All issues
Volume 17, Issue 6
Displaying 1-6 of 6 articles from this issue
- |<
- <
- 1
- >
- >|
-
Yasutoshi Saito1971 Volume 17 Issue 6 Pages 235-242
Published: March 25, 1971
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThermal decomposition of thorium oxalate hexahydrate, Th(C2O4)2⋅6H2O, has been studied by thermogravimetry (TG) and differential thermal analysis (DTA) in air and argon. The thermal decomposition took place in three steps. At temperatures below about 300°C. plateaus in TG and endothermic peaks in DTA indicated the appearance of dihydrate and monohydrate at the first two steps respectively. At higher temperatures monohydrate decomposed to the oxide at the third step. In argon the dehydration processes were essentially the same as those in air, but the decomposition to the oxide was sluggish. This might be due to the deposition of carbon caused by the disproportionation of primarily evolved CO. The decomposition to the oxide gave an endothermic peak in DTA in argon, but in air exothermic peaks due to the oxidation of CO and carbon were observed.
Hahn's emanation technique using thoron 54.5-second was applied to the studies of thermal decomposition. Three peaks were observed in the emanation curves and corresponded to the three steps as determined both in TG and DTA, .
In the electron microscope the oxalate particles were square platelets of a few microns, and the oxide appeared as the skeleton particles of the original oxalate.View full abstractDownload PDF (2171K) -
Yasutoshi Saito, Yutaka Shinata, Koji Tsuchida1971 Volume 17 Issue 6 Pages 243-250
Published: March 25, 1971
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThermal decomposition of cerous oxalate decahydrate, Ce2(C2O4)3⋅10H2O, has been studied by thermogravimetry (TG) and differential thermal analysis (DTA) in air and nitrogen. TG curves suggested that the decahydrate decomposed to the dihydrate and successively to the monohydrate giving an endothermic peak in DTA. The monohydrate decomposed to the oxide. In nitrogen the dehydration process to the monohydrate was the same as that in air, but the decomposition of the monohydrate to the oxide was sluggish and shifted to higher temperature. The decomposition products in nitrogen and in vacuum were black in color, owing to the deposition of the finely divided carbon particles formed by the disproportionation of CO.
The infra-red absorption spectra of the decomposition products indicated that the oxalate partially decomposed to the oxide through the formation of an intermediate carbonate. Surface area showed a maximum value at about 350°C due to the decomposition of the oxalate, and it was followed by a decrease with increasing heating temperature, which corresponded to the decrease in X-ray diffraction line broadening.
In electron microscopy, the oxalate particles were rectangular platelet and the oxide appeared as the skeleton particles of the original oxalate.View full abstractDownload PDF (3013K) -
The Effects of Average Particle Size of Raw Powder on SinteringOsamu Yamaguchi1971 Volume 17 Issue 6 Pages 251-255
Published: March 25, 1971
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSLead titanate-zirconate ceramics has been usually carried to synthesize at about 1300°C in PbO atmosphere. The author has attempted to synthesize non-stoichiometric PZT with excess of PbO in a previous paper.
In this paper, it was described that PbO-PZT ceramics with high density, low water absorption and high piezoelectric characteristics were produced by sintering fine powders. Samples were formed with raw powders of particle size 4.2, 3.5, 1.2 and 0.5μ in average respectively. Shrinkage, density, water absorption and electric characteristics were measured in relation with sintering time, temperature and the particle size. The structure of sintered ceramics was examined by the electron micrograph.
The following results were obtained.
(1) The shrinkage and density of this ceramics increased with the decrease in particle size of raw powders, especially in the case of 0.5μ powders the water absorption was below 0.1% by sintering 900°C for 2 hr.
(2) It was observed by electron micrograph that the liquid phase (PbO) remarkably penetrated into the grain boundary of PZT in the use of finer powder.
(3) Electro-mechanical coupling coefficient K was around 43% by sintering the 0.5μ powders at 900°C for 3 hours.View full abstractDownload PDF (2738K) -
Kiyoshi Tamura, Tohru Takeda, Noriharu Miyamoto1971 Volume 17 Issue 6 Pages 256-261
Published: March 25, 1971
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSAn attempt to eliminate complicated phenomena of Fe-Cu compacts during sintering, Fe-Cu prealloyed powders were produced by liquid atomization, and their pressing and sintering properties were examined. The results were summerized as follows:
(1) The suitable annealing condition to obtain good compressibility of atomized powders is of 900°C for 1 hour in hydrogen.
(2) Weight loss in Rattle test and transverse rupture strength of compacts pressed at 5t/cm2 are in the range of 0.5-2.0% and 0.7-1.2 Kg/mm2., respectively.
(3) With increasing Cu content, sintering properties of Fe-Cu alloyed powders are improved.
(4) Compacts pressed at 5t/cm2 and sintered at 1200°C for 1 hour in hydrogen show the tensile strength of 27.6 Kg/mm2 for 5%Cu and 44.0 Kg/mm2 for 20%Cu., respectively.View full abstractDownload PDF (4643K) -
Hisashi Suzuki, Kozi Hayashi1971 Volume 17 Issue 6 Pages 262-266
Published: March 25, 1971
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSEffects of addition-carbides such as Cr3C2, ZrC, NbC, Mo2C, TaC and WC on some properties of high carbon TiC-15% Ni and TiC-10% Mo-15%Ni alloys were investigated. Specimens were vacuumsintered at 1380 to 1480°C for 1.5 hr.
The results obtained were as follows; The addition of WC was found to be effective in increasing the strength of TiC-Ni alloy, though the effect was inferior to that of well known Mo2C. In the case of TiC-Mo-Ni alloy, the addition of each carbide except for Mo2C was confirmed to decrease sharply the strength.View full abstractDownload PDF (1768K) -
Katsuya Kudaka, Taijiro Onishi1971 Volume 17 Issue 6 Pages 267-269
Published: March 25, 1971
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe reaction and sintering processes in the preparation of TiC-12%Ni-12%Mo and TiC-12%Co-12%Mo cermets were studied by X-ray analysis, microscopy and measurements of the mechanical properties. As results, it was obtained that these processes, such as carbonization of Mo, diffusion of Mo to TiC, and solution of TiC to binder, are not substantially different in both the Ni and Co binder cermet. However, since the eutectic temperature (about 1370°C) of TiC-Co is higher than that (about 1280°C) of TiC-Ni, the densification of sintered body was slower in the Co binder cermet and completed at 1350° and 1400°C for the Ni and Co binder cermets, respectively.
On the other hand, grain growth of carbide began at about 1400°C in both the Ni and Co binder cermets. Therefore the optimum sintering temperature range is narrower in Co binder than in Ni binder cermet.View full abstractDownload PDF (2640K)
- |<
- <
- 1
- >
- >|