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Volume 23, Issue 6
Displaying 1-5 of 5 articles from this issue
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Takeshi Kameoka, Azusa Majima, Takashi Kimura1976 Volume 23 Issue 6 Pages 191-195
Published: September 05, 1976
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSIn Fe-X-C ternary system (X: carbide-forming element), high density ferrous sintered alloys were obtained by supersolidus hot pressing process. A relatively low pressure of 10 kg/cm2 was applied to mixtures of iron, graphite and carbide-forming element powders, which were heated to the range between solidus and liquidus lines of Fe-2%C in iron-cementite phase diagram. Tungsten or chromium was found to be the most effective to the mechanical properties as the third additive element. Further improvement in strength was obtained by the addition of the fourth element, Cu or Ni, due to strengthening of the matrix phase in the Fe-X-C alloy. For example, Fe-15%W-1%Cu-2.4%C alloy made by this process provided a bend strength of 300 kg/mm2 and a hardness of HRC 50. Addition of l%V, one of the fourth elements, made the wear resistance much improved.View full abstractDownload PDF (2206K) -
Shiro Kohara, Kiyohiko Tatsuzawa1976 Volume 23 Issue 6 Pages 196-200
Published: September 05, 1976
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe relationship between tensile strength and porosity in sintered compacts has been investigated with carbonyl iron powder. It was shown that the variation in the measured tensile strength with porosity could be expressed by dividing the whole range into three stages, that is, the low density range, the middle density range, and the high density range. Then, the relations of tensile strength and porosity in those three ranges can be represented by the following equation forms as a function of porosity alone.
For the low density range,
S=S'0-k1P(P1<P≤P0)
where S is the tensile strength, P, the prosity, P0, the green porosity, and S'0, k1 and P1, empirical constants. For the middle density range,
S=S0 exp(-bP) (P2<P≤P1)
where S is the tensile strength, P, the porosity, and S0, b, P1 and P2, empirical constants. For the high density range,
S=(Ss+k2Pa)exp(-bP)(P≤P2)
where S is the tensile strength, P, the porosity, and Ss, k2, a, b and P2, empirical constants.
The empirical constants contained in the above equation forms were determined from the experimental results. Thereby, the following equation forms representing the relations of tensile strength and porosity in the sintered carbonyl iron were obtained; when the compacting pressure is 4 t/cm2, for the low density range,
S=141-495P [kg/mm2] (0.24<P≤0.28),
for the middle density range,
S=40.1exp(-3.7P) [kg/mm2] (0.11<P≤0.24), and
for the high density range,
S=(22.6+94.7P0.8)exp(-3.7P) [kg/mm2] (P≤0.11).View full abstractDownload PDF (350K) -
Effects of Vibrational ConditionTadaaki Sugita, Kazuo Suzuki, Koichiro Atsumi1976 Volume 23 Issue 6 Pages 201-205
Published: September 05, 1976
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe wear behavior of MgO single crystals on sintered alumina has been investigated under the condition of vibrational sliding. As a result, it was found that the rate of wear of MgO in the period of initial and transient frictions was very high, but it was rapidly decreased after the vibrational sliding of 104 cycles. The wear, the progress of which was shown by a discontinuous wear diagram like step pattern, was caused by the internal cracks.
The wear volume of MgO in the initial and transient state of wear were widely changed by the amplitudes of vibrational sliding; the rate of wear below the amplitude of 100μm was lowered by two orders of magnitude smaller than that above the amplitude of 100μm. Meanwhile, the amplitude hardly affected the rate of wear in the steady state. Also, the rate of wear was linearly increased in proportion to the increase of contact load in all wear state.View full abstractDownload PDF (348K) -
Microscopic Observations and DisussionTadaaki Sugita, Kazuo Suzuki1976 Volume 23 Issue 6 Pages 206-210
Published: September 05, 1976
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSFrom some microscopic observations, the appearance of many cavities (slip-shaped wear scars) was found on the wear surface of MgO in the steady state after the vibrational sliding of 104 cycles. The less rate of wear in this state not only depends on the decrease of fatigue damage on the wear surface, which is due to the decrease of contact pressure at a real contact point, but may be explained by a phenomenon that many of the wear fragments were packed into the cavities without being accumulated in the wear interface. It is suggested that rolling contact of the wear fragments in the interface play a significant role in making the cavities. The cavities, however, were not produced at the condition below the amplitude of 60μm because the wear was too less.
Internal creack which appears to be independent from various types of surface damages was found within the areas about 50μm under the wear surface of MgO and was parallel to the surface (cleavage plane). In this case, there is a possibility that the surface material would be locally removed if the internal creack was connected with another type of creack perpendicular to it.View full abstractDownload PDF (3249K) -
Ryoji Chubachi, Katsuto Nakatsuka, Junzo Shimoiizaka1976 Volume 23 Issue 6 Pages 211-215
Published: September 05, 1976
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSWater base magnetic fluids were obtained by allowing anionic or nonionic surfactant to adsorb on the hydrophobic surface of magnetite colloid prepared by monomolecular adsorption of oleate. Sodium oleate, sodium dodecylbenzene sulfonate and polyoxyehtylene nonylphenyl ether (HLB=12) were used as a surfactant giving a double adsorption layer. In this paper, the influence of temperature and pH on the dispersion stability in water base magnetic fluids was investigated.
The influence of electrolytes on the dispersion stability was less in the fluid obtained by the use of nonionic surfactant than in that obtained by anionic one. When the temperature was raised, the viscosity of the fluid obtained by the use of nonionic surfactant suddenly increased at the cloud point of the solution of the surfactant. As a result, it was found that the fluid obtained by the use of sodium dodecylbenzene sulfonate was fairly stable against the change in temperature and pH.
Furthermore, it was found that when ethylene glycol was added to magnetic fluid, the freezing point of it was lowered, and simultaneously the evaporation of solvent was suppressed. Added amount of ethylene glycol over 60 vol% of magnetic fluid caused it to coagulate.View full abstractDownload PDF (366K)
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