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Volume 32, Issue 3
Displaying 1-6 of 6 articles from this issue
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Size Change and Deformation in Bonding ProcessTadaaki Sugita, Kimio Aburaya, Kanji Ueda1985 Volume 32 Issue 3 Pages 85-89
Published: April 25, 1985
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSSize change and creep deformation of sintered alumina in the bonding process have been investigated. The ratio of size change to total length of the specimen increases exponentially with the bonding temperature and is proportional to increase in the bonding pressure and the holding time. From the result of a hardness test on the bonding layer, it is suggested that the bonding process may be finished at 1400°C. Also, creep deformation of the specimen occurs during the bonding process. Creep behavior of specimen in the bonding process corresponds to that in compression creep tests for sintered alumina from the view point of the activation energy for creep deformation, although the bonding process in the bonding layer is similar to the desification process of bonding powder by sintering.View full abstractDownload PDF (1836K) -
Evaluation of Bonding Strength and MicrostructureTadaaki Sugita, Kimio Abraya, Kanji Ueda1985 Volume 32 Issue 3 Pages 90-94
Published: April 25, 1985
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe bonding strength of the sintered alumina is discussed in terms of the bonding conditions, and it is evaluated based on the fracture mechanics concept and the acoustic emission measurement.
The bonding process is obviously promoted with the aid of the binder. From the measurement of the relative density and the observation of the microstructure of the bonding layer, it is found that the bonding strength is improved by the densification of the bonding layer, independent of the thickness of the binder less than 60 μm. The bonding strength increases with increasing the bonding temperature, pressure and holding time up to certain limits, but it increases no longer beyond the limits due to the microstructural damage caused by creep defromation.
By regarding the residual pore in the bonding layer as a crack having an equivalent length, the relationships between the bonding strength and the equivalent crack length can be calculated for the circular shape crack model and the penetrate shape crack model. The measured bending strength of the bonding specimens lie between two curves representing calculated relationships. It is also found that the maximum root-mean-square value of the acoustic emission signal increases with an increase in the bonding strength.View full abstractDownload PDF (1694K) -
Tadaaki Sugita, Katsuyoshi Endoh, Kanji Ueda1985 Volume 32 Issue 3 Pages 95-99
Published: April 25, 1985
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSIn this paper, the fracture strength in low-temperature flux bonding (below 1000°C) of sintered alumina is determined in terms of bonding conditions such as temperature, time, pressure and grain size of flux, and is discussed in the basis of the linear fracture mechanics concept.
The fracture stress was measured on bonded specimens by a four-point bending test. The fracture stress increased with increasing bonding pressure and decreasing grain size of flux. As for the bonding temperature and time, peaks in the stress appeared at about 750°C and 60 min, respectively. The fracture stress was also closely related to the size of the residual pores observed by microscope on the fracture surface of the bonding flux layer, which in turn depended on bonding conditions. The maximum fracture strength which attained in the bonding conditions employed was approximately 80% of the strength of solid.
