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Volume 31, Issue 7
Displaying 1-6 of 6 articles from this issue
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[in Japanese], [in Japanese], [in Japanese]1984 Volume 31 Issue 7 Pages 223-230
Published: September 25, 1984
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (3349K) -
Junjiro Takekawa, Yoshimichi Masuda1984 Volume 31 Issue 7 Pages 231-235
Published: September 25, 1984
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSA dynamic compression test was carried out on sintered Cu and Fe compacts to clarify their deformation behaviour using a drop-hammer testing machine. The results obtained were as follows:
1) At the high strain rate of about 3×102/sec, the sintered Fe compacts showed sharp pseudo-yield points, but pre-strained specimens did not show such pseudo-yield behaviour.
2) For the first impact of Cu compacts, the dynamic load increased gradually with increasing time, but in the subsequent dynamic tests, the load increased abruptly and then became constant.
3) The dynamically-deformed sintered Fe showed upper and lower yield points. On the contrary, the specimens statically deformed showed only single yield point.View full abstractDownload PDF (3884K) -
Hisashi Suzuki, Hideaki Matsubara, Takeshi Saitoh1984 Volume 31 Issue 7 Pages 236-240
Published: September 25, 1984
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe TiC0.7N0.3- and TiC0.5N0.5-Mo2C-WC-Ni cermets were sintered in vacuum or nitrogen (PN2 ?? 2.7 kPa), and the structural changes were examined in relation to the amount of additional WC(up to 30 vol% in total amount of Ti(C, N) plus WC) and sintering conditions. It was found that an additional WC remained in the structure and the amount increased as the nitrogen content in the cermet and PN2 increased. This is because WC tends to be checked to dissolve in the surrounding structure (Ti(C, N)-Mo2C solid-solution) under the conditions as above. Such a non-equilibrium structure having a remaining WC phase is considered to be important for further development of nitrogen contained cermets.View full abstractDownload PDF (3469K) -
Takashi Yoshioka, Akira Doi1984 Volume 31 Issue 7 Pages 241-245
Published: September 25, 1984
Released on J-STAGE: July 12, 2010
JOURNAL FREE ACCESSEvaluating methods for the fracture toughness of brittle hard materials were investigated. For measuring the fracture toughness, (1) Vickers indentation method and (2) three-point bending method were adopted. For the latter method, precracks of different shape were introduced by various techniques, such as (2-a) mechanical machining by a thin disc diamond wheel, (2-b) knoop indentation, (2-c) thermal machining by CO2 laser or (2-d) spark wire cut.
The results obtained are as follows.
(1) Each method has its own merits and demerits. To obtain least scattering and better reproducibility in K1c. data, however, three-point bending method using spark wire cut technique was found to be most appropriate. For non-electrified materials, Vickers indentation method or three-point bending method using mechanical machining with a very thin diamond wheel (15μm thickness) seems relevant from the same view point.
(2) Apparent K1c value of hard materials from this work are as follows. (K1c, MN/m3/2)
(a) 70% Al2O2-30% TiC
K1c=3.6-3.9 (Vickers indentation method)
K1c=3.2-3.4 (three-point bend, 15μm thickness thin diamond wheel)
(b) (Ti, Ta, Mo, W) (C, N)-Co, Ni Cermet
K1c=7.4-7.7 (Vickers indentation method)
K1c=6.2 (three-point bend, 15μm thickness thin diamond wheel)
(c) WC-12% Co cemented carbide
K1c=12.4-12.9 (Vickers indentation method)
K1c=11.5-12.3 (three-point bend, 15μm thickness thin diamond wheel)
(3) As for the three-point bending method, apparent K1c values depend on √ρ strongly and we found that ρo is smaller than 7.5μm for ceramics, cermet or cemented carbide used for this work.View full abstractDownload PDF (267K) -
Sadao Date, Takao Kawakita1984 Volume 31 Issue 7 Pages 246-248
Published: September 25, 1984
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSWhen a core material such as mild steel is used in the powder matallurgical process of making diamond rotary dressers, the welding strength between the core and the infiltrated tungsten powder, which cements the diamond grits, is a matter of great importance. The authors made an experiment searching for a good material which shows a high welding strength to the infiltrated tungsten powder. It was found that a Fe-Cu-C powder mixture and the sintered porous compact of such powder mixture will be a good material if they are used as a core in the powder metallurgical process of making diamond rotary dressers.View full abstractDownload PDF (179K) -
Sadao Date, Takao Kawakita1984 Volume 31 Issue 7 Pages 249-251
Published: September 25, 1984
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSFe-Cu-C sintered powder compact was used as a core of diamond rotary dresser in powder metallurgical process. The rotary dresser made by this method showed very excellent accuracy compared with the one made by conventional process. The sustaining of diamond grits by infiltrated tungsten powder seems to be better than the one made by conventional process.
The damping capacity of composite material, tungsten powder and Fe-Cu-C sintered powder compact infiltrated simultaneously, was measured in comparison with other materials. The results showed that the above-mentioned composite material seems to be advantageous in its capability of resistance against abnormal vibration during the use of rotary dressers.View full abstractDownload PDF (1386K)
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