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Volume 32, Issue 2
Displaying 1-6 of 6 articles from this issue
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Hiroshi Utsugi, Atsushi Endo, Noboru Suzuki, Kazuya Ono1985 Volume 32 Issue 2 Pages 43-47
Published: February 25, 1985
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe characterization of the surface of silicon nitrides treated with the organo-silyl chrorides was performed by means of microanalysis, dispersive property into water, infrared spectra, pyrolysis and extrusion test of their blends with paraffine. The followings were recognized: (1) The number of surface group of the surface-treated silicon nitrides was estimated as 2×1014 CM-2 from the carbon contents which agreed with that of the silica gels treated with organo-silyl chlorides. (2) The characteristic absorption due to surface group was not observed in IR-spectra of the surface-treated silicon nitrides except that treated with octadecyltrichlorosilane because of the small number of surface group per unit weight of the substrate. (3) The pyrolysis temperature and products of the surface group agreed with those of silica gels treated with the corresponding organo-silyl chlorides. Therefore, it was ascertained that the silicon nitride was covered by SiO2-layer and thus the surface of silicon nitride was composed of the surface silanols. (4) The extrusion test of the blend with paraffine showed that the amount of paraffine for the blend of the surface-treated silicon nitride was needed to be smaller than that of the untreated silicon nitride in order to obtain a certain flow property.View full abstractDownload PDF (333K) -
on the Boronizing and SiliconizingTetsuo Sakai1985 Volume 32 Issue 2 Pages 48-54
Published: February 25, 1985
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThere are solid, liquid and gas processes in the diffusion coating technics and the first one is divided into a number of practical technics using paste, powder, etc. Moreover, this technics has lots of variations such as single, composite and progressive processes.
By means of combination of the above mentioned processes and a high frequency heating method, it is expected that hardness, resistivity to abrasion, toughness and durability of cemented carbides can be improved considerably.
Results obtained in this study are summarized as follows.
(1) Cemented carbide WC-Co system increased its weight after the treatments of boronizing without any protection atmosphere and its increasing rate depended on the Co contents in the alloy. On the contrary, siliconizing treatment in the same atmosphere caused to decrease its weight because of peeling.
(2) Intermetallic compounds formed by these reactions were identified by the X-ray diffraction pattern. They were Co3B in boronizing and Co2Si in siliconizing.
(3) Changes of hardness and transverse rupture strength of this alloy after these treatments depended on the treated conditions; in boronizing disproportionally, but in siliconizing proportionally.
(4) In order to carry out siliconizing effectively, a high temperature treatment more than 1000°C is recommended.View full abstractDownload PDF (3829K) -
Hisashi Suzuki, Hideaki Matsubara, Kunio Shibuki1985 Volume 32 Issue 2 Pages 55-60
Published: February 25, 1985
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe HIP-treated WC-(10, 20) %Co alloys were coated with Ti(C, N) or TiC layer (up to 8 μm) at 773K by hollow cathode type ion-plating (PVD) process. The transverse-rupture strength (TRS) of coated alloys and hardness of layers were mainly measured as a function of layer thickness, cobalt contents of substrate and temperatures at which coated alloys were annealed, comparing with the previous results by the authors on coated alloy with TiN layer.
The effects of the above factors on the strength of Ti(C, N) or TiC coated alloys as well as the interface structures between the layer and substrate were in common to the previous results on TiN coated alloy. The strength of Ti(C, N) or TiC coated alloys seemed to be somewhat higher than that of the TiN coated alloy. Hardness of the layers was in the order, TiC>Ti(C, N)>TiN, as expected. The formation of cracks in the layers at a low stress level below TRS was demonstrated for the coated alloys annealed at high temperatures, being a proof that the layers embrittled through annealing at high temperatures.View full abstractDownload PDF (6647K) -
Koji Hayashi, Hisashi Suzuki, Yoshihiko Doi1985 Volume 32 Issue 2 Pages 61-66
Published: February 25, 1985
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe transverse-rupture strength of WC-10%Co alloy double coated with TiC and Al2O3 (total thickness, <14μm) by CVD process was mainly investigated in the temperature range from room temperature to 1273K. The results obtained were compared with those of the alloy singly coated with TiC.
The number density of cracks observed on the surface of coated layer after CVD was larger in double coated layer. The room temperature strength of double coated alloys decreased with increasing total thickness of layer and it was equal to that of singly coated alloys having the same thickness of layer. The strength of two sorts of coated alloys varied as a function of test temperature as follows: it dropped with increasing test temperatures up to about 873K; then increased at the higher temperatures in the range from 873 to 1173K; and dropped again above 1173K, showing the same strength as that of substrate at 1273K. The strength dependence of coated cemented carbides on test temperatures was in good contrast with that of substrate.View full abstractDownload PDF (4847K) -
Yuji Tsukamoto, Kenichi Yamazaki, Kenjiro Honma, Fusao Hayama1985 Volume 32 Issue 2 Pages 67-73
Published: February 25, 1985
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe sintering process of Cu-Si mixed powder compacts was studied by dilatometric and microscopic examination, E. P. M.A. and X-ray diffraction. The sintering process depended on the particle size of added Si powder. The results obtained for Cu-5wt%Si compacts were summarized as follows:
(1) An intermediate η phase (Cu3Si) was produced by solidus diffusion at about 675°C, where an expansion was observed in the Cu-5wt%Si compact with a small particle size Si powder (-250 mesh), and this is due to the pore formation in the vicinity of the interfaces between Si particles and Cu matrix. This rapid diffusion was the first stage leading to homogenization. In consequence, a uniform structure was formed in the Cu-Si compacts with small size Si particles after sintering even at 700°C.
(2) The expansion due to Kirkendall effect was not observed in the Cu-5wt%Si compact with large size Si particles (-100+150 mesh). In this specimen, however, an abrupt expansion occurred at 835°C, and it was caused by the penetration of eutectic (Si+η) liquid into interface between Cu particles, leaving pores at the sites where Si particles were located. Afterwards, a homogenization process proceeded in the region filled with eutectic liquid.View full abstractDownload PDF (3630K) -
Tohru Kohno, Yoshio Nishino1985 Volume 32 Issue 2 Pages 74-77
Published: February 25, 1985
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSUnder existing circumstances, the determined measurement of maximum permissible PV value of oil impregnated sintered bearings is not established owing to the relatively obscure concept of the value. Accordingly in this study one measuring method was proposed, in which from the point of view that bearing temperature (libricant temperature) was the most direct indicator which showed the running state of the bearing, the precise coefficient of friction (μ) and the bearing temperature (T) corresponding to various PV values were measured by "step load method", then assuming the decay temperature of the lubricant, the PVμ value corresponding to that temperature was obtained from the PVμ-T line and besides knowing the μ value of the point, the maximum permissible PV value was finally obtained.
In this experiment, four kinds of oil impregnated sintered iron bearings were tested. Maximum permissible PV values measured were nearly propotional to the thermal conductivity of the bearings. This result seems to be natural because the measurement of maximum permissible PV value proposed in this study is based on the temperature rise of the bearings (lubricants), and conversely this seems to be the proof that the maximum permissible PV values measured in this study are reasonable.View full abstractDownload PDF (253K)
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