Based on the linear fracture mechanics concept, the fracture strength in bonding was interpreted by regarding the residual pores as an equivalent circular crack type defect. It was found that the fracture stress is proportional to 1/√a, where a is the equivalent crack size, so that the predominant factor affecting fracture strength is the residual pore size in the bonding flux layer.View full abstractDownload PDF (1565K) -
The Surface-Treatment of γ-hematite with Alcoxysilanes and their Surface PropertiesHiroshi Utsugi, Atsushi Endo, Noboru Suzuki, Kazuya Ono1985 Volume 32 Issue 3 Pages 100-103
Published: April 25, 1985
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe surface of γ-hematite treated with alcoxysilanes was investigated by means of the microanalysis, surface area, number of surface group, magnetic properties, pyrolysis and extrusion test of their blend with paraffine. The followings were clarified: (1) Since the number of surface group was estimated to be 3×1014 CM-2 from carbon content and surface area, and this value nearly agreed with the number of surface hydroxide of γ-hematite, γ-hematite was ascertained to be effectively treated with alcoxysilanes according to the following reaction, =Fe(OH)+RSi(OR')3→=FeOSi(OR)2R+R'OH; R', CH3 or C2H5 (2) Since the magnetic saturation, residual magnetization and coercive force of the surface treated γ-Fe2O3 agreed with those of the original one, the surface-treatment showed to be unaffected on the properties of the substrate (3) Since the CO or CH2=CH2 was not observed in the pyrolysos products of the surface-treated γ-hematite, the surface group was recognized not to include the alcoxy group and the unreacted alcoxy groups were displaced by hydroxyl groups through hydrolysis (4) The pyrolysis products were observed to be composed of water and hydrocarbon of the organic functional group in the surface group evolved at 200°C and CO2 generated remarkably at 350°C. The evolution of hydrocarbon was noticed to result from the following reaction, =FeOSi(OH)2R→=FeOH+RH+SiO2 and the vigorous generation of CO2 was recognized to be due to the reduction of =FeOH by RH thus generated (5) The extrusion test of the blend of surface-treated γ-hematite with paraffine showed the better flow property than that of original γ-hematite.View full abstractDownload PDF (270K) -
Rikuo Ota, Toshiya Kinoshita, Naohiro Soga1985 Volume 32 Issue 3 Pages 104-110
Published: April 25, 1985
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSA series of alkali silicate glasses of the composition 0.3 Na22O-0.5 Si02-x(MnO⋅Fe2O3); x=0.025-0.16, were heat-treated at temperatures from 200°to 800°C for 0.5-17 hrs, and ESR measurements were made on these glasses. Onlyg=2 line was observed in the ESR spectra both in the glass and the crystallized glass. The line width ΔH decreased with crystallization of the glass and increased with the growth of particle size of crystals. In the glassy state the line width shows a maximum at MnO⋅Fe2O3=7 mole percent, and the effective g-value shows a minimum at MnO⋅Fe2O3=10 mole percent. From these experimental results, the following implications are obtained on the change of distribution of Mn2+ and Fe3+ ions under the influence of heat-treatments;
(1) Mn2+ and Fe3+ ions are present not in isolation but in pairs by exchange or super-exchange interactions in the Na2O-SiO2-MnO Fe2O3 glass.
(2) The interactions between Mn2+ and Fe3+ ions are enhanced in the glass as the concentration of magnetic ions is increased. This is due to an increasing probability in finding shorter ion pairs with increasing population of magnetic ions in the glass.
(3) The interactions among the magnetic ions are enhanced as soon as nucleation takes place on heating. This is due to the atomic rearrangement in ion pairs from a disordered structure to an ordered structure.View full abstractDownload PDF (460K) -
Youn Chai Kim, Teruhisa Watanabe1985 Volume 32 Issue 3 Pages 111-116
Published: April 25, 1985
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSIn order to develop the iron base sintered alloys for porous bearing having superior properties, effects of chemical composition and sintering temperature on dimensional change, intercommunicating porosity and radial crushing strength of iron-tin and iron-tin-copper compacts were investigated.
The results obtained were as follows:
1) Dimensional change and intercommunicating porosity of iron-tin compacts admixed with 1.0-1.5 wt% tin powder were nearly equal to those of iron compact when they were sintered at 1130-1420K. Radial crushing strength of the iron-tin compacts exceeded that of the iron compact only when sintered at temperatures above 1320K.
2) Dimensional change and intercommunicating porosity of iron-tin-copper compacts admixed with 2.5 wt% tin-copper prealloyed and mixed powders having the Sn/Cu ratio 3:7 were nearly equal to those of the iron compact when they were sintered at about 1160K. Radial crushing strength of the iron-tin-copper compacts sintered at about 1160K was much higher than that of the iron-copper compact sintered at about 1420K.View full abstractDownload PDF (2057K)
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