Metal Injection Molding (MIM) process allows fully dense and net shaping of a variety of engineering materials. Therefore, MIM process is hoped to be an advanced powder processing technique to replace the conventional powder metallurgy (P/M) processes for exceeding the proven P/M capabilities.
This presentation introduces a few examples of how and what products are made via MIM process today, and reviews the progress being made in the elimination of critical technological barriers to the widespread application of MIM as a manufacturing process. The application of MIM process to wide variety of ferrous materials are also introduced from our studies, and comments are focused on the microstructure control needed for the MIM fabrication of high performance ferrous material components.

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Based upon the results of finite element analysis for an axisymmetric rock mass with a long HQ core, which is subjected to nonaxisymmetric far-field stresses, tensile stress near the base of the core was analysed to obtain a criterion on core disking in the general state of stresses.
The stress conditions of all 77 cases in this study were divided clearly into two groups by the direction of the maximum tensile stress in the central part of the core. In one of the groups the tensile stress is nearly in the direction of the core axis and in the other the tensile stress is nearly perpendicular to the core axis. Only 26 cases in the total 77 cases gave the stress conditions necessary for core disking. In these cases, the difference in the magnitude of the maximum tensile stress between in the central part and in the outer part of the core was small, which suggests that the stress conditions enable a crack initiated at the outer part of the core to penetrate through the entire core. These cases included the stress conditions where the far field minimum principal stress is not in the direction of the core axis.
To produce a through crack in the core by tensile stress, the stress contour plane of the tensile stress must exist throughout the cross section of the core. Therefore, it is assumed that core disking occurs if the tensile stress whose upper and lower contour planes just touch each other reaches the tensile strength of the rock. This tensile stress, called the critical tensile stress in this study, is given by the minimum principal tensile stress among the maximum principal tensile stresses which are determined by searching the maximum value along the core axis for a set of the coordinates in the core cross section. Thus, we have proposed the following criterion on core disking:
kS_t=0.302σm-0.340σ_z+0.0910 (σ_z-σ₃),
where St is the tensile strength, σ_m is the mean stress, σ_z is the stress in the direction of the core axis, 0.3 is the minimum principal stress and k is the coefficients of the disk thickness (k≥1). This criterion quantitatively explained the experimental results by Sugawara et al. in the conditions of σ_z=σ₃=0.

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The behaviors of circumferential strain in creep tests on Inada Granite and Kamisunagawa Sandstone were investigated. The following tests, as well as conventional creep and constant strain rate tests, were carried out:
(1) Reloading tests were conducted by reloading at a constant strain rate in the way of the creep tests.
(2) Unloading tests were conducted by unloading when the peak load appeared in the way of the constant strain rate tests.
It was considered from the test results that (1) the points at which the magnitude of the circumferential strain rate reaches the minimum and the magnitude of the circumferential strain acceleration begins to increase are closely related to the point of maximum load in the constant strain rate tests, and (2) the magnitude of the circumferential strain could indicate the degree of rock damage in creep tests as well as in constant strain rate tests.

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This paper presents a detection method of large rocks in the rock pile using an image processing. In this study, the shadow of the large rock was used to distinguish the large rocks from the background. Therefore, in order to change the location of shadow of the large rocks, 4 light sources were set around the CCD camera and 4 images were obtained with changing the light sources. The thresholding was carried out for these images, and the common area of these images was obtained because the location of the large rocks was not changed even if the light sources were changed. Then, some large rocks were detected by the area analysis and shape factor analysis. However, some other large rocks were still remained in the image. Therefore, then the shrinking procedure was made for this image. After this procedure, the shape factor analysis was carried out again to detect the remaining large rocks. It was confirmed that this procedure works well to detect the large rocks in the rock pile.

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Mechanochemical process for producing Mg (OH) ₂ from magnesite (MgCO₃) without heat treatment has been developed. This process is composed of two steps: The first step is to produce Mg (OH) ₂ and Na₂CO₃ mechanochemically by dry grinding the mixture of magnesite and solid NaOH powders in a mill. The reaction between the two starting samples proceeds as the grinding progresses. The second step is to separate Na2CO3 from the insoluble products in the ground mixture by washing with water. Reactivity of the insoluble products against H₂SO₄ solution is improved with increasing the grinding time, and levels off in the prolonged grinding. The reactivity of the insoluble products prepared from the mixtures ground for 0 minutes or more is much higher than that of magnesite powder. The separated Na₂CO₃ can be reused for appropriate purposes

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The solid state electrotransport of oxygen in yttrium was studied and the effective valence Z and the non-dimensional number δ(=uEL/D; u: mobility, E: electric field intensity, L: length of specimen, D: diffusion coefficient) of oxygen were measured by the tangent method under the following conditions; electric field intensity=7.2-10.6Vm^-1, temperature=1, 173-1, 563K, initial oxygen content=0.5 mass%. The extraction conditions (analyzing temperature, pretreatment of the specimen, and selection and content of flux) for the accurate determination of oxygen in yttrium was also studied. The results obtained were:
(i) For the oxygen analysis of yttrium, platinum was the best flux and should be added more than 0.5 of its molar fraction.
(ii) The absolute values of the effective valence and δE^-1L^-1 of oxygen decreased with increasing either electric field intensity or temperature.
(iii) The diffusion coefficient of oxygen in yttrium was determined as follows:
Do/m²s^-1=3.1×10^-8 exp (-68700/RT)
(iv) The mobility of oxygen in yttrium increased with increasing temperature.

