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Volume 22, Issue 1
Displaying 1-4 of 4 articles from this issue
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Effects of Si, Mn and C on metallurgical properties of wateratomized SUS 316 stainless steel powdersTetsuo Kato, Katsusi Kusaka1975 Volume 22 Issue 1 Pages 1-11
Published: March 25, 1975
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe main objective of the present work was synthetically to elucidate and evaluate the addition effects of Si, Mn and C on various properties of SUS 316 stainless steel powders produced by water-atomization of liquid metals. The results were summarized as follows:
1) Every component mainly affected particle shapes, the amount of surface oxide and metallographical phase states of powders, where especially Si and Mn gave each other some reverse effects. Consequently, apparent density, compactibility and the like were numerically correlated to Si/Mn ratio.
2) Compressibility was increased when Si: 0.6-0.9% and Mn≤0.2%, because of above-mentioned powder characteristics. On the other hand, for the higher C-content, green density less increased in the stage of plastic deformation of particles.
3) When the powders were vacuum-sintered at temperature below 1200°C, the same Si-component range as
2) gave a maximum sintered density, and also gave a lower activation energy for sintering than any other ranges.
4) The sintering rate and pore-spherodization of compacts were accelerated with increase of Si-content. Therefore, mechanical properties, especially porosity-sensitive ductility were appreciably improved in Si-rich materials which were sintered at higher temperature.
5) Corrosion resistance in boiling acid solutions was complicatedly related to every component, being overlapped by the influence of residual pore shape and oxides along grain boundary. All these sintered materials seemed stronger for boiling 65% HNO3-solution.View full abstractDownload PDF (5972K) -
Akio Hara, Masaya Miyake, Takaharu Yamamoto1975 Volume 22 Issue 1 Pages 12-16
Published: March 25, 1975
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe reason why WC powder of good quality cannot be obtained by the process of heating the WO3 and C mixture in H2 was examined by simple experiments. The authors obtained the following conclusions so that the 2 stage-carburization was adequate to solve the problem.
1) The reduction by H2 occurs preferentially to the reduction by C when the mixture of WO3 and C is heated in H2.
2) The H2O formed by the reaction of WO3+H2 reacted with carbon at the reacting zone. The quantity of the H2O depends upon both the way of charging and heating conditions, affecting the carbon content of WC.
3) WC crystals of abnormal shape were found when the coarse WO3 powder was used. The reason was discussed.
4) The WC powder of good quality was obtained when the H2O was either completely removed or not formed and when fine WO3 powder was used.View full abstractDownload PDF (2870K) -
Akio Hara, Masaya Miyake1975 Volume 22 Issue 1 Pages 17-21
Published: March 25, 1975
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe direct carburization of (WTi)C, using WO3 powder as a starting material, is not industrialized owing to many quality problems.
Therefore, in this paper the possibility of (WTi)C carburization from the mixture Of WO3, TiO2 and C was examined, As a result, a new process in which the mixture is first heated in N 2 and then re-heated in H2 at higher temperature was presented. By this process, (WTi)C powders of good quality, fine, and uniform grain size were obtained and the alloy made of this powder showed good properties.
The process of each reaction stage was studied. By the first heat treatment in N 2, WO3 was reduced by carbon to fine WC powder, and TiO2 was changed into Ti(NCO) containing a lot of nitrogen.
By the second heat treatment in H2 at higher temperature, N 2, O 2 and H2 gas contained were completely removed from (WTi)C solid solution by the reaction between WC and TiC.View full abstractDownload PDF (1388K) -
Junzo Shimoiizaka, Katsuto Nakatsuka, Ryoji Chubachi, Yoshiharu Sato1975 Volume 22 Issue 1 Pages 22-26
Published: March 25, 1975
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSMagnetic fluids consisting of stable colloidal suspensions of various ferrites have been produced by dispersing the precipitated ferrites in nonpolar solvents such as cyclohexane or kerosene. Prior to dispersing in organic solvents, ferrite powders were coated with oleate ion to the extent of bimolecular adsorption by aqeous reaction and then washed in order to remove the second layer surfactant.
The size of dispersed ferrite colloids was ranged from 100 to 150Å and coarser particles could not be stably dispersed.
It was found that the upper limit of colloid content in the magnetic fluid was about 0.6-0.7 g/ml.
The magnetization of the magnetic fluid was not saturated at 9 kOe field, as a result of super-paramagnetic behavior of the ferrite colloids. It was found that the magnetization of the fluid was depended proportionally on the content of ferrite colloid.View full abstractDownload PDF (1462K)
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