Preparation of ultrafine nitride particles has been performed using the reactive gas evaporation technique with electron beam heating. By evaporating metals of group IIIa, IVa, Va and VIa in an atmosphere of N₂ or NH₃ gas at about 1Torr, nine kinds of crystalline nitride particles, i. e. AlN, TiN, ZrN, HfN, VN, NbN, CrN, Mo₂N and W₂N, were produced. These particles were studied by means of electron microscopy and X-ray diffraction method. All the nitride particles were found to have a particle size smaller than 10nm, and were confirmed to be a single phase with the ordinary crystal structure: Wurtzite-type for AlN, NaCl-type for TiN, ZrN, HfN, VN, NbN and CrN, and partially disordered NaCl-type for Mo₂N and W₂N.
The crucible-less evaporation method, which is free from impurities caused by a crucible damage, can be adoped for the most metals of group IVa, Va and VIa.

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A series of silica almina pellets with tri-modal pore size distributions were prepared and their apparent steady state activities to the cumene cracking were tested. The pore structure of the pellets was measured by the nitrogen adsorption technique and mercury porosimetry.
The surface and bulk structures were checked through the secondary electron images on an Electron Probe Micro Analyzer and a Field Emission Microscope, respectively. The results of the variation of macro and micro pore volume fractions against the amount of the diffusion promoter added showed the same tendency as have been already reported.
On the other hand, the effectiveness factor (η_exp) for these pellets was obtained as to be the ratio of the rate constant for each pellet to that for the powder sample at the same reaction temperature (645K). The theory describing the effectiveness factor for the spherical pellet of porous catalyst with monomodal pore structure at an isothermal condition was extended to that for the multi-modal pore structure. The calculated value (η) of effectiveness factor based on this extended theory presented good agreement with the experimental value (η_exp).

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The equation of tensile strength proposed by Rumpf was extended to deal with the compacted power bed composed of granules. It was assumed that the cohesive force between granules in a compact body is proportional to the contact area brought about by the contact force. Then the tensile strength of such a granules-bed can be determined by estimating the contact force between granules in the bed. The extended equation shows how the tensile strength depends on the compaction force, the porosity and the granule size.
The equation sufficiently explains the results obtained from the tensile strength test of compacts. The compression test of a single granule was also performed to confirm the relationship between tensile strength characteristics of compact and deformability of granule. Parameter m, one of the two parameters in both equations for the tensile strength of compact and compressive deformation of granule, has almost the same value in both tests as expected. However, the other parameter b is larger in the tensile strength test than in the compression test of a single granule. This discrepancy should be further investigated.

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It is extremely important to clarify the relationship between mulling power requirement and tensile-breakup energy for rational design and evaluation of the industrial mulling processes.
In the present study, both transient and steady state mulling power has been measured and tensile process curves have been obtained by using a green mold sand with a bentonite as a binder calcined at various temperatures in a vertical cylindrical mixer.
The results obtained are as follows:
The tensile-breakup energy, time required to complete the mulling process and mulling power requirement are influenced by the tensile strength of the binder used and its calcined temperature. The mulling power requirement can be evaluated in terms of the tensile-breakup energy. These findings of the tensile process tests can be applied to estimate the power requirement for the mulling process.

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Characterization of three differently processed α-FeOOH powders and α-Fe₂O₃ powders obtained therefrom has been made by means of differential scanning calorimetry, thermogravimetry, electron microscopy and porosimetry.
It was shown that the particle properties of α-FeOOH depended on the aspect ratio. Generally, powders with high aspect ratios had low densities and high pore volumes. The decomposition proceeded in 2 or 4 steps depending on the starting α-FeOOH powders.
The particle properties of α-Fe₂O₃ powders were influenced by the heating temperature and impurities; a high heating temperature resulted in high density, small open pore volume and small specific surface area due to the sintering of particles. The sulfate ion was found to promote the spheroidization of particles. Incorporation of SiO₂, on the other hand, suppressed the surface migration, retarding the sintering and also the deformation of particles.

