observed under supercritical water condition, 653 K and 10 min even though hematite was included in the product as impurities. However, all the hematite was changed to Sr ferrite when the reaction time was enlongated to 60 min. Particle size was around 1 μm. In the case of a flow system that can achieve rapid heating by mixing precursor with high temperature water, even at very shot reaction time Sr ferrite was synthesized in a single phase without any inpurity. It is because of the rapid heating system that could suppress the formation process of hematite at a lower temperature range. The particle size was as small as 200 nm, which is probably because of the extremely high supersaturation in supercritical state just after the rapid heating. Effect of synthetic parameters on microstructure for obtained Sr ferrite nano-materials was investigated. Magnetization characteristic of Sr ferrite nanoparticle synthesized by the flow-through supercritical water synthesizer was also evaluated.
The quasi-skutterudite superconductor La3Co4Sn13 with the Yb3Rh4Sn13-type cage-structure presents structural transition at T* = 152 K. As in the case with isostructural compound Sr3Rh4Sn13, it has been shown that T* can be suppressed to 0 K by applying external physical pressure in La3Co4Sn13. In order to investigate chemical pressure effect on La3Co4Sn13, we have synthesized single crystals of (La1−xAx)3Co4Sn13 (A = Sr, Ca) and measured magnetic susceptibilities and specific heats. From magnetic susceptibility and specific heat measurements, it has been suggested that T* can change sensitively to the composition.
Powder metallurgy, PM method is one suitable method to produce metal parts with high accuracy and high cost performance. Powder compaction process using closed-die system is applied to mass production of various PM parts. However, failure of green compact during compaction such as slip clack often occurs especially on multi step parts. Finite Element Method (FEM) analysis is effective to predict such crack occurrence. In this study, we have tried to simulate iron powder compaction process by using general purpose FEM software ANSYS by applying Drucker-Prager Cap (DPC) Model as yield criterion for metal powder. Three kind of experiment, Uniaxial failure test, Single shear test and Lateral force measurement test was suggested to estimate initial and subsequent yield surfaces of the powder. As result, the materials input parameters for DPC model have been successfully identified as the FEM analysis fairly predicts density distribution of hollow shape with inner flange on several loading pass of the tools. Moreover, it is determined that the crack at the inner flange corner occurs in case of inappropriate loading pass as an intersection of stress state pass with shear failure yield line.