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The extraction of trivalent gallium, indium and thallium from aqueous solutions containing hydrochloric acid and/or lithium chloride by tributyl phosphate (TBP) and trioctylamine (TOA) in benzene has been investigated under different conditions. As the results, it was found that the extraction efficiency for metals of TBP is in the order Tl<Ga<In at low aqueous acidity and Ga<Tl<In at Niger acidities, and of TOA in the order Ti<Ga<In. Further the following equilibrium equations were given for the extraction by TBP: GaCl₃(aq)+2TBP(org)=GaCl₃·2TBP(org); InCl₃(ag)+3TBP(org)=InCl₃·3TBP(org); TlCl₃(aq)+2TBP(org) TlCl₃·2TBP(org) at low aqeuous acidity and TlCl₃(aq)+HCl(aq)+2TBP(org)=HTlCl₄·2TBP(org) at higher acidities, and in addition with increasing the concentration of thallium in aqueous phase TlCl₃(aq)+HCl(aq)+3TBP(org) HTlCl₄·3TBP(org). For the extraction by TOA, MCl₃(aq)+nR₃NHCl(org)=(R₃NH)_nMC1_3+n(org) where M=Ga, In and Tl, and n=1 for Ga or Tl and 2 for In, respectively. It was therefore seen that the distribution behaviour by TBP and TOA corresponds to that by TOPO, except for the extraction of thallium (III) from aqueous solutions at higher acidities by TOA. Although the extraction efficiency for trivallent metals of TOA is higher than that of TBP, the characteristic of TOA and TBP appears in the extraction from aqueous solutions at low and higher acidities, respectively.

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Cobalt crust, one of the mineral resources at the seabed, includes nickel, cobalt, copper, iron and manganese fairly.
At the beginning of this study, the dilute sulfuric acid leaching have been occurred on cobalt crust using hydrogen peroxide as a reductant. As a result of the leaching test, almost of all valuable metals in the cobalt crust were leached in the solution.
By addition of the calcium carbonate in the leaching solution, iron was removed completely as iron hydroxide. In this time, the other valuable metals were not effected by the calcium carbonate.
In the experiment of extraction, 10% LIX-84I kerosene solution was used. The extraction percentage from the leached solution with the 10% LIX 84-I kerosene solution were more than 99% for nickel, cobalt at pH: nearly 7.0 and copper at pH: nearly 2.0.
In the stage of extraction, the separation of nickel and cobalt was difficult, because of the same extraction behavior. Therefore, the studies were occurred on separation by stripping. In the stripping from the organic phase containing nickel, cobalt and copper, copper was stripped with the hydrochloric acid solution at pH: nearly O. Nickel was stripped at pH: 1. After this operation, cobalt may be got by hydrogen sulfide.

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The kinetic behavior of filamentous carbon formed on substrate of the transition metal (Fe, Co or Ni) from CO-H₂ gas mixtures is investigated. The filamentous carbon holds carbide particle on its head point. Experiments for each metal are carried out in the range of 773-973K with various molefraction of CO, Yco, in the gas mixtures. In the experimental results, the formation rates, γfor Fe-substrate are described by the following equation:_??_
where k is the rate constant, K is the adsorption equilibrium constant and T is temperature. The values of k and K give 92kJ/mol and 126kJ/mol as the apparent activation energy and the adsorption heat, respectively. This rate equation, however, is not applicable to the rates for Co- or Ni-substrate. Those data are explained by assuming the diffusion process of carbon adsorbed on the carbide particle as the determining step.

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For the development of lead-free solder, wettability of 41.2Sn-58.8Bi and 61.6Sn-38.4Pb solders was compared by use of meniscometer. It has been reported by several researchers that the wettability of Sn-Bi solder is poor as compared with Sn-Pb solder. In order to obtain fundamental data, no flux was used in this work because wettability of solder is significantly affected by the kind of flux and the available fluxes have been developed for Sn-Pb solder. Oxygen-free copper plate and copper alloy plate containing 0.3 mass % Cr, 0.1 mass % Zr and 0.02 mass % Si of 0.5mm in thickness and 10mm wide were immersed into the molten solders at the temperature range from 483 K to 543 K. It was found that wettability of both Sn-Bi and Sn-Pb solders to these plates was poor without use of flux. Then a parameter (surface tension) by cosine (contact angle) was used for the comparison of wettability of these solders. No significant difference in the parameter between these solders was observed. Consequently, it is thought that the Sn-Bi solder will be promising provided that flux suitable for this solder is developed.

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The effect of the structural properties of kaolin minerals on the intercalation process of urea was investigated using kaolinite and two kinds of halloysite. The results are summarized as follow.
(1) The urea intercalated gradually and regularly into the interlayer site of kaolinite with plate morphology, but intercalated immediately and irregularly into that of halloysite with tubular and spherical morphologies.
(2) The decomposition temperature of the urea intercalated into kaolin minerals were lower than that of pure urea. The difference between the decomposition of the urea intercalated and that of pure urea was examined by IR spectrum analysis. The asymmetric and symmetric ν(NH₂) stretching frequencies at 3, 504cm^-1 and 3, 389cm^-1 correspond to NH₂ groups interacting with the oxygens located on the basal tetrahedral layer. Intercalation of urea within the kaolin minerals structure increased the ν(CN) stretching frequency from 1, 468cm^-1 for the urea to 1, 477cm^-1 for intercalated molecules. These results indicate that the hydrogen bonding of urea molecules intercalated into the interlayer site of kaolin minerals are weak as compared with the hydrogen bonding of pure urea molecules.
(3) The ν(CN) stretching frequency of two kinds of halloysite showed broader pattern compared with that of kaolinite, but the ν(NH₂) bending frequency of halloysites shifted to higher frequency than that of kaolinite. These results show that the hydrogen bonding of urea intercalated into the interlayer site of halloysite is different from the that of kaolinite.

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