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The results of the particle size measurements by several methods based on different principles are almost equal to each other as far as these methods are applicable, when the powder is considered to be made of sphere shape particles. However, there are some questions about the particle size measurement of irregular shape particles such as plate or needle like powder. Using mica powders as samples of the thin plate like particles, we compared the results of particle size measurements based on six different principles; optical microscope, sieve, sedimentation balance, photo sedimentation, Coulter counter and Microtrac. The measurement of the particle thickness by the mono-particulate film method²⁾ gave a relation between the thickness and the projected diameter of mica particles classified by microsieves with a high accuracy. From this relation, the volume of the plate like mica particle was obtained and then the sphere equivalent diameter was calculated. We compared the particle size distribution based on this sphere equivalent diameter with the results measured by the other methods.

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In order to avoid complicated procedures for sampling, it is worthwhile to establish a simple method whereby the degree of mixing is measured immediately, non-destructively. In the previous paper, the method applicable to the system of smaller number of particles, (i.e. number of particles: 13∼25) was presented. In such a system of small number of particles as 13 particles or 25 particles, it was necessary to consider the edge-effect of the system.
When the number of particles in the system is increased, the edge-effect of the system in the total electric resistance has to be decreased. The decrease of edge-effect should be inversely proportional to the number of particles in the system, that is
Edge-effect∝2n/(n²+(n-1)²)≈1/(n-1) (1)
where n is the number of particles occupied at one edge (first line).
When n reaches 6 or above, there exists a good correlation between the degree of mixing (σ) and the total electric resistance (R) of the system.

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The adsorption process of water vapour on porous materials such as molecular sieves 3A, 4A, 5A, natural mordenite, natural clinoptilolite, activated alumina and silica gel was investigated by using a humidity sensor. The measurement of water vapour adsorption in the range from the initial relative vapour pressure of 0.6 to the final relative vapour pressure of about 0.2 was found to be suitable for the estimation of specific surface area of hydrophilic porous materials. The results obtained were compared with the data taken by the nitrogen adsorption method.
The measurement by this method is considerably simple and reproducible so that the study of water vapour adsorption process and the estimation of specific surface area of hydrophilic porous materials become easy. Thus, this method seems useful to be applied on such line processes as solar heating and cooling, production process of dry air and oxygen (or nitrogen) enriched air by pressure swing adsorption.

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Electric current carried by edge dislocations during the stress relaxation of NaCl single crystal was measured at room temperature. It was found that the current was proportional to the stress relaxation rate if the sample was strained less than about 1.3%. The inverse of current increased linearly with time at the beginning of stress relaxation. This is in accord with the results obtained by Ohring et al. for LiF and KCl single crystals. The fraction of charged dislocations, f, moving in the direction of the observed current is considered to decrease for large strains.

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A new criterion for the initiation of dynamic recrystallization is proposed. The criterion, Z_c is the critical value of the Zener-Hollomon parameter when the dynamic recrystallization can initiate. The specimens used in this investigation were the sheets of copper alloys containing 0.1at% each of Ga, Ge, Al, Sn or Au. The Z_c decreased by the addition of elements in this order: Ga, Ge, Al, Au and Sn. It is shown that an additional element, which raises static recrystallization temperature, also suppresses dynamic recrystallization.

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A set of constitutive relations relevant to the analysis of quenching process of steel was presented by taking the coupling effects of temperature, stress and metallic structure into consideration. A particular attention was given to the stress dependence of phase transformation from austenite into pearlite and martensite when the evolutional equation for the volume fraction of each phase was formulated.
The quenching process of S45C steel cylinder from 850°C was analyzed by means of the finite element technique with the proposed relations, and discussions were made on the effect of stress on transformation kinetics as well as the contribution of heat generation due to mechanical works.
The calculated results were compared with the experimentally measured distributions of temperature, structure and stress in the cylinder.

