The new armature produced in a simplified process have been developed. It has made a great contribution to high-speed and high-precision fuel injection, and have been installed as a solenoid valve part in diesel fuel injector for the 4th Generation Common Rail System. The manufacturing process was designed from the earlier stages of product design, what is called “Design-in”. The development concept is to make maximal use of sintering process feature.

Additive Manufacturing (AM) technology has advantages in building free shape and simplification of manufacturing process. In order to manufacture the high quality parts, it is important to find out the optimum fabrication parameters such as laser power, scan speed, scan pitch and so on. In this research, the fabrication conditions under high power and high scan speed were investigated to fabricate the sound parts of Al-10Si-0.4Mg alloy using a SLM machine equipped with a 1 kW single mode fiber laser. As a result, the effective process window in the process map of the laser power and the scan speed was found out by evaluating the density of the specimens. The range of the energy density that showed high relative density of the parts was 35~80 J/mm³, and it was similar to the result reported by other researches. In the case of the laser power of 700 W, it was found that the relative density keeps high value even at a scan speed of 2200 mm/s. Thus, it was found that the sound parts can be fabricated at high scan speed by increasing the laser power. And the optimum scan pitch was similar to the laser spot size.

The various properties of the ternary Fe-B-C and quaternary Fe-B-C-Si amorphous alloys have been investigated. It was discovered that some ternary Fe-B-C amorphous alloys with the Fe content close to that of the Cr₂₃C₆-type metastable Fe₂₃(B, C)₆ phase exhibit a glass transition prior to crystallization on heating. The alloys with the glass transition also have high mass magnetization of 176~178 A m²/kg at room temperature in an as-quenched state. In addition, the glass-forming ability (GFA) of the alloys is significantly enhanced by the addition of 4 at% Si and by adjusting the composition toward the slightly lower Fe and higher B side while maintaining high magnetization of approximately 170 A m²/kg at room temperature in an as-quenched state. It was also confirmed that the amorphous powders of Fe-Cr-B-C-Si alloys could be produced by a conventional water atomization method and exhibit the low core losses of 305~362 kW/m³ at 100 kHz and 100 mT. The quaternary Fe-B-C-Si amorphous alloys with high GFA, high magnetization and low core losses are suitable for a core material of various magnetic components.

The effect of the replacement of Nb by rare earth elements (RE = Nd, Sm or Dy) on glass-forming ability (GFA) and the magnetization of (Fe_1−yCo_y)₇₉B₁₇Si₁Nb_3−xRE_x (y = 0, 0.2, 0.4) alloys has been investigated. The RE-free melt-spun alloys do not show a glass transition and could not be obtained a single amorphous structure. On the contrary, the glass transition was confirmed in some Dy-contained alloys, and the alloys with the single amorphous phase have been obtained. In the alloys in which Nb is substituted with Sm, the alloys with a single amorphous phase were obtained. However, there is only one composition (y = 0 and 3 at% Sm) showing the glass transition. On the other hand, some Nd-contained alloys also exhibit the glass transition; however, the specimen with the single amorphous structure has not been obtained. These results indicate that the substitution of Dy is most effective to improve GFA. When Nb is substituted with Nd or Sm, the mass magnetization (σ_s) tends to increase. On the other hand, the substitution with Dy obviously reduces σ_s. These are due to the magnetic coupling properties between (Fe, Co) and RE elements.

The ferromagnetic Fe-Co-Ni-(B, C, Si) high entropy alloys (HEAs) with an amorphous structure were prepared by single-roller melt-spinning method and evaluated their thermal and magnetic properties. The single amorphous phase is obtained both the Fe₂₅Co₂₅Ni₂₅(B_1−xSi_x)₂₅ HEAs and Fe₇₅(B_1−xSi_x)₂₅ alloys (x = 0.3, 0.5, 0.7). It was confirmed that the HEAs with x = 0.3 and 0.5 exhibits the glass transition prior to crystallization. On the other hands, the Fe₇₅(B, Si)₂₅ alloys do not show the glass transition. The critical thickness for the amorphous formation is larger than 0.23 mm for the Fe₂₅Co₂₅Ni₂₅(B_0.7Si_0.3)₂₅ HEA and is approximately 0.10 mm for the Fe₇₅(B_0.7Si_0.3)₂₅ alloy. Therefore, the HEAs have much larger glass-forming ability than that of the conventional Fe-based amorphous alloys. The similar results were obtained in the Fe₂₅Co₂₅Ni₂₅(B_1−xC_x)₂₅ HEAs. On the other hand, the amorphous phase could not be obtained for the Fe₂₅Co₂₅Ni₂₅(Si_1−xC_x)₂₅ HEAs and Fe₇₅(Si_1−xC_x)₂₅ alloys. It was also confirmed that the saturation magnetization at room temperature of the HEAs is about a half that of the Fe-based amorphous alloys.

