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Volume 17, Issue 4
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[in Japanese]1970 Volume 17 Issue 4 Pages 143-154
Published: November 25, 1970
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (10111K) -
Kunio Suzuki1970 Volume 17 Issue 4 Pages 155-160
Published: November 25, 1970
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSDistributions of pore sizes greater than 100Å in tungsten and tungsten carbide powders have been determined by a Hg-porosimeter, (with the Hg-pressure up to about 1000 kg/cm2).
Pore sizes were corrected, assuming that the total surface area of pores calculated from the pore distribution curves is consistent with that by BET method.
Following results are obtained ;
(1) Relations between mean particle size obtained by permeability method (Fisher Sub-Sieve Sizer) and mean pore size determined by a Hg-porosimeter have been recognized.
(2) Ratio of mean particle size to mean pore size was about 1.0 for tungsten and about 0.5 for tungsten carbide powders. The discrepancy would be probably due to differences in pore shape between the powders.
(3) Pore distribution curves of each sample are characteristic of its shape. In almost all samples, one peak of maxima was present, but in exceptional case, in one of the tungsten powders, two peaks were observed.View full abstractDownload PDF (1723K) -
Tadaaki Aoyama1970 Volume 17 Issue 4 Pages 161-167
Published: November 25, 1970
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSAn equation for the specific surface area of powder, not dependent on the porosity for F-SSS, has been derived from the Kozeny-Carman formula.:
Sx=Kx/ρp(x-ε)√h1-h2/h2√ε3/L
Using the equation, measurements of mean particle size of tungsten and tungsten carbide powders, was determined at different packing methods, sample weights and porosities.
Results obtained are as follows:
(1) The equation applied, to tungsten powder, but not satisfactorily to tungsten carbide powder since the catter possibly has an unstable packing structure.
(2) The particle size was affected only slightly by the packing method, as examined by analysis of variance.
(3) The obtained correction factor x was about 0.95 for tungsten and about 1.0 for tungsten carbide powder.View full abstractDownload PDF (1830K) -
Manufacturing of Fine TiC Powders by Vacuum CarburizationYasuhiko Hashimoto1970 Volume 17 Issue 4 Pages 168-175
Published: November 25, 1970
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSA new process for fine TiC powder of high purity has been studied, which consists of the following two stages:
(1) The mixture of fine TiC powder and free carbon is obtained from the mixture of TiO2 and C (TiO2:C<1:3). Mixing agent is added for homogeneous dispersion of TiO2 particles.
(2) The carburized lump produced in the first stage is heated with metallic Ca and then treated by dilute acid to remove free carbon.
This paper reports the effects of mixing agents such as castor oil, poly-oxyethylene nonyl phenyl ether, phenol resin (diluted by toluene) and pitch (medium viscosity) on the particle size of the vacuum-carburized products in the stage (1).
These mixing agents were all effective in dispersing TiO2 particles in the mixtures, but the vacuum-carburized products were not always fine. The best result was obtained by using castor oil as mixing agent.View full abstractDownload PDF (6089K) -
Katsuya Kudaka, Naoto Asami, Takashi Ishimori1970 Volume 17 Issue 4 Pages 176-178
Published: November 25, 1970
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe application of dynamic pressure to the forming of titanium carbide cermet has been studied. The TiC-20wt%Ni and TiC-l5wtooNi-5wt% Mo cermets with high density were obtained by impact forming with high energy (142-200 kg-m/cc) and at high temperature (1100°C-1280°C), and by subsequent annealing at 1200°C for 90 minutes. Density and hardness of the obtained cermets are higher than those of normally sintered ones, with almost the same transverse strength. Excellent results were obtained at cutting performance test also. The microstructures were fine and dense, because the annealing temperature was lower than that in normal sintering so that grain growth was retarded.View full abstractDownload PDF (1396K)
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