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The limit drawing ratio is important in manufacturing deep-drawn cylindrical products because it determines the size of the products.
In this paper, a simple method for determining the limit drawing ratio of deep-drawing plastic sheet is proposed. A Rockwell superficial hardness tester (HR15-Y) was used to measure the impression depth with or without a test load and the limit drawing ratio was expressed as a function of the ratio of the two values obtained.
The experimental results indicate that the limit drawing ratio (LDR) for plastic sheet can be given by one of the following formula:
(1) When the material yield conditions follow the maximum shearing stress theory,
LDR=e(h₀/h_p+0.5)
(2) When the material yield conditions follow the maximum main stress theory,
LDR=1+(h₀/h_p+0.5)
where h₀=impression depth without test load
h_p=impression depth with test load
e=natural logarithm

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The compression molding process using SMC or BMC has a good advantage to a mass production technology. However, concerning with the design of the die the plastic production technology for metal can not be directly transferred to the case of composite materials because several troubles appears in the products. To obtain the guide to the design of the die for composite materials, it is necessary to investigate the flow state of the materials in the die during the molding process and obtain the fundamental data.
In order to characterize the flow states of BMC, linear colored marks made of the same materials were buried in each lamina at a definite interval to obtain finite displacement vectors by measuring the location of marks before and after the molding process. Deformation diagrams were drawn from the state of each lamina.
In this paper, the dependence of flow state of BMC on the charge pattern was considered. At first, the experiments were carried out on the materials prepressed well or not well. Nextly the effect of various charge pattern on the flow state of BMC was examined.
The results indicate that the flow state of BMC prepressed well shows anisotropic nature exceedingly. In the case of Charge type A a complicated flow state can be seen at the small value of charge ratio. Charge type A is possible to prevent the troubles in comparison with Charge type B.

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In the strength design phase of high speed rotating machinery such as turbines and turbocompressors, structural integrity assessment of impellers or disks is of prime importance. Since the rotating disks are, in many cases, made of high toughness material, stable crack growth occurs from material defects, preexisting cracks, or notches in case of over speed, followed by unstable fracture, i.e., a final burst. It has been reported that the onset of stable crack growth can be predicted by the J_Ic fracture criterion and that the unstable ductile fracture of a rotating disk with inner symmetrical notches can be predicted by the average stress criterion or the modified average stress criterion.
In the present study, rotating tests were performed on disk specimens with fatigue cracks or notches existing at various locations in order to determine the effects of notch sharpness and its location upon unstable ductile fracture strength. The validity of the J-R curve as an unstable fracture criterion was also investigated.
The results obtained are as follows:
(1) Notch sharpness exerts no influence on burst strength provided that the location and length of the notch remain constant.
(2) The unstable fracture strength of rotating machinery having cracks or notches can be estimated with a sufficient accuracy by the modified average stress criterion. Strictly speaking, this criterion is prone to overestimate the unstable fracture strength of disk with neighboring cracks, notches or unsymmetrical cracks.
(3) The R curve methodology using the J integral calculation with body force and thickness effects taken into account can adequately predict the stable crack growth and the unstable fracture strength of rotating disks.

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An ultrasonic method was applied to elastic-plastic fracture toughness testing, and the relationship between the plastic blunting at the fatigue precrack tip or the onset of stable crack growth and the echo difference output voltage characteristics during fracture toughness loading were clarified. The elastic-plastic fracture toughness test procedure based on Top-on and End-on ultrasonic methods was proposed by which the J_Ic value can be determined using a single specimen. The J_Ic values for various metallic materials from medium strength steels to aluminum and titanium alloys were evaluated according to the proposed J_Ic test procedure. The J_Ic measurements were also compared with those determined according to the SZ method using multiple specimens and those determined according to the AE method using a single specimen. It is confirmed that the proposed J_Ic test procedure based on Top-on and End-on ultrasonic methods is very useful.

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In assessing the fracture mechanism of materials, it is often necessary to treat it as a stochastic process. This report discusses the distribution of time to failure when the fracture is regarded as the (r+1) states-(r) steps stochastic process.
By analyzing the distribution of time to failure on the assumption that the failure probability of each state obeys the Weibull distribution, the function of the failure probability for the (r+1) states-(r) steps stochastic process could be obtained.
By using the function derived, a simulation for the failure probability of (3) states-(2) steps stochastic process was performed with a computer, and the results were plotted on the Weibull paper to investigate the features of the distribution of time to failure on the paper. The main features are summarized as follows: (1) the distribution of time to failure can be approximately expressed as either one straight line (simple Weibull distribution) or two straight lines the slopes of which differ each other (composite Weibull distribution), and (2) the number of cracks appearing on a test specimen, as well as other testing conditions, has a significant effect, e.g. the distribution is more likely expressed as one straight line on the Weibull paper with an increase in the number of cracks.