Solid solution strengthening effect by oxygen (O) and nitrogen (N) atoms of α-titanium (Ti) materials was quantitatively evaluated using Labusch model by consideration of the experimental data. When using Labusch model to predict solid solution strengthening improvement, an application of the isotropic strains by solute elements is generally assumed to estimate Fm value, which is the maximum interaction force between the solute atoms and dislocations. It is, however, difficult to exactly calculate Fm value for α-Ti materials with O and N solute atoms because the anisotropic strains are induced in α-Ti crystal with hcp structure by these elements. In this study, Fm value was experimentally derived from the relationship between 0.2% yield stress and solute elements (O and N atoms) content of Ti sintered materials. As a result, the strengthening improvement was proportional to c^2/3/S_f (c: soluted atom content, S_f: Schmid factor), and its factor of proportionality of Ti-O and Ti-N materials was 4.17 × 10³ and 3.29 × 10³, respectively. According to this analysis, it was clarified that Fm value of Ti-O and Ti-N materials was 6.22 × 10⁻¹⁰ and 5.21 × 10⁻¹⁰, respectively, and then the estimated strengthening improvement by using these values was significantly agreed with the experimental results of Ti sintered materials with O and N solution atoms.

A large-scale spray pyrolysis apparatus in which the mist is pyrolyzed by a flame using a gas burner was developed for the mass production of Ag powder. Forty ultrasonic vibrators with a frequency of 1.6 MHz generated 4 dm³/h of mist. The thermal stability of the ultrasonic vibrators was improved using water-cooling. Spherical Ag powder was continuously produced, and the yield of the powders remained above 95% over 60 hours of continuous production with starting solution concentrations of up to 1.5 mol/dm³. Scanning electron microscopy (SEM) analysis showed that the particles were sub-micrometer in size with a dense microstructure, and they did not aggregate. Powder X-ray diffraction (XRD) demonstrated that the as-prepared Ag powder exhibited high crystallinity. The particle size of the Ag powder was approximately in agreement with the predicted size, calculated under the assumption that one Ag particle was formed from one droplet of mist. Moreover, 7 kg of Ag powder was produced over 12 h at 1.5 mol/dm³. This apparatus exhibited good reliability for the continuous mass production of Ag powder.

The effect of NaOH on the synthesis of Cu nanoparticles was evaluated. For synthesis, the reducing agent used was NaBH₄, the polymer protective agent was PVP, and the source of copper was Cu(OH)₂. The highest generation of hydrogen as a reaction by-product occurred after 59 min of reaction when NaOH was added; this was an increase from 43 min for the case where NaOH was not added. The proportion of the volume of Cu nanoparticles 20 nm or more in diameter to the total volume changed from 0.7% to 73.9%.

These results are believed to be due to the fact that the pH increased when Cu(OH)₂ was stabilized, so that the degree of supersaturation at the time of nucleation declined and a small amount of nuclei was generated. In addition, because the retention time of NaBH₄ as a parent agent became longer, it is thought that copper was precipitated around the large particles grown from the plurality of the nuclei; the particles subsequently became enlarged. From this, the possibility of pH adjustment using NaOH was demonstrated, and as a result, the diameter of the Cu nanoparticles could be intentionally controlled.

Probably the most decisive benefit of Powder Injection Molding (PIM) is the wide range of materials. As a logical consequence current R+D activities target on the adaptation of new metal and ceramic materials.

Modern high-performance materials like e.g. Ni-based super alloys are widely applied. For further progress development of so-called High-Entropy-Alloys (HEA) characterized by a minimum of five elements with all of nearly the same content, i.e. an equiatomar composition, started. These alloys represent a quite new field in metallurgy expected to offer attractive properties like high thermal strength and/or increased ductility. For initial trials a Co20Cr20Fe20Mn20Ni20 alloy was used. Injection and sintering procedures were developed and the resulting densities were examined.

Processing of Ceramic Matrix Composites by PIM represents a considerable challenge. Development of a process chain for the ceramic injection molding of Al₂O₃ short fiber CMC has been performed. Fiber content varied between 10 to 50 vol.% whereas for binder a well-examined system from KIT was chosen. As expected the fiber content showed a major effect on the rheological properties and fiber orientation depended strongly on the apparent shear profile. Both parameters affected the sintering behavior as well.

In recent years, the use of additive manufacturing (AM) technology in the fields of aviation, medical devices, and so forth has been investigated. Electron beams and lasers are used for metal AM as heat sources. Metal powder can be re-used for both processes, although the particle size of the powder differs for each process. However, there is concern over the change in the characteristics of the re-used powder. The re-used powder particle distribution may vary from the original distribution. In this study, we investigated the effects of different particle sizes on pure titanium fabricated by AM using a laser beam as the heat source. Correlations of the laser strategy and quality characteristics of products fabricated using four types of powder particle size distribution were experimentally verified.