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A new method was established to determine the orientation of individual grains on the specimen surface of commercial pure iron by analyzing the characteristic etch pits developed on its surface. This method was applied to determine the crystallographic configurations of crack nucleation sites and neighboring grains on the specimens tested under completely reversed plane bending fatigue stress. it was concluded that fatigue cracks nucleated along grain boundaries, and at each nucleation site, there were two primary slip systems intersecting approximately at right angle, in which {110} plane of one primary slip system was found to be parallel to the grain boundary and a slipping motion of another primary slip system was completely blocked by the former.

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The statistical fatigue tests were carried out on low carbon steel specimens by using a multi-type rotating bending machine developed by the authors, in which fifty specimens were assigned to each of five stress levels. The fatigue life distributions obtained experimentally at these stress levels were well fitted by either the three parameter Weibull distribution or the log-normal distribution, and, hence, equations were derived to transform three parameters of the Weibull distribution into two parameters of the log-normal distribution. Stress dependency of the distribution parameters was discussed and it was suggested that, at lower stress levels near the endurance limit, the distribution parameters are independent of the stress and only probability of survival at ultra long life region is increased with the decrease of stress. Discussions were also made on the dependency of the estimates of distribution parameters on sample size and on the distribution of fatigue strength at a given life.

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In order to clarify the effect of strain-aging on fatigue strength, rotating bending tests were made on interference fitted car axles, φ 12mm and φ 50mm, aged after cold surface rolling as well as on those subjected to warm surface rolling. The results obtained are as follows;
(1) The microstructure of specimen was hardly changed by aging, but the surface hardness was increased by 1.1 times in comparison with the cold rolled specimen due to strengthening of ferrite.
(2) The surface compressive residual stress of the aged specimen was 400MPa and the depth of hardened layer was 4mm. Then in comparison with the cold rolled specimen, the residual stress was decreased by 50MPa and the depth of hardened layer increased by 2 times.
(3) The maximum value of fatigue strength of the press-fitted specimen of φ 50mm was obtained at 300°C aging. The value was 216MPa, 1.1 times in comparison with the cold specimen and 2 times in comparison with the normalized specimen. Because of the size effect, the fatigue strength of the φ 50mm aged specimen was decreased by 0.9 times in comparison with the φ 12mm aged specimen.
(4) The fatigue strength of the aged specimen was closer to that of the warm surface rolled specimen than that of the cold rolled one.

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The objective of this study was to investigate the distribution properties of fatigue life and fatigue strength in sharply notched specimens of a carbon fabric laminate, which was made of three layers of eight-harness-satin/epoxy prepreg sheets. Fatigue life distributions were obtained at six stress levels by performing the carefully designed fatigue tests of four point plane bending under a constant temperature and humidity condition. The sample size used was 30 for the three high stress levels and 12 for the three low stress levels. The amount of scatter and distributional form of fatigue life and fatigue strength were discussed based on test results. It was found that the fatigue strength distributions were practically normal and their standard deviations were constant regardless of fatigue life.

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The factors causing tuberculation of carbon steels in a variety of synthetic cooling water have been investigated. A standard solution containing normal amounts of inorganic compounds was prepared as a synthetic cooling water, and it was concentrated several times to simulate practical operation of heat exchangers in the process industries. Tubercles formed on the steel tube covered with the mill scale, and the chemical composition of the water was a small factor in this case. The acid-pickled carbon steel tube experienced general corrosion in the standard solution, but was attacked seriously by the concentrated solutions to form tubercles. An important factor was found to be the corrosion potential, and it is necessary for the potential to remain at the transition region between active dissolution and passivation of carbon steel when tuberculation takes place.

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